Warning on auxiliary batteries

[Wilbur]

This is a warning to D4 owners particularly, but it probably also applies to the D3 and the RRS.

It is NOT satisfactory to use the simple dual-battery systems that work on simpler vehicles. The best system for charging auxiliary batteries on a D4 is a DC-DC converter type.

Now a simple solenoid/relay operated dual battery controller may work adequately for SOME users for SOME of the time, but it will NOT work adequately for ALL users ALL of the time.

Further, there is a very real risk with the use of ANY dual battery system that the vehicle ECU will malfunction, causing anything from engine shut-down to a flat cranking battery. DC-DC converters are less likely to cause problems than solenoid types.

Apologies for the length of this post. Acting on ‘information received’ I have tried to give a full explanation with references and methods of verifying what I write.

Below is a brief explanation followed by a more detailed explanation with some references to support what I say. Where I don’t quote references, I will suggest the type of person to ask so that anyone interested can easily verify what I write.

However, it would be ideal if an un-biased moderator would show this post to an expert for comment. By expert I mean someone with no vested interest in promoting one thing over another, someone with electronic ECU skills, and someone who understands battery charging requirements. This may not be easy to find – I am sure I am not alone in being surprised how many people who should be experts aren’t. In a recent post I noted that Sneigy works for MLR. I wonder if he could be persuaded to use his position at MLR to have this post studied by engineers at Land Rover UK for comment? I don’t think it would be worth troubling anyone at LR Australia….

Anyway, here goes. First are the points made briefly, followed by a more detailed explanation of each point for anyone interested. I will try to keep it easy to understand.

IN BRIEF

1. The D4 has a multi-stage charging system (aka smart alternator) that uses a higher voltage until the cranking battery is fully charged then drops back to a float voltage of 13.2 volts. Reference, a phone conversation with Peter, service department, MLR.
2. AGM batteries will take an impossibly long time to fully charge at 13.2 volts. Even at 13.5 volts, a Fullriver AGM battery takes 60 hours charge to just 55%. Reference, Fullriver batteries, their graph included in details section.
3. Because the D4 has a multi-stage charging system, extra loads MUST NOT be connected directly to the battery posts. Hopefully when I get my D4 I will be able to find the correct connection points and advise the forum.
4. Any extra electric loads have the potential to cause problems with the car ECU. With most devices, the risk of trouble is vanishingly small but with dual battery systems there is a slim but real risk of trouble. This presumably is why Land Rover won’t honour warranties if such after-market electronic devices are fitted. To make the ECU impervious to interference by other electronic devices is possible but extremely difficult, especially in an automotive environment. DC-DC converters are less likely to cause problems than solenoid based dual battery systems.

Right, now the boring detail.

1. Multi-stage charging results in extended battery life. In a vehicle like the D4 that takes such huge advantage of electronics this is very important. Multi-stage can mean anything up to seven stages, but broadly the important stages are the bulk charging and the float charge. Broadly, single stage charging just applies a fixed voltage to the battery, regardless of the state of charge of the battery. This can result in overcharging the battery, and reduced battery life. Multi-stage charging drops the voltage down after the battery is fully charged.

The time taken to fully charge a cranking battery can be very small. This is because normally there will only be a tiny amount of power taken from the car battery, ie, that used to start the engine plus a tiny amount while the car is at rest. If accessories are used while the car is idle, then of course it will take longer for the battery to become fully charged and for the system to go into float mode.

The point here is that there will seldom be enough time to put a significant charge into auxiliary batteries before the charger goes into float mode. Most of the time there will only be 13.2 volts available for charging the auxiliary battery.

For confirmation, anyone with a D4 (or an RRS or a D3) can easily check this themselves. Buy a cheap digital multi-meter. With the battery fully charged after a reasonable run, switch off the engine and wait maybe 15 minutes. Start the engine and measure the voltage across the battery posts. You should observe that the voltage reads about 14.5~15 volts for a short time, then drops back to around 13.2 volts.


2. Below is a graph sent to me by Fullriver batteries. It shows the time taken to charge an AGM battery at various fixed voltages. As can be seen, at 13.5 volts the battery only charges to 55% after 60 hours! I asked them about 13.2 volts – they simply replied “We do not recommend charging at 13.2 volts”. Put simply, you will need MORE batteries to run your gear if you don’t charge them fully. I don’t know how much DC-DC converters cost these days – I bought mine from GSM at the Sydney Caravan show a couple of years ago, for about $330. Whatever, they are smaller and lighter than extra batteries would be, and probably cheaper.

For confirmation, ask your battery supplier what they think of the success of charging with a voltage of 13.2 volts.

3. The correct way to determine when a battery should be put into float mode – ie, fully charged - is to measure the CURRENT the battery draws when supplied with a fixed charging voltage. As the battery becomes more fully charged with this fixed voltage, the current it draws reduces. When it reduces to a specified amount, (typically a few amps) the battery is considered fully charged and the charger drops into float mode.

In a vehicle it is therefore necessary to measure the current being drawn by the battery to determine its state of charge. If another load is placed directly across the battery posts, the current drawn by that load will fool the charging system into thinking that the battery is not fully charged, and it will thus keep the voltage at the higher level instead of dropping into float mode. This could result in over-charging and possibly reduced life of the cranking battery. It may also result in a fault code being logged.
The car system may measure the current going into either the positive or negative battery post via a current shunt. If it is in the negative lead, then it should be simply a matter of connecting any additional load to the chassis of the vehicle, NOT the negative battery post. If the current is measured in the positive lead, it will be more difficult to locate the correct point for connection of leads. I do not know the answer to this, and Land Rover won’t tell me, they just say that adding aftermarket accessories will void the warranty. When I get my D4 next month, I will investigate and report back.

Remember, this applies equally to solenoid based and to DC-DC converter based systems.

I don’t know how you can confirm this. If Land Rover know, they ain’t saying!

4. Damage to the ECU is not easy to discuss in simple terms. Broadly, problems are caused by voltage spikes getting in to the wrong part of the ECU. I will discuss this in two parts – CAUSES of voltage spikes, and RESULTS of voltage spikes.

4a CAUSES. Whenever there is a sudden change in the amount of current flowing through a wire, there is a possibility that a voltage spike will be generated. The greater the change of current, the greater the spike. The more sudden the change of current, the greater the spike. Also inductive coils, like those used in relays and solenoids cause voltage spikes in exactly the same way that the ignition coil generates a spark in a petrol engine. Suddenly connecting auxiliary batteries to the cranking battery by a solenoid gives a sudden large change in current and can cause a voltage spike. Likewise, the application or removal of voltage from a solenoid or relay coil can cause a voltage spike. It is possible to filter these spikes to an extent with the use of diodes etc, but that is rarely 100% effective.
A DC – DC converter is much better in this respect. The current drawn normally builds up slowly (slow in ECU terms – maybe the current builds up in 1/200,00ths of a second, that is slow in ECU terms and unlikely to cause a spike). Also, the current drawn is limited, usually to a maximum of about 1.5 times the rated output current.

4b RESULTS. Ideally, there would be no results. All voltage spikes would be filtered out before they reached the ECU and there would be no problems. However, this is incredibly difficult in an automotive environment. There are numerous switches and sensors all over the vehicle connected back to the ECU, and the wires leading to them act like antennas picking up spikes generated by wires leading to other equipment, such as dual battery systems. Some of these sensors produce only tiny voltages and must be amplified before the ECU can deal with them. This makes them more sensitive to spikes.

It is much easier for the designers to protect against KNOWN spikes such as those caused by starter motors etc than it is to protect against UNKNOWN spikes such as are generated by after-market equipment.
It is also very difficult to test if a particular installation has the potential to cause problems. This is because the processor in the ECU has a very busy and hugely complicated life. It is continuously polling all the switches and sensors for data, then processing that data and instructing various systems in the vehicle to make appropriate changes. A micro-processor can only do ONE thing at a time. Thus when a spike appears, the ECU processor could be involved in any of many thousands of different things. The results, if any, of the spike will depend upon exactly what the processor was doing at the time of the spike. Most of the time there will be no result. But there will be times when there COULD be a result, and that result will be quite unpredictable.

Thus to fit an after-market dual battery system and try it out and have everything work fine is meaningless. The test would need to be run a huge number of times with the vehicle in a huge number of states to be meaningful. No, the best thing the designer of the car can do is protect against LIKELY spikes in the design stage with correct hardware layout and ‘defensive’ programming.

It is clear to me that the Land Rover engineers in this respect have done a fantastic job on the D4 (and presumably also on the D3 and RRS). The electronics are hugely complicated and are a good part of the reason why these cars are just so damn good! To grumble because this makes it slightly more complicated to run auxiliary batteries seems very ungrateful. Besides, troubles with the ECU seem comparatively rare even with dual battery systems fitted.

However, I have seen on this forum posts relating to unexplained drops into ‘limp home’ mode, unexplained flat batteries and others. It would be very interesting to do a poll on this site to find out of all those who HAVE had ECU problems how many have dual battery systems fitted, and what type?

For confirmation of this part of the post, show this to someone who designs micro-processor based systems – a professional hardware and software designer, not the sparky at work.

[awabbit6]

Interesting read ...

but ...

Starter motor solenoids are connected directly to the positive battery terminal. If the ECU is protected against spikes due to the starter then surely they are equally protected against spikes due to dual battery system solenoids connected to the positive battery terminal.

[CaverD3]

Drivesafe has already done it. Been available for years.
I am sure he will understand the issue.

[Outlaw]

From memory Drivesafe's unit is also authorised by Land Rover. At least the D3 version was :)

[rmp]

A good topic for discussion.

Given the way the other thread went, a general warning this time - contributions, corrections and discussion all welcome and appreciated. Anyone who gets personal or plays the man not the ball will have their post deleted and possibly incur infractions.

So far my infraction-awarding score is 0 even after several years and I'd like to keep it that way!


Another general note re LR, LRA, and dealers, and that's applicable to all motor manufacutrers. Dealers are rarely permitted to go talking direct to the head office engineers. There are channels to go through and that starts with the local support techies. Then you also need to consider why the question is being asked. Manufacturers have enough to do with looking after their own kit without worrying about supplying information to help others create kit they will not be testing nor warranting, and they take a dim view of dealers promoting non-standard kit (this is why LRA created their own bullbar when aftermarket alternatives exist). Therefore, manufacturers typically provide little or no assistance to the aftermarket in Australia. This is not the situation in the USA, out of interest, where aftermarket support is seen as a way to sell more cars.

[ If you want to comment on the above start a new thread please ]

[CaverD3]

I think drivesafe has pointed out it has to be connected directly to the positive terminal as there is a module/filter attached to it.

As Robert pointed out,
LR do not officillay endorse drivesafe's system. However they helped him develop it by giving as much info as they could about the system.

[isuzurover]

1. The D4 has a multi-stage charging system (aka smart alternator) that uses a higher voltage until the cranking battery is fully charged then drops back to a float voltage of 13.2 volts. Reference, a phone conversation with Peter, service department, MLR.

2. AGM batteries will take an impossibly long time to fully charge at 13.2 volts. Even at 13.5 volts, a Fullriver AGM battery takes 60 hours charge to just 55%. Reference, Fullriver batteries, their graph included in details section.

3. Because the D4 has a multi-stage charging system, extra loads MUST NOT be connected directly to the battery posts.

A few comments...

1. - I would not regard this as definitive proof... I have known landrover "experts" to be wrong in the past (no comment on Peter or MLR, who I have know knowledge of)

2. - Assuming 1 as correct - How do you know that a properly designed dual battery system won't mean the alternator will provide a higher voltage until BOTH/All batteries are fully charged??? It shouldn't be hard to get the alternator/ECU to charge based on the aggregate rather than the cranking battery state of charge.

3. - Why???

[roamer]

Hi Wibur,
You seem to have researched this well,during your research did you find charge times for the DC-DC charger, that you could post so I can get a comparison ?


Cheers Ken

[Wilbur]

Interesting read ...

but ...

Starter motor solenoids are connected directly to the positive battery terminal. If the ECU is protected against spikes due to the starter then surely they are equally protected against spikes due to dual battery system solenoids connected to the positive battery terminal.

Yep, quite right, starter motor solenoids and starter motors themselves can create dreadfull spikes, much worse than any dual battery system. But the LR designers know about that one, and can design around it. It is the aftermarket ones that they can't predict.

Cheers,

Paul

[Blknight.aus]

In brief....

If youve direct coupled the batteries through say, a dampned solenoid like they've been using in pinball machines since they started putting electronics in pinball machines driving a set of contacts that've got a a choke on it you'll not get your initial spike on connection or disconnect.

and the cranking battery wont take a full charge till the aux battery has approached full charge... (assuming youve actually flattened it as much as your claiming)

not sure why youd want to bring a computer hardware engineer or software engineer to solve a problem thats been solved by electrical engineers and automotive electrical engineers (as well as aeronautical and maritime engineers) for years (all the way back to steam driven electrics) with no great hassles.

Just out of curiosity have you yet tried to see what a D2+ does when you just manually hook the 2 batteries together with a pair of decent jumper cables?

[Wilbur]

A few comments...

1. - I would not regard this as definitive proof... I have known landrover "experts" to be wrong in the past (no comment on Peter or MLR, who I have know knowledge of)

2. - Assuming 1 as correct - How do you know that a properly designed dual battery system won't mean the alternator will provide a higher voltage until BOTH/All batteries are fully charged??? It shouldn't be hard to get the alternator/ECU to charge based on the aggregate rather than the cranking battery state of charge.

3. - Why???

1. Agreed, I too have known LR experts to be wrong. The chap I spoke to at MLR sounded totally confident in his answer, so I believed him. Another authorised dealer tech hummed and hawed and gave a different answer. Also I subscribed to TOPix and while I couldn't find specific voltages, they do describe it as a 'smart' alternator.

2. A dual battery system could easily be designed to cause the charge voltage to remain at the higher voltage until the auxiliary battery was charged. However, unless it ALSO disconnected the cranking battery, the cranking battery would over-charge. Clearly not practical.

3. Because if the auxiliary battery needed charging, the car charging system would keep the voltage high until the extra battery was fully charged. If the extra battery is connected directly across the cranking battery posts, the charging system would have no way of knowing WHICH battery needed charging.

Cheers,

Paul

[drivesafe]

1. The D4 has a multi-stage charging system (aka smart alternator) that uses a higher voltage until the cranking battery is fully charged then drops back to a float voltage of 13.2 volts.
WRONG, and not even close, what you are referring to is the way a D3 and a 2.7L D4 alternator works.

A D4 3L and RRS TDV8 alternators have a completely different operating system.



2. AGM batteries will take an impossibly long time to fully charge at 13.2 volts. Even at 13.5 volts, a Fullriver AGM battery takes 60 hours charge to just 55%. Reference, Fullriver batteries, their graph included in details section.
This one is a ripper. Not only can you fully charge any battery, not just Fullriver batteries, with as little as 13.2v, there are plenty of D3 owners on this site who not only have Fullriver batteries, but their batteries are mounted in a caravan or camper trailer who have no problems fully charging their batteries down a long length of cable, while they drive.

Or are you implying they jump in the D3 and drive for 60 hours straight. The reality is that the average drive time to bring two 100 Ah deep cycle batteries ( Fullriver or otherwise ), mounted in a caravan or camper trailer, with a tow vehicle voltage of 13.2v, from around 50% SoC to at least 95% SoC would be less that 6 hours, not 60 hours.



3. Because the D4 has a multi-stage charging system, extra loads MUST NOT be connected directly to the battery posts. Hopefully when I get my D4 I will be able to find the correct connection points and advise the forum.
With both the D3 and the D4 ( and for that matter the RRS and RR Vogue ) there is a designated earth post clearly indicated in the manual.




4. Any extra electric loads have the potential to cause problems with the car ECU. With most devices, the risk of trouble is vanishingly small but with dual battery systems there is a slim but real risk of trouble. This presumably is why Land Rover won’t honour warranties if such after-market electronic devices are fitted. To make the ECU impervious to interference by other electronic devices is possible but extremely difficult, especially in an automotive environment. DC-DC converters are less likely to cause problems than solenoid based dual battery systems.
Since when won’t LR honour warranties if a standard dual battery system is fitted. A number of DEALERS have stated they won’t warranty a vehicle with a dual battery system in it, but LR has not made any such statements, furthermore, where customers of those same dealers have gone ahead and fitted a dual battery system, not one, NOT ONE VEHICLE has had a warranty voided when they have fitted one of my dual battery systems, here or anywhere else in the world.

So again, got any evidence to back this claim, especially when you concider that quite a few LR Dealerships fit my gear to NEW LRs



I’m not going to waste my time and everybody else’s time by correcting all you have posted, I will cover one specific section.

You posted about voltage SPIKES but most of the "info" you post about relates to voltage SURGES. Every single electronic device in use everywhere in the world, has SPIKE protection built in, and this includes your ECU. Furthermore, it would take something like someone using an electric welder for an ECU to be damaged by voltage spikes, or you could just have the vehicle struck by lightning.

Whereas voltage SURGES are a way of life in DC systems and are NOT protected against because they cause no problems.

To back the point, do a Google of voltage SURGE protection devices. They are ALL for AC applications.

DC systems, especially those in a motor vehicle will tolerate massive voltage surges with no effects being caused and again a perfect example of the biggest voltage surge that occurs in EVERY VEHICLE, numerous times EVERY DAY is when you start your motor.

Before you turn the ignition key, the cranking battery will have, on average, about 12.5+ volts. You turn the key and the volts cans drop to 8v and then rise to over 15v once the motor fires up. And all this happens over a second or two.

Voltage SPIKES have a duration of millisecond.

[drivesafe]

Some “FACTS”.

The alternators in D3s and D4s are NOT multi stage chargers.

Multi stage charging is something that battery chargers and DC-DC devices do because of the limitations. They don’t have the grunt needed to “BOOST” charge a battery when it’s in a low state of charge.

Most people think that when you hook up a battery charger or DC-DC devices, the battery is charger 14+ volts. Not so and what actually happens, if the battery is low, the charge will apply a given current ( based on the size of the charger ).

Again, if the battery is low, when this current is first applied, the voltage at the battery will not be 14+ volts, if the battery is very low, the charger voltage could easily be as low as 12v.

As the battery charges, the voltage rises until a point is reached where the charger’s output voltage will be at 14v or higher, BUT this is only when the battery is near fully charged.

The charger will then go though a number of different cycles till the battery is fully charged and the charger then goes into a Float mode.

As for the different voltages for charging different battery types, like 14.4v for AGMs, 14.7v for flooded wet cell batteries, these are NOT the voltages the charger charges at, these are the maximum voltages that the charger can apply to these types of batteries without risking damaging the battery and again, these voltages are only obtainable once the battery is nearly fully charged.

Now once again, the alternators in D3s and D4s are NOT multi stage chargers, they are constant voltage chargers, also known as tapered charging.

What new alternators do is a “BOOST” charge straight after the motor is first started. NOTE, the is a BOOST charge where a MAXIMUM voltage is applied to the cranking battery in an attempt to allow the battery to rise to a fully charged state in the shortest time possible.

Again note, an alternator applies both a high VOLTAGE and a high CURRENT when the battery is in it’s lowest state. This is the exact opposite to how battery chargers and DC-DC devices work. So at the very time when a battery needs the highest charging voltage and current, an alternator can deliver what is needed, but the reverse is the case for battery chargers and DC-DC devices, they can not deliver when they are needed to.

After a given time, with a D3 and 2.7L D4, a time of 10 to 30 minutes, the alternator voltage level drops to the operating voltage, and this can be anything from 13.2v up.

This is not multi stage charging, the vehicle manufacturers don’t give a rats arse if the battery has reached a fully charged state or not, all they are interested in doing is getting a rapid replacement charge into the battery and then lower the operating voltage down as low as they can, as soon as they can so they can reduce the load the alternator is putting on the motor.

A quick electrical lesson. In DC circuits, most devices will reduce their current draw as the voltage applied to them is lowered. So the lower the operating voltage, the lower the current draw, and as the amount of current being draw from an alternator equates to the amount energy the alternator needs to pull from the motor, lowering the operating voltage means less energy required from the motor.

This in turn means less fuel is needed so ultimately and what the vehicle manufacturers are aiming at, there is less exhaust emissions.

This is what lower alternator operating voltages are all about, lower exhaust emissions, and has absolutely nothing to do with “multi stage charging”

D4 alternator voltage operations ( excluding 2.7L d4s ) goes much further but I’ll only go there if others what more info.

[roamer]

[QUOTE=drivesafe;1470281]Some “FACTS”.

A quick electrical lesson. In DC circuits, most devices will reduce their current draw as the voltage applied to them is lowered. So the lower the operating voltage, the lower the current draw,



Umm, not if P=EI still

example 60w= 12v X 5A
60W= 10V X 6A

Or I'm confused :confused::confused:but lower voltage and current increases

Cheers Ken

[Graeme]

..... I’ll only go there if others what more info.
ISTR this topic was done to death not so long ago.

[Graeme]

Umm, not if P=EI still

example 60w= 12v X 5A
60W= 10V X 6A

Or I'm confused :confused::confused:but lower voltage and current increases

Cheers Ken
You're assuming the device can increase its current draw to maintain power consumption, yet most devices (eg lights) have no ability to increase their current draw so the result is lower power consumption as the supply voltage lowers. 5A X 10V = 50W

[Blknight.aus]

Umm, not if P=EI still

example 60w= 12v X 5A
60W= 10V X 6A

Or I'm confused :confused::confused:but lower voltage and current increases

Cheers Ken

I'm backing VVV that...


You're assuming the device can increase its current draw to maintain power consumption, yet most devices (eg lights) have no ability to increase their current draw so the result is lower power consumption as the supply voltage lowers. 5A X 10V = 50W


if you lower the voltage and maintain the same power output then yes the current draw must increase....

what generally happens in the real world (automotively speaking) is that as you drop the available voltage in a circuit it uses less power and functions less well. IF the case you are proposing was correct as the power level in the battery deminished (assuming an alternator failure) the headlights would remain at a constant brightness until the current draw became so high that the wiring melted or the fuse blew.

The basic exception to the rule is your startermotor or a dead short... Providing your batteries have the guts to push the volts into a dead short or a stalled motor. While the battery is "healthy" enough to push massive amps into the load there will be a higher current flow even though the voltage reading will be lower than the nominal 12v. As the battery discharges the amps will drop off and we're back into the normal world of deminishing volts=deminishing power.

[roamer]

Got it, thanks that makes sense.:D

Cheers Ken

[wrinklearthur]

I'm backing VVV that...




if you lower the voltage and maintain the same power output then yes the current draw must increase....

what generally happens in the real world (automotively speaking) is that as you drop the available voltage in a circuit it uses less power and functions less well. IF the case you are proposing was correct as the power level in the battery deminished (assuming an alternator failure) the headlights would remain at a constant brightness until the current draw became so high that the wiring melted or the fuse blew.

The basic exception to the rule is your startermotor or a dead short... Providing your batteries have the guts to push the volts into a dead short or a stalled motor. While the battery is "healthy" enough to push massive amps into the load there will be a higher current flow even though the voltage reading will be lower than the nominal 12v. As the battery discharges the amps will drop off and we're back into the normal world of deminishing volts=deminishing power.

A light bulb filament has to be made from a material that has a positive temperature coefficient. (As temperature increases, resistance increases.) Then, as the bulb's temperature rises, its filament's increasing resistance causes less current to be taken than when it was cold. Quite quickly a stable "steady-state" temperature and "running" resistance is reached so that the bulb simply continues to give out a steady amount of light according to the current it is taking from the electricity supply.

Read more: Answers.com - How does a light bulb work (http://wiki.answers.com/Q/How_does_a_light_bulb_work#ixzz1KizR8cpN)

I thought I would just throw this one in ! :wasntme:

Cheers Arthur

[irondoc]

we're not going down this pathway again are we.....?

[bbyer]

we're not going down this pathway again are we.....? I understand the concern, however for me, I think these threads are helping me to understand how these multi battery charge systems work, or do not, or at least some of the problems.

I recall back in 2005 when the VW Phaeton arrived here with a CaCa starting battery located on one side of the boot and an AGM on the other. The CaCa was set up for starting and a few other things, the AGM, for the computers and radio etc.

Winter time comes and along with our daytime running lights, pretty soon the Phaetons will not turn over. The CaCa starting battery is fully charged and the AGM is down. It seems the computers run the ignition system so even though there is power to operate the starter, no go.

Eventually the dealer warranty solution is to include a CTEK charger with every deal, (not many of them), with instructions to once a week, put the AGM on the CTEK for a couple of nights in a row.

I assume VW has somewhat resolved that concern with the Bentley's now, however the CTEK is still included with every Bentley deal around here. The reason for the choice of the CTEK is that it is near impossible for the car driver to destroy the AGM, no matter how rich they are.

It seems automobile power systems are not as simple as they used to be when the Prince of Darkness travelled the highways and byways.

[VladTepes]

That's a disgusting "solution" for such expensive cars.

[Graeme]

This in turn means less fuel is needed so ultimately and what the vehicle manufacturers are aiming at, there is less exhaust emissions.

There have been battles between vehicle manufacturers and their alternator suppliers because the vehicle manufacturer has refused to increase engine idle revs even just slightly in high current drain instances yet don't want to pay for higher output alternators. The end result - lights dim at idle with the battery being flattened over time if the vehicle is driven only in slow traffic with the alternators and batteries copping the blame.

[Wilbur]

Hi Wibur,
You seem to have researched this well,during your research did you find charge times for the DC-DC charger, that you could post so I can get a comparison ?


Cheers Ken
Thanks Ken, good question. No, I don't have direct figures on charging times for the DC-DC converters on the market, but it is easy to work out from the graph I posted.

Mine is the GSM converter, and I am sure the others would be very similar, or better because they are more expensive(!). It charges at 14.5 volts with 25 amps available. Looking at the graph, you can see that it would take about 10 hours to reach 55% charge as opposed to the 13.5 volt graph where it would take 60 hours.

The graph specifies a maximum charge rate of C/5 - that is, one fifth of the battery capacity. Thus my converter would charge a 125 AH battery in that time. It would take longer (but now twice as long) with a 250 AH battery.

Cheers,

Paul

[Wilbur]

In brief....

If youve direct coupled the batteries through say, a dampned solenoid like they've been using in pinball machines since they started putting electronics in pinball machines driving a set of contacts that've got a a choke on it you'll not get your initial spike on connection or disconnect.
As I said in my first post, the spikes can be flitered to a certain extent and in a closed system the designers can take account of them. It is when people add extra electrics that trouble can happen.


and the cranking battery wont take a full charge till the aux battery has approached full charge... (assuming youve actually flattened it as much as your claiming)
Perhaps you would care to explain that?


not sure why youd want to bring a computer hardware engineer or software engineer to solve a problem thats been solved by electrical engineers and automotive electrical engineers (as well as aeronautical and maritime engineers) for years (all the way back to steam driven electrics) with no great hassles.Simply because a computer hardware engineer or software engineer is more likely to be able to understand the post than your average diesel mechanic or sparky at work.....


Just out of curiosity have you yet tried to see what a D2+ does when you just manually hook the 2 batteries together with a pair of decent jumper cables?I don't understand the question. Please elaborate.

[Wilbur]

WRONG, and not even close, what you are referring to is the way a D3 and a 2.7L D4 alternator works.

A D4 3L and RRS TDV8 alternators have a completely different operating system.

I only investigated the 2.7 D4 because that is what I have ordered. Maybe the 3.0 D4 and RRS are different, but if so I found no indication of this on the TOPix site.




This one is a ripper. Not only can you fully charge any battery, not just Fullriver batteries, with as little as 13.2v, there are plenty of D3 owners on this site who not only have Fullriver batteries, but their batteries are mounted in a caravan or camper trailer who have no problems fully charging their batteries down a long length of cable, while they drive.Yes, possibly you could partially charge a battery from 13.2 volts, but as the Fullriver supplied graph I attached shows it would take a huge time to do so. Look at the graph again and you will see what I mean.


Or are you implying they jump in the D3 and drive for 60 hours straight. The reality is that the average drive time to bring two 100 Ah deep cycle batteries ( Fullriver or otherwise ), mounted in a caravan or camper trailer, with a tow vehicle voltage of 13.2v, from around 50% SoC to at least 95% SoC would be less that 6 hours, not 60 hours.Again, I refer you to the Fullriver graph.




With both the D3 and the D4 ( and for that matter the RRS and RR Vogue ) there is a designated earth post clearly indicated in the manual. Thank you, that will make it easier for me when I finally get my D4.





Since when won’t LR honour warranties if a standard dual battery system is fitted. A number of DEALERS have stated they won’t warranty a vehicle with a dual battery system in it, but LR has not made any such statements, furthermore, where customers of those same dealers have gone ahead and fitted a dual battery system, not one, NOT ONE VEHICLE has had a warranty voided when they have fitted one of my dual battery systems, here or anywhere else in the world.I sent an email to Land Rover Australia explaining that I wanted information about connecting a dual battery system and their "customer care" person stated categorically that fitting such a device would void the warranty. I asked again for the information, but he just confirmed the warranty statement and told me to contact authorised dealers for any more information.


So again, got any evidence to back this claim, especially when you concider that quite a few LR Dealerships fit my gear to NEW LRs No evidence whatsoever, apart from what I was told by Land Rover Australia.




I’m not going to waste my time and everybody else’s time by correcting all you have posted, I will cover one specific section.

You posted about voltage SPIKES but most of the "info" you post about relates to voltage SURGES. Every single electronic device in use everywhere in the world, has SPIKE protection built in, and this includes your ECU. Furthermore, it would take something like someone using an electric welder for an ECU to be damaged by voltage spikes, or you could just have the vehicle struck by lightning.

Whereas voltage SURGES are a way of life in DC systems and are NOT protected against because they cause no problems.

To back the point, do a Google of voltage SURGE protection devices. They are ALL for AC applications.

DC systems, especially those in a motor vehicle will tolerate massive voltage surges with no effects being caused and again a perfect example of the biggest voltage surge that occurs in EVERY VEHICLE, numerous times EVERY DAY is when you start your motor.

Before you turn the ignition key, the cranking battery will have, on average, about 12.5+ volts. You turn the key and the volts cans drop to 8v and then rise to over 15v once the motor fires up. And all this happens over a second or two.

Voltage SPIKES have a duration of millisecond.Semantics. The term "Spike" generally refers to a very short duration transient increase in voltage, whereas the term "Surge" usually refers to a longer duration increase in voltage. It figures really, 'spike' is a sort of sharp sounding word, while 'surge' is probably slower, like a river in flood.

[Wilbur]

Some “FACTS”.

..........

This is not multi stage charging, the vehicle manufacturers don’t give a rats arse if the battery has reached a fully charged state or not, all they are interested in doing is getting a rapid replacement charge into the battery and then lower the operating voltage down as low as they can, as soon as they can so they can reduce the load the alternator is putting on the motor.

A quick electrical lesson. In DC circuits, most devices will reduce their current draw as the voltage applied to them is lowered. So the lower the operating voltage, the lower the current draw, and that is why it takes a long time to charge a battery at 13.2 volts
and as the amount of current being draw from an alternator equates to the amount energy the alternator needs to pull from the motor, lowering the operating voltage means less energy required from the motor.

This in turn means less fuel is needed so ultimately and what the vehicle manufacturers are aiming at, there is less exhaust emissions.

This is what lower alternator operating voltages are all about, lower exhaust emissions, and has absolutely nothing to do with “multi stage charging”I can't agree with you there. You see, if you take electrical energy OUT of a battery, you must put the same amount back in. If you keep taking electrical energy out of a battery but don't put the same amount back in, the battery will eventually go flat.
It makes no difference if the charging system replaces that energy quickly or slowly - the total amount of energy put into the battery is the same.
That energy comes form one source only - the fuel that the engine uses to turn the alternator.
Thus the exhaust emmissions will be the same regardless of how fast or slow is the re-charge process.
Car manufacturers put in multi-stage chargers because the battery manufacturers advise them to, not because they think it will reduce emmissions.

[CaverD3]

I sent an email to Land Rover Australia explaining that I wanted information about connecting a dual battery system and their "customer care" person stated categorically that fitting such a device would void the warranty. I asked again for the information, but he just confirmed the warranty statement and told me to contact authorised dealers for any more information.

Nothing you do can void a warranty. The manufacturer can refuse a warranty claim if a modification or addition has caused the fault. e,g. They could not refuse a warranty claim for a drivetrain failure if you have a second battery. At worst case you may mave to fight for a claim if they make such a claim. The reality is LR are one of the better manufacturers when it comes to warranty claims.

[drivesafe]

we're not going down this pathway again are we.....?

Mate, when someone comes along, FOR THE SECOND TIME, posting up nothing but porkies about a field I not only work in but make my living from, you bet we are going down this path again.

[Wilbur]

Nothing you do can void a warranty. The manufacturer can refuse a warranty claim if a modification or addition has caused the fault. e,g. They could not refuse a warranty claim for a drivetrain failure if you have a second battery. At worst case you may mave to fight for a claim if they make such a claim. The reality is LR are one of the better manufacturers when it comes to warranty claims.

Yes, my fault, I summarised what LR wrote. In fact, they wrote:-

"Thank you for your enquiry regarding technical information in relation to your Discovery 4.

Please allow us to confirm that Land Rover Australia do not recommend any after market modifications to our vehicles. Please be aware that the fitment of after market items may void the warranty of any component requiring replacement as a result of modifications to your vehicle."

As I implied in my original post, I don't blame them in the least. I don't see why they should be required to cover the cost of repairs for which they are not responsible.

[drivesafe]

Wilbur, I make my living by working in this field of automotive electrics. I have NEVER deliberately set out to mislead any of my customers and I have made it my business to keep up with all the advances and deceptions relating to this field and DC-DC devices most certainly fall into the deception category.

As above, I make my living from this field, and anything that I can make an honest buck from, I’ll research.

I have access to the worlds best DC-DC devices, these are the Sterling from the UK and Pro Mariner from the USA, and by selling these devices, I could make a killing, but I’d be ripping off my customers if I tried to make out these devices would improve charging over what the standard alternator can do.

Wilbur, if you had any real experience in this field and bothered to carry out the slightest bit of research about these devices, ( instead of being blindly lead by the grossly misleading info used to sell these devices ) you would not be making such ridiculous claims about these devices you have been posting about.

The better quality DC-DC devices will fully charge batteries while driving, BUT in only a very few cases will they do it quicker than an alternator can and this is the problem.

Why should people with a small battery capacity set up spend heaps of money on a device that at very best will only do what an alternator can already do or they might give a marginal improvement over an alternator, and worse still, with larger battery capacity set ups, by the end of a days drive, these DC-DC devices will actually leave your batteries in a low state of charge than what an alternator can do.

This ultimately means, by using one of these DC-DC devices, you not only have less power available at the end of a days drive but you are actually shortening your auxiliary/house battery’s life span.

But Wilbur you claim it’s better to destroy your batteries, all because you THINK these DC-DC devices are the ants pants and your quite happy to run down a much cheaper device, by using false claims, for no other reason than to big note yourself.

FACT, if someone is after the fast recharge set up while driving then NOTHING beats my SC80 dual battery systems, and this includes being faster than these wonder DC-DC devices

[Wilbur]

Mate, when someone comes along, FOR THE SECOND TIME, posting up nothing but porkies about a field I not only work in but make my living from, you bet we are going down this path again.

No Drivesafe, I am not telling porkies. I have given enough information for others to check and judge which of us is straying from the truth. I am sure anyone who bothers to check will be able to work out why anyone in particualr might be straying form the truth.

[Wilbur]

Wilbur, I make my living by working in this field of automotive electrics. I have NEVER deliberately set out to mislead any of my customers and I have made it my business to keep up with all the advances and deceptions relating to this field and DC-DC devices most certainly fall into the deception category.

As above, I make my living from this field, and anything that I can make an honest buck from, I’ll research.

I have access to the worlds best DC-DC devices, these are the Sterling from the UK and Pro Mariner from the USA, and by selling these devices, I could make a killing, but I’d be ripping off my customers if I tried to make out these devices would improve charging over what the standard alternator can do.

Wilbur, if you had any real experience in this field and bothered to carry out the slightest bit of research about these devices, ( instead of being blindly lead by the grossly misleading info used to sell these devices ) you would not be making such ridiculous claims about these devices you have been posting about.

The better quality DC-DC devices will fully charge batteries while driving, BUT in only a very few cases will they do it quicker than an alternator can and this is the problem.

Why should people with a small battery capacity set up spend heaps of money on a device that at very best will only do what an alternator can already do or they might give a marginal improvement over an alternator, and worse still, with larger battery capacity set ups, by the end of a days drive, these DC-DC devices will actually leave your batteries in a low state of charge than what an alternator can do.

This ultimately means, by using one of these DC-DC devices, you not only have less power available at the end of a days drive but you are actually shortening your auxiliary/house battery’s life span.

But Wilbur you claim it’s better to destroy your batteries, all because you THINK these DC-DC devices are the ants pants and your quite happy to run down a much cheaper device, by using false claims, for no other reason than to big note yourself.

FACT, if someone is after the fast recharge set up while driving then NOTHING beats my SC80 dual battery systems, and this includes being faster than these wonder DC-DC devices

The lad doth protest too much, methinks.

You just can't help yourself being offensive, can you? Yes, I know (now) that you make your living selling these things. I don't. My only interest was to offer advice to those who needed it in exchange for excellent advice I have received on this forum.

Clearly this is not a suitable venue to place posts about auto electrics. If anyone wants unbiased information, they are welcome to PM me.

[rmp]

Thread locked AGAIN before it degenerates into another slanging match.

Drivesafe and Wilbur - if you cannot keep this discussion:

- directly on the topic of batteries and electrics
- free from personal references to others, implications of truth or other accusations

then it will remain locked, which will be a great pity.

Please edit your posts to remove the references as above so the thread can be unlocked and the discussion can continue.

You have both been warned repeatedly.

Please note this is not a question about who is right or wrong, it is a question of complying with the forum rules by refraining from personal attacks (however subtle) regardless of the underlying facts.