Warning on auxiliary batteries

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Originally Posted by irondoc

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

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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.

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

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Originally Posted by drivesafe

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

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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.

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Originally Posted by 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

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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

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Originally Posted by 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.

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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.

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Originally Posted by Blknight.aus

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)

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Perhaps you would care to explain that?

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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.

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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.....

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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?

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I don't understand the question. Please elaborate.

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Originally Posted by drivesafe

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.

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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.

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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.

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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.

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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.

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Again, I refer you to the Fullriver graph.

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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.

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Thank you, that will make it easier for me when I finally get my D4.

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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.

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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.

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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

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No evidence whatsoever, apart from what I was told by Land Rover Australia.

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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.

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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.

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Originally Posted by drivesafe

Some “FACTS”.

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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,

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and that is why it takes a long time to charge a battery at 13.2 volts

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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”

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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.

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Originally Posted by Wilbur

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.

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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.

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Originally Posted by irondoc

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

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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.

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Originally Posted by CaverD3

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.

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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.