DC-DC charger- which one?

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Originally Posted by SilvaD4

Hi Peter, I will take you up on the kind offer...

I have all the equipment from a 40A RedARC DC-DC system that was neatly installed in my previous ride.
Although it was only installed for 3 months the system worked very well (no issues at all). All batteries were at 100% charge when it was removed.
The next step is to have the same set-up installed into my 2014 D4 SDV6 HSE.
The charger is of the LV variety so it should suit the D4.

• So what is the model of your DC-DC charger and where is it mounted?
• Are you using a relay kit for the solar?
• Where did you mount the charger, the relay and the battery (or batteries)?
• Did you add any wiring in the cargo area (extra sockets)?
• Any hints as to the wiring routes would also be appreciated.

Thanks in advance,

Jacques

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Jacques,

I have had a MY10 D4 and now a MY15 D4. I have learnt some things which I used to refine the installation of the DC/DC charging in the MY15. Answers to each of your questions below:

MODEL:

MY10: Redarc BCDC1220. Note: LV models did not exist back then. I experience initial problems asthe installer had wired the negative wire directly to the car battery rather than to the body earth. Once I moved the wire the charger worked fine. That carnever went below 13.2V.

MY15: Redarc BCDC1225LV. This has the Low Voltage switch wire. It is also a solar MPPT charger.The MY15 will run for periods of time at around 12.2V and so it needs the LV version. Note it doesn't run around at 12.2v for long period of time (I haven't measured the time it will stay at 12.2v).

SOLAR RELAY:

MY15: No solar relay. My DC/DC charger is mounted on the battery box in the rear of the cargo area behind my fridge. We have this in the car 95% of the time. A cable runs from the Main Battery down along the driver's side door channels and ends in an Anderson Plug. The DC/DC charger input cables also have an Anderson Plug. Normally the car battery power and DC/DC charger Anderson plugs are connected. When I want to use solar charging I just unplug the Anderson Plug and Plug in my portable 150W Solar panel. Make sure you bypass any Controller on your solar panel as the Redarc will manage the solar charging. Its a much better MPPT charger than installed on most solar panels.

WHERE:

MY10: This was installedby a 4x4 accessory store familiar with Land Rovers. The battery and Redarc were mounted under the bonnet between the Main Battery and the Coolant/WasherBottles. A battery tray was mounted there. I could only fit a 55AH battery there and I thought this may not be enough. So I had a second 55AH battery mounted in the rear cargo area. Thick cables were run between these batteries.

While it all worked well for 4 years, I was not happy with this install as the batteries would be at different temperatures resulting inthe battery in the engine bay being potentially overcharged. The rear battery may not have been fully charged at the end of the cable run. I was also concerned that the high engine compartment temperatures may cause the DC/DC charger to downrate itself so it didn't overheat although I don't know if it ever did.

MY15: I have one 100AH AGM battery in the rear cargo area (as described above). This is secured to a shelf and cargo barrier system. The DC/DCcharger is mounted on top of the battery box. This way there is minimal distance between the charger and the battery. The DC/DC charger is in a cool area of thecar so will charge at full rate.

WIRING:

I have a Merit and cigarette lighter plug in the Cargo area for the fridge. I have another cable running to the UHF radio under the driver's seat. I have a two USB charger socket also in the rear cargo area. All this runs off the 100AH battery in the cargo area.

One large cable to handle 50amp runs from the car battery to the DC/DC charger. Note that the negative is connected the ground post in front of the car battery compartment (NOT DIRECTLY TO THE BATTERY!) The cable runs across the back of the engine compartment, through the firewall grommet on the driver's side and then along the floor channels and pops out at the rear of the driver's side rear door.

You also need to find an ignition active cable. We picked one up from the trailer plug at the back of the car. We were doing other wiring in that area as we were installing a Redarc TowPro at the same time.

If you are installing your battery in the cargo area the please ensure it is a fully sealed battery (to avoid potentially dangerous gases in the car interior). Read the Redarc instructions to ensure you connect up the other wires to correctly set the charging Algorithm of the DC/DC charge to match the type/chemistry of battery you use.

OTHER:

I note that you have the 40 Amp DC/DC charger model. I suggest that you check your second battery manufacture's web site to determine the maximum Amperage your battery can accept. Not all batteries will accept a 40Amp charge.

I have a voltage monitor for the main car battery and the GME Radio display shows the voltage for the Second Battery. This is a handy way of keeping an eye on things.
I have a second set of heavy cables running to an Anderson plug near the TowBar. This connects to another Redarc DC/DC Charger in the caravan to charge 2 x 120amp batteries.

BENEFITS:
Independent and 100% charging of all the batteries.
Correct charging foreach battery chemistry.
Not effected by differences in battery temperatures.
You can charge from a solar panel.



Yes it costs a lot but I use the car and equipment and I want it to work at its optimum.



Peter

Thanks Peter, a most informative post. Having done this twice (2010 D4 and later in a 2015 D4) has allowed you to iron out the bugs very nicely.

Yes, my 40A DC-DC charger is way to big for my batteries. However my son has a 20A LV version in his Prado (and a larger aux battery set up) and he has expressed an interest to do a swap.

Jacques

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Originally Posted by drivesafe

Hi Wheelan here is the thing, with your system and your 100Ah battery, you had 80Ah available if you discharged your 100Ah down to it's safe limit of 20% SoC.

If you had one of my isolators, you would have had 125Ah available.

But even if you still only used the same 80Ah, then the two batteries in my system, your auxiliary and your cranking battery, will only be discharged down to about 60% SoC and this means your batteries would be fully charged in a shorter drive time than your single 100Ah battery could be with or with out your DC/DC device.

The recharge time in a D4 is even quicker with one of my isolators fitted.

Then add the fact that with short driving trips around town and my system will actually keep your cranking battery in a higher state of charge, something no other system can do.

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My thing is I am a bit old school and want to keep my starter battery for starting, and possibly winching if required the next day. I also feel my second battery has never been in better shape when properly charged from a proper 5 stage charger. Both systems have their merits, I actually dont need any more battery power than what I have already, 2 spares in the CT as well as the one in the car keeps everything going for a long time.

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Originally Posted by drivesafe

The Optima D34 Yellowtop battery is a genuine AUTOMOTIVE GRADE AGM, specifically designed to tolerate the harsh conditions found in a engine bay.

These batteries also have NO CHARGE CURRENT LIMIT, and can and will take everything the alternator can produce.

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Out of interest I have pasted the below info from Optima on the D34

"Model: D34
These batteries are designed for starting and deep cycling applications and for use in vehicles with large accessory loads.

Recommended Charging Information
Alternator: 13.65 to 15.0 volts
Battery Charger: 13.8 to 15.0 volts; 10 amps maximum; 6-12 hours approximate
Float Charge: 13.2 to 13.8 volts; 1 amp maximum (indefinite time at lower voltages)
Rapid Recharge (Constant voltage charger): Maximum voltage 15.6 volts. No current limit as long as battery temperature remains below 125?F (51.7?C). Charge until current drops below 1 amp.
Cyclic or Series String :14.7 volts. No current limit as long as battery temperature remains below 125?F (51.7?C). When current falls below 1 amp, finish with 2 amp constant current for 1 hour.
All limits must be strictly adhered to."

Food for thought....

Yes rapid recharge and cyclic recharge as stated is no current limit in the doc you posted:) note the limit put on chargers though

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Originally Posted by RoverLander

BENEFITS:
Independent and 100% charging of all the batteries.

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Well I would like to know how you know your battery is at a 100% charged state. Short of removing the battery and taking it to a laboratory for testing, there is NO WAY the determine if a battery is at a 100% state of charge while the battery is in a vehicle.

So that one is an advertising myth.

The industry standard is that any battery that is over 95% is fully charged.

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Originally Posted by RoverLander

Correct charging foreach battery chemistry.

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Yep this is a big problem when using a DC/DC device to charge batteries. You MUST have the same type of batteries if using one of these new DC/DC device to charge them.

Another one of these advertising myths.

If you let the alternator do what it has been doing for many decades, it will easily and CORRECTLY charge any mix of battery types and sizes with out any problems at all.

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Originally Posted by RoverLander

Not effected by differences in battery temperatures.

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Neither is charging by an alternator.

So once again another advertising myth

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Originally Posted by RoverLander

You can charge from a solar panel.

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NOT AT THE SAME TIME.

So I am not sure how you think this is a benefit???????

Whereas, if you are towing a caravan with solar on the roof, you only need a solar reg in the caravan ( which you will need anyway ) and you can be charging ALL BATTERIES from the alternator and solar at the same time.

So in a nut shell, charging from an alternator is far more beneficial and a hell of a lot cheaper to setup AND OPERATE

Quote:

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Originally Posted by Wheelan

My thing is I am a bit old school and want to keep my starter battery for starting, and possibly winching if required the next day. I also feel my second battery has never been in better shape when properly charged from a proper 5 stage charger. Both systems have their merits, I actually dont need any more battery power than what I have already, 2 spares in the CT as well as the one in the car keeps everything going for a long time.

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Hi Wheelan and as the operating system of my isolators has been around for more than 25 years now, I reckon that makes it OLD SCHOOL technology but my old school technology is still proving to be FAR SUPERIOR at charging batteries than any of these NEW wonder devices.

As for using a 5 stage charger goes, well thats a pretty simple way to charge lead acid batteries when you could be using something like a charger with an INFINITE number of charge stages, you know like how an alternator charges.

The problem with battery chargers, DC/DC devices and Solar regulators is that they are trying to copy what an alternator does, and does naturally, but battery chargers, DC/DC devices and Solar regulators are constant CURRENT charging devices and this is a major limitation for these devises.

Whereas, an alternator is a constant VOLTAGE type charger and constant voltage type charging is FAR SUPERIOR when it comes to charging lead acid batteries.

For example, when was the last time you heard of an alternator cooking a battery. It does not happen. But it is a common occurrence with both battery chargers and DC/DC devices.

Battery chargers and DC/DC devices just can not compete with how well an alternator works at charging batteries.

Now to your winching operation. It is known in the industry that there is a huge advantage to connecting two batteries together while winching.

Using one of my USI-160 isolators, you not only get the advantage of shearing the load while operating accessories but you get the huge advantage of linking batteries together while winching.

A win-win setup.

Quote:

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Originally Posted by SilvaD4

Out of interest I have pasted the below info from Optima on the D34

"Model: D34
These batteries are designed for starting and deep cycling applications and for use in vehicles with large accessory loads.

Recommended Charging Information
Alternator: 13.65 to 15.0 volts
Battery Charger: 13.8 to 15.0 volts; 10 amps maximum; 6-12 hours approximate
Float Charge: 13.2 to 13.8 volts; 1 amp maximum (indefinite time at lower voltages)
Rapid Recharge (Constant voltage charger): Maximum voltage 15.6 volts. No current limit as long as battery temperature remains below 125?F (51.7?C). Charge until current drops below 1 amp.
Cyclic or Series String :14.7 volts. No current limit as long as battery temperature remains below 125?F (51.7?C). When current falls below 1 amp, finish with 2 amp constant current for 1 hour.
All limits must be strictly adhered to."

Food for thought....

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Here is some more food for thought, when using an alternator to charge Optima batteries, you will NOT exceed ANY of the limitation set for these batteries.

So mate, sorry but I don't get your reasoning for making that statement?

For example, two and a half years ago, my wife's Toyota Seca's battery died so I put an Optima D34 Yellowtop in to replace it till I got around to replacing the battery.

About 2 months back I finally had to charge the battery because the Optima died.

It was 7.5 years old when I put it in the Toyota, making it 10 years old when it died.

It had been in my D3, then my D4, then my Range Rover, then is sate in the work shop for nearly a year and in the ten years I had that battery it was only ever charge by a battery charger on about three occasions.

So charging straight off the alternator really shortens the life of these batteries NOT.

Quote:

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Originally Posted by RoverLander

If you are installing your battery in the cargo area the please ensure it is a fully sealed battery (to avoid potentially dangerous gases in the car interior).

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A couple of other points, there is no such thing as a fully sealed lead acid battery and if you check, most lead acid batteries are now marked as "SPILL PROOF", not "SEALED" and as a DC/DC device can cook a battery, while an alternator will not.

So you are far safer charging a lead acid battery, mounted in the cab of a vehicle with an alternator, not a DC/DC device!!!

Quote:

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Originally Posted by RoverLander

MY15: I have one 100AH AGM battery in the rear cargo area (as described above). This is secured to a shelf and cargo barrier system. The DC/DCcharger is mounted on top of the battery box. This way there is minimal distance between the charger and the battery. The DC/DC charger is in a cool area of thecar so will charge at full rate.

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For less money, you could have fitted one of my Triple Battery systems, which simply mounts two Optima D34 batteries in the engine bay.

This would give you more available space in the cargo area.

It would also give you more usable capacity. 80Ah with your system and around 125Ah with my system.

It would save fuel.

But the biggest advantage is that with your setup and a low battery, it will take 5 hours of driving time to fully recharge your battery, mine will fully recharge the two Optimas in less than 90 minutes.


Now if you only need that 80Ah that you have, you could still have fitted one of my standard dual battery systems, with a single D34 Optima battery.

You would then have had around 90Ah available instead of your 80Ah.

The setup would have been heaps cheaper than the one you have.

You would still fully charge the optima in under 90 minutes.

My setup is lighter and therefore you save even more fuel.

Both my standard and triple battery systems look after the cranking battery as well as the auxiliary batteries, your is only looking after your auxiliary battery.


I'm sorry mate but I just can't see how you, and the others, think that you have better systems when they all have so many inherent drawback.

Your logic just does not make sense

In the 101 I run 1 x lead acid cranking battery, 1 x 100AH deep cycle battery and then when towing the van, that has a 90AH Calcium battery in it (that I had lying around). 99% of the time they all stay connected. I'll manually switch the starter battery out of circuit if I'm going to be camping in 1 spot for several days and I know I won't be starting the car. All charge off a half knackered 55amp alternator when driving along (I can tell how loaded the alternator is by the note it 'sings' at :D ), and all stay fully charged. I do have a solar panel mounted on the roof of the 101 and you can see by the status LEDS's on the regulator that it stops working when the car starts as the alternator has bought the bus voltage up high enough. When I stop after a couple of hours, the solar doesn't kick in until I turn a load on and I know through checks I've done that everything is fully charged.

Each battery only draws what it needs so battery type - and using a different mix of batteries, etc is irrelevant.

IMO, save you dollars for something useful - the cars alternator is all you need.