Thread: Beware Charging Dual Battery in D4.

Originally Posted by RoverLander

Hi Drivesafe, a slow reply.. i've been out and about.

The facts remain:

The SC80 PARTIALCHARGER dischargers your main battery. The D4 has a mind of its own when it comes to keeping lights and other accesories running. I still want my main battery as full as possible. The DC-DC charger delivers that.

The SC80 PARTIALCHARGER will never get a battery upto 15.2V because the D4 never charges up to that voltage. This is a FACT as I've witnessed it while driving my D4. The DC-DC charger does as I've also seen that. Are you confirming that the SC80 PARTIALCHARGER will reach 15.2V?

The SC80 PARTIALCHARGER will suffer from voltage drop if the second battery is placed more that a metre or so from the main battery. The DC-DC charger will deliver full voltage as you can place it close to the battery to be charged and it will deliver full voltage.

The SC80 PARTIALCHARGER will provider faster initial charge before it stops when partialcharge has been achieved. The D4 may be able to deliver 180AMP but I never want to go near the upper end of that capacity... I'm not THAT confident in Landrover electronics and computers. I know that the DC-DC charger will never compromise the vehicle electronics because it has a set draw limit. The SC80 PARTIALCHARGER will expose the electronics to whatever is connected.

You are correct that my current DC-DC charger has an issue. I identified that. It is still fully charging my batteries... it is just taking a little longer than it should due to the charge stopping at times due to the D4 voltage dropping below 12.7V. A solution to this is being found but is a refinement.

I'm about to head of for 3 weeks of bush camping... I'll let you know how the DC-DC charger goes... I sure hope I don't come back asking for a SC80 PARTIALCHARGER!

Roverlander, GSM in Queensland make an excellent DC-DC convertor that is ignition controlled rather than voltage controlled. I agree with you entirely, you always want the maximum possible charge in your cranking battery. In extremely cold weather, or if an accidental over-use of accessories occurred, one could become stranded.

Paul

Originally Posted by Wilbur

In extremely cold weather, or if an accidental over-use of accessories occurred, one could become stranded.

Again another case of seeing one thing and jumping to the wrong conclusions.

Cold whether and a low battery have little to do with one another.

You can have a battery with a an SoC of 50% and the vehicle will have no problems firing up in the coldest temperatures.

Not only do I have hundreds of customers in the UK and Europe who have never had a problem in winter, I have customers up in the Arctic Circle and none have ever complained of not being able to start the D3s after a camping stay, and this is with the cranking battery being down to 50% SoC.

So that myth doesn’t hold water.

On the other hand, if your cranking battery is on it’s last legs, cold temperatures are usually the final cause of the battery giving up the ghost.

In this case it wouldn’t matter if the battery was near flat or fully charged, or whether you had an isolator or a DC-DC converter or anything else. If the battery is stuffed, it’s stuffed.

So Wilbur, once again you’re making nothing but scare mongering statements that have no substance in the real world.

As for “accidental over use of accessories”, thats what the SC80 is designed to protect against, so people won't get stranded!

Originally Posted by Wilbur

Roverlander, GSM in Queensland make an excellent DC-DC convertor that is ignition controlled rather than voltage controlled. I agree with you entirely, you always want the maximum possible charge in your cranking battery. In extremely cold weather, or if an accidental over-use of accessories occurred, one could become stranded.

Paul

sounds like a bloody expensive way of wiring in a relay.

Here we go again...

cheers,
Terry

Hi
I've got an interesting observation on charge rate.

Original LR battery has always been suspect, and I thought the aux battery and traxide had been hiding the fact, so car was going to dealer and I disconnected jumper between batteries, sure enough main battery went down to 11V overnight, dealer replaced battery.

Had run fridge off aux battery (no recharge) and it went down to 11.5v then fridge cut out.
Put on diagnostic screen it shows main battery 12.7v, (motor off)
Hooked up aux battery .
Start car voltage goes to 14.7v and stays there for 1hrs drive, no reduced voltage when motor underload (which it does when batteries are charged).

Would seem that car knew battery needed charging and did so, not going into a float stage,even though main battery was fully charged

Could be wrong, but now both batteries fully charged and all is good

Cheers Ken

Hi roamer, this is something that may or may not be a problem, but the SC80 does hide problems with a cranking battery but it also helps a cranking battery that’s on the way out, to last that bit longer.

Still can’t make up my mind if this is a good thing or not, although it will help you get back to civilisation if your cranking battery is on the way out.

BTW this is an observation I’ve made over the last couple of years, Calcium/Calcium batteries ( the standard LR cranking battery ) seem to be much harder to load test and get a correct indication of whether the battery is OK or on it’s last legs.

simple reason for that is they push out more amps for their given rating on a CCA test.

I test them as a combo battery (deep cycle test then the CCA test) on the good meter at work and that seems to pick it correctly about 80% of the time for the more exotic batteries.

the new electronic testers get them right more often as the tests have been adapted to the new battery standards, older units will give a dying battery a pass. If a calcium battery fails on an old school unit (assuming you set the test up correctly) then its well and truely dead.

Originally Posted by Blknight.aus

older units will give a dying battery a pass. If a calcium battery fails on an old school unit (assuming you set the test up correctly) then its well and truely dead.

This would be the reason MOST auto electricians can’t pick up a dying Ca/Ca battery and only when it is dead, is the owner assured the battery is stuffed.