battery charging with two batteries...

Robzimbo

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I am in kenya
Dec 4, 2016
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I've been away for work for a while, and Pam (my 1998 105 Standard spec LC) was a bit sluggish to start when I got home.

So I've connected my Optimate 3+ conditioner/charger which I will leave connected for 24 hours or so (I don't have a fast charger).

I have two 70Ah batteries, in series: Earth - Neg batt 2 / Pos batt 2 - Neg batt 1 / Pos batt 1 - Starter + vehicle power - Earth.

Question for the experts:

If I connect the pos / neg charger to Battery 1, will it charge both batteries? Or do I need to charge Batt 1, then charge batt 2? Or should I connect the charger to Neg Batt 2 and Pos Batt 1?


If it's the former, then I guess if I leave the battery conditioner connected while I'm away next time, it will keep both batteries in good nick.

Hope you're all having a sunny Sunday.

Rob
Nairobi
 

StarCruiser

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Oct 7, 2014
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Hi Rob,
It depends on the voltage from your charger conditioner. If it's a 24V one then across both batteries will charge both batteries. If it's a 12V one then it needs to charge one at a time.

You have a few options, assuming it's a 12v charger.
1, as above, swap over after a day or two.
2, buy a 24V charger conditioner and put it across both batteries.
3, disconnect at least one battery completely, insulate the clamps and connect + to + and - to - so the batteries are in parallel while you are away (jump leads would do but make certain they won't short circuit. Then put the charger conditioner on the + and - ideally + on one battery and - on the other but it doesn't really matter.
 
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GeekOKent

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Looks like you are running 24v constantly. The '98 105 would have been 12v throughout. So do you really have a 24v setup pit in after market? If so, what drove that decision?
 

Robzimbo

Active Member
I am in kenya
Dec 4, 2016
51
37
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Um, yes. So it does.

Interesting.

This is exactly how my 12v 80 series has been wired, for 150,000 kms and over 8 years. So when I got the 105, I just did the same thing. Of course it's still 12v electrics all the way through. I'm away from Kenya at the moment. Looks like I better get the spanners out when I get back.

Thanks for pointing this out. How embarrassed should I be, do you think, on a 1-10 scale?
 

Robzimbo

Active Member
I am in kenya
Dec 4, 2016
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As a matter of interest - what damage would you expect this to have done? It doesn't, as yet, appear to have done any damage, which is interesting and slightly surprising.
 

GeekOKent

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Iirc, the 80 is wired up with the batteries in parallel and not in series. For the 24v start it uses a relay to switch and then back to 12v since everything else is 12v. Once you are near the truck it might be worth checking once to make sure it really is in series.

Note that polarity of the batteries is reversed between left and right in a way that negative is always on the outside.

Running 24v on a 12v system, i feel, would have cooked a few things pretty much on the turn of ignition. The fact that you have been running OK for a while makes me wonder what is going on. Do you have a picture handy?
 

Towpack

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The 80 series (for some markets) is indeed 24v start and 12v vehicle systems. I can't imagine for a minute that you'd get away with running a 12v system on 24v. Some LR's, notably military spec, came with 24v electrics. Is it possible that some LC's left the factory as 24v?
 

Robzimbo

Active Member
I am in kenya
Dec 4, 2016
51
37
18
Ok - I'm not in Nairobi (or Harare) at the moment, but I am confident of the following:

1: Both my 80 series and my 105 are 12 volt NOT 24 volt. Both originally only had one battery when I bought them.
2: Both have two 75Ah (I think) batteries installed - and fitted by competent mechanics.
3: The 80 has had this fitment since 2009, and done 150,000kms. The 105 has had a second battery since January, and 10,000 kms. No bulbs have blown, all dials and gauges run true, both vehicles start first time every time.
4: As long as there is one battery in the original position (near side front of the engine bay), both vehicles will start.

I must have got my description of the wiring in the OP back to front; because I'm pretty certain that I have a 12volt 150Ah set up on both vehicles.

One of my buddies has a 1993, auto box Japanese import 80 series with a 24volt starter circuit. As Towpack notes above, that needs two batteries to start, but runs everything else (I think) on 12v.

Thanks, all, as ever, for your good advice. I feel a bit stoopid that I don't know what I'm talking about though... :)
 
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