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Over charging.

This sounds like it may be over complicating things I think Ben. DCDC chargers run the voltage they are set to for the battery type they are programmed to be dealing with.

I'm only really suggesting getting one of these chargers because they are brilliant at reviving sick batteries.
 
Might be worth a look at Dave's post on 24v battery setup issues he had with a Nissan here,
https://www.landcruiserclub.net/community/threads/24v-battery-system-question.149274/

For my money he's explained it rather well.

Strangely enough just read it before reading this!! This looks like a very credible reason as to why me and ben are only shagging one battery. After my voltage dropper failed I ran the 12v supply off the one battery, assuming the batteries would just balance it out. I have 2 12v oulets, the compressor relay (but not the compressor) and the stereo running off the 12v. It also explains why one long run from Italy was enough to shag the battery. I was, at the time running my cool box, stereo and twatnav off the 12v. So, first course of action is to get a new dropper and get it wired in.
Here's the important bit of the thread to save you reading the whole lot. What it appears is that your producing a Chernobyl style reaction!!

In the case of my old Nissan, the previous owner had wired a trailer light coupling to the mid point of the batteries.
What this did was
1/ on a long night towing the lower battery was loaded down to 13.9V while the upper sat at 14.4 (max for a good battery at normal temp).
2/ the alternator saw 13.9+14.4=28.3 (0.5 v below full charge) so it poked out more juice.
3/ This overcharged the upper battery and made it hot.
4/ As a battery heats up it's full-charge voltage drops!.
5/ More from the alternator.
6/Bottom battery reaches full charge but top battery is now hot (and therefore low voltage).
7 / Alternator pokes out even more juice.
 
And with perfect timing, I've had a response from Intervolt. They make voltage converters, two of which can be used as battery chargers for a second wet 12v leisure battery from which you also run your 12v loads. You don't have to have the battery so it can run stand alone as well. Two models, isolated and non isolated. In discussions, for your 4x4 use, although they recommend the isolated version, the non isolated is in fact fine for this application.

I'm hoping to get some pricing sorted on them soon if they are of interest.

Have a lookee here. http://www.intervolt.com/product/voltage-converters-non-isolated-maxi/

One caveat to these is that the starter batteries must not be regularly disconnected from the input to the non isolated version I have shown. For any application where this is likely then a fully isolated version is needed. Lookee here.
http://www.intervolt.com/product/voltage-converters-isolated-maxi/
 
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So presumably, as I have a battery isolator switch fitted, I need the second type? It would be a handy thing as I do want to fit a second battery at some point
 
So presumably, as I have a battery isolator switch fitted, I need the second type? It would be a handy thing as I do want to fit a second battery at some point
I spotted that on your post on another thread. :)
If you wish to keep the battery isolator as a regular use item rather than for emergencies only then yes, the isolated version is essential to stop the leisure battery discharging through the converter in reverse. If the isolator will likely be left closed (should the discharge problem be sorted) then the non isolated version will be fine.
 
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I spotted that on your post on another thread. :)
If you wish to keep the battery isolator as a regular use item rather than for emergencies only then yes, the isolated version is essential to stop the leisure battery discharging through the converter in reverse. If the isolator will likely be left closed (should the discharge problem be sorted) then the non isolated version will be fine.
The long term solution though is probably just to fit a 12v leisure supply and run everything 12v from that
 
The long term solution though is probably just to fit a 12v leisure supply and run everything 12v from that
With regularly switched or emergency only/rarely opened 24v isolator?
 
With regularly switched or emergency only/rarely opened 24v isolator?
24v usually isolated via the -ve when parked up
At some point maybe a solar panel for the 12v as well, but given the size of rooftent I need to sleep four that may not be practical. It may just be a fold up panel for when parked up.
What you want to avoid though I would guess is the 12v discharging back into the 24v side
 
That would need the isolated version then.
 
Im looking to install a dropper off the ignition circuit for the 12v things so the second battery has nothing extra attached other than a swiched voltmeter which will have a negligible impact. Once that is done then i want to include some security devices to prevent the car starting
 
These have an ignition sense wire, they can be switched off with the ignition.
 
Ben, I have a dropper from a lorry, has been in my toolbox drawer for a few years you can have if you want?

20180110_085236.jpg
20180110_085242.jpg
 
Wow, thats very kind of you Richard, will PM to arrange. Thanks very much.
 
Thanks for meeting and bringing the dropper Richard. It was good to see your truck in the flesh and the stonking progress, and to talk cruiser for a while!!
I will let you know how I get on. Cheers Ben
 
Good cruiser talk, the 60 looks great! Nice to meet you Ben
 
15182112-C5D3-48DF-A350-0D520AB9638E.jpeg New CTEK arrived and is now on its maiden voyage. Spare battery was 12.43V at the start.
 
The charge cycle has ended after a “restore” and the battery is now at 13.7v so a big improvement but not quite up to 14ish that I expected.
This battery had gone flat a few times though
 
The 14.4 will be the bulk charge that the charger puts in if its happy with what is coming back from the battery. 13.7 isn't bad. How long was it on for? It may benefit from partially discharging and another charge. If it's gone flat a few times it all depends on how flat and if any damage has been caused by doing so.
 
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