24v to 12v system conversion

[Outlaw]

Hoping for some insight please.

Recently purchased a military radio landy currently running 5 batteries (how's that for overkill) It has a 12v alternator charging the 12v battery under the passengers seat as per normal defenders for general vehicle operation and also a twin battery bank either side of the vehicle charged by a 24v generator under the bonnet.

First thought was to push aside the idea of removing all that weight... now to take that back to 12v for easy use as not running anything requiring 24v... i could either just change the cables and hookup method so can be charged by the alternator, though that would be a bit of a load keeping 5 batteries going.

So would like to keep the 24v generator doing it's job but then utilise 12v.

Thoughts??

[Outlaw]

if i can find out how much output power from the generator how about putting an MPPT in line between it and the batteries?

[Lotz-A-Landies]

If you were running a full kit of military radios, then 4 batteries for the radios may only just keep up. The dual voltage system was designed so that the vehicle would still operate even if the radios flattened the batteries on the 24V system, it also meant that the parts supply for the vehicle systems were compatible between GS, FFR, Snr Commander and RFSV variants.

You can run the 24v system on only two batteries on one side. You either remove the cables across to the RH side or protect the RHS end terminals and use the box for something else.

The 12V vehicle system is independant of the 24V radio system, sou can remove the belt off the large CAV alternator and the vehicle will still operate normally.

[Blknight.aus]

The 24.v alternator is configured for 40amps output.

You won't get a dc/dc charger that will charge them.and run the load without killing the 12v system if the 24v side is flat, the 12v side just doesn't have the grunt.

A workable solution is to convert the 12v alternator to 24v use that to run the radio batteries and then use a 24/12v dc dc charger to look after the 12v electrics. You only need to hit 25a to run all the standard 12v electrics and still slowly bring the battery up.

[Outlaw]

Thanks for that Diana but didn't answer my question

That helps Dave

[Mick_Marsh]

A few products I am collecting for my Perentie.
24- 12V DC-DC Converter 40A - Jaycar Electronics
12V/24V 30A MPPT Solar Charge Controller - Jaycar Electronics
2000W 24VDC to 230VAC Modified Sine Wave Inverter - Jaycar Electronics
Oh, and some solar panels.

I've almost collected them all.

I also might get a 24/12V DC charger in case the 12V battery goes flat.

[THE BOOGER]

you can keep it all original and use a 24 to 12 volt transformer you will have so 12 power you wont know what to do with it all

ECMP3066 - 24- 12V DC-DC Converter 40A

something like this there are plenty around on ebay or jay car

[Blknight.aus]

you can keep it all original and use a 24 to 12 volt transformer you will have so 12 power you wont know what to do with it all

ECMP3066 - 24- 12V DC-DC Converter 40A

something like this there are plenty around on ebay or jay car

Or you could just buy your accessories in 24v format and run them direct and save the losses.

Additionally some items are more effecient on 24v, the Eva cool fridge runs about an 8.5a draw on 12v and about 3 on 24...

[isuzutoo-eh]

I have two deep cycle batteries for the 24V, and have the nominal 20 amp version of what Mick has: 24 - 12V DC-DC Converter 20A - Jaycar Electronics
I figure that is enough for two fridges and some low power (USB ) accessories. I can't decide if to bypass the junction box and have individual fuses per battery or take an output from it to the converter.

Problem is, the convertor will keep pulling current till the batteries are down to 20V, before it'll cut out. A fair bit too low!
As such, I don't yet have a (pair of?) low voltage protector/cut out.
The most easily available are 12V, and up to 40 amp, whilst those suited for 24V tend to be 10 amp only, and I expect to exceed that often enough to cause problems. A pair of 12V 10amp cut outs might be my best bet, for the money involved.

[Outlaw]

Finally had a chance to get back to this and new problems I didn't notice before

Mine still has the generator in place and I added new belts last week to it... However the brightspark who had it before me removed the distribution box, cables etc.

Any idea a part number on the 3 prong connector or where I can find it. Plus a wiring chart would be handy to get it charging the batteries again please.