My 24V to 12V plans

arnott1t

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Jan 5, 2005
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1,609
Well I've been cheating for a while now and finally decided it was time to stop. Curren't my 87 HJ 60 has a 12V tap on the first battery I use to power the radio and gauges from the turbo install. I know this is wrong and is stealing the life out of my batteries but it soon will be stopped. My plan is as follows:

I just ordered a 15amp 24V to 12V DC/DC converter. This converter will be fed from the second battery on a switched/relayed line and mounted somewhere in the cab. The converter will then feed a 3rd battery located in the engine bay. This third battery will feed my radio's gauges and coming CB. I'll make the converter switch so that in high demand situations like winching I can shut that additional draw off of my alternator and still not loose presets and the like sicne the regular battery will still provide power.

The converter should act like a alternator that is not powered by the motor. I also think 15 amps should be enough to power the sytems. I wish I had room to mount another alternator but no such luck.

Once all this is set up I'll need to remove the rats nest of wiring I have and do it properly. Wiring is something I pay no attention to detail on and hate. I need to do it well so I don't have to worry about it and so I don't affect teh reliability of teh vehichle.

Any thoughts or improvements you might add?

Also once I do all this I'll be purchasing new fresh marine deep cycle batteries for the 24V side of the truck. I hear these are the cats meow.....

Thanks in advance,
 
Joined
Dec 10, 2008
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Benders, OZ.
Hi Arnie,

I have a 24V JDM and have had the same problem as you. The previous owner had the stereo wired to one of the starters and it was causing an imbalance in the starter batteries.

I put in a Redarc 24v battery isolator and ran another couple of fullriver 85 AH Deep Cycles off that to the cargo area. Everything other than the stock standard electrics comes off the Auxillary batteries. Stereo, CB, Fridge, Reverse, Cabin and Camping Lights come from the Aux Batts. I have a convertor for the 12V stuff and keep everything else 24V as much as possible, lights etc, because it uses less battery power (more economical I believe).

This Set-up will cost a bit more than the one you described cause there is one more battery and a bit more electical cabling but it would be worth the trouble. With a decent dual battery system you will get 5 - 10 years out of the Aux batteries, as long as you dont abuse them.

If you want some plans to do the install u can pm me.

Cheers buddy.

Gav.
 

Greg_B

 
 
 
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Mar 28, 2002
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If you are never going to need more then 15 amps @ 12V you need to decide if the added expense is justified. If not, then run the 12V line to a fuse strip, take your draws there and be done with it. If it is worth it to you, then going to a 3rd battery is a good system.

Make sure your wiring is up to the task, long term.

Make sure you isolate the 3rd battery from the 24V side when the truck is not running. It sounds like you are going to switch the 12V line with key power, so it will be automatic. Good.

Make sure the converter load limits itself, meaning if you are drawing 30 amps off the battery for a short period, the converter will still only dump 15 amps through itself. It probably does, but double check with the manufacturer.
 

1High61

 
Joined
Nov 17, 2004
Messages
52
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Toronto
Hey There I was having trouble with my 12 volt setup on my hj 61 as well.
I purchased a solar converter to help fix the problem but it didn't work that great untill I decided I needed a seperate 12volt system consisting of two batterys in the rear of my truck. I now use the solar converter as a step down
transformer and have a relay with a switch on the dash so I can charge from the truck when needed or seperate it to avoid draining the starting batterys. This works well due to the fact I get my power from the 24volt side and its much simpler of a device when compared to one of those big inverter types. I have a sub and extra speakers and it all runs great with extra power for my 120volt inverter etc. it took some time to find a solution and for 2 years now this has worked great.
 
Joined
Aug 21, 2006
Messages
172
Location
West Kootenays BC
Hey There I was having trouble with my 12 volt setup on my hj 61 as well.
I purchased a solar converter to help fix the problem but it didn't work that great untill I decided I needed a seperate 12volt system consisting of two batterys in the rear of my truck. I now use the solar converter as a step down
transformer and have a relay with a switch on the dash so I can charge from the truck when needed or seperate it to avoid draining the starting batterys. This works well due to the fact I get my power from the 24volt side and its much simpler of a device when compared to one of those big inverter types. I have a sub and extra speakers and it all runs great with extra power for my 120volt inverter etc. it took some time to find a solution and for 2 years now this has worked great.

Will the Solar Converter/ Equalizer produce more then 12V to charge a 3rd battery? Wouldn't it need a separate ground from the 24V system? I would like to set it up to charge the battery in my tent trailer too.:beer:
 

Greg_B

 
 
 
Joined
Mar 28, 2002
Messages
4,567
Depends on which model you buy. If it is the EQ version, then yes: while the unit is trimmed at the factory at 1/2 total input voltage, you can adjust the output to running above or below the 50% mark. Chassis ground is fine.

If you have the PT version, then all load neutrals need to come back to the unit, so it can load limit itself.
 

iron_giant

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Jun 28, 2003
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Here again...
This is the way I did it and works very well (off the top of my head).
Between the 24v bank and a 12V deep cycle in the cab I wired in a 24v solar charge controller and a switch. On one side of the switch the 24v charge is reduced to 12v via a small 15A converter to charge the deep cycle. All accessories run off of a fuse block linked directly to the deep cycle so there are no restrictions on amperage. When the truck is running (alternator) or I have a 24volt solar panel hooked up, the 24 volts produced charge my deep cycle via the converter. When I am sitting I can switch the panels to charge the 12 volt or the main 24volt bank. I'll sketch something up to illustrate more clearly.
 
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