Tell me why this is a bad idea...

[Flea]

After bouncing some ideas off a friend of mine, I had mentioned I wanted to do a dual volt system (12 and 24 volt).

I told him there are three ways to go about doing it - 12V or dual-volt alternator, 24 to 12 converter and just tapping off one battery and hoping for the best.

I told him i wanted to do the alternator route, but that required a lot of work. Reason being is that I can have a 12 volt system separate of the vehicle's system and one can still work while the other is out. But, there is some fabrication required and I'm not sure I'm equipped to fab the stuff up.

He said "why not get another battery and use the converter to do the charging?"

Could this work? I'm wondering because the 12V system won't have too much drain; just the occasional trailer and perhaps a radio & power outlet for a cell charger.

My instincts tell me bad idea, but then the logical side of me sees how it could work...

Ideas?

 

[sermis]

I picked up a duel output ALT a while back. Both 12 / 24 volt. I think they are from the HUMVEE. I thought about it for my M725. I am running a 350. The truck could be 24V and 12V for starter, HEI, radio.
I also have a couple 25 watt DC power supply which changes the 24V to 12V. Would power everything except the starter.
Trailer, just change your bulbs.

 

[MikeON]

I've beening thinking of the same thing.

I have a Tekonsha brake controller powered from the 24v - 12v converter that I got from an ebay seller. The converter is supposed to be overcurrent protected.

As a test of my setup, I stopped the deuce and civvy trailer on a slight upgrade and tried holding them there with the trailer brakes only, using the manual lever on the Tekonsha in the fully on position. The trailer held me there for a few seconds, then everthing started rolling backwards. No trailer brakes or lights after that.

Got home and found the converter no longer worked, although the fuses were not blown and the 24v side still drew current. Contacted the seller and he sent me a new converter. It has been working fine, but I haven't repeated the test with the Tekonsha lever fully on. To avoid loss of trailer brakes at an inconvenient time, I'm thinking of wiring in a motorcycle battery parallel to the converter, or wire up a switch to power the trailer from one of the deuce batteries in an emergency.

I look forward to other replies to your question.

Mike

 

[rosco]

Hey Mike
A breaker of the proper size/voltage, is best used on the trailer brake controller, rather then a fuse. It will re-set automatically, but the fuse is done for. Also the controllers spec's a heavy wire from the power source all the way to the brakes. Maybe there was just too much draw on your system, in that application, some of which, was just resistance.

Otherwise, I think the the inverter to another 12 volt battery, is the way to go, for accessory power.

Lee in Alaska

 

[rmgill]

A standard 24-12 volt converter is going to put out 12 volts and not properly charge the battery. There are 24-12 volt converter that have settings for charging a battery and won't over charge the battery as they'll put out the 13 volts or so needed to properly charge.

Newmar (http://www.newmarpower.com/) makes one that's water resistant and made for marine applications. They're well made but not cheap. I have another unit on my deuce that works well, but it's not sealed so I'm expecting it to fail eventually.

Here's the line of DC-DC converters:
http://www.newmartelecom.com/DC-DC-...Standard/DC-DC_Converter_Standard_Series.html


For anything but tiny amperage draws don't pull from one battery. It'll eventually leave you stranded as the other battery will over charge and the 1st one will undercharge.

 

[emmado22]

Get a 100 amp HMMWV 12/24 amp generator, thats the easiest way. You might have to mess with the pulley, but thats what I would do!

 

[BFR]

Now paging blythewoodjoe...Now paging blythewoodjoe...

I really would like to know what all you had to do to make the hmmwv setup work on your bobbed deuce.

 

[sermis]

Here are some pic's of the one I have.
I have not mesured the deuce alt but I think they are the same.