its pretty straight forward. my hmmwv (humvee) is 24v and im wanting to put a 400w power converter in it. im wondering if the power back feedsto the first battery.

 

well it works on a cycle right so it would be 24 volts according to your drawing.

 

I don't think the drawing's right. For a 24V series connection, the starter should be connected to the positive side of one battery and the negative side of the other.

Without trying to create a fancy drawing it should look something like this:

To starter----<|+ -|<---|+ -|<----From starter

You've got the starter connected to the positive and negative terminals of the same battery. It will see only 12V. (So will your inverter, if you hook it up the way you show).

And, you do not want to hook the batteries up this way (in a loop). They're each trying to negate each other.

Actually, my first statement was wrong about your drawing. The starter and your inverter will both see zero volts.

However, if you hook the inverter to only one battery and that battery is connected to the circuit in series, then the inverter WILL see 12V.

- Jack

 

yea jack is right your drawing is wrong your batteries would probally explode or melt down if connected like they are in the drawing. if you connect to only one batt in the series with the inverter it will only see 12v just make sure you connect directly to the positve and negative terminals on 1 battery only and dont ground the negative cable of the inverter to the frame and have the positive to a battery.

 

Thanks I thought that maybe it was wrong i did it without really seeing them. But I know that they use two 12v to make a 24v system. so as long as i only hook up to one battery im good right?

 

Yes as long as you hook to only one battery's terminals you should be ok. But you will be pulling from just that one battery. You can buy a 24 to 12 volt converter so you pull from both evenly.

 

And, to add to this, it's really not a good idea to drain a single battery in a series circuit more than the other. If you do, the drained battery will cause the other one to overcharge, since the same current has to flow through both during charging. It's even possible, by discharging a battery far enough, to drive a cell into a "sub-discharged" state, which is really bad for the battery.

I'd go with ab46501's suggestion about a 24V converter or, maybe there's such a thing as a 24V inverter.

- Jack

 

That's what I was thinking but didn't say? Thanks Jack! LOL

I don't know much about humvees but I would almost guess that the truck is already equiped with one someplace? I would think the interior and exterior lights and any stereo system it might have would be 12v? It would seem very expensive and not real practical to manufacture all that stuff for 24v? If that is they case and you could locate it then your problem would be solved? But maybe not if it's a military version type of thing?

 

The best move is to convert the truck to 12V. If it has a 24V winch, it gets tricky, but it should be pretty easy to sell it to someone keeping a 24V truck & buy yourself a 12V winch.

 

I knew you were thinking it ab46501! I could tell from your post, but, the point was important if he runs the inverter for a long time on the single battery, so I decided to add my 2 cents.

I have to agree! I cannot believe they've created a whole bunch of 24V accessories for just one vehicle. Or, maybe this is why GM has gone bankrupt?

I'm trying to think of why it would be 24V in the first place and I'm coming up a bit short. The only advantage I can see is that 24V will "burn through" corrosion/poor contacts better than 12V. Maybe, under the "severe" conditions the military version this thing sees, this is important. I cannot recall what input voltage military radios use. It's possibly 24V and that could be the whole reason too. Wish I still had an old tech manual, but after 25 years, they're all gone.

I'd sure look for a step down voltage regulator somewhere in that system.

- Jack

 

there is no feasable reason to convert a 24v vehicle to 12v just so you could use a 400 w inverter they make 12v, 24v, 36v, and 48v inverters for rv's and solar powered homes. just pick up one of them for 24v and all your problems are solved. they even make some that use all voltages and they regulate it internally.

he may run into a problem if he finds and uses a factory stepdown to 12v on the vehicle if the inverter over taxes the power that the stepdown can safely provide to the inverter and the vehicle equipment that uses it.

 

US military vehicles have historically run 24VDC-gnd, so there's a LARGE market, and most of the stuff in them is the same (starter switch, headlight switch, lights, radios, etc.). It requires 1/2 the current (smaller wires, less heat loss) of 12V.