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Discussion Starter · #1 ·
I went into town today and talked to an electrician and think I want a second opinion. I am trying to run a 12v system and a 24v system off one 12v alt. Let me know your opinions. The drawing depicts 2 systems. What troubles me is the electrician said I can run the 24v system both parallel and in series. He sketched out this drawing/I redrew it and cleaned it up so you could have a clear depiction.

So far I have all the pieces depicted. Give me your opinions and technical solutions.
 

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so your plan is to charge (4) 12 v batteries off of a single 12v alternator, and have some solenoids so you can switch off, or open, the 12v pos lead, and then connect the intermediate cable and the 24 pos lead?

I'll number the batteries 1-2-3-4, left to right in the drawing...

on the left two batteries (1 and 2) in the drawing, the cable between the two neg posts will also need to be opened when in 24v, the no. 1 neg post is technically niether pos or neg when connected as intermediate, so leaving it connected to ground would essentially be a short circuit...same goes for the pos charg cable...when connected in 24v, the neg on batt 1 and the pos on batt 2 cannot be connected to anything but each other...you will need alot of solenoids to do it that way, and you will have alot of problems with the system, and diagnosing those problems can be a nightmare...

by telling you that you can run them in series and in parallel, I'm assuming he meant that you can run the 4 batteries in two packs, either:
A: each pack hooked in series for 24v, and the two packs hooked in 24v parallel for higher amperage

or

B:each pack hooked in 12v parallel, to raise the amperage, and then the two packs hooked in series to get 24v

you cannot run them in series and parallel at the same time. That would be hooking all 8 terminals from all 4 batteries togethor...big badaboom...

btw, I work on heavy equipment, so I deal with both 12v and 24v systems on a daily basis, and I do most of the electrical work in the shop, and I have built a few dual voltage systems, so I do have a bit of experience with this...

the easiest and most reliable way I have found to do both voltage is using an Anderson connector, and having a plug that can be plugged into either the 12v or the 24 v outlet essentially...its really just sort of a jumper, and the same battery cables are used...done that way, it switches from having the batteries in series to having them in parallel, so both (or all 4) batteries are evenly loaded and charged at all times...I think I have that schematic on photobucket, so I'll post it for you


what is it you are trying to run at 24v anyway? I'm assuming you are trying to do this on a basic automotive (12v neg ground system) vehicle, of some sort, correct?
 

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substitute the LH batteries for two hooked in parallel, and then do the same for the RH battery, if you really think you need 4 batteries, but thats going to put a huge strain on your alternator and extremely shorten its lifespan...it better have a high output...

to run that, just leave it hooked into 12v for running the vehicle and charging the batteries, and then when you need 24v, disconnect (using a switch) the charge wire from the alt and swap the Anderson connector over to the 24v position
 

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Discussion Starter · #4 ·
Yota Bill,

I like your idea A LOT better. I have two 24v Warn Mil-12,000 winches, one is a spare and the other is mounted to the truck. I have it connected using a pair of Red 175amp Anderson connector It works under 12V but it is slow, I have to admit it is powerful though. I also mounted it so I could unhook it and hook jumper cables to it using another Anderson connector. My truck currently has 4 Excide Blems (12 days old) $55.00 each plus tax in place of the old 2 D8 style batteries that the state of Oregon had installed many years before I bought it. I have two under the hood and two under the bed. My alternator puts out 180amps, I bought it from Maniac Electric Motors a year ago. No problems with charging batteries or running other devices (inverters, driving lights or powering the camper).

I thought there was a problem with his drawing, I didn't believe you could run them in series and in parallel at the same time. I appreciate the help and advice. I look forward to hearing or seeing other peoples ideas.
 

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OK, for that, just using the Anderson connector like I posted when running the winch would work fine, and not cause alot of headaches in the future...glad to hear you do have a solid charging system already in place, though...

one other thing I would consider is looking into what it would take, if possible, to rewire the winch for 12v use...not sure if they are set up in a way that you can just rewire them, or if it would mean replacing the electric motor, but its worth looking into
 

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Discussion Starter · #6 ·
I used this truck to pull a 5th wheel for years, so I have always had a solid charging system in place. Camping out in the middle of nowhere and waking up to a dead battery is not something I look forward too, so I have two of the batteries isolated currently by a solenoid on the positive terminal wire. The solenoid is rated for 300amps continuous, I have it mounted to the frame of the truck forming a ground and a 12v lead coming off a toggle switch in the cab. Switch in the on position = charging, off = isolated. I had a solenoid fail a year ago and blow a 200amp circuit breaker that is also in line. Not quite sure what happened but it melted the solenoid. I installed a second 200amp thermally protected breaker on the positive 2 gauge power source for the winch. Neat thing about these breakers is you fix the problem and flip it back to the power on position and go. Nothing to replace out of the trails. I looked into getting the winch rewired, the only option is a 340$ motor replacement, I can get a cheap Chinese motor for 199$ w/ a 3 month warranty. I am looking into all my options....
 
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