charging both batteries at once

[MJL61]

What would be the proper way to charge both batteries at the same time? Can I simply connect a pair of jumper cables: POS-POS & NEG-NEG, then attach a 12v charger as with a 12 volt system? I an seriously considering coverting from a 24v to a 12 v system in the future. Is there a good 'sticky' or comprehensive list of items required to perform such a conversion? I'm SURE there's more to it than the obvious... bulbs, generator, regulator, starter/coil/distributor, etc. Thanks for all the great info on this site!!!

[FrankenJeep]

Don't think so. It *may* pull down a "good" battery instead of charging, and a 12V charger ain't gonna do the job anyway. The experts can chime in here........ I always charge each battery separately, isolating both batteries from each other. This will also tell you if one of the batteries is bad (dead cell, etc). Matter of fact, I've got one now that must go back to AutoZone Monday....................


FJ

[Ben Dover]

A 24 Volt charger is a must, unless you disconnect the batteries and charge them individually using 12 Volt setting. I use a H.D. 6-12-24 Volt shop charger for this purpose.

[62gp]

I use a 24 volt battery minder/tender - stays connected all the time. It's computer controlled, keeps both batteries equally charged and desulfinates as well - Sonny

[Ben Dover]

And a battery tender will add substantial life to the batteries, especially if one is using the original GI Issue 2HN batteries, 3-4 extra years is possible. For quick charging tho a charger is needed.

[MJL61]

Has anyone tried to make an adapter that would allow you to convieniently hook-up a 24v battery maintainer to the slave cable plug (... if equipped)? I think that would be a nice feature...unless there is some systemic reason why doing so would not be advisable... any thoughts?

[Ben Dover]

Star Electric made up and sold slave cable adaptors with their battery maintainers. They were tpigtails with machined brass "bullets" having color coded (red and black) sleeves. The owner must use caution as to the polarity when attaching the wires.
These adaptors are no longer sold by Star Electric.

[W. Winget]

If you want to charge both batteries at once with a 12 Volt charger you will need to disconnect the cables, then rig pos to pos and neg to neg in parrallel so they are one BIG 12 volt battery. This will also equalize the charge in the batteries (assuming they are both healthy) and give best results.

If you want to pull 12 volts off the batteries you can use the grounded battery and run something like a cigarrette lighter or such. Best though is an inverter that will bring 24 Volt down to 12 volt for the device you want, available from trucking stores. Reason: Draining the grounded battery will never allow the generator (altenator) to fully recharge the drained battery, or it will overcharge the full battery as it's running. Not a problem if you swap batteries fairly frequently in the Army and have a budget, but at home it will cost you...$$$

I've seen some places (maintenance from memory) put together an Ammo Can with two small 12 volt gel batteries in it making a short 24V Jumper (Slave) cable assembly they can insert into the Slave receptacle, then move the vehicles around, disconnect and not worry about two batteries draining down when stored. (I assume the vehicles batteries were removed and the ends secured to prevent grounding.)

In my Command Car (12v) I run two 12 volters in parrallel so I have more amperage similar to the large (expensive) long Wiard that it originally came with. Totally not needed as I'm not pulling the battery down with a radio for hours on end, so a common car battery will do me fine for years.

Don't forget, Interstate battery dealers sell a LARGE 12 volter you can get for around $40 as a Blemish and two of these do well in a Deuce or other 24 volt application where you need some cranking amps.

You should not run a vehicle without some sort of battery connected into the system, as the diodes in the charging altenator will fry. Unlike the old trick of disconnecting the battery to see if the system is charging when we had older tougher charging systems.
V/R W Winget

[FrankenJeep]

I use a 24 volt battery minder/tender - stays connected all the time. It's computer controlled, keeps both batteries equally charged and desulfinates as well - Sonny

Where did you find yours? That's another item on my long list of things to get!

FJ

1951 M38 (running mostly restored)

1952 M38 (not running)

1953 M38A1 (parts)

[FrankenJeep]

If you want to charge both batteries at once with a 12 Volt charger you will need to disconnect the cables, then rig pos to pos and neg to neg in parrallel so they are one BIG 12 volt battery. This will also equalize the charge in the batteries (assuming they are both healthy) and give best results.

If you want to pull 12 volts off the batteries you can use the grounded battery and run something like a cigarrette lighter or such. Best though is an inverter that will bring 24 Volt down to 12 volt for the device you want, available from trucking stores. Reason: Draining the grounded battery will never allow the generator (altenator) to fully recharge the drained battery, or it will overcharge the full battery as it's running. Not a problem if you swap batteries fairly frequently in the Army and have a budget, but at home it will cost you...$$$

I've seen some places (maintenance from memory) put together an Ammo Can with two small 12 volt gel batteries in it making a short 24V Jumper (Slave) cable assembly they can insert into the Slave receptacle, then move the vehicles around, disconnect and not worry about two batteries draining down when stored. (I assume the vehicles batteries were removed and the ends secured to prevent grounding.)

In my Command Car (12v) I run two 12 volters in parrallel so I have more amperage similar to the large (expensive) long Wiard that it originally came with. Totally not needed as I'm not pulling the battery down with a radio for hours on end, so a common car battery will do me fine for years.

Don't forget, Interstate battery dealers sell a LARGE 12 volter you can get for around $40 as a Blemish and two of these do well in a Deuce or other 24 volt application where you need some cranking amps.

You should not run a vehicle without some sort of battery connected into the system, as the diodes in the charging altenator will fry. Unlike the old trick of disconnecting the battery to see if the system is charging when we had older tougher charging systems.
V/R W Winget

But that's what I've always been afraid of. IF you have a bad cell in ONE battery, it will also pull down the other one, right? That's why I always have charged each battery individually. And so that I could tell WHICH battery had a problem, if so.



FJ

[62gp]

Sorry for the delay in responding - I have used the Battery Minder model 24041 for two years and have it wired in so that hook up is a simple matter plugging it in to the battery circuit. I bought it on the internet - just Google search and you will find it. Don't know about other folks, but I like it - Sonny