BATTERYS CHARACTERISTICS

[M37DODGE]

Hi every body,

I wish to know what kind of batteries do the m37 needs. I know it is a 24 volts engin, so it need 2 12 volts batteries, but how many AH each battery?

thank you very much

William

[peter e mark]

Hello there fellow offroad enthusiast. Automotive Fundamentalism and Vehicle Restoration Purist Society put aside, my particular choice for batteries is the ULTIMA redtop 12 volt jelley batterey , That's right ! They are rated near 1000 amps for good starting in cold weather, and I have had alot of success with them. Carry on trooper

[greencom]

I've had great results with two smaller size 12v units from Walmart. The stock engine in these trucks are a small displacement with a rather low compression ratio so there is no need for expensive heavy duty batteries.
Even with a heater going and lights on the generator is supplying the current not the batteries.
Greencom

[Lifer]

I was taught that, in a fully functional system, the current is provided by the battery and the generator keeps the battery replenished as current is drawn from it. This way, the current provided to electrical components is constant.

If you disconnect the "hot" cable while the engine is running, the generator will pick up the slack and the engine will continue to run, but the current to the various electrical components will vary with engine speed.

[Nickathome]

I do not know what the actual rated battery should be, but I think I would want something with a generous amount of CCA (cold cranking amps) for cold weather starts. That said, I personally see no need to buy top shelf (read high $) batteries. I must lean also toward what greencom said but from the standpoint of a secondary hobby vehicle whereas even the wal-mart batteries will probably have something with a good enough rating to suffice.

[greencom]

Hi Lifer,
As it was explained to me in Tech school the battery is kept charged by the generator mainly for it's next starting job only. Aside from that it's just along for the ride although it does help in keeping the voltage constant but the voltage regulator does the bulk of that job regardless of engine speed. The two batteries in my M are for a Ford Escort, fit really nice in the box. Nice talking to you and all you guys again. Take Care
Greencom

1953 M37
1962 Jeep CJ3B
1930 Ford Tudor

[greencom]

I forgot to add that If you draw more current than the generator can provide the battery will soon go dead, so the generator not the battery determines the amount of current you can pull from the system long term. Again, this is what my instructors taught me. Makes sense to me.
Greencom

[Lifer]

Makes sense to me, too. Could it be that my high school shop teacher didn't have all the facts?

[MSeriesRebuild]

I'll share my thoughts on this backed by many years of heavy duty experience. The higher amp batteries are better built, will stand up to much rougher service, such as severe off road. Those of you who love them, forgive me, but Wal-Mart batteries are cheap for a reason. Think about it, Wal-Mart has batteries built especially for them, (cheap). They are not top quality by far & their warranty is of course based on use only in on highway vehicles such as Mom's grocery getter type vehicles. In a high vibration environment such as heavy duty vehicles, off roading where they will receive the shock treatment from rough roads or no roads, you will see fairly soon what Wal-Mart batteries are made of. Auto parts suppliers also offer the same cheap stuff, but along with much higher quality batteries up to & including the jells. In a small package, jell batteries can't be beat as their make up provides extreme quality to go into a small physical size. That said, they offer the best battery that will easily fit into an M37 battery box. Wet cell batteries, brands like Caterpillar, John Deere & a few others who offer extreme duty batteries are the best bet. This is because they are designed for the extreme off road, high vibration environment. Their heavy duty design of course calls for a more rugged case & internals than something that will be run strictly on highway in a passenger car. For this reason they are physically larger & may be hard to fit into a confined area in a size adequate to offer good cold cranking capability. Long story short, install a passenger car type battery in an application where it doesn't belong, it's life will be significantly shorter than you think it should be. All products that have any manufacturer backing are designed & built with specific applications in mind, batteries are no different. As far as the generator question, a 25 amp capability ain't a lot. To think you can run lights & other accessories for any period of time without good batteries in place is just obsurd. You will find out just how obsurd when you go to start the next morning in the cold & find out your batteries don't sport a full charge, it's because the generator can't keep up with demand. On more modern vehicles where high output alternators are used, this isn't an issue. On our Cummins repowers we spec 120 amp alternators on the engines when new. Issues such as weak batteries are never an issue. Not a problem for the alternator to keep up & it's capable of doing it at a very low RPM.

[knattrass]

Charles - Believe I have an original gen at 25 amps. Are there higher output ones that would still be considered "correct" for the m37?

[MSeriesRebuild]

Charles - Believe I have an original gen at 25 amps. Are there higher output ones that would still be considered "correct" for the m37?

There is a 100 amp system that was used on radio trucks or the 60 amp military alternators that were used on later military vehicles.

[peter e mark]

Hello LIFER, nice to see you got another stripe. In light of this thraed , as I just bought a 25 AMP, 24 volt generator from Big John B, I now want to exchnge it for a 60 Ampere model. By the way troopers, I finnaly got my war wagon running today, although it remains at 12 volt , for now.

[Lifer]

Thanks, Pete! The promotion party will be at your house tomorrow afternoon. You buy the beer!

On the current debate, I fired up the old Pontiac which is equipped with a generator, not an alternator, and then disconnected the battery cable after the engine warmed up. It continued to run, as it should, but there was an easily noticeable variation in the current flow. The ammeter needle would fluctuate with engine speed. The headlights became noticeably dimmer when engine rpm dropped down to idle speed but got brighter as rpm increased. Obviously, then, the battery is the stabilizing component in the system, not the voltage regulator. Maybe my shop teacher was right after all?

[MSeriesRebuild]

Thanks, Pete! The promotion party will be at your house tomorrow afternoon. You buy the beer!

On the current debate, I fired up the old Pontiac which is equipped with a generator, not an alternator, and then disconnected the battery cable after the engine warmed up. It continued to run, as it should, but there was an easily noticeable variation in the current flow. The ammeter needle would fluctuate with engine speed. The headlights became noticeably dimmer when engine rpm dropped down to idle speed but got brighter as rpm increased. Obviously, then, the battery is the stabilizing component in the system, not the voltage regulator. Maybe my shop teacher was right after all?

Well Charles, you nailed it. Your test also explains why generators have taken a back seat to alternators many years ago. Alternators are capable of producing much more current at low RPM where as the generator will be down next to extremely low or no current output at low RPM. The fact that your system has an ammeter tells the story very clearly.

[peter e mark]

And now the question begs: Did the military ever make an alternator for the M37?