Hotchkiss Jeep Battery Capacity

[Jessie The Jeep]

My jeep batteries ( 2 x 12v ) are starting to be a little poorly after the 3 1/2 years I've had it and how ever long they were in before that. I'm assuming that the batteries are at fault as they don't seem to be holding charge. After a week in the garage unused, it can be a little slow to turn over, if at all; but if I've been out for a drive, and then try to restart, it's fine. This suggests to me that they are receiving a good charge while being driven, but won't hold the charge over a longer period.

 

So my question is, what amperage should I be looking for. There were no markings on the batteries when I first got the jeep, so I wasn't sure of the amperage considering it is running 24v rather than 6 or 12v. Am I right in thinking there is a larger current draw when running a higher voltage?

 

Steve

[Tony B]

the power in Watts is found by Voltage X Ampage, so to get 24 watts, a 6 volt battery would use 4 amps a 12 volt 2 amps and 24 volt 1 amp. Try discharging batteries completly and then slow charging over three or four days. there is a post somewhere over rescuitating battries.

[Jessie The Jeep]

The batteries have been fully discharged, and trickle charging hasn't helped. I happened to be in Halfords the other day for some paint, and while their had a look at their batteries. They all seemed to be labelled by start current in Amps, so it's the Amp draw at start up I'm looking for.

 

Steve

[N.O.S.]

Don't batteries usually just give you the Ampere-Hour rating (Ah)? A 12V battery with a 80 Ah rating will give you 80 hours at 1 amp or 40 hours at 2 amps etc.

 

A bigger capacity battery may not give you any higher maximum current capacity but will crank the same motor over for longer. The current is determined by the load (i.e. starter motor) subject to the battery being physically capable of delivering that current. If the current capacity of the battery is low it might not turn the motor as quickly as a high capacity battery.

 

I now only use the Optima spiral cell type, which seems to give about 20% higher max. current capacity, so it will crank an engine over a lot quicker which can make the difference between starting or not, especially with diesels! Because a low current capacity battery will crank a motor slower than a high capacity one will.

 

My GMC and Jeep 6V batteries are only 50Ah but will spin the engines over much quicker than a heavy duty 6V conventional battery of greater Ah capacity. Another advantage is you get less voltage drop - my jimmy used to have only 3V at the coil when cranking :shake: Mind you, it still started :-D And the 6V ones are only 1/2 the size of a standard 6V battery!

 

For heavy duty 24V applications, using two 56 Ah 12V batteries (112Ah total) to replace two conventional 140 Ah ones (280Ah total) still gives much faster cranking speed (if the engine starts instantly you dont need the extra Ah 'cos you are not cranking the engine for anywhere near the same length of time, so you never drain them). But they do come at a price.

 

Back to your problem, sounds like the batteries are simply tired, and need changing. With batteries you usually get what you pay for - a cheap battery will tend to have less lead and often of a much lower quality, so may last little time compared to something heavy and expensive :cool2:

 

Sorry just changed some of this 'cos it was scribble - hope it makes more sense now!

Edited October 7, 2008 by N.O.S.

[Jessie The Jeep]

I'd agree the batteries are tired. As I said earlier, I've had them 3 1/2 years, and I have no idea how long they were in the jeep before that.

 

Steve

[Jessie The Jeep]

The reason I asked about higher voltage and current draw was that in radio controlled models, servos pull more amps when running on higher voltages. That's why I was wondering if the jeep would pull more amps at start up on 24v compared to 6v.

 

Steve

[N.O.S.]

I would expect a 24V jeep starter to have a power rating roughly the same as a 6V one, so the current draw at 24V should be a lot less, but I guess in reality the 24V motor spins a lot quicker so drawing more power, thus current may not be a lot different?

[REME 245]

I think this sites states two 12 volt 45 amp hour battery's.

 

http://ourworld.compuserve.com/homepages/Jeep_man/spec.htm

[Jessie The Jeep]

Thanks everyone. Just need to raid the piggy bank now!

 

Steve