40amp 12v charger or 5amp 36v charger

[Tscjcampbell]

hey guys,

Let me start out by saying i know 12v batteries are not recommended in a 36v cart. That being said i have a 1977 ezgo 3 wheeled cart that has 3 12v batteries installed by the previous owner. I will mainly be using this cart heavily one week a year at a vintage tractor show to get around with. I will be without electricity while camping other than my generator. I was wondering if it would be possible to run a separate parallel circuit on the batteries to "fast" charge with a 40amp 12v charger, instead of the 5amp 36v charger. I know you can charge a single battery in a series setup by just connecting the leads to the single battery. kind of what i'm thinking about just on a bigger scale. I can't run my generator all day waiting for the 36v 5amp charger.

Any constructive thoughts would be appereated

Tim.

[yurtle]

First things first. Are the 12 volt batteries specifically made for golf cart service? If not, they won't last. All deep cycle batteries aren't made alike.

If you really want to get some life out of these batteries, neither will work. 12 volts - one at a time - won't charge them equally, and likely isn't made for golf cart batteries. The 36 volt charger is too weak at only 5 amps.

[Tscjcampbell]

They are not golf cart batteries, they are Walmart marine batteries. (good stuff) I know they won't last, but a 41 year old cart with a rotted out battery tray to be used 1 week a year isn't worth the $800 for the correct batteries. I'm not concerned about the life of the batteries as much as I am wether the 12v paralled charging will work. The batteries are equal in age and capacity so I would think it should work for a couple days, but I'm sure there is somebody smarter than me here to confirm or correct me.

[yurtle]

I'd opt for the 12 volt parallel charging IF the charger is made for deep cycle batteries. 40 amps is a lot. Are you sure this isn't for BIG cranking batteries?

The 36 volt charger would be better at keeping them balanced, but I doubt 5 amps is enough to do the job.

[cgtech]

For the 12v parallel setup, you would need to remove the blue wires while charging, or you are gonna get a real good light show. also, 40a wouldn't be a problem because while charging parallel, the batteries would theoretically get 13.33 amps each.

[yurtle]

A charger doesn't "push" amperage. It only "allows" what the batteries "ask for", but it may be too much. I don't know if discharged batteries need to be "moderated", or if they binge on amps.

[Tscjcampbell]

Well the smart charger that I usually use to charge those batteries and my camper batteries outputs 15amps. So I was figuring that 40amps/3 would put it below that. In any case the charger is also capable of 30amps as well. I'll just drop it down to that if the batteries get too hot

[Tscjcampbell]

Cgtech

I was playing with the idea of putting in some sort of disconnect on the blue cables to isolate the 12v circuit while charging.

[yurtle]

It would have to be capable of handling the massive amount of current the controller needs. Stock controllers are 275 amps. Assuming this is output, and given that there is a heat sink (heat losses), you may be looking at a number of 300 amp disconnects = $$$.

[Tscjcampbell]

No fancy controller nonsense in this old girl. Just wiper speed contacts, resistors, and the motor. Anybody have a guess at what amps a 1977 36v motor draws at full warp?