Is it ok to charge my entire system if one or two batteries are low?

CabinetGuy · 11-12-2013, 04:06 PM

I just bought my first 36v cart a few weeks ago and am still learning, so please forgive me if this is a stupid question.

My charger took a crap so I have been using 2 - 6v/12v car chargers (1 - 3amp and 1 - 6amp) until I can afford to get a new 36v charger. I noticed that a few of the batteries had a lower percentage of charge (car chargers have gauge that shows percentage of charge). I've been trying to keep them all relatively the same charge percentage, but with a 3a and 6a charger, it's been taking a while to get them all charged and I tend to use the cart before they are all at 100%.

My question is; when I get a new 36v charger, will it charge the lower batteries to equal out or will I end up overcharging the ones that have a higher % of charge because the charger is trying to get the weaker batteries up to 100%? My current chargers will do 12v or 6v but I've been just doing one battery at a time on 6v because I was worried that going across 2 batteries with unequal charge % would ruin one of them if I charged at 12v.

As an example of that scenario, I had one battery at 60% and the other at 80%. When I connected the two and set the charger to 12v, it told me the charge percentage was 66% (not sure how that worked out...). I was worried that I would overcharge the one that read 80% by itself so I just went back to doing them individually.

Thanks in advance for any help/suggestions.

jakesnake27 · 11-12-2013, 05:26 PM

No stupid questions on this forum!

Are all of your batts the same brand and age?
If so, when you get a 36v charger, plug it in and it will charge the pack evenly. Also, make sure the water levels are ok before charging (covering the plates before, then recheck after charge cycle completes; water level should be 1/4" above plates).

scottyb · 11-12-2013, 05:28 PM

You are playing with fire but in a mild way..... these batteries require a 10% capacity bulk recharge rate to maintain healthy plates. That is about 20 amps. 3-6a is not properly charging.
Additionally the cart charger will not compensate for any imbalance in the pack. it looks for the pack to reach say 45v and cuts off. If there are batteries which vary more than 10% in the pack some battery abuse can result. Your high batteries charge up first - and keep charging up while they wait for the low ones to come up high enough to reach the sum total. Once the total is reached the charger shuts off. But what have you got? You have some batteries at 8v and some at 5v ( in extreme cases) but you get the idea.
When this happens it tends to not resolve itself. The low ones stay low and the high ones stay higher, cycle after cycle. You need to manually balance the pack .
I hope this helps

Andy4639 · 11-12-2013, 08:13 PM

U need to do as SB suggested. I would suggest charging each battery by it's self with a good 6 volt charger. Get them as close to 100% of charge before U use the cart. Even if U have to take them out of the cart.

If the first suggestion isn't going to work then charge 2 of the batteries that are close to the same % of charge and charge as 12 volts.

Try to charge them as pairs with them as close as u can with the same % of charge.

But a 36 volt cart charger will not equal out the pack depending on how far out of range they are.
This is why most suggest to change the wires for the lights, to swap it every so often to keep the pack better in balance. If U leave the lights hooked to the same 2 batteries all the time and use the lights a lot they will always be a little less charged than the rest.

Just about every customer I have had to look at batteries the 2 with the lights and other 12 volt stuff hooked to them is the 2 troubled batteries.

sportcoupe · 11-13-2013, 05:23 AM

You can get an "ok" 36v golf cart charger at Sam's Club for $99 plus about $10 shipping. It'll work way better then what you're doing now and isn't terribly expensive. I do not recommend it for 48v carts, charging takes way too long on those.

http://www.samsclub.com/sams/stanley...prod1841149.ip

If no Sam's membership you can get it for $104 at Amazon (free shipping now)

Amazon.com: Stanley GBCPRO Golf Cart & Vehicle Battery Charger: Automotive

CabinetGuy · 11-15-2013, 02:09 PM

Sorry for the delay in response... I wish this forum would email me when I had a response (probably does if I set it up correctly, huh?)

Anyways, thanks everyone for the suggestions. I charged up all batteries to 95% +- so they all drain the same when I get the proper charger.

Thanks Sportcoupe for the link! I'm hesitant to get it though since some of the reviews are pretty poor. I think I'll keep looking on craigslist and such until I can find the right one for my cart.

scottyb · 11-15-2013, 02:15 PM

A proper charge requires close to 10% of the battery's capacity for bulk charge. Most cart batteries are 200 amps plus so a 10a charger is not really going to knock the stuff off the plates as intended.... resulting in shorter battery useful life. Maybe that's why the reviews are less than good?

11-12-2013, 04:06 PM	#1
CabinetGuy Not Yet Wild Join Date: Oct 2013 Location: Oldsmar, FL Posts: 21	Is it ok to charge my entire system if one or two batteries are low? I just bought my first 36v cart a few weeks ago and am still learning, so please forgive me if this is a stupid question. My charger took a crap so I have been using 2 - 6v/12v car chargers (1 - 3amp and 1 - 6amp) until I can afford to get a new 36v charger. I noticed that a few of the batteries had a lower percentage of charge (car chargers have gauge that shows percentage of charge). I've been trying to keep them all relatively the same charge percentage, but with a 3a and 6a charger, it's been taking a while to get them all charged and I tend to use the cart before they are all at 100%. My question is; when I get a new 36v charger, will it charge the lower batteries to equal out or will I end up overcharging the ones that have a higher % of charge because the charger is trying to get the weaker batteries up to 100%? My current chargers will do 12v or 6v but I've been just doing one battery at a time on 6v because I was worried that going across 2 batteries with unequal charge % would ruin one of them if I charged at 12v. As an example of that scenario, I had one battery at 60% and the other at 80%. When I connected the two and set the charger to 12v, it told me the charge percentage was 66% (not sure how that worked out...). I was worried that I would overcharge the one that read 80% by itself so I just went back to doing them individually. Thanks in advance for any help/suggestions.

11-12-2013, 05:26 PM	#2
jakesnake27 Gone Wild Join Date: Aug 2009 Posts: 14,245	Re: Is it ok to charge my entire system if one or two batteries are low? No stupid questions on this forum! Are all of your batts the same brand and age? If so, when you get a 36v charger, plug it in and it will charge the pack evenly. Also, make sure the water levels are ok before charging (covering the plates before, then recheck after charge cycle completes; water level should be 1/4" above plates).
jakesnake27 Gone Wild Join Date: Aug 2009 Posts: 14,245

11-12-2013, 05:28 PM	#3
scottyb Happy Carting Join Date: Dec 2007 Location: Southern California Posts: 73,410	Re: Is it ok to charge my entire system if one or two batteries are low? You are playing with fire but in a mild way..... these batteries require a 10% capacity bulk recharge rate to maintain healthy plates. That is about 20 amps. 3-6a is not properly charging. Additionally the cart charger will not compensate for any imbalance in the pack. it looks for the pack to reach say 45v and cuts off. If there are batteries which vary more than 10% in the pack some battery abuse can result. Your high batteries charge up first - and keep charging up while they wait for the low ones to come up high enough to reach the sum total. Once the total is reached the charger shuts off. But what have you got? You have some batteries at 8v and some at 5v ( in extreme cases) but you get the idea. When this happens it tends to not resolve itself. The low ones stay low and the high ones stay higher, cycle after cycle. You need to manually balance the pack . I hope this helps

11-12-2013, 08:13 PM	#4
Andy4639 48/400/Alltrax HS motor Join Date: Jan 2007 Location: Liberty SC, Garden City SC Posts: 6,190	Re: Is it ok to charge my entire system if one or two batteries are low? U need to do as SB suggested. I would suggest charging each battery by it's self with a good 6 volt charger. Get them as close to 100% of charge before U use the cart. Even if U have to take them out of the cart. If the first suggestion isn't going to work then charge 2 of the batteries that are close to the same % of charge and charge as 12 volts. Try to charge them as pairs with them as close as u can with the same % of charge. But a 36 volt cart charger will not equal out the pack depending on how far out of range they are. This is why most suggest to change the wires for the lights, to swap it every so often to keep the pack better in balance. If U leave the lights hooked to the same 2 batteries all the time and use the lights a lot they will always be a little less charged than the rest. Just about every customer I have had to look at batteries the 2 with the lights and other 12 volt stuff hooked to them is the 2 troubled batteries.

11-13-2013, 05:23 AM	#5
sportcoupe Gone Wild Join Date: Sep 2012 Location: Savannah, GA Posts: 2,760	Re: Is it ok to charge my entire system if one or two batteries are low? You can get an "ok" 36v golf cart charger at Sam's Club for $99 plus about $10 shipping. It'll work way better then what you're doing now and isn't terribly expensive. I do not recommend it for 48v carts, charging takes way too long on those. http://www.samsclub.com/sams/stanley...prod1841149.ip If no Sam's membership you can get it for $104 at Amazon (free shipping now) Amazon.com: Stanley GBCPRO Golf Cart & Vehicle Battery Charger: Automotive Amazon.com: Stanley GBCPRO Golf Cart & Vehicle Battery Charger: Automotive

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11-15-2013, 02:09 PM	#6
CabinetGuy Not Yet Wild Join Date: Oct 2013 Location: Oldsmar, FL Posts: 21	Re: Is it ok to charge my entire system if one or two batteries are low? Sorry for the delay in response... I wish this forum would email me when I had a response (probably does if I set it up correctly, huh?) Anyways, thanks everyone for the suggestions. I charged up all batteries to 95% +- so they all drain the same when I get the proper charger. Thanks Sportcoupe for the link! I'm hesitant to get it though since some of the reviews are pretty poor. I think I'll keep looking on craigslist and such until I can find the right one for my cart.

11-15-2013, 02:15 PM	#7
scottyb Happy Carting Join Date: Dec 2007 Location: Southern California Posts: 73,410	Re: Is it ok to charge my entire system if one or two batteries are low? A proper charge requires close to 10% of the battery's capacity for bulk charge. Most cart batteries are 200 amps plus so a 10a charger is not really going to knock the stuff off the plates as intended.... resulting in shorter battery useful life. Maybe that's why the reviews are less than good?

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