Batteries Won't Fully Charge

Big Jim

New Member
Hi again guys, I have a question about my golf cart batteries that won't fully charge. The batteries in my cart are almost 2 years old. I have had it for just over a month. It has been through 2 different owners since battery install. So I am not sure on how well they were treated, break in period, how many times they have been ran dead, etc. I have also tried 2 different chargers and have let the batteries charge up to 24 hours, and they will never fully charge. The charger will start out at about 30 amps, eventually get down to about 6 amps and sit there. I have checked and filled the water. When I got it i added a gallon and a half across the bank. Yes they were low . A month later I checked them again and added another gallon. Low again. After talking to some other people in our community, they only charge their carts every week or 2. I charge mine nightly and only get a couple hours use before they die. I did I load test on the batteries. They all seemed to be fine, I only had a 12 volt load tester, but each battery never dropped below a half a volt under load. I don't want to buy new batteries if I don't have to. Especially if they are just shy of 2 year old . Any help would be greatly appreciated.
 

Diode

Cartaholic - V.I.P. Sponsor
You most likely have one or more bad batteries also your OBC is more than likely bad it should shut off after 16 hours
 

Diode

Cartaholic - V.I.P. Sponsor
Check your batteries negative terminal look for a letter and a number stamped into the lead post the letter and number
 

Big Jim

New Member
The battery terminals are stamped B7 which I talked to the guy who installed them said that was Feb 2017. He is the one that let me borrow his charger and his didn't shut off either after 14 or so hours.
 

Big Jim

New Member
The guy I bought it off of said he thought one or two of the batteries may be bad. How would I go about finding out which one is bad if there is a bad one? I have used the load tester and a voltage meter, and they are always within a half a volt with each other. After an all night charge or low charged.
 

Diode

Cartaholic - V.I.P. Sponsor
OBC controls charging not the charger. OBC will turn charger off after 16 hours, did you replace cables one cable must run through the obc. 1/2 volt is way off.

state-of-charge-chart-6-120.jpg
 

big mack

Cartaholic
Hi Big Jim, The way I test individual batteries is using a multi meter, you will need to drive the cart or have someone else while you watch the meter. Set the meter to dc volts either 20v or 200v hook the negative to battery negative and the positive to battery positive. Read and record the lowest drop in voltage, repeat with each battery. You may need to use jumper leads if your meter leads are not long enough to reach out from under seat. Batteries must be charged as full as you can get them. You can charge each individual battery with a 12v or 6v charger depending on 12 or 6v batteries. Each 6v should test 6.2v or higher at rest fully charged. Hope this will help.
 

Big Jim

New Member
Thanks Big Mack I will have to give that a try . I have tested them with a volt meter at rest after a full charge and I have around 7.2 to 7.5 across the bank, but I haven't tried checking under it's load, only the load tester I borrowed from a friend .
 

big mack

Cartaholic
this will give you readings at real time loads. theses readings will bounce around so be sure and get the lowest
 
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