Golf Cart Battery Post Burn Out

by Ernest McConnell
(Chelsea, AL USA)

I purchased my used 2002 EZ-Go with new batteries three years ago with new (no visible name) batteries. The cart is used for neighborhood cruising 3-4 times per week in summer and less in the winter. The batteries are charged every time I use it regardless of the usage.

I have had trouble with battery post corrosion despite new cables and careful attention to water levels. However, the battery water apparently boils over (even with careful water levels just above the cell) and leaves an acid residue on the garage floor.

During a 45-60 minute ride in the evenings, the cart will stop at least once while going forward (with the back-up bell beeping), and then, once stopped, start forward again as if nothing happened.

Last evening, I was riding, the cart stopped and would not restart forward again.

I looked at the batteries and one battery post had completely melted down and the cable was about an inch over to the side, and still connected and burning (small).

I hesitate to replace the batteries alone for fear that there is another problem other than the batteries.

What should I check or should I turn it over to a professional cart mechanic?

Hi, Ernest -
Don Stokes from Zap of New England says:

"Batteries in general heat up when they are being discharged quickly. This condition can cause the speed controller to shut down for a brief time and once cooled, start operating again. This can at times also cause standard lead acid batteries to "boil over", for a lack of a better term.

The batteries that are usually used for EVs are of the maintenance free variety called AGM batteries which are a sealed battery with the interior chemistry as a gel. These batteries are far less likely to leak due to charging and jostling.

If the batteries are creating a mess all the time, the charge controller may be using too much voltage to charge the batteries.

First, check the output voltage on the charger; it should be the same as your batteries. Next, donโ€™t use the cart flat out for long distances, vary the speed so the batteries and speed controller donโ€™t overheat.

Last, replace the old style liquid lead acid batteries with a deep cycle AGM battery."


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Cable insulation burning off
by: Anonymous

Noticed a burning odor while driving the golf cart. Checked, the cable to the fifth battery had the insulation burned off of it at the very end where the loop fixture connects to the cable. The cable was about 18" long and I replace it with a cable about 12" long. Ran fine for two weeks or so and the same thing happened to that cable. Noticed the agm battery was bowed in the middle after setting with no use for three days. No one has an answer as to the cause.

It sounds to me like that fifth battery is overcharging. After you let the AGM battery sit for three days without use, it bowed in the middle. For this to happen, pressure had to have built up inside from excessive heat boiling the electrolyte; and when you let it sit, the pressure had dropped and was now negative.

So I headed over to learn from the smart people at Battery University: the AGM batteries page.

They said: "As with all gelled and sealed units, AGM batteries are sensitive to overcharging. A charge to 2.40V/cell (and higher) is fine; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive."

Most golf carts chargers are for floodies, just like the automotive charging system. These vent themselves when they happen to overcharge a bit, and that is why we have to fill them with distilled water every so often. Maybe the chargers "top-up" is too much for the AGMs, just like it is in the automotive setting.

If ALL your batteries overheated, that would be my diagnosis, and the cure would be to take it off the charger at 100% (lead acid prefers to stay full, though, so not a perfect solution) or get a charger that floats at a lower voltage.

But that doesn't explain why it's only this one battery that's overheating.

If all of your batteries are the same type (AGM), the same age, and the same voltage (on the label, anyway; as you probably know, voltage decreases with age) and the same AH, and all your other batteries in the string are charging just fine, then I suspect you've got a weak battery. A voltmeter should tell you for sure.

If they are still under warranty, I believe you can take your batteries back to the place where you got them and get them replaced. It doesn't sound like you did anything wrong.

Hope this helps.

Battery post burnout
by: Greer

We did as Jedmeister by drilling and using screw and nut to. make another "post" because battery probably still has "life" in it. Problem is, the batteries "won't charge". Any help out there?

Ez go
by: Anonymous

We have a 2006 ez go golf cart replaced all batteries and replace the cellunoid , was running great for about two weeks until this weekend after driving around our camp ground coming up a big hill with over 600 lbs on it I smelled something burning then it died would not move lifted the seat one of the battery post was melted off the battery ,so first off bought a new battery not sure if this will work it is charging now also will excessive weight cause this and will it run if the maintenence switch is on

Fix Post
by: Anonymous

Lead post melted creating a hole' I put a brass bolt in the hole then melted solder to seal the difference. Clamped on the cables and drove away.

Interstate burnout
by: Anonymous

I replaced my EZ go with six new interstate batteries less than a year ago after 3 years with no problems on my original set of another brand. I thoroughly cleaned the post and cables and keep close watch to see all are tight. Within 2 months I lost the first interstate to post meltdown. The interstate dealer refused to warranty saying I must not have had the connection tight. Second mistake was I bought another interstate. 3 more meltdowns later being especially conscious of connections and corrosion I have slowly replaced them with power torn brand and had no problems whatsoever. Moral to this story, run from interstate golf cart batteries as they have an inferior post design and will readily melt. Buy anything else as their warranty sucks.

battery post breakge
by: Dave Robie Weymouth MA

Battery post breakage is due to the cable being not long enough to allow for expansion/contraction/movement/vibration. Especially with L posts. To solve this, make your cables a couple inches longer and bend them to an
"S" shape, and to a perfect fit before installation.
The "S" will absorb any strain or vibration rather than the post. Incidentally, do not overtighten an L post it will crystallize the lead then break when under load. BE SURE that the contacting surfaces are clean, wire brush them just before bolting them in.

battey post burnup - post melting
by: Dave R. Weymouth MA

ONLY reason these posts burn out is that you didn't clean the post and clamp with the proper tools and tighten it properly. As to water coming out of the fill caps you got too much water in them Level should be about 1/4-1/2" below the ring. How do I kow? Drive a Chev pickup that uses 20 of them, previously had a Ford pickup that used 20, and both of my garden tractors use 6 apiece. Experience over many years. To learn these things with minimum pain you should join the electric automobile assn most of us drive home converted vehicles using T105 0r 125 size lead acids. As to charging, sounds as if you are or have been overcharging or the batts themselves are badly sulfated. Test them individually with a load tester. Voltmeter itself will not tell you much, a tester draws bout 100A and checks voltage that it would have in use.

by: Anonymous

I had exactly same situation as lst comment -batt cale burned into, replaced with new cable worked for 2 days and cart stopped sudden and the same batt cable and half of same battery post burned off . I had noticed after replacing batt CABLE THE cHARGER WAs not recording any charge. During the night I left Charger unplugged. This is a 2003 EZ Go Cart I bought used. Just my luck when buying used product.

burned off terminal
by: jedmeister

I had a battery cable burn off last month.To salvage it I drilled a small hole down the center of the terminal and screwed down the cable to the post. Works fine as a temporary fix till you can replace the battery. JED

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