Question about charging 8volt golf cart batteries

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mikef

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Feb 10, 2011
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Coburg, Oregon
My 90+ year old neighbor has a golf cart that he has been trying to get going for the past 2 months. Now his granddaughters' husbands have gotten involved. I finally stuck my nose in there today.

The golf cart batteries (6 @ 8 volts) are about a year old. I think they have been drained dead. The charger that comes with it, will not kick in, until there is some sign of life in the batteries. The guys had placed a 12 volt charger set at 2 amps, hoping to get it up high enough to use the regular charger.

I don't think that will work. They asked me if I would take the 12 volt charger off in the morning and hopefully the cart's charger will take over. I agreed, but not sure anything  will happen. I offered to take them into a Battery's Plus, but they think this will work.

Is it possible to get some type of charge into the 8 volt batteries' with a 6/12 charger?

Thanks

 

Ken & Sheila

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I would think these batteries are at least partially hooked up in series - as either two sets at 24 volts or one at 32 volts.

Unless charging them individually a 12 volt charger would do anything to charge them

Check the wiring.

ken
 

jim and di

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Sun Citu, Hilton Head, SC
When I left SC last spring I forgot to leave the charger plugged in, in October the battery was dead. Like your friend the cart charger would not start. I charged each 8 volt battery with the 6 volt charger for a few hours, when all 6 had about 6 volts I reconnected the cart charger. Been fine since then.
Jim
 

Lou Schneider

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You can charge an 8 volt battery with a 12 volt charger.  It's similar to putting an equalizing charge on a 12 volt battery.

Two things to watch.  First, the charging current.  You can start on the normal 10 amp range, but be prepared to reduce the charging rate if the battery draws more current than the charger can supply.  What will normally happen is the charger's transformer will overheat and the thermal overload will trip, shutting it down until things cool off.  If the battery is completely dead you'll see little to no charging current at first, then it'll increase dramatically as the charge gets going.

It shouldn't take long to put enough of a charge into the battery to let the regular charger pick up - no more than a half hour or so.  If you want to put a full charge into the battery via the 12 volt charger, watch the end of the charging cycle.  Unlike charging a 12 volt battery the charging rate won't taper off at end of charge, it'll just make the battery outgass a lot and get hot.  Shut off the charge before it reaches this point.

Charge each battery individually, not more than one at a time.

Another thought is to connect the 12 volt charger across the entire 48 volt battery bank, turn it on and then connect the cart's main charger.  The 12 volt charger may supply enough voltage to fool the cart's charger into picking up - when it does, disconnect the 12 volt charger.
 

mikef

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Feb 10, 2011
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Coburg, Oregon
You guys gave me some great ideas and hope that it can be done. First however is the need to disconnect them first and do them separately; something none of the grandkids' have done. Looks like most importantly, you must monitor the charging activity. There ARE advantages to being retired!

Thanks guys. I let you know what happens.

Mike
 

Alfa38User

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No need to disconnect them all, simply clip the charger onto each battery's + and - terminal in turn and give each a bit of a charge, (a half hour each should do it). Then try the big charger. (I would be tempted to disconnect the main + feed though until ready to use the big charger...)

If the big charger still fails to kick in, then measure each battery with a voltmeter. Should you have a bad one, you may get away with one battery if they are fairly new, but most likely, all 6 will need replacing. (~ $800.00 or so.)

If the big charger does not appear to kick in immediately, this is normal in some Club Car chargers. They are a little more sophisticated than the average small charger and work in conjunction with a small "computer" in the golf cart. They turn on after a short delay, to sense the charge required then cycle off again. Shortly after they will turn back and  do the charging.

A 36 Volt golf cart can use a 6 volt charger on each battery as each battery is 6 volts. Most 48 Volt golf carts use 6 - 8 volt batteries and thus requires a 12V version of the commonly available chargers to get any charge but it does requires careful monitoring as mentioned in other posts.

 

John From Detroit

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Davison Michigan
There is a way to "Bypass" the sensor for low voltage,  I do not have a manual on this laptop but I can tell you I downloaded the manual for a club car, (I figured it out before I downloaded the manual though).

That said, if the batteries are that dead that the charger can't "Sense" them.. You may be due for new batteries.. The guy who's Club Car I was working on.. Had to get new batteries.

But all it takes is a single jumper wire to bypass the sensor.. Where to put it I can't tell you.... You need to download the manual.
 

mikef

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Coburg, Oregon
Thanks John. I'll give that a try. I cleaned all the connectors. I checked each battery and they are between 2.3-2.8 volts. I tried charging one battery individually and it comes up at a rate of about .01 volt, every 20 minutes. I also tried connecting the 12 volt battery charger, then the Club Car charger, hoping to fool it. No dice.

Downloading the manual is next. I like the jumper wire idea.
 

Alfa38User

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There you go John!!! And I thought I had invented that bypass by jumper idea!!! LOL

Yes, that works but you have to open the charger for that, and like John, I don't have the manual available. If all batteries are under 3 volts like that, Houston, We Have a Problem!!!! You might still have a chance though but it will take patience, Grasshopper!!
 

mikef

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Feb 10, 2011
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Coburg, Oregon
Ah, open the charger first. Finally, after playing all day, trying any and everything, I found the diagram, how to jump it. I plugged it in and it immediately jumped to 2 amps; first time I have seen any movement, anywhere. After 10 minutes, it is up to 9 amps. I'll let it go for a bit, then shut it down and remove the jumper. Now to only hope, the batteries are still good.

You guys rock!!!!
 

mikef

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Feb 10, 2011
Posts
236
Location
Coburg, Oregon
I buttoned everything up and took it for a test ride around the park. All is good. Batteries were getting weak at the end, but I'm hoping it's because the pack was dead for so long. Plus the fact I need to leave it charge a complete cycle; something I haven't done because of all the playing around with the electrical system. I just had to reset the OBC and it kicked right in.

The owner was ready to lay out the cost of new batteries, but I hope we postponed that. I never would have got it, if it wasn't for the tip about bypassing the timer in the charger.

Thanks guys!


Failed to mention. After about 2 hours using the jumper, I unplugged it and removed the jumper. When I plugged it back in, it was good to go.
 

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