connecting new batteries

[cgtech]

Sure, the light bulb is a resistor, it just happens to make light with the waste heat. I always think of resistor first, because I always have a extra pre-charge resistor laying around at the shop, and a huge selection of resistors at home. I bet a light bulb would do the job just fine.

[jkredman]

Disconnect the charger turn the cart off. Put the run/tow switch in tow.

Disconnect a wire from the middle battery. I doubt you'll get any sparking here.

Make sure the loose end doesn't touch any metal and remove the other end of the from its battery.

Once that's out, the circuit is broken. You can remover the other wires. Just make sure the loose end doesn't short across the other terminal of its battery.

Change out your batteries. Expect to have a sore back when your done because they are heavy and your off balance taking them out and putting the new ones back in.

Reverse the process of connecting the wires on the new batteries leaving the middle battery the last to connect.

When you make the final connection you'll probably get a small spark. It's nothing to worry about.

Put the cart back in run mode, take a very short drive, then plug the charger in and let the batteries fully charge.

(Done it a few times over the years.)


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[Newbuggyboy]

Originally Posted by JohnnieB

Here is the Service Manual procedure.

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There are some filter capacitors with bleed resistors in the controller that are kept charged while battery pack is connected. They discharge while battery is disconnected, so you get an arc when last battery cable is connected.

Manual says connect B- last. Touch edge of connector to top of stud to avoid screwing up the threads with the arc.

Thanks everyone. I have a 2five a B- last worked for me.

[JohnnieB]

FWIW: Some thoughts on which cable to connect last and how to reduce the arc when last cable is connected.

As previously mentioned, all types of electric golf cart controllers have a bunch of filter capacitors between the B- and B+ terminals and for safety reasons they have bleed resistors across them, so the capacitors will be completely discharged in a few minutes after the battery is disconnected. The instant the battery is reconnected, the capacitors will try to draw an infinite number of amps, limited only by the resistance of the conductors between the battery and the capacitors and to minimize the arc, add temporarily resistance between the battery and capacitors.

Any resistor you have will work. The higher the resistance, the smaller the arc, but the longer it takes to charge the capacitors, so low power low Ohm resistors might get very hot. Incandescent light bulbs will work, the higher the Watt rating, the lower the cold resistance, so a 40W/120VAC bulb will have less of a spark than a 100W/120VAC bulb. Be sure to use a bulb whose operating voltage is equal to or more than the battery pack voltage.

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There may be some validity to connecting the cable in the middle of the batter pack last. I can see that theory both ways. The battery is a series circuit, so current flow ought to be equal throughout, but the batteries do have internal resistance, so resistance is being added between battery and capacitor. Need some empirical testing to figure that one out, my battery knowledge is too limited and my electronic theory too rusty.

Bottom line, there is going to be an arc, but there are ways to reduce it.

[yurtle]

This only works for incandescent bulbs. I wouldn't try LED or CFL bulbs, but set up a webcam just in case.

[jkredman]

Originally Posted by yurtle

This only works for incandescent bulbs. I wouldn't try LED or CFL bulbs, but set up a webcam just in case.

Correct.

Only incandescent bulbs light based on resistance. CFL and LEDs light base on a form of Lasing.


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