12 to 8 volt conversion, 2007 Precedent

Pick10353

I have a 2007 precedent club car...
I just replaced the 48 v cluster (4 12v batteries) with 6 8 volt batteries.... All batteries are in series, checked 3 times for my own sanity.
I put the new system on my charger overnight... We began at 15 amps reducing to 5 amps in the morning (still charging)... each battery was at about 9.5 volts...
I removed it from the charger.... I have reduced the voltage to 8.5 by running the lights. The cart moves fine....
Is there something besides the mechanical work and placing the batteries in series that I may have missed? I am pretty savvy when I comes to this type of activity but I a bit perplexed.... can ya help?
Thanks, Larry

BGW

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TahoeDawgZ71

The onboard computer on your 4x12 cart is designed to charge 12 volt batteries. With 6x8V batteries you need a different OBC with an entirely different algorithm.

97ccds-custom

OBC bypass required?


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TahoeDawgZ71

If you're using an aftermarket charger that doesn't require an OBC, yes.

If you're using the factory charger, no. Just replace the OBC with one designed to charge 8 volt batteries.

Fairtax4me

I don't entirely understand what the problem is. Are you concerned that it was still charging?
Depending on the initial voltage a new pack can take anywhere from just a few hours up to 12 hours or more to fully charge. On the first charge after a reset or having the pack disconnected the OBC has to evaluate the pack condition and that means the first charge can take longer than normal. Also during charging the OBC will control charge voltage and current. The pack voltage can reach as high as 65V during charging depending on pack condition. It's not uncommon for an 8v battery to show over 10v during charging. The rest voltage (approx 12 hours after charging) should be around 8.49v or maybe a bit higher depending on which brand and model of batteries you bought. Most brands, the pack should rest around 50.9v. Some such as US Battery or Crown will rest a bit higher. Trojan tends to rest around 51V in my experience.

Having read other threads of people doing this conversion I don't remember anyone replacing the OBC to match the new pack. Some people upgrade to a smart charger at the same time, but it seems like others continue using the original OBC with no major issues. Though the pack capacity is higher, the OBC is capable of adjusting to batteries of different capacity. Maybe it's not 100% ideal, but the OBC was never 100% ideal in the first place as it's designed to be able to charge multiple different brands of deep cycle batteries, which all vary in plate design and AH capacity.

If your charger is still running after about 16 hours then you have some reason for concern, because the OBC should time out the charge around 16 hours.
If it was only plugged in for 8-10 hours and it was down to 5 amps, it was probably pretty close to finishing the charge. Plug it back in and keep an eye on it, but let it finish charging on its own. Chances are its doing what its supposed to