Buggies Gone Wild Golf Cart Forum - View Single Post - 1986 Yamaha Sun Classic Lithium Conversion Help

lithiumsupplement · 11-14-2020, 02:34 AM

I did a bit of hillbilly science today. I had a 60.8V, 2.6KWH LG Chem battery from a different project. Problem was that battery had a few dead cells, so I somewhat indelicately removed those 3 bad cells, and 2 good cells and got it down to 36V (11 cells, currently low on charge), wired it up with jumper cables and to my surprise it worked.

Happy to report that having lost over 300 pounds in lead the cart was zippy enough to conquer the steepest section of incline near my house without hesitation during my short test.

Now that I know it works I have a few more specific questions...

1. I believe that most 36V carts are designed to handle a little under 39 volts on a full charge. How much higher can I go before I start damaging the controller or motor? I'm debating if I should have a 9s that peaks at 37.8V or a 10s that peaks at 42volts. I could also charge a 10s to a lower voltage, but I'm not sure if that will yield a better outcome.

2. What BMS do you recommend for my situation? Stupid question but can I use a 10s BMS for less than 10 cells? Seems like generally no.

3. It seems trivial to find 10s/42V lithium chargers but 9s/38V appear to be less common.

Anyhow you can see all 3 questions are related. Your help on the 9s vs 10s question would be deeply appreciated.

11-14-2020, 02:34 AM	#14
lithiumsupplement Not Yet Wild Join Date: Aug 2019 Location: Point Richmond CA Posts: 21	Re: 1986 Yamaha Sun Classic Lithium Conversion Help I did a bit of hillbilly science today. I had a 60.8V, 2.6KWH LG Chem battery from a different project. Problem was that battery had a few dead cells, so I somewhat indelicately removed those 3 bad cells, and 2 good cells and got it down to 36V (11 cells, currently low on charge), wired it up with jumper cables and to my surprise it worked. Happy to report that having lost over 300 pounds in lead the cart was zippy enough to conquer the steepest section of incline near my house without hesitation during my short test. Now that I know it works I have a few more specific questions... 1. I believe that most 36V carts are designed to handle a little under 39 volts on a full charge. How much higher can I go before I start damaging the controller or motor? I'm debating if I should have a 9s that peaks at 37.8V or a 10s that peaks at 42volts. I could also charge a 10s to a lower voltage, but I'm not sure if that will yield a better outcome. 2. What BMS do you recommend for my situation? Stupid question but can I use a 10s BMS for less than 10 cells? Seems like generally no. 3. It seems trivial to find 10s/42V lithium chargers but 9s/38V appear to be less common. Anyhow you can see all 3 questions are related. Your help on the 9s vs 10s question would be deeply appreciated.