Regenerative prob w/lithium conversion?

[MDLNB]

2004 G22E Yamaha with regenerative braking.

Has anyone done a DIY lithium conversion on a G22E and noticed any problems with regenerative braking? Sorry if this has been covered before. I did a search and haven't yet found a thread that covers my particular inquiry.
Thanks for anyone with any thoughts or experience on this subject.

[Pat911]

Although I don't own one, there are many here that have Yamaha carts and have converted them to lithium with no problem with Regen braking. In fact, Regen braking is generally not a problem for Lithium batteries. Are you just inquiring or have you encountered a specific problem?

[augiedoggy]

if the battery is 100% charged you immediately take it down a huge decline while riding the brakes you might have a bms issue from what ive read but aftermarket controllers have a setting to correct even this highly unlikely scenerio

[MDLNB]

Thank you for the responses.
I am installing a seven mod, leaf on my wife's 2004 Yamaha and planned on just a straight out swap for her (finally) weak lead batts. Of course it has a cheap Chinese BMS, so I am not too confident with the BMS until I see if it really works properly. She doesn't use the golf cart very often would probably not put more than 8 miles round trip on it so I want to see if this 50+ volt, ??? AH package will suffice. I had heard somewhere that someone had trouble with the regen attempting to over charge the fully charged battery pack and the BMS(?) or controller caused the cart to shut down. This is straight stock cart, having the only mod of new seats, some led lights on the sides and 10" wheels. Otherwise, it's running stock. She did not want me to "experiment" on her cart, so it's been hands off until now. Her Trojan batteries are seven years old and weak, but replacements are over a grand, so I have a lithium battery pack sitting on my work bench that I have never used. She agreed to let me install it in hers. I had been wanting to put it in her Yamaha for a couple years now, but she wouldn't let me. I keep checking the voltage on it and it has held it's charge for a long time without draining as would the lead acid ones. The only time it has drained slightly was when I left the charger connected with it unplugged from the power. And then it was only a slight leaching of power over a few weeks.
I was thinking of disconnecting the regen plug to see if it would work OK, but I am not sure if I would have to make any other changes if I unplugged it from the motor. I just don't want her to get stranded if it was to shut down due to over charging from the regen.

[Pat911]

Leave Regen active. Charge to no more than 4.15v/cell, which is 58.1v, or even a round 58v. Don't charge to the maximum 58.8v. This will leave a bit of room in the pack and place less stress on the cells. You'll still get over 98% SOC. Unless she starts off with a full battery and the first thing she does is head down a long steep hill, she will have no problems. Under normal driving conditions, Regen cannot practically put more charge into a battery that normal driving takes out.

Having the BMS trip on high charge current may be an issue though if the BMS cannot handle it. Your Leaf cells are very capable of the high currents. What is your configuration like? Does your BMS pass all current through it or is it based on Sergio's Cheap Chinese BMS thread where discharge and regen currents bypass the BMS? What is your BMS rating and do you want to post your BMS configuration for us to go over?

Your 7 module leaf pack is probably around 40Ah capacity now. It was originally 66Ah. That should give you around 15 miles of range.

Cheers
Pat.

[augiedoggy]

Originally Posted by Pat911

Leave Regen active. Charge to no more than 4.15v/cell, which is 58.1v, or even a round 58v. Don't charge to the maximum 58.8v. This will leave a bit of room in the pack and place less stress on the cells. You'll still get over 98% SOC. Unless she starts off with a full battery and the first thing she does is head down a long steep hill, she will have no problems. Under normal driving conditions, Regen cannot practically put more charge into a battery that normal driving takes out.

Having the BMS trip on high charge current may be an issue though if the BMS cannot handle it. Your Leaf cells are very capable of the high currents. What is your configuration like? Does your BMS pass all current through it or is it based on Sergio's Cheap Chinese BMS thread where discharge and regen currents bypass the BMS? What is your BMS rating and do you want to post your BMS configuration for us to go over?

Your 7 module leaf pack is probably around 40Ah capacity now. It was originally 66Ah. That should give you around 15 miles of range.

Cheers
Pat.

[ I think you meant to say 3.63volts per cell

[Pat911]

No, they’re Leaf modules, so 4.2v max/cell (NMC chemistry).

[augiedoggy]

Originally Posted by Pat911

No, they’re Leaf modules, so 4.2v max/cell (NMC chemistry).

So they are.. got my threads mixed up sorry..

[Pat911]

All good.

[DaveTM]

If she's traveling a max of 8 miles on one "run" in the warm temps of Florida and the essentially "flat" terrain, the 7 module pack should do her just fine.

As others have stated the regen feature should not harm or overcharge the pack or any one cell.

I don't have regen on my cart, but I would think the BMS would be "involved" if regen would cause a given cell to reach the HV cutoff. Then, if such an event would occur, a resetting of the BMS would likely get her on her way.