Ancient Cushman 36v cart - Tech Direct leaf pack
 

Just came across this forum, starting to learn a lot! Just got my first cart that came with old dead batteries, and found that the Tech Direct 5-cell pack costs barely more than buying refurb lead acid batteries, so thinking it might be worth a shot. I'm guessing that this stone-age cart doesn't have regen or any fancy controllers, but I can't find much documentation. I have a few questions:

Will pretty much any charger work with these, and the BMS does all the hard work? Or do I need a specific charger?

I've seen some threads about the Tech Direct pack tripping its internal breaker and cutting out at full throttle. But I've also seen some threads about beefing it up with bus bars and heavier gauge cables. Think that would address some of the cutting out?

I see they say "indoor use only"... I don't plan on fording rivers or anything, but is it possible to seal these up without causing overheating concerns?

Or would I be better off just sticking with traditional lead batteries? $1500 for a more advanced lithium battery just isn't in the budget.

Re: Ancient Cushman 36v cart - Tech Direct leaf pack
 

You want the BMS to be the backup. So a charger that cuts off at XX.X volts and then the BMS would cut charge if the charger stayed on.

I don't know the 5 cell pack you're talking about. I'm assuming it's really a 10 cell just made with Nissan modules which are really 2 cells each. I don't know if that'll give you enough capacity though.

We switched my buddies Taylor Dunn to lithium. His cart was 36v so we put it on charge with his stock onboard charger and watched the V. I think his reached 44v so put in an 11S pack which is 4.0vpc. Well below the battery max, but the increase in voltage directly correlates to an increase in speed. His lead acid max speed was 12.5mph and it went up to 15+ on lithium. Guessing on the speed increase, can't remember exactly what it did, but it was something like 20 or 30%.

We made the assumption that the cart could handle the voltage that the charger put out. We made that assumption because we were OK with buying new stuff if it fried the controller and/or solenoid. Nothing fried. That was about 3 years ago now, still driving at the increased voltage.

But what we did find out was the batteries didn't have enough capacity. This is due to us only charging them to 4.0v. That's about 81% charged. If we went with more voltage he'd have to get a different charger and hope his current controller/solenoids could handle yet another increase. Or we could go with fewer cells which would also mean a different charger but it'd also mean less total V so less speed. In the end we just opted to triple his pack capacity. So he has a 3P11S pack for 141ah (if we were to fully charged it) and it's been great for him. Plus with only charging to 4.0vpc we put very little stress on the cells and they should live a very long life.

Re: Ancient Cushman 36v cart - Tech Direct leaf pack
 

Why, oh why, do people try to skimp on the charger? :roll:

Lead acid chargers are absolutely NOT suited to charging lithium. End of story!

A lithium charger is a very simple device and should cost no more than $100 for a 10 amp example.

The correct charger will enable you to get the most out of your lithium battery investment, both with run time and pack longevity. You will not get the long term life out of a lithium pack that is not charged correctly. So not spending the $100 now will cost you much more in the long run.

Cheers
Pat.