Correct Pack voltage for 36v cart

[FrancisZ]

Hey guys. I just purchased a 1999 36v club car utility cart from the school that I work at. It was used nightly to take trash bags to the dumpster and was plugged in after each use, stored inside, never taken off road, etc. Overall it’s in very good shape. I plan to use it as a general utility cart at my house and as a light duty hunting buggy mostly for scouting without scaring everything away. (I also have an ATV for the real rough terrain)

I’m trying to gauge the condition of my batteries. They do seem to hold a charge but I lose a lot of speed up hills. (More so than out of other 36v carts I think). Reverse was also painfully slow but I figured out it was only running off 3 batteries so I moved the reverse wire over a battery and it helped a lot.

anyway, after a full charge each battery is between 6.47 and 6.51 volts and the pack voltage at the charger receptacle and at the batteries is 39.1 volts. I’m guessing my next step will be to hook the meter up to the charging receptacle and see how much my voltage drops while climbing a hill.

What’s an acceptable range? I’m getting answers literally all over the board from different web sites and I’m starting to get confused. If it drops significantly I guess I should then measure each battery as I’m climbing hills? Do specs change for different battery manufacturers?

I’m just trying to get a read on my overall battery condition. I’d like to put a lift kit and new tires on this thing but I’m not going to do that right away if I need to drop a grand in new batteries right off the bat. Unfortunately due to a change of personal I couldn’t find any records of how old the batteries are from the school and I don’t see a date stamp on them anywhere.

[handtools]

This should help.

CartsUnlimitedStateofChargeChart.png

[FrancisZ]

Thank you. I’ll test it under load and see how low they drop under full pedal.

[Bama Brad]

I think these numbers are after rest (for a few minutes), not while driving.

[Fairtax4me]

You only get a finite number of charge cycles from a battery, so if those are more than say 4 years old if they were used every day then they are probably on their way out. The lead plate structure erodes away as the batteries age which leads to lower capacity, and that equates to shorter run time, and lower amp output when under load. Even if the rest voltage appears fine, they can fall flat when loaded.
Typically this will start with one battery, and the others will soon follow.

The best approach here is probably to replace the pack, but given the age of the cart and the fact you want to use it for hunting, you will not get good results using that cart with its current drive system. The old resistor carts do not handle moving at slow speeds for long periods. The resistors overheat and burn out, and the motors will overheat due to the amp draw when moving slowly, and when going over rough terrain.

Consider upgrading the cart to a solid state controller drive system, and replacing the battery pack with a 48v pack. More power, more torque for off-road use, and longer run times.

[FrancisZ]

I may consider selling it eventually and buying an electric fat tire bike. I only paid a couple hundred dollars for it so even if I sell it for 500 I’ve made a profit. Our network of roads are pretty good at the hunting property so I may see how it does stock first.


Today, under full acceleration up a hill, the pack voltage dropped to a pretty consistent 35.1 volts after being fully charged overnight. So I’m guessing new batteries are in this carts future.

[handtools]

Personally I don't see anything wrong with 35.1v under load. My gauge of battery health is as long as they are doing what you want or need them to do they don't need replaced! A stock series resistor cart is gonna slow down on hills it's the nature of the beast.

[FrancisZ]

Thank you. Sounds like maybe that’s not a terrible number going up a hill. I’m familiar with these batteries mostly from reservoir boat conversions so I’m still trying to get my bearings on the voltages.

[Mooncarter]

Originally Posted by FrancisZ

Thank you. Sounds like maybe that’s not a terrible number going up a hill. I’m familiar with these batteries mostly from reservoir boat conversions so I’m still trying to get my bearings on the voltages.

Charge the cart. Wait 12 hours. Using the chart Handtools provided for you above compare the voltage to the chart.

Post the voltage here as well.

[FrancisZ]

Originally Posted by Fairtax4me

Y

Consider upgrading the cart to a solid state controller drive system, and replacing the battery pack with a 48v pack. More power, more torque for off-road use, and longer run times.

Initially I was a little hesitant but doing a little more research- I found the date code and the batteries are from 2018. They do seem ok. I guess I just want more power.

From what I’ve read I understand going to a solid state controller from the resistors and needing a 48 volt solenoid but I can keep my original v-drive wiper and also my two pin charging port? The charger they gave me was a Lester Summit II which seems like it automatically switches from 36 to 48 volts so I’m thinking I’m good to go there.

If all I need is a controller and a solenoid it seems like a pretty manageable swap next time I need batteries. The cart is from 1999 and starts with an A in the model number.