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Discussion Starter · #1 ·
I have a 2002 ezgo golf cart that I have the following upgrades:
400 amp controller, high amp forward-reverse, 4 gauge wiring and 6:1 gear ratio rear end.
I can easily run 28 mph but need more power if starting on hills.
My question- Can I add one 6 volt battery to make 42 volts and also will my 36 volt charger work?
 

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I have a 2002 ezgo golf cart that I have the following upgrades:
400 amp controller, high amp forward-reverse, 4 gauge wiring and 6:1 gear ratio rear end.
I can easily run 28 mph but need more power if starting on hills.
My question- Can I add one 6 volt battery to make 42 volts and also will my 36 volt charger work?
Hi mat,

What you need for improving hill starting capability is more torque. Starting torque for these types of controllers is proportional to the current rating; 400 Amps in your case. Raising the battery voltage will not affect that.

The controller may or may not work with the extra 6 Volts. The charger would not fully charge the pack with the added battery.

I recommend you take a voltage and current measurement on the hill condition to see what is really happening with the battery and at the motor before doing any modifications.

Regards,

major
 

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More thoughts. 42 Volts is an oddball pack voltage. 48V is common in golf carts. In fact, some motor controllers are rated to run at 36/48V, meaning 36 or 48. Using the same motor, 48V will yield higher RPM. Torque would be the same dependent on the current, like 400 Amps.

Now the suggestion to get improved hill starting. Keeping the same motor torque at 400A, change the axle ratio to like 8:1. That should give you 33% more wheel torque over the 6:1. It would also slow the cart speed proportionally. That could be regained by increasing from 36 to 48V.

Chargers are rarely if ever dual voltage, so it would require a 48V charger.

All that for an old cart may not be worth it.

Good luck,

major
 

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Discussion Starter · #5 ·
Thanks again. That sounds like a better solution. More expensive though. I might have to wait a bit to do that.
Clay
 

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In fact, they came out with an 8 Volt battery same size as the 6V so guys can upgrade to six 8V and keep same weight/size as six 6V.
 

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I have a 2002 ezgo golf cart that I have the following upgrades:
400 amp controller, high amp forward-reverse, 4 gauge wiring and 6:1 gear ratio rear end.
I can easily run 28 mph but need more power if starting on hills.
My question- Can I add one 6 volt battery to make 42 volts and also will my 36 volt charger work?
Nope voltage is speed, and current is torque. You need more current, not voltage.

You screwed yourself with a 6:1 speed gear. Your original cart, depending on the model, had roughly 12 to 14:1 differential ratio. You traded speed for torque and acceleration. Put the 12:1 gear back in and you can climb a tree at 14 mph.

You cannot have both torque and speed with your cart motor. You have to pick which one. I have built 3 racing golf carts. My current one does 70 mph and will squeal the tires with a 6:1 ratio speed gear. To do that requires a AC constant torque motor, 650 amp controller operating at 96 volts with Lithium batteries. Hills do not affect acceleration much.

Keep in mind you have a Series DC Wound Motor. It produces maximum Torque at 0 RPM. As RPM increase torque goes down proportionally to Red line max RPM. At max RPM torque = 0. So what you experience with a series DC Wound Motor when cruising along and start to go up hill, you have minimum torque at the higher RPM. So your cart slows down (RPM)and keeps slowing down until the torque is high enough to maintain RPM.

Only way to over come that is with AC motors with Constant Torque at all RPM's. So when you hit that hill, the motor/controller produces more current to produce more torque.
 

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The controller may or may not work with the extra 6 Volts. The charger would not fully charge the pack with the added battery.
If he is using an after market Controller like an Altrax, they work at 36 or 48 volts. Some as high as 72 volts.

Any of the older EZGO 36 volt motors work at 48 volts to give you a little more speed. His main issue or road block I assume is his factory motor and the speed gear he changed.

As for the charger, yep it needs to be the right voltage.
 
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