3 Questions about using RV deep cycle batteries for 36 volt cart

[scottyb]

The bottom line is there are no cheaper batteries than lead golf cart batteries capable of powering a golf cart without sustaining significant degradation rather quickly. The problem lies in purpose built batteries. Each purpose has a different plate construction specific to it intended discharge and recharge rate.

So while the cost may be 1/3, the service they provide may be 1/4 of the value
A. reduced performance & run time
B. Reduced useful life

You may end up needing to buy 4 sets of the cheaper batteries if you keep the cart. If not the person who buys the 'side hustle' cart may get sour grapes.

I believe I may be quoted out of context above. The information I posted about using an automotive charger to raise the voltage of cart batteries is used when trying to get a dead pack high enough to allow the cart charger to take over.
GL.

[BobBoyce]

I can help here, when it comes to the typical wet/flooded Lead/Acid cell batteries. There are specialty batteries, but they cost more, so they are not typical...

Automotive starting batteries are designed for a maximum discharge of 10%, which is 90% SOC.

RV/Marine Deep Cycle batteries are designed for a maximum discharge of 20%, which is 80% SOC.

Golf Cart and other true Deep Cycle batteries are designed for a maximum discharge of 50%, which is 50% SOC.

Discharging more than the design specification will greatly reduce the life of the plates in the cells. There is less lead to lose, so damage occurs more rapidly.

The largest factor noticed will be maximum current that the batteries can produce, and the heating damage cause by overcurrent of the plates AND intercell connections. Trying to make an RV/Marine Deep Cycle battery supply the same current as a Golf Cart battery will result in greatly reduced battery life. You MAY get 16 to 18 months of acceptable operation before you'll be ready to replace them. Likely less, when you try to pull several hundred amps from a battery designed to deliver less than 50 amps and the internal connections fail. Many will explode when this happens, as it ignites the hydrogen gas in the cells.

I have experience in this regard. I have seen quite a few EVs where people have tried to replace their Deep Cycle batteries with the RV/Marine Deep Cycle batteries, and it never ended well. They overdischarged the batteries and ended up replacing them quickly.

The proper batteries for the task can last 5-7 years or more. I don't remember seeing a RV/Marine battery used in an EV ever make it to 2 years of service life, and range was greatly reduced as well. I've designed solar power system Lead/Acid battery banks to last for 15 years or more, simply by increasing the capacity of the battery bank by a factor large enough to prevent overdischarge during extended periods of bad weather. Most engineer for 3 days of no sun, I engineer for 5 to 7 days of no sun.

Bob

[mutant]

thanks Bob, i never heard the soc for those varying battery types, fascinating...

[texman38]

Originally Posted by BobBoyce

I can help here, when it comes to the typical wet/flooded Lead/Acid cell batteries. There are specialty batteries, but they cost more, so they are not typical...

Automotive starting batteries are designed for a maximum discharge of 10%, which is 90% SOC.

RV/Marine Deep Cycle batteries are designed for a maximum discharge of 20%, which is 80% SOC.

Golf Cart and other true Deep Cycle batteries are designed for a maximum discharge of 50%, which is 50% SOC.

Discharging more than the design specification will greatly reduce the life of the plates in the cells. There is less lead to lose, so damage occurs more rapidly.

The largest factor noticed will be maximum current that the batteries can produce, and the heating damage cause by overcurrent of the plates AND intercell connections. Trying to make an RV/Marine Deep Cycle battery supply the same current as a Golf Cart battery will result in greatly reduced battery life. You MAY get 16 to 18 months of acceptable operation before you'll be ready to replace them. Likely less, when you try to pull several hundred amps from a battery designed to deliver less than 50 amps and the internal connections fail. Many will explode when this happens, as it ignites the hydrogen gas in the cells.

I have experience in this regard. I have seen quite a few EVs where people have tried to replace their Deep Cycle batteries with the RV/Marine Deep Cycle batteries, and it never ended well. They overdischarged the batteries and ended up replacing them quickly.

The proper batteries for the task can last 5-7 years or more. I don't remember seeing a RV/Marine battery used in an EV ever make it to 2 years of service life, and range was greatly reduced as well. I've designed solar power system Lead/Acid battery banks to last for 15 years or more, simply by increasing the capacity of the battery bank by a factor large enough to prevent overdischarge during extended periods of bad weather. Most engineer for 3 days of no sun, I engineer for 5 to 7 days of no sun.

Bob

excellent info, thanks you!

[ThreeCW]

Thanks Bob! A great explanation.

[rib33024]

And your 36 volt cart was made to run on 6 - 6 Volt golf cart batteries. Not car or RV batteries. And 3 - 12 volt batteries are not made to run a golf cart, you will not go far , and the batteries will die a fast death