Charging - too often?

[codetoad]

If I only take a short, less than 1/2 a mile trip for the day - is it best to plug the cart back in or let the batteries run down to at least 90% or lower?

I've read some suggestions to charge once the batteries are below 90%, others say to always charge.

[teecro]

Lead acid batteries do not build memory thus it is considered best to keep them on charge as much as practical...

[JohnnieB]

Recharge after each use, no matter the distance traveled.

If you only make 1/2 mile trips, it would be a good idea to makes some longer trips occasionally.

[Cruise Master]

Originally Posted by JohnnieB

If you only make 1/2 mile trips, it would be a good idea to makes some longer trips occasionally.

Why?

[scottyb]

For the same reason lying on the beach all day every day isn't good for you

[teecro]

Originally Posted by Cruise Master

Why?

Occasional heavy charging helps knock sulfation off the plates.

[JohnnieB]

Originally Posted by Cruise Master

Why?

Drive only 1/2 mile a day gets boring, driving further is more fun.

If the cart is only driven 1/2 mile each day, it sits still over 23 hours per day and when sitting still the diluted sulfuric acid electrolyte stratifies. The lighter H2O molecules tend to rise and the heavier H2SO4 molecules tend to sink, so the specific gravity of the electrolyte at the bottom of the cells is higher than the specific gravity of the electrolyte at the top of the cells. In other words, the top of the cells are at a lower SoC (State of Charge) than the bottom of the cells and the lower the SoC, the faster aging occurs.

Driving does agitate the electrolyte, but a short trip may not mix it thoroughly enough while a longer trip will mix it more. Also by discharging the battery further, it will stay in the gassing stage longer during the subsequent charge, which more thoroughly de-stratifies the electrolyte.

If the 1/2 mile drive is over rough terrain, the electrolyte might get mixed well enough, so longer trips may not be needed.
If the 1/2 mile is over smooth roads, it might be a good idea to do something to mix the electrolyte occasionally.

FWIW: During the winter months, my cart may sit for weeks without being moved. The batteries are being float charged, so I don't have deal with the self-discharge issues, but the float charge voltage is below the gassing voltage, so stratification occurs and every month or so, I use a hydrometer to draw a few ounces of electrolyte out of each cell and squirt it back in to mix the electrolyte.

[cgtech]

I actually think under-used batteries get "lazy", and doing a discharge test (a good long drive would be as good) once or twice a year is good for them. Although this may just be the unscientific way of saying what JohnnieB just said.

[codetoad]

Thanks for the responses and thoughts, very interesting!

I agree, long trips are the best trips. I just wanted to make sure I was doing the right thing on the days when there's only time for a short ride.

[cgtech]

No, frequent deep discharges are not good (always long trips). Im saying that batteries that only get 1/2 mile trips could possibly benefit from the occasional long trip. It is well known in the lead battery world that "shallow discharges" are better for battery life. But i feel that the occasional "long trips" are also good. Not "several 1 mile trips, 1 mile per day, until the batteries are dead a week later". The batteries hate to sit at a partial charge during days/weeks of non-use, thats bad.