Crown battery recharge

[Capt. Lenny]

Somewhere on this site I think I remember reading that you can discharge Crown batteries lower than other brands without causing damage. True or false? I know the general rule is don't run them below 50% or 48.41 volts for a 48 volt pack. I've looked all over and can't find the post.

[JohnnieB]

Originally Posted by Capt. Lenny

1. Somewhere on this site I think I remember reading that you can discharge Crown batteries lower than other brands without causing damage. True or false?

2. I know the general rule is don't run them below 50% or 48.41 volts for a 48 volt pack. I've looked all over and can't find the post.

1. False, or at least from what I've been able to determine from the information published by various battery manufacturers and other sources, the minimum voltage for all lead-acid wet-cell deep-cycle batteries is 1.50VPC (Volts per Cell), which is 36.00V for a 24 Cell 48V pack and off the bottom of the SoC charts.

Most battery manufacturers claim their batteries can be safely discharged down to 20% SoC. They typical state it as 80% DoD (Depth of Discharge), but we tend to use SoC (State of Charge) on BGW.

The tricky part is the battery voltage drops when amps are drawn from the battery and the lower the SoC, the more the voltage drop is, so if the SoC is only 20%, dropping below 1.5VPC can happen and irreversible damage to the plates starts occurring. Material is literally sucked off the plates.

Also, 48.41V is 50% SoC for Trojan brand batteries. 50% SoC for Crown batteries is 48.00V. (The differences in voltages is mostly due to the acid concentration of the electrolyte used)

Attached are SoC charts for Trojan, Crown and US Battery brand batteries.

2. The don't discharge below 50% rule of thumb is more for increasing the usable lifespan of the batteries. In a nutshell, the higher average SoC maintained, the greater number of charge cycle available.

Attached is a chart showing cycle available based on average SoC maintained, for four popular brands of cart batteries.

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FWIW: When doing non-destructive testing, battery manufacturers stay above 1.75VPC or 42.00V for a 48V pack.

[Cobra,1]

Above is good advice 👍
Personally I never allow my batteries to get to or below 49 volts. And always allow charger to charge till done. No such thing as a top off/ quick charge imo.

[JohnnieB]

Originally Posted by Cobra,1

Above is good advice 👍
Personally I never allow my batteries to get to or below 49 volts. And always allow charger to charge till done. No such thing as a top off/ quick charge imo.

Golf carts, forklifts and other electric vehicles using lead-acid batteries do realize some benefit from "Opportunity Charging", but it isn't always convenient or practical to do so.

I suspect the first paragraph of US Battery's recommended charging instructions is aimed more towards working vehicles than personal runabouts.

Basically it is better to return a few AH to the battery pack rather than none.

For the most part, my batteries have either been in-use, or on-charge, or on float charge since I bought them 8.8 years ago in Nov-2012. If I know I'll be making another trip someplace, the cart will sit idle between trips, sometimes several hours, but other than that the charger is connected.

[Capt. Lenny]

Thank You JohnnieB for that information! I was hoping you would respond and knew you would have the answer.