Question on charging.

[hawmarine]

I know a fully charged 36v pack is 38.2. However since I've put these new batteries in I'm consistently get 40.5-41 when fully charged. Will this hurt anything? Does that mean that the charger is overcharging then?

[usgicollector]

Is this 12 hours after the charger shut off?

[JohnnieB]

Originally Posted by hawmarine

I know a fully charged 36v pack is 38.2. However since I've put these new batteries in I'm consistently get 40.5-41 when fully charged. Will this hurt anything? Does that mean that the charger is overcharging then?

38.2V is the at-rest voltage, which is taken after the batteries have rested for about 12 hours.

The at-rest voltage also depends on what brand the batteries are. Trojan is 38.2 and US Battery is 38.5V, other brands are someplace in between those two.


The on-charge voltage typically rises to about 45V, which starts decreasing as soon as charger shuts off, so your ~41V read was likely to have been taken shortly after the charger shut off.

[hawmarine]

Originally Posted by JohnnieB

38.2V is the at-rest voltage, which is taken after the batteries have rested for about 12 hours.

The at-rest voltage also depends on what brand the batteries are. Trojan is 38.2 and US Battery is 38.5V, other brands are someplace in between those two.


The on-charge voltage typically rises to about 45V, which starts decreasing as soon as charger shuts off, so your ~41V read was likely to have been taken shortly after the charger shut off.

This is after the charger has shut off, and I've moved the cart out of the Garage and its been sitting for a few. This is the highest charge I've gotten, but pretty much its 40.5-41. I have the gauge from Scottyb in my dash.

[usgicollector]

Wait 12 hours then tell us what you have.

[JohnnieB]

Originally Posted by hawmarine

This is after the charger has shut off, and I've moved the cart out of the Garage and its been sitting for a few. This is the highest charge I've gotten, but pretty much its 40.5-41. I have the gauge from Scottyb in my dash.

If you drove the cart out of the garage, 42.5V may be an okay reading. As soon as any amps are drawn from the battery, the pack voltage is going to drop and it takes an hour or more to fully recover to the starting voltage, but since it just came off charge, it will also be self-discharging the surface charge acquired during the final stages of charging at a fast rate, so it won't get there.

Also, unless the DVM is connected directly to the battery pack (stays on all the time) it might be reading a bit low due to the extra resistance in the way it is connected.

If you have a legacy charger such as a PW 28115, or PW-II, the voltage at the moment the charger shuts off should be in the 44V to 46V range. If not, you have excessive resistance in the charging loop.