Excessive discharging of 11-month old batteries

[cgtech]

Originally Posted by rngilliland

This is the voltmeter I have. https://www.ebay.com/itm/EZGO-RXV-Ch...AAAOSwhMFZb1PX

Its easy to install and the voltage display matches my multimeter. The charge percentage doesn't seem to be very accurate. I just leave it on the voltmeter all the time.

This meter's percentage gauge is displayed from the same controller input the original gauge was, so it will read the same as the OEM gauge. But, as said, the voltmeter function is still useful.

[Al H]

Per JohnnieB’s suggestion, I checked the batteries today an hour after returning from golf, and to my surprise they had recovered (without charge) to between 75% and 80%. I am going to order the digital SOC meter that rngilliland recommended. Thanks for all the useful info!

[JohnnieB]

Originally Posted by Al H

Per JohnnieB’s suggestion, I checked the batteries today an hour after returning from golf, and to my surprise they had recovered (without charge) to between 75% and 80%. I am going to order the digital SOC meter that rngilliland recommended. Thanks for all the useful info!

When amps are drawn from a battery the sulfuric acid in the electrolyte reacts with the lead and lead dioxide of the plates, forming lead sulfate and water plus some electrons are released. Since some of the sulfuric acid in the electrolyte has been converted to something else and some water has been left behind, the electrolyte in close proximity to the plates now is a lower acid concentration (lower specific gravity or SG) than the electrolyte further away from the plates. In other words the electrolyte becomes horizontally stratified.

Battery voltage tracks the SG of the electrolyte, so battery voltage drops when amps are drawn. (Technically, there are there factors involved, but SG is the major one for recover time.) Since the battery voltage reflects the SG of the electrolyte in intimate contact with the plates, the battery voltage measured at the battery terminals when the cart stops is artificially low.

It takes about an hour for the SG of electrolyte to equilibrate throughout its volume and produce a voltage that closer reflects the true SoC of the battery.

The opposite happens (more or less) when a battery is charged, but it takes longer (about 12 hours) for the terminal voltage to come down to a voltage that can reliably be used for SoC estimates.

[Al H]

Interesting that Scoots commented about the stock charger not being good for the 12 volt Crown batteries. I took my cart in to the Crown distributor for central Florida and he said all six of my batteries were bad, and he replaced them under warranty. However, he mentioned that my Ezgo Powerwise charger was not good for these batteries because it does not charge batteries 100% because it knocks off at about 85%. Any thoughts on this, and does anyone have a suggestion for a better charger for these batteries?

[JohnnieB]

Any of these three: https://www.cartsunlimited.net/chargers-36-48v.html

If you don't use cart every day, or not use it during the colder seasons, I'd go with one that goes into a float charge mode after the regular charge cycle terminates.