Excessive discharging of 11-month old batteries

[Al H]

My EZ-GO RXV was purchased new in Oct. 2014 and the initial batteries (six 8-volt U.S. Battery brand) were replaced at the end of March 2018 -- not great performance, but I do play golf about 5 times per week. Two months ago, I noticed the SOC voltage meter level indicating the new Crown CR-165 batteries beginning to decline significantly with a round of golf. It has worsened over the past two months, so I did a voltage test yesterday after charging up the battery pack. When the charger (Powerwise QE) finished charging, the total voltage measured 51.15. The voltage stabilized at 50.33 (about 85% SOC) by 6 1/2 hours later. When I got up this morning it was still at 50.31, but when I returned from playing 18 holes this morning it had dropped to 48.57 (about 53% SOC). Does this seem normal for 11-month old batteries, or is this an indication that I will likely not get nearly the 3 1/2 years I got out of the original batteries? The six batteries have almost identical voltage in all tests.

[JohnnieB]

First, your batteries should never be allowed to sit overnight in a partially discharged state. They ought to be charged after each use, or at least put on charge each night after being used during the day.

Second, I'm not sure if a PW-QE set up to charge US Battery brand batteries will charge Crown batteries properly.

Third, the SoC chart you are using isn't for Crown batteries. The one attached is from the Crown Deep Cycle Battery Maintenance brochure, which is also attached in a PDF format.

50.3V is better than 95% SoC and 48.6V is above 50%SoC.

Also, how long had the batteries been resting when you got the 48.57V reading?
If it was less than half an hour, the reading will be artificially low. (actually, it take over an hour for the voltage to fully recover after use, but most of the recovery is within 30 minutes or so.)

[Al H]

I usually golf in the early morning and am back home by noon, at which time I hook up the charger. After the charger goes off, I do not recharge the batteries before the next day after returning from golf. Today I checked the voltage as soon as I got back from the course (about a half mile) before hooking up the charger, so the batteries had not had any time to recover. I am still trying to learn how these battery systems function. The Crown batteries were installed by the EZ-Go dealer who sold the cart initially. Thanks for the Crown voltage table. This is a big help! Very much appreciated.

[Fairtax4me]

Is the water level correct in the batteries?

If you just have a bar meter battery guage, replace it with a digital volt meter to get accurate readings of your battery voltage. The bar gauges are usually pretty useless if you actually care about proper operation within the recommended SOC range.

I would expect slightly higher voltage immediately after a charge. Something to consider would be a new smart charger such as the Lester Summit II. With the proper charge profile and a float charge that will keep battery voltage at full charge for several hours after the regular charge cycle is complete. This could be especially helpful for you since you use the cart almost every day.

Also keep in mind, any battery has a finite lifespan. They can only be charged and discharged so many times. This tends to vary by battery manufacturer, and is simply due to wear of the lead plates in the battery. Typically thicker plates give a longer lifespan. Using the pack for a full run every day will give the lowest overall lifespan, simply due to the loss of lead from the plates during the normal process of discharging and re-charging the battery. Some manufacturers list the typical cycle lifespan of their batteries, which can be useful in determining how long a set of batteries will last for you.
It should still be quite a lot more than 11 months, so hopefully yours are not taking the short way out.

[JohnnieB]

Oops! I misread your original post and thought the batteries had been allowed to sit overnight before charging.

Sounds like you are charging them properly. How are the fluid levels?

Also, batteries don't have as high of storage capacity in colder weather. They are rated at 80°F and lose about 10% of their rated capacity for each 15°F lower.

It also might help to give them a back-to-back charge (Initiate a charge on fully charged batteries) about once a week.

[Al H]

The water levels are correct as I have a Flow-Rite watering system and I have checked to make sure it is functioning properly. I am located in Central Florida with fairly warm temps. I like the suggestion of a digital SOC meter. The analog meter that came on the cart seems very unreliable. Any suggestion on a particular digital meter vendor?

[Scoots]

Might want to look up what crown recommends for amps to charge their batteries. I know the 12v crown batteries and a stock charger are not a good combination due to the batteries needing at least 17 amps to mix everything up for a good charge. Depending on the charger you have, it might not be pushing enough amps to the batteries.

[BobBoyce]

Originally Posted by Al H

The water levels are correct as I have a Flow-Rite watering system and I have checked to make sure it is functioning properly. I am located in Central Florida with fairly warm temps. I like the suggestion of a digital SOC meter. The analog meter that came on the cart seems very unreliable. Any suggestion on a particular digital meter vendor?

That "analog" meter is a simulated analog display controlled by a digital output from your controller. Your controller tracks charge/discharge and tries to keep track of your battery packs State of Charge. It is calibrated for batteries that are between 150 and 160 Amp/Hour. If your batteries are not of that rating, it will affect the accuracy of the calculated readings.

[Al H]

My batteries are 165 amp hours rated, so that could be a factor in my meter always under reporting the actual voltage. Can the controller be recalibrated? If so I would bet that my ezgo dealer who installed them did not recalibrate the controller.

[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.