Battery condition - 4x12v

[acrosteve]

I have 4 12v batteries - Maxx Everstart Model-MAXX-29DC. Date on them is 10-17.

I also have this battery indicator - https://www.ebay.com/itm/Lead-Acid-L...uGw:rk:30:pf:0 It looks like it is drawing 0.01 amps - 10ma or so.



I have the EZ-GO Powerwise QE charger. Switch on the cart is in Maint mode.

When I got the cart, the thermal battery sensor was not there. I have since installed a 10k resistor it its place.


Still collecting some hard data, but the battery "slowly" loses charge after the charger completes. Leaving the + cable connected to the pack does not seem to effect the discharge rate, but it is disconnected for these readings. Other than the 10ma for the meter, there are no other loads on the battery at all. Water level is fine, but did not check SG.

During a previous charge, the charge rate was just over 15A. When I checked near the end of the recent cycle, the charger was charging at about 4 amps and 63.9v. Shortly after it completed, I disconnected the charger and the charge indicator showed 94% and I read 51.26v. Over the next two minutes, it dropped to 50.85 at 90%.

I know I am relying on a very cheap device for the charge % level, but my meter is accurate and the pack is discharging. Are there different values for different 48v pack configurations?

I am about 10% off of this chart.

I would like to find a chart that shows a voltage for the top 80-100% or so.

I have been just going off of my gut until today, when I took some actual measurements.

It has now been 20 minutes off of the charger. Indicator is showing 85% and the voltage is 50.37. This is actually matching the chart a little more closely than is was when the charger was 1st removed.


I may be answering my own questions with this data, but what does this discharge rate tell me about the condition of the pack?

I will update in a while with new readings as time goes by.

Thanks

[rib33024]

After a complete charge. It take about 12 hours at rest to get a true reading of your battery pack.

[acrosteve]

Originally Posted by rib33024

After a complete charge. It take about 12 hours at rest to get a true reading of your battery pack.

Cool - will wait until then to check.

[LukeL]

Are those deep cycle batteries?


Sent from my iPhone using Tapatalk

[ThreeCW]

Originally Posted by acrosteve

I have 4 12v batteries - Maxx Everstart Model-MAXX-29DC. Date on them is 10-17.

It has now been 20 minutes off of the charger. Indicator is showing 85% and the voltage is 50.37. This is actually matching the chart a little more closely than is was when the charger was 1st removed.

I may be answering my own questions with this data, but what does this discharge rate tell me about the condition of the pack?

The higher voltage you see on any battery pack after charging is only a "surface charge", it does not reflect the actual state of charge of the battery pack. It takes 12 to 24 hours after charging for your battery pack voltage to stabilize (without using the cart) ... and once the voltage is stable (no real change in voltage over an hour), then the battery pack voltage can be used to determine the state of charge using the chart your have. Let us know what your stable voltage and state of charge is (12 - 24 hours after charging, with no use and with the charger disconnected) and we can help you evaluate the health of your batteries.

I don't know the MAXX-29DC battery but looking at the specifications, is it NOT design as a golf cart battery ... which are specially designed for high amperage draw of an electric motor. Your batteries are designed for marine and RV use, which have much lower amperage requirements.

I suspect that your batteries might be prematurely failing based on being used in a golf cart application ... but the stabilized voltage after charging will help to evaluate that possibility.

What sort of run time are you getting from your cart? What cart do you have?

[acrosteve]

Yes, the batteries are deep cycle - but you are correct, they are likely not designed for golf carts. "Cheap" WalMart marine battery.

Cart is a 2010 TXT.

So at about 6hrs after charging, I had 74% and 49.76v. Now, it has been 8 hrs and I am still at 74%, and 49.70v. So nearly stable and the little % gage is pretty much on track with the 48v chart.

Not sure on the run time, as I just got the cart and replaced the drive coupling/shaft. Figured I'd give the charging system a once over after installing the resistor.

This last charge is the 2nd charge I gave it. With about a week between them, without the cart being operated. So, I charged it, it sat a week, and I charged it again to current condition.


Thanks again.

[acrosteve]

Maybe not quite stable yet.

OK, now a full 12hrs later, the indicator says 72% and 49.59v

I will check again in the morning -

[yurtle]

Should be 50.96 fully charged. Your 72% looks to be accurate.

You should start looking for replacements soon, unless you only drive it infrequently and/or short trips before recharging.

[ThreeCW]

Originally Posted by acrosteve

During a previous charge, the charge rate was just over 15A. When I checked near the end of the recent cycle, the charger was charging at about 4 amps and 63.9v.

How long did your charge cycle take? Did you hear your batteries bubbling strongly during the final portion of the charge (4 amps x 63.9 volts)?

Find attached a typical Trojan battery charge profile for your reference. What you describe for charging sounds about right so far. The C20 on the profile is the Amp Hour rating of your batteries at the 20 hr discharge rate.

[ThreeCW]

Originally Posted by acrosteve

Maybe not quite stable yet. OK, now a full 12hrs later, the indicator says 72% and 49.59v-

Those batteries are looking pretty weak ... perhaps drive it around for a while to see what kind of run time you can get out of it ... but don't get too far from home to avoid getting stranded.

Also make note of the voltage of the battery pack when driving under different conditions (soft acceleration, hard acceleration, flat driving, hill driving) ... that might be the final nail in the coffin ... the voltage should not drop to less than 1.75 volts per cell or 42 volts in the case of a 48 volt battery pack.