Battery issues on an 2009 RXV

[Scruff]

I have run into an issue with my batteries. The cart will charge to full 51.0 volts and then within a day in a half it will drop to 50.0 with out using the cart at all. Three of the four batteries show 12.3 and one shows 12.7 (this is the readings when the cart is at 50.0) Then over the next week it will only drop .1 per day... which was normal throughout the summer.

That is without using the cart.

These are the original batteries in the cart - They read B9 on the neg term.

Is it time to replace these or does the cooler weather have that much of an effect on them?

[cheapjeep2]

That sounds normal to me for colder temps, batteries of that age, and them being 12volts... B9 indicates they were made in February 2009, so they are nearly 4 years old. Average life span of the 12volts tends to be 3-3.5 years.

Yes colder temps will make them sluggish as the chemical reaction slows down, no different than a normal car battery that sits in a car during colder weather, it may crank a little slower than normal.

[JohnnieB]

Originally Posted by Scruff

I have run into an issue with my batteries. The cart will charge to full 51.0 volts and then within a day in a half it will drop to 50.0 with out using the cart at all. Three of the four batteries show 12.3 and one shows 12.7 (this is the readings when the cart is at 50.0) Then over the next week it will only drop .1 per day... which was normal throughout the summer.

That is without using the cart.

These are the original batteries in the cart - They read B9 on the neg term.

Is it time to replace these or does the cooler weather have that much of an effect on them?

New batteries self-discharge at about 1% per day and older ones self-discharge faster, but this in in energy stored rather than voltage.
In voltage that is about 0.002V per day per cell and there are 24 cells in a 48V battery pack, so it's about 0.05V per day and up to around 0.15V per day for older batteries (3%)

Looks like you've got one battery that only discharged about 1% and three that discharged around 45%.
However, I don't know what the "fully" charged voltages were, only the pack total.
Also, 12.3V + 12.3V + 12.3V + 12.7V = 49.6V, which is 0.4V less than the stated 50.0V pack voltage stated.

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You might try charging the three lower voltage batteries separately with a 12V charger to see if you can get them the match the the other battery better.
Take them up to an on-charge voltage of 15.0 to 15.3 volts, then charge the whole pack with your 48V charger.

Might get a little more useful life out of them.

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The storage capacity decreases as temperature decreases, but the voltage vs State of Charge doesn't.
The battery simply acts like a lower AH capacity battery.

Here is a chart showing storage capacity vs temperature.
Basically, if you have Trojan T-1275 batteries, they are 150AH at 80°F, they are 120AH batteries at 40°F and only have 90AH of storage capacity at 0°F.

[Scruff]

Thanks JohnnieB - can I charge each battery separately without disconnecting all the cables? Just basically throw a charger on each battery and let her rip?

Originally Posted by JohnnieB

New batteries self-discharge at about 1% per day and older ones self-discharge faster, but this in in energy stored rather than voltage.
In voltage that is about 0.002V per day per cell and there are 24 cells in a 48V battery pack, so it's about 0.05V per day and up to around 0.15V per day for older batteries (3%)

Looks like you've got one battery that only discharged about 1% and three that discharged around 45%.
However, I don't know what the "fully" charged voltages were, only the pack total.
Also, 12.3V + 12.3V + 12.3V + 12.7V = 49.6V, which is 0.4V less than the stated 50.0V pack voltage stated.

---------------

You might try charging the three lower voltage batteries separately with a 12V charger to see if you can get them the match the the other battery better.
Take them up to an on-charge voltage of 15.0 to 15.3 volts, then charge the whole pack with your 48V charger.

Might get a little more useful life out of them.

--------------

The storage capacity decreases as temperature decreases, but the voltage vs State of Charge doesn't.
The battery simply acts like a lower AH capacity battery.

Here is a chart showing storage capacity vs temperature.
Basically, if you have Trojan T-1275 batteries, they are 150AH at 80°F, they are 120AH batteries at 40°F and only have 90AH of storage capacity at 0°F.

[JohnnieB]

Originally Posted by Scruff

Thanks JohnnieB - can I charge each battery separately without disconnecting all the cables? Just basically throw a charger on each battery and let her rip?

You don't have to disconnect the cables.
Be sure to match the 12V charger's + and - cables to the + and - posts on the batteries and "let her rip"

[Scruff]

Ok - I am still chasing my tail here. Tried fully charging the batteries again, individually this time. They fully charge but then discharge the pack voltage overnight. Goes from 50.9 to 50.0 almost overnight without using the cart.

I decided to take it to the shop I bought it from - and within minutes, he contradicted everything on this board lol... so I knew that he was clueless.

He told me I charge it too much if I am charging after every ride, the batteries have memory, the natural state of a 12v is 12.2, my led meter is drawing the batteries down ( I laughed at this one ), I should run the cart until its almost dead then recharge, overfill the batteries because the rxv fill system will hold the water if it bubbles over during charging ( that doesnt work by the way ) blah blah blah....

Anyway - he did load test the batteries and showed me that they were good. So now I don't really know what to do here... about to the point of just buying new batteries and being done with it...

Originally Posted by JohnnieB

You don't have to disconnect the cables.
Be sure to match the 12V charger's + and - cables to the + and - posts on the batteries and "let her rip"

[JohnnieB]

You gotta remember, the guy also sells batteries.

If you have 150AH batteries, such as the Trojan T1275, Dropping from 50.9V (100%) to 50.0V (80%) means that 30AH have been used.

If "overnight" is 12 hours, the discharge rate is 2.5A per hour, so I suspect there is more than just a battery problem.

I'd expect a self-discharge rate of 1% day for new batteries and about 5% per day for older ones approach the end of their usable life.
Using the higher percentage, that would be an effective discharge rate of 0.3125A per hour.

So the question is, where are the other 2.2A per going?

I know next to nothing about RXV carts, but I'd start by disconnecting all the accessories and see how much the battery pack drops over night after being fully charged.

!!!!!!! Be sure to flip Run/Tow switch to Tow before disconnecting anything !!!!!!!!!!

If it still dropped a lot, I'd try it the next time with the Run/Tow switch in the Tow position.

If it didn't drop nearly as much, something is sick in the drive system.

Good luck, and let us know what you find.