Test of 1000XLC Batteries

Discussion about the OutBack Energy Cell Batteries
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Vince
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Joined: Thu Jun 02, 2022 7:31 am

Test of 1000XLC Batteries

Post by Vince »

We have an install with two 1000XLC battery racks and three Radian inverters. The system has been operational for two years. All equipment is in a room kept at 77F. The maintenance manual says that individual cell voltage tests should measure within 5% of average. In doing a voltage test of them recently I found the following:

- First thing in the morning when batteries are most drained the average cell voltage was 2.05 and all 48 cells were within 0.3% of average.
- When measured at the end of the charge cycle, the average cell voltage was 2.41. A total of 42 cells were within 2% or less of average, four cells were between 3-5%, one cell was 7.9%, and one cell was 10.4%

Numbering the cells left to right, top to bottom, the three outlier cells in string one are in positions 5, 12, and 17. The three in string two are positions 5, 15, 17.

I'm wondering what action I should take and whether or not I should make a warranty.

Thanks in advance for your help,
Vince
raysun
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Re: Test of 1000XLC Batteries

Post by raysun »

VRLA batteries are by far the most challenging to keep in balance.

Testing for cell charge and health is particularly challenging because the battery is usually in service constantly. The standard voltage measurement tests need to be undertaken with the battery in an open circuit (disconnected from load), and at rest for an extended period (24 hours for cells that size is not too long an idle period.) Since there are two racks, it would be at least possible to take one at a time off line and permit it to idle for 8 - 10 hours before taking full-charge voltage measurements. The remaining bank could then be fully charged, the two racks recombined, and the test on the 2nd rack executed the next cycle.

A warranty claim will require an exhaustive capacity test under stringent test conditions. For battery banks the size of an XLC1000, the load test will take equipment in the professional class. It will be an expensive and time consuming process.
Vince
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Joined: Thu Jun 02, 2022 7:31 am

Re: Test of 1000XLC Batteries

Post by Vince »

Thanks for the good info raysun. I'll shut each rack down when I check voltages in the future.
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