2013 EnerSys Genesis NP18-12B KOP Battery/FIRST Choice Weak?

[Ken Streeter]

Originally Posted by Chris_Elston

Have you load tested these batteries?

...

1. Do you load test batteries?
2. Did you load test the EnerSys Genesis NP18-12B 2013 KOP and FIRST Choice Batteries?
3. What was your results?
4. Can you confirm if your batteries meet your team spec?

Interesting.

Quick summary to your questions is immediately below. Details farther along

1. Do you load test batteries?
Yes.

2. Did you load test the EnerSys Genesis NP18-12B 2013 KOP and FIRST Choice Batteries?
Yes, but we only have the 1 KOP battery

3. What was your results?
Our new 2013 EnerSys KoP battery gave comparable performance as prior years, with a capacity (in our test setup) of around 12Ah to 14 Ah (I can provide more detail tonight.)

4. Can you confirm if your batteries meet your team spec?
Yes, our 2013 KoP battery seemed to have performance typical of prior year's new batteries.

More details follow...

First off, we started load testing our batteries a few years ago. We used to make use of an automotive load tester like you describe, drawing a high-current load of 150 amps for 15 seconds, similar to what you describe.
Our automotive load tester wasn't very good and didn't have a good CCA read out, however. We were also concerned about the possible battery damage from doing such a harsh test on our batteries.

So, a few years ago we switched to using a West Mountain Radio CBA III. (See http://www.westmountainradio.com/cba.php - the current model is now a CBA IV). With that tester, we now "slow discharge" the battery with a continuous load of 7.0 Amps until the battery voltage drops to 11.0 volts. This is much more benign to the battery and is a test we feel we can do without risking battery damage. When doing this test, the CBA III produces a nice plot, which can be very informative, especially when compared with plots from other batteries and/or the same battery from prior tests. The key metric we use from this test is how many Amp-Hours is sourced from the battery before dropping to 11.0 volts.

However, neither of the above tests really reproduces "FRC Match Conditions." The first case is way too much current too quickly, and the second case is much less current than in a typical match.

We did test our 2013 KoP battery, and I can provide the plot tonight. My recollection is that our test methodology gave a capacity of about 12Ah to 14Ah, which is right in line with what we have seen with brand new batteries in past years. We typically see between 12Ah and 14Ah for a "good battery" with our test methodology. I believe the 18Ah rating from the manufacturer is for an even slower discharge rate (less than 7.0A) to a lower voltage (less than 11.0V), which will successfully extract even more charge from the battery.

From your tests, it seems like the 2013 batteries you have did not do as well with high-load (100A) test, but the one that I tested was fine in the low-load (7A) test that we did.

I would note that in the past with the test that we've been doing, we haven't seen a difference between the Enersys and MK batteries. (We have a mix of both, as FIRST has been putting Enersys ones in the kit, but all our purchases have been MK batteries.)