Our team just purchased the CBA5 Battery Analyzer and we are reading over documentation on this new tool for our team. We were wondering if any other teams have any suggestions or perhaps a team user manual on this great tool. Any help would be most helpful and appreciated in advance!
It is pretty simple to use. One thing I do ( I test the teams batteries) is run a test and then do another one right after and add the 2 values together to get a more accurate result. I would also always test at 7.5A. also I would advise having separate test files for each battery as well as not using a battery in competition if it tests below 12AH.
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AndyMark has a pretty good guide on using it for testing FRC batteries.
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You may find that different chargers give you different capacities… my cheap-o fleabays seem to under charge.
I did NOT find that repeated cycles with the same charger improved things. I saw small degradation.
I’ve got a cheap Chinese one and I test at 12 Amps FYI. Data if you want it 
Andymark links to team 1640’s wiki on how to use the analyzer as well as some good battery practices for FRC. My team just bought one a week ago and have finished testing all of our batteries after suffering some brownouts. It has really helped to identify the problem batteries and either designate them for practice or recycling depending on their state.
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Avoid deep discharge on lead-acid batteries during testing. It is bad for battery longevity.
Per the Andymark video, they recommend setting it at 10.5v. Do you agree with this value?
That is a reasonable and conservative value. 9.6 is considered the lowest advisable by the industry. A dozen discharges to 10.5 won’t be particularly harmful.
@EHutson in his post above advises taking 2 readings and averaging them: This is good advice. Just remember to recharge the battery before the second test… 
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That’s not quite what I meant. I meant to take another test right after you finish and add that instead of average 
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So, double-discharge the battery while testing a nearly dead battery?
I’m not sure of the logic behind that. Further discharging a discharged battery is not good for the battery. One should test under use conditions, and few teams put dead batteries in for competition matches.
Or am I missing something here?
When the battery drops below 10.5 volts it is because it is under a constant load. If you do a second test then the battery starts at 11volts or so. It will give you another .5AH. in comp you are not always drawing the same load on the battery.
I get the thought process here, but I’m not sure the juice is worth the squeeze.
If you’re consistently testing to the first time the battery meets 10.5V, you’ve got a number you can make decisions on even if it isn’t every last bit of capacity it has in it. If your battery is so close to the 12Ah Mendoza Line that it needs that extra half-an-amp-hour to get above, better to make it a pit battery and replace it.
That is true. I still don’t see the logic or value. Wringing the last Ah out of a battery isn’t the point of testing.
Once terminal voltage has reached the cutoff, the voltage recovery is actually an important parameter for characterizing battery health, but testing a discharged battery to cutoff twice isn’t a typical test routine, as it adds no new information.
But I don’t argue that if this seems reasonable and prudent to you that you should change anything. Always using the same procedure for testing is an important practice, so that results can be compared.
Aaah, I get it. You think that by displaying more Ah you have a better test.
No.
The 18 Ah nominal rating for an FRC battery comes from very specific test conditions. Probably the most important one is the discharge rate, I20, where the little subscript 20 stands for 20 hours.
Test at a constant 900 mA (18/20=0.9) and you should get your 18 Ah. BUT remember that the normal I20 cutoff voltage is quite a bit lower (9.6 volys IIRC) than your selected cutoff voltage of 10.5 volts (which is a good idea!)
Test at 100 mA and you’ll get a lot more Ah. Test at 40 A and see what you get, maybe 5 Ah.
OK, so I’ll draw a line in the sand: Testing for maximum Ah requires minimum test current. Repeating a test so your Ah number goes up is just plain silly, adding no meaningful data to the battery condition question while discharging the battery more than necessary.
Note that a battery (of the FRC type) discharged to cutoff voltage more than about a dozen times can reasonably be expected to deliver only about 60% of its rated capacity. That’s what I meant by “bad for battery longevity”. Battery manufacturers all use the same test routines (so data is comparable) but after a test they don’t care if the battery is injured or not. Using 10.5 volts as a cutoff is far less harmful.
When you guys choose a battery for competition, do you use freshly top-charged batteries, or let them rest after they’ve been charged?
In a perfect world I would let them rest after charging. Charging raises the internal temp of the battery. Resting allows it to cool back to ambient. Reality: I would use a freshly charged battery rather than a partially discharged battery in a match.
My team is definitely in the “unplug the charger, test with the Beak, and run it” camp.
In a perfect world, I wouldn’t.
When we CBA a rested battery, we consistently see a rise in voltage a couple minutes into the test once it’s warmed up.
Might not be as friendly to the battery lifespan to run it hot and fresh off the charger, but banners will long outlive a battery.
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