At the offseason events 1885 attended in the last two weeks, we struggled to maintain proper charge on some of our batteries. I’m not sure who/what/why or even how we got the batteries we have, but they’re a mixed bag of some of the FRC legal batteries from 2014.
Problem is, not all of the brand new batteries hold proper charge for an entire match. The Sigma battery had the worst “life” - as in, it would start at 13.5V and always come back at < 10V according to the Battery Beak.
It stays on topic about as well as most CD threads do, but has a few tidbits of useful information.
One addition about he Werkers, they get hot when charging and never seem to reach a full charge. Not scary hot, but noticeably warm to the touch. I would not reccomend them for use by any team. We have had nothing but good luck with the Enersys and will continue to use them.
Sigma, National Battery (all black), Enersys, MK all worked well.
We had a couple of Sigmas and National Battery that had questionable cells, so we reserved them for non-competition. This is likely what you’re experiencing too. For the most part, the Sigmas have been good. I did notice that the Sigma batteries we bought in 2012 are different than the Sigmas today in terms of color scheme and price (almost $10-13 more each!).
How long have the batteries been sitting? SLA needs to be charged to 100% every 6-9 weeks or so when in storage if I recall correctly (pinging adciv).
Our Werkers lasted through a match just fine, but had odd charging right from the store. We use a ten battery battery tender unit and they never reached full charge on that unit. Tried a higher end Optima charger/maintainer and had the same result. The KOP charger never passed 75%. But the batteries got noticeably warm to the touch. Voltage read fine (13.4-13.6V) at full charge, but using a automotive load tester, we only got readings of 140-165 CCA. The Enersys and MK batteries all came in around 220-230 CCA.
We use the battery tender unit on the batteries for a week or so every month or two.
No matter what the care was, I still wouldn’t recommend the Werkers as they both were lower performing straight off the shelf. We even picked the newest ones they had.
Sorry for the late edit. I got sidetracked while I was trying to verify the statement I made. It is still in a “I think that’s the time recommended to me” category.
Have you performed a controlled test on your batteries? Different matches yield different power usage. Time to data log!
Jesse,
The indication of a drop of two volts indicates a damaged cell. Check the case and I bet you find a flat spot on one of the corners indicating a drop. Any SLA battery will get hot once it achieves full charge. All current that is not used for reversing the chemical reaction goes into heat. In general, the heat confuses smart chargers. For that reason, all charging should be performed on room temperature batteries.
Our batteries should be able to make it through a summer (3 months) without being charged. Many old timers might recommend they be left on trickle charge but only certain smart chargers will switch on a trickle/maintenance charge periodically. We do not charge over the summer except when participating in post season events. However, once we are back in the shop on a regular basis, we top all of our batteries off. We use a multi-station smart charger that produces a 5 amp charge rate at full charge per station.
Not all chargers are created equal and yours may be intended for 50 amp hour batteries or above. If so, your charger may be producing significantly higher charge currents than the 6 amps stated for these batteries. High charge currents could result in heating and less than optimal charging. CCA testing with a car type test set will result in extremely high and possibly damaging current draws. I recommend the Battery Beak for quick checks and the West Mountain Radio CBA IV for controlled testing.
Al, not sure if the hot battery comment was directed at my post or not, but our charger/maintainer is a 10 bank 2 amp charger. I’m not denying the fact that a battery will get warm when charging, but the Werker batteries we tried last year got warm immediately and never made it to full charge. This charger isn’t going to damage the batteries, nor will the Optima 400 with a setting specifically for mulitple size AGM batteries.
Also, there are many forms of automotive CCA testing meters out there, don’t jump to conclusions about what they do. You can’t say every automotive tester will damage them (automotive includes motorcycle/moped), however I would accept that certain methods could damage a battery. All of our equipment is recommended and operated with the assistance of an electronics engineer and a lead acid battery specialist that work with us to make sure we can save money on batteries. We still use batteries in competition from four years ago because they still perform just fine and only slightly lower in performance than the brand new ones we get each year.
Andrew,
If the charger is truly making only 2 amps per output, then batteries should not get immediately warm. Either the batteries are defective or the charger is making way more than 2 amps (as in the charge circuit is shorted). Even with defective batteries, the KOP charger takes a while to heat a battery. The documentation talks about the four charge cycles but it doesn’t really explain if the charge current is average or maximum. In general, CCA testers put a very low resistance load across the battery. I would be interested to know the model of the tester you use.
This is the reason I can’t recommend a Werker brand battery in this application. Ours were hand picked from separate shipments and both showed the same problems. Not a good sign for Werker in FRC. Their large batteries for NECA racing were great however. I will have to check on the tester as it is expensive and they don’t let me play with it much. It lives at another mentor’s house who owns it.
Edit: Thisis one of the ones that we use to evaluate our batteries. It is a micro-processor controlled tester that measures the internal resistance of the battery at no load, while measuring the voltage.
Andrew,
The linked tester looks interesting but the documentation doesn’t really document how each test is performed. I have contacted the manufacturer to see if I can get any additional info. My suspicion is that the load test is performed for a very short period of time that is not controlled by the human tester. That makes the test fairly benign. The PBT-50 looks like a more appropriate tester for our size batteries but both should work.
This stuff is all fairly far outside of my wheelhouse. I know how batteries work and I can take care of them well enough, but my desire to get into the numbers and specifics of testing and data logging is about as strong as my daughter’s desire to clean her room.
With that said, our electronics mentor told me that it doesn’t technically do a load test. It finds the internal resistance and measures the voltage, then works as a calculator to work through a little ohm’s law and gets it’s answer. The only downside of the lower models of the Midtronics is that the batteries we use don’t generate enough amperage to fully make use of the test. For example, they will most always return a reading of their being a bad or failed cell in the battery simply due to the size of the battery. The PBT-300 allows you to look down to 100 CCA which allows our batteries to be tested to our needs. We will have to test the PBT-50 sometime though and see how it works.
He did mention that the West Mountain Radio tester is something he would be interested in as he has used them before, but $200 is a lot of money for us and we need to make sure we can fund registration before we look at anything like that.
Andrew,
I received a very informative reply from Midtronics Tech Support on these testers. It is my understanding from the reply that the CCA test does not use a load and does not require a fully charged battery. The test makes a calculation based on a “conductance” test. The test generates an AC waveform that is used to determine the internal conductance of the battery. This is an indication of the available plate area within the battery. That value is then used to generate a CCA display in the unit. This value when used with other tests that the device performs can determine the true health of the battery without a lengthy test. The manufacturer does recommend that any odd readings be performed a second time after the battery is fully charged as well. The full set of readings, if interpreted correctly, can point to a battery with a failing cell or a battery that is nearing end of life and therefore good for practice but not competition worthy.
Tech support also provided me with a document titled “Transportation Battery Testing Q&A” that describes the test in more detail. I also did a search of their website and found this page… http://www.midtronics.com/transportation-about/technologies
It has several informative articles on batteries and testing. My contact suggested that the larger tester may not give you the most accurate readings on FRC batteries as they are designed with “wet” cell batteries in mind. Since our batteries are not specified in CCA, users will have to come up with a “good” CCA value when using this test.
I would like to thank Midtronics tech support for their helpful and hasty reply. I was fairly impressed with their website and product line. It is easy to see why they are the official battery tester for NASCAR. I would like to see one of these testers in use if anyone has a unit at an event I attend.
Tech support suggested that a MDX-640 might be a better device if a team is looking at Midtronics testers.
Thanks for the update, it is a nice little unit and seems to do a great job for us so far. Something seemed wrong to me when I said internal resistance. Conductance sounds better.
The only funny reading we get is the meter tells us we have a failed cell no matter what. Our established CCA value for a competition ready battery is anything over 180 CCA. If they drop below that they are used for practice or for emergencies. A good new battery will typically be in the 230-250 CCA range, with some higher and some lower.
