Hi guys, I was wondering if you know another battery analyzer like this: https://www.andymark.com/products/computerized-battery-analyzer
that does the same job just cheaper?
If you may know another way to check your battery it will also be very helpful!
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If you are only looking to test your batteries once a year, reach out to local teams? Maybe you can borrow one, maybe you can go halfies on one and split the time with it.
You can run a drivetrain on a battery, and use the PowerDistribution API from WPILib to monitor the battery voltage and current.
If you want really repeatable results, you could run a fixed autonomous program.
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this is amazing. we love it.
it hooks up to a pc over usb and graphs all the data you might want
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You’d be looking for a “DC Electronic Load”, used commonly for testing batteries and power supplies. Pretty expensive normally. Check Ebay or other local listings, or ask mentors to check at their companies. We picked up an old used Sorensen SLH 600W (50A) tester recently for about $300, but it does require writing some interface software.
The suggestion above to use your robot is a good one to save some money and learn wpilib features in the process!
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Here’s a how-to for making your own 50 Amp tester 
At -some- point I will manage to get my kids to come up with a box and a guide for this thing. The one I built isn’t replication-friendly, as its based on a huge-o-moley heat sink and costs a lot more than the one below.
https://www.andymark.com/products/battery-beak-frc-ftc-usage?via=Z2lkOi8vYW5keW1hcmsvV29ya2FyZWE6Ok5hdmlnYXRpb246OlNlYXJjaFJlc3VsdHMvJTdCJTIyYnV0dG9uJTIyJTNBJTIyc2VhcmNoJTIyJTJDJTIycSUyMiUzQSUyMkJhdHRlcnkrYmVhayUyMiUyQyUyMnV0ZjglMjIlM0ElMjIlRTIlOUMlOTMlMjIlN0Q I don’t know if this is what you need but it’s great for comps
The battery beak is a great competition tool to choose a charged battery!
However, its only one tool in the battery measurement suite. For smaller/rookier teams, the Beak and “born on dates” is all they need.
Having a standard automotive 100 Amp tester with an Anderson connector is a good “next step up”. It allows you to identify a failed cell quickly; something the Battery Beak won’t tell you.
The final step up is to have a tool to rank the energy storage capacity of the batteries. The CBA and similar tools tell you this information.
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Better to specify what job you want to accomplish then pick the right device. We are all mostly guessing that you want to know if a battery used last season can be used for a second season and still be highly competitive. The BD-250 is posted often over the past couple of years as a reasonable substitute at half the price of the Radio CBA (which my team uses). [I’ve used battery testers from free Harbor Freight promotion to $6000 Flukes; they do different jobs and are durable in different ways.]
I have one of these for load testing (not on batteries): https://a.aliexpress.com/_mq0etG8
There’s a PC app for it that works well enough to plot the results. By seeing how much the voltage dips right after you apply a 10A load, you can calculate the resistance using V = IR. It will also find the capacity of the connected battery and cut off automatically when the battery gets too low. Great value for the money. Larger loads exist but are generally a lot more expensive.
A better software than stock (supposedly) is here: GitHub - misdoro/Electronic_load_px100: 150W Electronic load / Battery discharge capacity tester PX-100 v2.70 protocol and control software.
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I also recommend the BD250. Higher wattage than the CBA at half the price. No frills, does the job it’s supposed to and does it well. It’s given us much better insight into the state of our batteries.
A note if you’re new to this: be careful not to over-discharge your batteries with testers like this (or the CBA or similar). 10.8V (1.8V/cell; FRC batteries are 6-cell) is a good safe cut-off voltage to avoid unnecessary wear on the batteries, while still giving a good sense of health.
It’s also important to understand a bit of how batteries behave when interpreting the data (e.g. why your “18Ah” battery tests at considerably less than that).
At some point we’ll do a write-up of how we use it…
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We use the CBA and it or similar is well worth it.
Example Battery: MK purchase Aug 2023 and used pretty heavily for this season. This battery would brown out within the first 60 seconds.
Resistance was below 13.5mΩ. We put a 100amp Battery tester on it and it tests good with that tester. Results from CBA:
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I love the CBA! Try reaching out to west mountain radio and asking about an education discount. I was able to get a refurbished CBA 4 for much less than andymark (I think I paid about $50).
Here are some experiments I ran on the device last year. Good luck!
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Brett, new to the forum, new to FRC as a mentor. I’ve been tasked with investigating possible battery test equipment and test methodology. I’ve read through many posts here on CD, and the BD250 appears to be the dominant choice as a tester. My question is, is the BD250 at 250W discharge power sufficient for FRC battery needs or would the BD350 with a higher discharge power of 350W be more useful? I am leaning towards the 250 as sufficient, but would appreciate your feedback.
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That looks sweet. They have a BD380 too. When it comes to realistic discharge testing for FRC, more amps and watts is better.
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An important factor is “how many tests can you do in one meeting?”
With the CBA, its one or less. With a 50 Amp tester, its “most of the batteries in one meeting” 
So, I suggest considering as high powered a tester as you can put up with!
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I hadn’t seen the BD350, looks like it was introduced more recently. So obviously I don’t have direct experience with that one. But if I were buying now it would for sure be on the list to look at.
FWIW, the “reference” West Mountain Radio CBA is either 150W or 200W depending on model, unless you purchase a (expensive) “amplifier” that takes it to 500W.
The ability to test using more current means you can test a battery faster, but the measured capacity will be lower. It’s also somewhat harder on the battery. Of course none of these devices approach the worst case load the robot will present - even 350W is only about 30A. But, that’s OK; you’re not using these analyzers to duplicate a robot load, but to characterize the discharge curve and total capacity.
We typically test and record each battery’s capacity as measured at the maximum, 250W load of the BD250. Standardizing on a discharge rate lets us compare measurements each time we test and from battery to battery. It’s also the fastest way to test (~30 minutes per battery) which is important when you’re trying to characterize your whole fleet of batteries. But it’s also only a ~22A load which, compared to what a robot demands, is low enough I’m not worried about an occasional test shortening the battery’s life. That said, if the charger went up another 100W, we’d probably have used that as the standard.
Bottom line, I think the 250W model is sufficient but if I had the choice to get the 350W one for $40 more, I probably would have done that. It’s not enough different that I would seek to replace the one we already own, though.
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Thanks for the feedback
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Brett, looking at the BD250 vs the BD350, two things are apparent. FIrst, the BD250 has a digital display which displays real time battery voltage, discharged capacity and discharge current. The BD350 does not have a display. Do you rely on the BD250 display, or do you rely primarily on the DisCharger PC software for data. The second note is, when reviewing the manuals for both, the BD250 manual shows the unit directly connected to the battery under test, while the BD350 shows the unit connected through the T1000 charger, which is then connected to the battery under test. It’s unclear with the BD350 if the T1000 charger is required to perform the battery tests, or whether you can directly connect the battery to the BD350. The manual doesn’t show this. Appreciate any guidance you may have on these.
Sanddrag, yes that looks interesting. Looking into it.