FNIRSI HRM-10 Voltage Internal Resistance Battery Tester，Battery Voltage Meter for Types of Batteries, Car Battery Tester, AAA AA Battery, 100V 200Ω, Digital Battery Analyzer for Household Automotive

I've owned this tool for a couple of months, and it has proven itself many times.-----BEFORE YOU BUY ONE, read this:This particular listing is just the tool and a set of Kelvin clips, which are fine for batteries with tabs or posts, but are a pain to use for any cylindrical cell. They make a cylindrical cell holder accessory for the HRM-10, but the only way to get one (as of July 2025) is to order directly from FNIRSI from China.Luckily, it seems they listed another version of the same tool, but it includes the cylindrical battery holder AND a set of Kelvin-style probes. Trust me, it's well worth paying more to get the complete kit with those accessories. I wish they had this option when I bought my HRM-10!-----Okay, now the review:Using a multimeter to check a battery serves most people well enough; if it shows somewhere near the expected voltage, it's most likely a good battery. But voltage is only half the story -- if the battery has a high internal resistance, it won't perform well in high-power devices (if it even works at all) nor last very long, and in the case of a rechargeable battery, it won't recharge fully (or the battery charger might not "see" it). That's where having a tool like this comes in handy.As for my use, I have a large pile of unprotected 18650 and 21700 cells, and ever so often I'll find one of them dead. I have a "smart" charger for these batteries, and sometimes it acts like I didn't just insert a battery. When I put that battery in the HRM-10 and see that its internal resistance is several ohms, then I know why the charger can't "see" it, and I can discard the battery without any doubts about whether it was a savable battery with a false reading.Over the past few years, I've picked up a FNIRSI tool here and there, and now that I own about three of their tools, I've got to say that I am supremely impressed with their design, functionality, material and build quality, and craftsmanship. The HRM-10 is no exception -- it feels great in your hand, and there's nothing cheap about it.If you're an electronics hobbyist who works with batteries, this is an invaluable tool. But make sure you get the one that includes the battery holder!

Works great, got a pretty accurate reading for my batteries and were able to figure out which ones could be wired together in parallel

This is great for me when dealing RV owners, many a aware how maintain these batteries, others do not understand them at all. This gives me a quick look and the customer can see what they are missing. For the money it's just fine.

What a (battery) life saver. Tested 4 batteries and IR was between 3.3 and 3.7 mOhms. Charged and balanced the batteries and retested. Volts ranged from 13.34 to 13.6v. and IR was between 3.35 and 3.45 mOhms for 3 batteries. The 4th battery - had an IR or 221 Ohms - clearly a bad sign of immanent failure and potential damage to the other batteries in my system. I will be returning it.The tester "volts" is accurate compared to my other testers. Better than the BlueTooth BMS for another battery which was off by 0.20 volts and I could adjust (calibrate) the BMS of that battery.First use, I accidently started off with getting the Chinese language set. To get out of this quandary: Press the right arrow (settings) and select option 8 and arrow to select the English language.

Got this with a $15.00 "coupon" offer so it was just the right price. I am building my own 21700 packs for FPV wings and quads so having the ability to match cells by internal resistance is key. Fnirsi for me has been a solid brand. The quality is definitely there.

This is a gem of a device for a hobbyist. They are giving you a near lab grade voltage and resistance measuring meter here for a crazy inexpensive price. The nice gator clip leads top it off. Put it into a manual resistance mode and see for yourself. I could use this to make a very precise meter shunt because I can get a very precise resistance measurement across a short conductor, then see that reading decrease moving the probe a millimeter over. You are getting at least a couple extra digits of measurement you're not going to find on a DMM twice the cost or more. And yes, you can measure voltage and internal resistance of a battery at the same time with it.