Fnirsi HRM-10 battery voltage Internal Resistance tester

Batteries and Chargers Chargers
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I recently stumbled upon this (new) battery internal resistance tester from Fnirsi, the HRM-10.

All the specs can be found on this link: FNIRSI HRM-10 Battery Voltage Internal Resistance Tester

It’s a bit more expensive than the couple of “cheap” Chinese IR testers that have been discussed here on BLF in the past, but I must say that it has some nice extra features.

I also found a written review on the electronics website Elektor(.com): https://www.elektor.com/blogs/review-blog/unveiling-the-precision-of-the-fnirsi-hrm-10-battery-resistance-tester?srsltid=AfmBOorxpAKR9nT3uYOyYMKe5Mwf1ko0dSkVNavx-JlItxgLNF0U3MJ3

A few “highlights” from that review:

Assessing Accuracy: How the Fnirsi HRM-10 Measures Up

Using the Fnirsi HRM-10 is straightforward, especially in auto-ranging mode—just clamp it onto a battery and read the results. But how accurate are those readings? The voltage measurement, displayed with four decimal places, is impressively precise. When connected to a bench power supply set at 5 V, the HRM-10’s reading differed by only 100 µV from my trusted Fluke 189 multimeter. Although my Fluke hasn’t been calibrated in over a decade, its reliability still holds up.

As for resistance measurements, the HRM-10 displays two decimals in milliohm mode, indicating a potential accuracy of 10 µΩ. I tested it with a 5 mΩ, 0.1% precision resistor, and the HRM-10 reported values fluctuating between 5.07 mΩ and 5.08 mΩ—slightly higher than expected, according to the resistor’s manufacturer, Vishay Precision Group. However, when I switched to ‘Resistance calibration’ mode, the reading stabilized between 4.99 mΩ and 5.00 mΩ, which is spot on.

These results convinced me of the HRM-10’s accuracy, and I opted not to tamper with its calibration, trusting that Fnirsi’s tools are more precise than anything I have on hand.

There is something that is important to know though:

Important Note on Using Kelvin Test Leads

Before you dive into testing batteries with the HRM-10, it’s crucial to carefully read the user manual, as it contains a key detail hidden in the ‘Precautions’ section about the Kelvin Plus test leads. The manual specifies that the clamps must always remain open during testing for accurate measurements—the jaws should never touch each other directly. While this is easy to achieve when testing batteries with protruding contacts, like the positive side of an AA cell, it can be challenging with flat contacts, such as the negative side. It’s important not to overlook this, as closed clamps can lead to unreliable results, especially when using the Pass/Fail test mode. This crucial detail should have been highlighted more prominently in the instructions.

Besides that there are several (creative) workarounds, Fnirsi also do offer possible solutions for this in the form of a specific two-pronged probe and battery holder/carrier, which can be bought individually, but Fnirsi themselve (on their website and on the official Aliexpress store) sells them also as a bundle with the HRM-10, which basicly means that you get both for the price of what afterwards only 1 of the 2 would cost.
Unfortunately I’ve read today that the battery holder tester doesn’t support 21700 batteries, but if you’re planning to buy the other probe anyway, you can just as well buy the bundle and get the battery holder “for free”.

There are several (review) video’s about the HRM-10 to be found on youtube, but I also found this one with a teardown usefull, since it gives an idea about the build quality on the inside:

Anyway, I’ve ordered one (the complete ‘bundle’) which will hopefully arrive just before Christmas. I’m looking forward to see how I will like it! :grin:

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This device feels modern and high quality comparing to cheap IR testers like RC3563.
I bought it at a time when Fnirsi did not offer any other probes than Kelvin clips. I immediately discovered these clips are absolutely unusable for measuring cylindrical cells. So I replaced the connector on probes and battery holder from RC3563.
This one can hold 21700.
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Nice tip, thanks!

Unfortunately I only discovered it today, that the Fnirsi holder didn’t support 21700, after I already ordered it. But because I wanted to buy the other probes (seen below) anyway and because I bought the “bundle”, I basicly paid the same than if I would have only bought the probes seperately.

There are a lot of stores on Aliexpress selling the HRM-10, but almost none do sell the bundle deal or even the probes seperately.

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Looks like my holder is similar to one sold by Fnirsi, it has same size marks and no 21700 among them.

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But as you can see 21700 fits fine.

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I ordered the attachments. Here’s a short video that I made:

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Ordered one with a new Clamp Meter. Can’t wait to see how it compares to the others I have.

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That’s perfect, good to know! I was already thinking if there was enough room left, to dremel out those tracks, so that the slide side good move back a little further, but know that wouldn’t be necessary, which is good to know!

Thanks for the video @TimMc! Those were the exact same reasons that I decided to instantly opt-in for the extra attachments.

@chops728 I’ve seen that clamp meter pass by several times and it is really tempting me… But fortunately I remembered just in time that I alreaday have 3 or 4 clamp meters laying around which I also almost never use! :sweat_smile:

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You can never have too many Meters. :grinning:

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Why did you replace the connectors on the probes and battery holder of the RC3563? Are the RC3563 connectors different from those used in the Fnirsi? Is the Fnirsi HRM-10 using a GX12 4-pin connector?

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Yes.
And RC3563 uses GX16.

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Is worth it to buy RC3563 probe and battery holder and change connectors or go for fnirsi’s probe and battery holder ?

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If the goal is to save money then worth buying RC3563 attachments and swaping the connectors.

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RC3563 test probe and battery holder is little bit cheaper than Fnirsi. Do you know, Is RC3563 probe cable longer then Fnirsi? Fnirsi probe length of the wires between the tester pens to the junction are short.
Price on Aliexpress for test probe and battery holder.
RC3563 - 28USD with 2 Pcs GX-12 connectors.
Fnirsi - 34USD

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In real videos they are not as short as on the poster. Seems to be the same length as RC3563’s.
But that length is still insufficient. Working with 18650/21700 was quite inconvenient, and when I got 32140 I decided to take off a bit of external insulation.

RC3563’s pen probes:

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Wow, that’s a bit pricy! For me the leads cost much less, and currently difference between RC3563’s and Fnirsi’s test leads is 2 times.
In your case there is not much sense in going for RC’s attachments.
Also I actually don’t use the battery holder. Pen probes are more convenient if we only need to measure IR. I think in future I might rework that holder for capacity testing purposes.

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I was thinking something similar, but for a different reason and with a different holder.

I’m having a 46950 battery coming in and I need a way to charge its, so I was thinking of purchasing the battery tester holder shown below, and reusing it for charging. There is a way cheaper option that also works (with wires and magnetic contacts), but this one looks cooler! :rofl:

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Finally received these meters today. I did a quick test with both.

The Resistance meter matched my other two closely, it reads somewhat faster than the others ( the other two jump back and forth a few seconds before they stay stable)

The Voltage / Amp meter is quite nice. I quickly compared it to my small UNI-T. It matched when the Uni-T was on the 100 amp setting ( I have several meters and they all seem to be a little one way or the other ) What I really like it doesn’t have that pain in the butt zero button the Uni-T has. It also has a min / max screen for Voltage and Amps. Pretty cool feature and both meters are rechargable. Well worth the $35 I paid for the DMM

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I have also bought (and recieved) a DMC-100 in the meantime, since I could get it for € 30,- on Banggood. :sweat_smile:

The DMC-100 also has a zero button, but only for DC current I believe; if you do a short/quick press on the On/Off button, it will zero and it will show ‘zero’ on the top of the screen, next to the flashlight symbol. If you do a quick press again, it will go back to the ‘normal-mode’.

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Thanks . I need to get around to reading the Manual I guess.

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bit off topic. but I got a dmc-100 meter too. voltage and current seem to match other shop fluke pretty good, but resistance and temp, temp looks to be based off resistance is pretty far off. about 15deg hoter and down in the low 10-15 ohm range about 5 to 10 ohm off in the ohm scale.

I see your resistance reads correctly? can you give me an idea of how you tested and how close it is? have you tried the temp probe? I got mine thru Amazon, so exchanging it wouldn’t be do difficult if it’s I just got a bad one.

thanks.

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I was talking about the HR10 when I mentioned the resistance matching my other testers.