Battery Cell Internal Resistance Meter

[boostjuice]

http://www.chinasampo.cn/Digital-Multimeter/SM8124.htm

http://cgi.ebay.com.au/SM8124-Voltm..._Measurement_Equipment_ET?hash=item45f0ea26f9

Does any member here own or has any member used one of these meters? Google brings up no user reviews on them. I am looking for an easy, fast, reliable and inexpensive way of measuring the IR of A123 M1 cells and one of these meters seem like the cheapest and easiest option. I realise they measure internal resistance at AC @1kHz rather than DC. That shouldn't matter for cell matching as i am only chasing relative measurement, not absolute values @ DC loading.

Any thoughts on potential/experienced accuracy, precision, resolution and range of these meters?

I already have a cheap RC charger that reports battery capacity @ 1A max discharge, so all i really need to know is IR measurements to have the info needed for cell matching into parallel groups.

I'd rather not go through the hassle of manually inferring IR by Delta V, Delta I through variable loading. Also, i don't think i need to fork out the cashola for a CBAIII for what i am trying to achieve.

Should i take a gamble on one of these or just buy an RC charger with an inbuilt IR function? What sort of accuracy, precision, resolution and range do the majority of these high end RC chargers feature? I don't really need a high end RC charger as i will be running a Goodrum/Fechter BMS with the finished Battery pack, so all that is needed is a much cheaper CC/CV PSU or Pb-Acid charger.

Cheers

 

[BMI]

You will find that a cheap Chinese meter such as the one you have shown will be OK for quick measurements but don't expect it to be very accurate. I have a KT97-A which cost four times what this meter costs and even my meter is only OK for general testing. The reading you get will vary considerably depending on how hard you push the probes against the battery terminals of the battery under test due to contact resistance.
View attachment BMI Cell Impedance Test.JPG
It really is a case of "you get what you pay for". If you want to be able to test accurately and reliably you need to spend about $1000 on a good quality meter such as a Hioki 3555.

I really like the quality of Fluke test instruments. Unfortunately a battery impedance tester is about the only electrical test instrument which Fluke doesn't make. If they made one I would definitely buy it.

 

[dnmun]

this last post was spam and has nothing to do with testing internal resistance. however, if you do find that your battery has internal resistance in the megaohm range, please post up about it.

 

[deVries]

Does any member here own or has any member used one of these meters? Google brings up no user reviews on them. I am looking for an easy, fast, reliable and inexpensive way of measuring the IR of A123 M1 cells and one

Doctorbass has a thread with this IR meter, and he talks about his mods for protecting against reverse polarity. Even has a video. Recent posts to this thread have appeared in the last few weeks in Battery Technology. This is just an FYI for anyone not already aware of this. The quote above was asked years ago.

 

[Ratking]

I have one, and have used it for measuring a couple hundred konion cells. As mentioned, the reading will vary depending on pressure and how clean the surface is. When you get used to that, it is okay. I find it accurate enough to weed out the bad cells.

 

[Ypedal]

:lol: could not resist.

 

[deVries]

this last post was spam and has nothing to do with testing internal resistance. however, if you do find that your battery has internal resistance in the megaohm range, please post up about it.

:lol: Hilarious.