Nice one HKJ, thanks. Very useful info to measure battery internal resistance with stuff we already have.
Very nice article! You answered a question I had. Thanks very much for the details. Sticky’d.
Accucel 6 has a way to measure IR supposedly. I have an Accucel, but haven’t done it, because it apparently involves using some additional cabling which I don’t think that I have. If I did do that, do you all think it would be an accurate IR measurement?
It will probably do a DC measurement at a unknown current. If it uses four wires and you connect them correctly to the battery, I would expect it to do a accurate measurement.
But if it only uses two wires, it will not be very accurate.
What is most interesting is the repeatability, i.e. does it give the same reading (or very close) each time. If it does, you can use it to follow the ageing of the batteries.
Hi,
I didn’t look into it much, because, like I said, I got info that you had to use the side-port and I think cable using something like a balanced charging type configuration, and I only have the default cables that came with the Accucel. But, they do make a deal about it, with even a small yellow flyer that says it’s like the most important thing to measure (but no instructions how to cable) :).
Thanks. If I ever get around to doing it, I’ll post about it.
Jim
Thanks for this great info HKJ!
Thanks HKJ for a very interesting read! Of course, I’ll have to read it about 10 more times for 25% of it to sink in….
+1 except I’d be lying if I understood 2%.
As usual, sure I can learn new thing by reading HKJ post. Thanks for sharing, HKJ.
I had long wanted to have easy way to keep track on my battery condition, but recently lazy to keep track on them.
I think I remember seeing an iCharger 208B in one of your many informative posts. Have you looked at its IR measurement function, and if so, what do you think of it?
Yes, I have a iCharger 208B or two. They can measure IR, but I have not really used it or analysed it. It uses two wire and will give an error due to that.
Thanks for the quick response
. I will have to study the OP more closely to learn about what the error may be.
meant for capacitors but does ok for batteries.once you get the feel for good esr readings for a certain cell go/nogo tests are fast.like when grading laptop pack salvage cells.
http://www.amazon.com/Anatek-Corporation-blueesrkit-Blue-ESR/dp/B005NB6CKS
i have one of the original kits from 15+ years ago.great tool.
I’m new to all of this but would like to replicate this set up. Would you be able to explain how the resistance/capacitor boxes were built.
I bought a Reed R5001 LCR meter for measuring impedance. Can I use that with this set up?
Thanks!
That is just resistors/capacitors connectors to the binding posts. When doing a lot of different test setups this is much easier than soldering the wires each time.
Even though I have a bunch of electronic loads, I uses that resistor box all the time.
Probably not, the problem is the battery voltage. When measuring the internal resistance you are not going to work on a voltage free circuit, due to the battery it will have about 4 volt.
@HKJ
1: while measuring internal resistance , do we need to be concerned with the wattage rating of a resistor ?
2: how can we conclude some usefull information from internl resistance figure ? like how good/bad is it ? how much int r is good how is bad ? bad would mean it cant supply great amperagess ?
3:Battery is pretty much dc source so how does ac comes into play ?
pardon me for those bunch of questions as it has been long time i studied electronics/circuits.
Yes, but if you are fast, you might get away with some overloading of the resistor.
Yes, but I do not have a table with good/bad values for different batteries.
Probably because it is easy to make a device that can measure impedance in-circuit, i.e. you can check the battery without disconnecting it. AC and DC gives different values, but in both cases the battery will be bad when the value has increased significantly from the initial value.
how much should be the battery charged (ideal no load voltage ) to do this test .
There is no rule about that, but you want the same charge each time to get the best comparison.
One charge level that is easy to get each time is fully charged.
Only lead acid batteries needs to be tested fully charged (and rested ideally).
IR of li-ion batteries does not change with state of charge (only very slightly) and can be neglected for practical reasons.