Battery Resistance Test?

MrMemory

War Hero
I'm trying to ascertain how much life or milli amp hours (if that is the correct phrase) are left in this NiMH battery. I understand I need to put a load on it to test the resistance. Can I do it with a multimeter like the one in the photo?

Thanks in advance.

MM

71307821_10219857621780347_1118154998476177408_n.jpg
 
Good question

imho No, multi-meter will melt

You need a load/resistor eg a 12v 55w bulb and measure voltage drop

Battery analysers & internal resistance meters are used in garages now - Bosch etc sell them
 
No, you can't simply measure amp hours with a multimeter.

Testing the voltage of dry cells (AA, AAA etc.) can be done but needs a resistor to get an accurate result. Some multimeters have a battery test function on the dial.

I don't know enough about rechargeables, so I wouldn't mess about with them and I wouldn't stick meter leads in the socket. Best guide is how long it works after a full charge.
 

Blogg

LE
Dirty secret: by virtue of the battery chemistry, even if well maintained and with a modest number of charge cycles a NiMH battery is doing well if it lasts five years.

Cheapo ones three.

Modern battery power tools are relatively cheap because the makers real business is selling you new battery packs at a vast margin.

(Unless of course you are a cheap sod like me who opens them up and replaces the cells with quality units and all for about 15% of what the OEM unit sells for)
 
No, you can't simply measure amp hours with a multimeter.

Testing the voltage of dry cells (AA, AAA etc.) can be done but needs a resistor to get an accurate result. Some multimeters have a battery test function on the dial.

I don't know enough about rechargeables, so I wouldn't mess about with them and I wouldn't stick meter leads in the socket. Best guide is how long it works after a full charge.
NiMH cells have a flatter discharge curve than alkaline cells (standard AA etc.) so measuring their terminal voltage doesn't give a good indication of their charge state unless it's done at close to maximum discharge current. As they have a relatively high self-discharge you can almost guarantee that unless they have been recently charged, they will be empty.
 

ugly

LE
Moderator
I'm trying to ascertain how much life or milli amp hours (if that is the correct phrase) are left in this NiMH battery. I understand I need to put a load on it to test the resistance. Can I do it with a multimeter like the one in the photo?

Thanks in advance.

MM

View attachment 418898
If I recall correctly there was a 1 ohm shunt designed for this, it was designed to go into the meter before the leads and created the dummy load. It could have been a 1k ohm shunt but it's been 30 years since I was taught about it and I dont recall being issued one. I do have a box of 150kohm shunts in the barn unused and out of warranty that I was supposed to use when testing after replacing a core of a cable. Never used those either I just used to mark my test certs as skipping the relevant sections due to not having the kit.
Trains still seemed to run
 
I'm trying to ascertain how much life or milli amp hours (if that is the correct phrase) are left in this NiMH battery. I understand I need to put a load on it to test the resistance. Can I do it with a multimeter like the one in the photo?

Thanks in advance.

MM

View attachment 418898
Get a nail, join the positive and negative terminals together. Use the fluke to test the nail to earth.
 

ugly

LE
Moderator
The way I test car and leisure batteries for the pen fences is simple, dont worry about load, stick your meter on v DC and just go across the terminals. A 12v car battery with any life when fully charged should show 13 plus volts, anything less than 11 and its watches closely, anything under 10 and the charger lights showing fully charged gets it in the scrap pile.
 

anglo

LE
A multimeter some times as a battery test that allows you to test a single cell,
as for testing a battery with multiple cells in series, fully charge the battery then
load the battery to full rated load and see what the voltage does, if one cell as
gone u/s you will find a sharp drop in output voltage under load, if the cells have lost capacity
they will not give the rated AH rating [Amp/hour]
An example, a 12volt 100AH battery should give you 10 amps for ten hours
for 100% capacity
[or multiples of that adding up the AH rating ]
 

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