TOPIC:

Is there a way using a multimeter to see, once a battery has been charged, how many amp hours it will produce, or do I just have to put it on a car and run it til dead?
If using a multimeter is possible what settings etc and formulae if required
TIA Alan

You will have to discharge, so you need two meters if you want to DIY, one for voltage and one for amps.
www.ebme.co.uk/...-batteries

Cheers for the input WB
I’m gunna give one of these a try when they are back in stock, I know it don’t tell me potential mah but at least it will tell me if all cells are taking a charge to full capacity, which is a good indication I would assume. If I’m wrong on my understanding of this please put me right.

That only shows voltage, so not much use imo. You will need to measure how much amps go into or come out of your cells. What kind of charger do you use?

iMAX B6 charger shows mAH in/out on charge/discharge

Jonny wrote:

iMAX B6 charger shows mAH in/out on charge/discharge

And with the B6 you can charge all type of batteries. I use it for my 1/1 car's batteries.
I bought it with JR advices. No regrets.

Jonny wrote:

iMAX B6 charger shows mAH in/out on charge/discharge

This is sounding like something I should look at then

Yep, I too love my B6 style charger
Keeps track of mAh in and out, very nice, not like the old days where my " really good " Astro Flight charger had an analog amp meter and a clockwork timer

But battery maths have not changed, amps out for a given time period equals capacity at a given voltage. That last part is even more critical now with lipo batteries because if you go too far......game over...

To be completely honest I have not really studied lipo theory other than to understand what I need to know to work with them. With the capacities available in a standard RC car pack size now, I more worry that I will get board with it before the battery quits .

I my previous life as an aircraft engineer ni-cads and lead acid are a very well know subject, charging , dis-charging, cell levels, cell blocking, all fairly important when you are dealing with ni-cad pack that cost more than $10,000 just crazy I tell you .

But a basic capacity test is still the same, applying a known load and timing the output until the voltage drops below the accepted level....not to zero. With big ni-cads we would block them out when the cell dropped below 1 volt, that is the actual working voltage of a ni-cad under load, so yes boys our old 6 cell 7.2 volt packs are really 6 volt packs
....but I digress.......
So if I apply a constant 1 amp load to my old 1200mAh pack it should go for 1.2 hours before it drops below 6 volts ( 1200mAh does sound much bigger then 1.2 Ah doesn't it ) this still applies to all battery types, the bigger the load the faster it will run out of amps.
Ni-cad chemistry is very good at giving off its capacity in a big hurry, shorting out a big battery could be fatal it really came down to how much current the wires and connectors could handle. Lipo is a bit different hence the "C" ratings given on the packs relating to the speed (amps) of charging and dis-charging the packs so as not to " over work" the chemistry and ruin the battery. But I think this doesn't have much relevance to someone like me running a 30 year old 540 powered RC car, it is more for the 1/5 scale off road racers with their giant brushless motors and the heavy lift quad copter folks and now probably Tesla spaceships too.....

So a bit long winded as usual but its my 2 cents worth, perhaps it might be of some use......


As for a meter to do it, just use the B6 discharge function it is simple and it works....