How to test batteries MaH?

How do you go about testing a battery to find out the "real" MaH or "battery power"?
What equipment is needed?
Thanks

Analyzing chargers like the SkyRC MC3000, Opus BT-3100/3400, Liitokala Lii 500 Engineer, Maha C9000, La Crosse BC-700/1000, or a light with a known load and a stopwatch, perhaps?

Chris

The problem with those analyzing chargers is that they have to completely drain the cell and then recharge it in order to approximate the capacity. That means the voltage is drained down to around 2.5v, which is far lower than you would typically want to run your cell to. It's probably okay to do infrequently but I wouldn't make a habit of it as a way to monitor your cell's health.

bwalker said:

The problem with those analyzing chargers is that they have to completely drain the cell and then recharge it in order to approximate the capacity. That means the voltage is drained down to around 2.5v, which is far lower than you would typically want to run your cell to. It's probably okay to do infrequently but I wouldn't make a habit of it as a way to monitor your cell's health.

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Ehhh, my Opus drains down to 2.80v on li-ions, my Maha to .90v on NiMH, before the cells/batteries rebound. Just charge them back up. The new Opus BT-3100/3400 v. 3.1 chargers drain li-ions down to...wait...wait...wait for it...3.1v!

Much like rifle barrels, where every shot wears down the throat a tiny bit, cells and batteries are consumables and aren't meant to last forever.

Chris

waynejitsu said:

How to test batteries MaH?

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Did you mean mAh (millie Ampere hour)?
Normally, capital M stands for Mega.

bwalker said:

The problem with those analyzing chargers is that they have to completely drain the cell and then recharge it in order to approximate the capacity. That means the voltage is drained down to around 2.5v, which is far lower than you would typically want to run your cell to. It's probably okay to do infrequently but I wouldn't make a habit of it as a way to monitor your cell's health.

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That is not true, they drain cells to between 2.8v-3.1v depending on the charger which is perfectly within Li-ion specs.

bwalker said:

The problem with those analyzing chargers is that they have to completely drain the cell and then recharge it in order to approximate the capacity. That means the voltage is drained down to around 2.5v, which is far lower than you would typically want to run your cell to. It's probably okay to do infrequently but I wouldn't make a habit of it as a way to monitor your cell's health.

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LOL the reverse is true! those so called analyzing chargers don't discharge NCA chemistry cells deep enough to get all the juice out e.g. Panasonic NCR-B and Sanyo GA are NCA cells that have to be squeezed down to 2.5v to get all the electrons out

another issue is that those chargers only do a very low-current discharge. to do higher currents you'll need a hobby charger like an iCharger 106b+. up to 7.0A discharge current

Thanks EVERYONE Your help is much appreciated!!

In reality mah in use is based upon what current draw you are using the battery for.
The higher the current draw from the battery the less the mah of the battery in use.
If you are going to use the battery at 100mah then you will probably get most of the capacity in mah out of the battery but when you raise the current draw into the 1000ma range and up (1A) then capacity (in mah) is usually reduced due to losses in the battery itself (internal resistance).

What I want to do is, test some batteries to see if the advertised rating is actually what the batteries are..., you know, to check out "truth in advertising"

waynejitsu said:

What I want to do is, test some batteries to see if the advertised rating is actually what the batteries are..., you know, to check out "truth in advertising"

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You can either get a regulated light with a known current draw and time it till it runs out or a battery charger/analyzer

mAh is the area under the power(not voltage) discharge curve. It can be tested and calculated by accumulation/integration.
Below is the chart I calculate my NCR18650GA battery discharging at 0.2C(0.7A) at 10 seconds sample interval.
I measure the voltage and current by my Graphtec GL220 data logger.
There is a small mAh value for every 10 seconds, and the total energy is the sum of all till the cut off voltage(2.85V in my case).