# mA vs mAh



## Wiggle (Oct 2, 2014)

I just wanted to post an explanation of some of the terms related to batteries, charging and electricity in general that are used. I've noticed there seems to be some confusion among even more experienced users in these terms:

*mA* - _Is a measure of electrical current_. 1 mA is one-thousandth of an ampere. This refers essentially to how much charge is moving through the wire per unit time. In a physical analog you could consider it like the flow rate of water through a pipe. The "m" in "mA" is always lower case and the "A" is always upper case.


*mAh* - _Is a measure of charge_. 1 mAh is the amount of charge transferred by moving 1 mA of current for a period of one hour. It would be how much water has flowed through the pipe over a period of time.

A battery is a "holding tank" for charge, so it has a capacity in mAh. Remember current is instantaneous (like speed) while charge (mAh) is cumulative (like distance).

*C* - C is a rate of charge or discharge. It has a unit of h^-1 (which can seem a little confusing and it doesn't really matter for our purposes). It is current at which a battery will be fully discharged from full in exactly one hour. So for example, if you had a 3000 mAh cell and drained it at a rate of 3000 mA it would take 1 hr and this rate would be *1C.* If the cell was drained at a rate of 1500 mA this would be *0.5C.* 
This value is important to know because different cell chemistries have different levels of charge and discharge they can safely endure. For example if you take two li-ion based cells of the same chemistry and one is a 14500 cell with 800 mAh capacity and the other is an 18650 with 3000 mAh capacity they will not have the same ideal rates of charge or discharge. Pretend we are charging at 2A (2000 mA). This would represent a rate of 0.67C for the 18650 but a rate of *2.5C* for the 14500. Therefore both are li-ions of the same chemistry being charged at the same current but the 14500 is more "strained" by the high charging rate and could suffer damage.


Hope this is helpful for others, I know these terms get confused often.

Please comment if this is helpful or if there are any other terms that are not making sense.


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## ven (Oct 2, 2014)

Very helpful and thank you


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## teacher (Mar 26, 2015)

I may get "scolded" for replying to an older thread.......... 
But I just ran across this and it is very helpful and concise.
Thanks for taking the time to post it and also put it in your 'signature' line. :thumbsup:


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## tyoda0202 (Apr 16, 2020)

Thanks for the aforementioned explanation on difference between mA and mAh. 6yr later tagging onto this thread 
New question - why does my battery charger display mA only? For instance while charging 2550mAh rated batteries, it displays 375mA. What does this tell me about my batteries or charging state? Thanks!


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## ven (Apr 16, 2020)

The 375ma is telling you thats what charge you have put in the battery. Note what you have put into the battery since putting in the charger. Not a measure of the full capacity. 

So for an example, the battery was nearly fully charged. Its put on charger, it reads 375ma when terminated. Its took 375ma to fill the tank up to max. Meaning it would have been around 2200mah to start with(rough). 

If its a nimh battery, you could put on the charger at 1.0v or 1.3v, to get as an example to 1.47v, you would have 2 different ma figures to get to termination.


:welcome:


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