# How long to charge 9v nimh battery

Started by December 19, 2021
```I have a 9V 180 ma  discharged Nimh battery that I am charging at 25ma.

How long will it take to charge?

Thanks,
Andy
```
```AK wrote:
-------------
> I have a 9V 180 ma discharged Nimh battery that I am charging at 25ma.
>
> How long will it take to charge?
>

** What you have is a 180 mAh battery:  h  = hour.
You do the math.

......  Phil

```
```Am Sonntag, 19. Dezember 2021, um 05:57:15 Uhr schrieb AK:

> I have a 9V 180 ma  discharged Nimh battery that I am charging at
> 25ma.
Isn't it 180mAh?
milliampere hours and not only milliampere?

> How long will it take to charge?
(180mAh)/(25mA)=7,2h

```
```On Mon, 20 Dec 2021 11:22:04 +0100, Marco Moock <mo01@posteo.de>
wrote:

>Am Sonntag, 19. Dezember 2021, um 05:57:15 Uhr schrieb AK:
>
>> I have a 9V 180 ma  discharged Nimh battery that I am charging at
>> 25ma.
>Isn't it 180mAh?
>milliampere hours and not only milliampere?
>
>> How long will it take to charge?
>(180mAh)/(25mA)=7,2h

For nickel based batteries, you normally add 40-50% to compansate for
charging efficiency.
--
RoRo
```
``` Robert Roland wrote:
==============
> For nickel based batteries, you normally add 40-50% to compansate for
> charging efficiency.
>

** The OP posted a question from some test he had to do.
So no such correction factor is needed.

For slow charge (8hr) rates -  40% might be OK.
But absolutely not for fast charging, or the cells will cook.

.....    Phil

```