How To Measure A Battery's Mah?

[BitBandit]

I've seen people talking on this forum about the importance of the mAh (milli-amps per hour) when using batteries with the GP2X. Things have been said such as "get batteries with at least 2300mAh".

How do I measure the mAh of a battery? The batteries that I use with my GP2X don't have the mAh rating written anywhere on them, so I guess I have to measure it with a multimeter? I've got a multimeter that I often use for testing voltage and continuity, but I've never used it for testing mAh and I'm not sure which setting on the dial I should use as there's nothing that says "mAh".

 

[Vimacs]

if it dosnt have a mah rateing writen on it than its probably a non.rechargable one. you should realy use nimh rechargeables.

To mesure mah you hook up a fitting resitor and stop the time.

 

[BitBandit]

if it dosnt have a mah rateing writen on it than its probably a non.rechargable one. you should realy use nimh rechargeables.

To mesure mah you hook up a fitting resitor and stop the time.

Ah, so only rechargables have mAh ratings, not normal non-rechargables? That would explain why there is no rating on my batteries then! Thanks!

 

[Fishbong]

You don´t measure a battery´s mAh, you measure its CAPACITY. Which is measured in mAh (milliAmpere x hour).

Shikaku also donesn´t measure his penis´s inches, but its length.

 

[Vimacs]

hair splitter...

 

[buntz]

If a battery is rated for 1000mAh, the it can supply 1000 mA or 1 A for one hour at the batttery's specified voltage. The higher the mAh, the longer a battery will last. All batteries have a Ah (Amp hour) rating, but it becomes more important when dealing with rechargibles becasue it is a direct indication of how long the battery will last, and thus how often it will need recharged.

The only way to really test the Ah rating of a battery is to put a known load on the battery, lets say 1 amp, then monitor the voltage until it begins to drop. So if you had a battery that had a one amp draw on it, and supplied a constant voltage for 2 hours, the the batery would have a capcity of 2000 mAh or 2 Ah.

The bigger the mAh rating the better. You cant hurt an electronic device with a battery that has too much capacity. The voltage, however, has to be no higher that 1.5 volts per cell if using two batteries to power the GP2X for a total of ~3 volts.

If you hooked a 3.3 volt regulator to a car battery, you could power your GP2X for days from the plug on the side.

I'd go with NiMH cells as they have a high capactiy than thier NiCd counterparts, and arent affected by "memory" effects, so their capacity doesn't decrease over time. You will have to get a charger specific to your battery's type. So don't put NiMH batteries in a NiCd charger or vice versa, unless you like fire.

Search on the net for the biggest mHa number you can find in a AA size battery, get those, and you shall be happy.