Testing Battery For Mah Capacity
How do you test a single battery to determine it's MAH capacity?
I have several batteries that came out of some old packs that I found, but they are not marked with the MAH capacity.
Poor Man's Capacity Measurement
Well, if you have a good DVM, some electronics experience, and LOTS of free time, then you can make a poor man's discharge acquisition system. It can give approx mAH values:
(1) Take a wild guess at the cell's capacity. Don't worry about being wrong, but attempt to nail it as close as possible.
(2) Charge the cell at a C/10 rate (per your guess) for 14-16 hours. Second best is to use a quick charger set to single cell mode.
(3) Divide the guessed capacity by 5 (C/5). This will be your discharge rate. For example, a 600mAH cell will be discharged at 120mA.
(4) Choose a resistive load that provides the C/5 current draw. A 3V flashlight bulb makes a good load. It does not have to be exactly C/5. But you must record the load current for later use.
(5) Continue discharging until your cell measures exactly 1.0VDC. The voltage monitoring will require you to check every 5-10 minutes. When the voltage is met, then record the number of hours it took. Re-measure the current draw at the lower voltage.
(6) Calculate the average load current: mA = (Current1 + Current2) / 2.
(7) Calculate mAH: mAH = mA X Hours.
After doing this once or twice I expect that you will decide that those unmarked cells are best used in the kids' toys.
|Category||Thread||Thread Starter||Forum||Replies||Last Post|
|What capacity battery for a axi 4130/20?||ElectricFlight||Batteries and Chargers||7||Sep 13, 2004 03:44 AM|
|Lipo battery of about 500 Mah capacity?||flierbk||Batteries and Chargers||4||Mar 27, 2004 10:06 AM|
|biggest capacity AA battery?! (for JR Tx)||henke||Batteries and Chargers||17||May 08, 2003 03:59 PM|
|5-channel PiCO transmitter with 6/1000 mAh battery for $125.00||sbuechler66||Aircraft - Electric - Airplanes (FS/W)||0||Mar 12, 2002 12:24 PM|
|Higher Capacity Tx Battery for 8103???||cactus||Power Systems||15||Jan 08, 2002 10:56 PM|