Great little device. Just mounted 4 units on an old piece of wood with a 4 way 18650 battery holder to make a 4 cell discharger. Each Battery Capacity Tester shows Amp-hour, Amps & Voltage of the cell in sequence as the process takes place. The resistor's do get hot, so do not touch them and keep them away from anything that could melt when in use. The 7.5 ohms resistor supplied causes a 0.5 amp load on a 3.6v 18650 battery.

Great little device. Just mounted 4 units on an old piece of wood with a 4 way 18650 battery holder to make a 4 cell discharger. Each Battery Capacity Tester shows Amp-hour, Amps & Voltage of the cell in sequence as the process takes place. The resistor's do get hot, so do not touch them and keep them away from anything that could melt when in use. The 7.5 ohms resistor supplied causes a 0.5 amp load on a 3.6v 18650 battery.

Great little device. Just mounted 4 units on an old piece of wood with a 4 way 18650 battery holder to make a 4 cell discharger. Each Battery Capacity Tester shows Amp-hour, Amps & Voltage of the cell in sequence as the process takes place. The resistor's do get hot, so do not touch them and keep them away from anything that could melt when in use. The 7.5 ohms resistor supplied causes a 0.5 amp load on a 3.6v 18650 battery.

Does one thing and does it well. I've used it to test 18650 Li-Ion cells and NiMH cells. Simply measuring open circuit voltage, or voltage under load will not find weak cells. This unit measures the cell Capacity in mAh (milliAmp hours) at whatever C-rate (amperes) draw you choose. The unit came with a 7 ohm 5W resistor, which tests LiIon cells at just under .5 amps. By switching to a 1.2 ohm resistor I changed that to 2.4A. That is about a 1-C drain for a 2400mAh 18650, allowing the test to complete in ~1Hr. You will want several different resistors for different voltage batteries and different C-rates. With a simple resistive load like this, the current falls slightly as the battery is discharged. (A better, more expensive unit would maintain a constant current.) But this does not affect the accuracy of the capacity measurement. The best 18650 cells I tested measured 2200mAh. Some older ones were between 600-1100mAh. Those are still usable. The worst cells measured 50-150mah. But they would still charge to 4.2V. You need a capacity tester like this allowed me to spot those and replace them. Also, I had a few 'UltraFire' '4500mah' cells I had foolishly bought on ebay a few years back. They measured less than 200mAh. Total crap.

Does one thing and does it well. I've used it to test 18650 Li-Ion cells and NiMH cells. Simply measuring open circuit voltage, or voltage under load will not find weak cells. This unit measures the cell Capacity in mAh (milliAmp hours) at whatever C-rate (amperes) draw you choose. The unit came with a 7 ohm 5W resistor, which tests LiIon cells at just under .5 amps. By switching to a 1.2 ohm resistor I changed that to 2.4A. That is about a 1-C drain for a 2400mAh 18650, allowing the test to complete in ~1Hr. You will want several different resistors for different voltage batteries and different C-rates. With a simple resistive load like this, the current falls slightly as the battery is discharged. (A better, more expensive unit would maintain a constant current.) But this does not affect the accuracy of the capacity measurement. The best 18650 cells I tested measured 2200mAh. Some older ones were between 600-1100mAh. Those are still usable. The worst cells measured 50-150mah. But they would still charge to 4.2V. You need a capacity tester like this allowed me to spot those and replace them. Also, I had a few 'UltraFire' '4500mah' cells I had foolishly bought on ebay a few years back. They measured less than 200mAh. Total crap.

Does one thing and does it well. I've used it to test 18650 Li-Ion cells and NiMH cells. Simply measuring open circuit voltage, or voltage under load will not find weak cells. This unit measures the cell Capacity in mAh (milliAmp hours) at whatever C-rate (amperes) draw you choose. The unit came with a 7 ohm 5W resistor, which tests LiIon cells at just under .5 amps. By switching to a 1.2 ohm resistor I changed that to 2.4A. That is about a 1-C drain for a 2400mAh 18650, allowing the test to complete in ~1Hr. You will want several different resistors for different voltage batteries and different C-rates. With a simple resistive load like this, the current falls slightly as the battery is discharged. (A better, more expensive unit would maintain a constant current.) But this does not affect the accuracy of the capacity measurement. The best 18650 cells I tested measured 2200mAh. Some older ones were between 600-1100mAh. Those are still usable. The worst cells measured 50-150mah. But they would still charge to 4.2V. You need a capacity tester like this allowed me to spot those and replace them. Also, I had a few 'UltraFire' '4500mah' cells I had foolishly bought on ebay a few years back. They measured less than 200mAh. Total crap.