Charger AA AAA NiMh 18650 Lithium Ion
Four completely different batteries can be charged at once by the Liitokala Lii 500. How many mAh have already been charged, the internal resistance and the voltage are displayed.
My first order of 12 pieces of 18650 cells came with a rotten one. While the other cells arrived with 3.7 to 3.8 V, this cell had only 3.2 V. The Lii 500 charged fully at 584 mAh to 952 mAh, only the rotten cell required 3085 mAh. Why only?
The next day brought the answer. Recharge 2 cells again. 13 mAh, 176 mAh on the rotten cell. So the cell had probably been charged normally, but the enormously high self-discharge caused this cell to arrive nearly empty.
I was able to use the readings from the Lii 500 as proof at the cell dealer and got a cell with the next shipment.
In a device without BMS, the rotten cell could have destroyed the whole pack. How? In the laptop powerbank there are 3S4P, so 3 in series and 4 cells in parallel each. The row with the rotten cell would have discharged itself much faster. After a few weeks, it might have looked like this: 3.4 V- 4.0 V - 4.0 V. There would still have been at the charge indicator of the laptop power bank all 3 LEDs lit.
After only a short operation, there would have been a surprising shutdown: With a cutoff voltage of 10 V, it might have already looked like this: 2.4 V - 3.8 V - 3.8 V. This would have made the 4 cells from the first row dangerous and unusable due to deep discharge. Then charge up to 12.1 V, now it eats into the other two rows of cells: 3.3 V, 4.4 V, 4.4 V. By the way, overcharging to 4.4 V is common in smartphones, that's why smartphone batteries age so fast.
. For all applications where single 18650 cells are inserted into a device, I strongly recommend a charger of this type. This is the only way to detect and correct different states of charge of individual cells.
. You can order in 3 variants, without power supply, with 12 V 2 A power supply or additionally with a cable for the car socket. Since I have been accumulating power supplies for 3 decades, I took the variant without power supply. Also a cable for the 12 V socket in the car I have found in my old stocks.
The power supply should have 12 V. During testing I once made a mistake, accidentally connected 19 V and only noticed it after a few seconds. Has the Lii 500 fortunately survived.
Here are 3 power supply options right away: the new notebook powerbank, an old universal power supply adjustable to 12, 14, 16, 18, 20, 22, 24 V and a cable with a plug for use in the car.
The old powerbank is unfortunately unsuitable because it simply cuts off the 12 V supply below 150 mA.