So, I have a Einhell NHS 24 battery powered hedge trimmer but I don't have the battery for it :)
genuine battery was NiCd 24V /1700mAh, don't have NiCd but I have some laptop pulls and I thought to try and use what I have.
I connected 6 x 18650 in serial, got 24.something volts, tried it out and it works (used it for a couple of seconds just to do the measurements) but, trimmer doesn't have any electronics inside just one micro switch rated for 10A and that's it!
I measured consumption and it pulls about 2.6A but is that 2.6A from each of 6 cells (so, total of 15.6A) or is that 2.6 for all 6 cells? Ah, this confuses me every time! I think it's the first case, ~15.6A in total, because when I measure consumption in multi-cells flashlights I need to multiply number shown by DMM with number of used cells! If that is the case, I need to limit the current to under 10A!
What the trimmer sees is 2.6 amps at ~24 volts, or about 62 watts. The switch should be happy because it was seeing 24 volts from the NiCd pack and unless the trimmer has been damaged or modified it should be presenting the same load to the Li-Ion pack as it was to the NiCd pack. I would be more concerned about how well balanced your pack pulls are. Have you soldered them together or can you charge them separately?
So, it’s not 15.2A as I thought.
Batteris are not soldered and I can charge them in standard (i4) charger.
No damage or modification has been done to the trimmer.
If it wasn’t a pain to disassemble it I would take a readings of consumption directly at the motor.
If this proves as a good permanent solution I will add something like this (2-in-1 1~8S Lipo Battery Low Voltage Buzzer Alarm) for monitoring batteries.
That voltage alarm might be useful for monitoring the pack voltage, but it would be a good idea to check the individual cell voltage regularly because they will probably discharge at different rates.
