Hello
I hope i can find some support here.
For a projekt with an mikrocontroller an a small motor i need a power supply.
After readig about LiIos im a little bid affraight of damaging the Batterie by discharging with very less current.
My case will look like this:
Two LiIos support 7,4V, after a voltage regulator 5V.
The µC needs just very low current ~10mA.
And every 5min the motor needs for 30s 1A.
Do the protected 18650 Batteries stop with this low current?
Best regard K.
Well they run for long periods on moonlight
When the voltage gets too low the protection will cut the cell off
I’ve found with very low currents the protection doesn’t always trip.
And the cut of is indipendently from the current?
Great!
Is there a Modey you can recommend to me?
The protection would trip when the motor came on.
If I understand correctly you need a 5V power source right? Then why not use batteries in parallel and a boost circuit instead?
It would be even cheaper to buy a Xiaomi 10,000mAh power bank at $13, it already comes with 3x 3350mAh LG18650F1 and a 2A capable boost circuit with 87% efficiency, and low voltage cutoff at 3.0V
In Germany it costs 24€
http://www.amazon.de/Xiaomi-tragbares-Ladegerät-Ladeanzeige-Aluminium-Silber/dp/B00LAUTANM
That’s the older version with 4x 2600mAh 18650 and less efficienct circuit, try this one:
But price has gone up a little, it was $13 when I ordered mine. Excellent power bank, I get 32Wh of output energy. You can also tear it down so it doesn’t look you’re using a built power bank.
Hey Will
Big Up for this great Idea!
A Powerbank is the solution, i searched for!
Great, great, great 
There are a lot ob PB on Ebay, i will check it out
Be careful, most ebay power banks do not meet claimed specifications!! This is why I recommended the xiaomi, it’s been tested and proven.
Can you prove that?
I tested down to 100uA without finding any problems. I would also be silly to add a extra circuit to disable the protection at low current.
Can’t prove it like you could, but a direct drive light i had would run the cell past safe voltage. What do you think, defective protection circuit?
What do you call safe voltage? I had protections that did not trigger before the cell was down to 2.0 volt.
If you do that at low current the cell will be very slow to recover voltage.
I wouldn’t want a li-ion cell to go below 2.5v for an extended time.
Yes, they do.
And 1A motor current is no problem for any protected 18650 (unless maybe it’s an XxxxFire).
In German:
Geschützte Akkus schalten unabhängig vom Strom ab, also auch bei sehr niedrigen Strömen, so wie HKJ das geschrieben hat. Die Abschaltschwelle ist unabhängig vom Strom. Wer anderes behauptet, hat nicht richtig gemessen oder die falschen Schlüsse gezogen.
1A Strom sind für keinen geschützten 18650er ein Problem (außer es ist ein Schrottakku). Selbst die allerschwächsten Schutzschaltungen schalten frühestens bei 2,5A ab. Üblich sind 5-6A.