I have a tomo v8-4 and a tomo m3 and they both work great so far with the cells that I am using but I also have 3 different single cell 18650 power banks from ebay.
When I use any of the 3 that I have (they are different styles) none of them can charge my phone when it is off past 19% (I have a 3000mah battery)which is about 500mah for my phone before the power bank shuts off. If i remove the 18650 cell from any of the three power banks after it no longer wants to charge my phone it will measure 3.8V. If i use them to charge something else like my 3ds itll work fine but then again my 3ds only draws about 500-600 mah when it charges according to my meter.
I figured the single cell power banks wont be able to do high drain.
I put in an order for a ML202, its small enough and hopefully itll be able to charge up stuff in a pinch. I hope the enclosure on that thing doesnt open easily though. I might have to rubber band it down or something if it does cause I dont want 18650s falling out.
I really like the Xiaomi power banks… larger with 4cells but their 10000 mAh model is reasonably compact. They have a 4000 & a 5000 too IIRC. Well made.
Just curious, have you tried charging your phone past 19% when it is off using a wall plug? The reason I ask is I wonder if the phone has to be turned on to activate something in the charge circuit at about 20%?
My tomo power banks can charge from 1% to full same with wall chargers. I even tried charging my phone at 70% since it will draw less current vs dead but it will still go into a start stop cycle around 90%
When I use two cells on my tomo I get a full charge and a bit left over. I tried one cell on my tomo but my power bank started to get hot but the cell was room temperature still. I stopped it to not damage my power bank.
I ended up giving up on single cell power banks and ordered an ml202 which should get here sometime this week.
Im most likely going to buy a power bank from ravpower. My first power bank ever was an anker astro e1 and it broke in a week but anker didnt honor the warranty cause I bought it off Newegg.