Portable mini power bank/tp4056 issues

Thread Starter

Cont3mplation

Joined Sep 10, 2017
3
I'm currently attempting to make a disposable phone charger (w. 600mAh liPo battery) rechargeable, so I purchased the tp4056 board with battery protection circuit included to simply add inbetween the booster circuit/phone connector and the battery. I then realised that the tp4056 had a 1A output, so i changed the 1200ohm resistor to a 4700ohm to lower the charge current. The charging worked perfectly, charging the battery to 4.2V and cutting off, but when I attempt to charge a device with it, it stops charging when the battery is at 3.5V. Could changing the resistor possibly have raised the cut off voltage? Or is there a small mistake I've missed? (New to hobby electronics and forums in general so apologise for any mistakes in this post)
Thanks in advance
(This is the circuit I'm modifying:
)
 

LesJones

Joined Jan 8, 2017
4,208
It is probably designed to cut of when the liPo cell gets down to 3.5 volts to avoid damaging the cell. One of the pound shop chains have these power bank units so it is not worth trying to make one.

Les.
 

Thread Starter

Cont3mplation

Joined Sep 10, 2017
3
You're probably right that there's no point in making one, I'm less doing it for the practical use and more as just a fun project, and I've checked it and the issue does seem to be the voltage breaking down, not the cut off as the dw01 IC it has seems to have a cutoff point off 2.5V, so I just need to find out why the voltage is collapsing
 
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