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custom cellphone battery charger drains out the cellphone battery..why?? Answered

I made a cellphone battery charger from 3 AA batteries.The combination of 3 AA batteries was at a higher potential than the cellphone battery, but when i connected both of them for charging, the potential of 3 AA batteries remained same but the cellphone battery was completely drained.why??If someone could explain maybe??



Best Answer 5 years ago

  • You do not have the schottky diode wired correctly
  • The charge current limiter is actually drawing the CB
  • AA batteries are No-load voltage high but discharged
  • Connector wired to  the wrong bins.

These are some of your possible problems when there is a utter lack of
information beyond the main complaint and we have to use the
Jedi remote viewing to see your schematic

A low forward diode prevents reverse discharge.


a 1N4007 will do, i suppose
I already have it at home

While a 1N4007 will do as well as a 1N4001.
A 16¢ 3A 40V schottky diode with a lower forward drop can charge a little bit more.

Thanks for selecting my answer.


the batteries were connected in series
+ve of 3 AA batteries was connected to +ve of cellphone battery and -ve of 3 AA battery was connected to -ve of cellphone battery

What is the voltage when you have them hooked up together Without the electronic one way valve special diode I texted about ??

wires are not connected to wrong pins certainly
and i dont think they are no load voltage cz they lit a number of leds
here are the circuit and led lighting

potential of 3 AA batteries(4.44V) was higher than cellphone battery(was lesser than 2.5V)

Did you connect the batteries in series (for a total of 4.5 V), or in parallel (for more current, but only 1.5 V)? The charger must have a higher voltage (usually significantly higher) than the battery being charged.


5 years ago

Can you show your schematic?