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lipo usb charger drains phone battery Answered

Hi guys, tried to make my own minty boost.

I used a 3.7v battery 14.8 w/h
Dc/dc booster
lithium charge controller
switch and a blocking diode.

my phone when plugged has a smaller charge than when i started charging.

I have a diode from the charge controller going to the dc/dc boost and a diode from the incoming solar panel. 

please help!!


1N5819 is the diode you should use however that may not be your problem.

If you are using a LM7805 or other 7805 voltage regulator your source needs to be 7 volts or more but not over 35 volts, the regulator may be draining the battery.

Another possibility is Solar cells are not the most reliable power source even if you wired the cells for 12 volts they can drop below 7 volts without you knowing and the regulator can drain the battery make sure there is a diode after the regulator and before the USB.

You might want to use a BA50BCOWT or some other BAxx series regulator that will work as low as 3 volts input.

You can check the datasheets here:


If you need to buy something try here their prices are good:



It could be producing 5v at such a low current that the phone *IS* charging, but technically using power faster than its receiving it.

i was thinking the same thing. i will try with the phone off over night

i should also note that the charging light and icon appear on my phone, although it is apparently draining.

Bit fussy but if I see it right why are you powering the one circuit board from two places on the same switch.


Hi Josehf,

thanks for your reply. Let me clarify the picture for yo. The upper red wire is an input from a solar panel. the lower red wire is comes from a terminal in the lipo charger, also joined with the battery. that wire then goes through a switch, through a diode and into the dc/dc usb 5v booster.

the diode in yellow box is from the solar input to the lipo charge controller.

i will heat shrink the 'possible short' in red box.

attach is a sketch for better understanding.


looks like its working. thanks for your time. It means a lot to have an expert lend some advise!

When times are hard, what can you do?

It takes them around, to make dreams come true.


Hi Joe,

Still having some issues with my device. when I plug in a phone or ipod it says its charging but does so very very slowly. I have an app on my phone that says its charging at 3.9%/hr. When i plug my solar panels directly into a usb charger (not through altoids tin) it will charge at 29.9%/hr.

How can I improve the current so my devices charge faster. I am using a 4000ma battery.

would replacing all my n14001 diods with 1N5819 make a large difference

thanks so much

It can improve your circuit to change the diodes.

I can’t believe I have this committed to memory.

All three of these diodes are 1 amp.

1N4001 has a voltage drop of 1 volt and carries 50 volts.
1N5817 has a voltage drop of .45 volts and carries 20 volts.
1N5819 has a voltage drop of .6 volts and carries 40 volts.

Since you are working with less than 10 volts I would go with the 1N5817 and the .45 voltage drop.

Without getting into it to deeply, as strange as it sounds everything in electronics is a resistor. With a diode it has little resistance in one direction and massive resistance in the other and electricity takes the path of least resistance.

Going with a 1N5817 is like going with a smaller resistor so it should improve your current.

When I was looking at your circuits I noticed they look like Arduino.

If they are is the regulator a programmable regulator?

And if it is a programmable regulator what is it set to?

What diode do you have and is it wired the correct way?

i am using a 1n4001. One of the diods connects the battery from the lipo charger going to the usb dc/dc boost.

the other diode, not currently being used is also 1n4001 from the solar panel input. I have them wired so the colored white line is at the outgoing end. >>{ | }>>>

The end with the stripe is the cathode or side that should go to the negative lead of the panel. The other end goes towards the battery being charged. Or you can have the stripped end towards the battery and the other end on the positive lead from the panel. Otherwise your allowing the power from the phone to go to the panel.

Get a meter and make some measurements in-circuit. Check for short circuits to the tin etc too.

What circuit are you using?

It sounds like you'll be barely getting 5V out of the circuit without any load, and significantly less once there is a load on the solar cells.

Im not quiet sure what you mean by the circuit question.

right now I am just charging my lipo battery from the micro-usb.

ill worry about the solar system once i figure out the problem at hand

Possibly your blocking diode isn't....