This is an easy to do mod for an electric shaver.
The reason I made this was my so called water proof electric shaver broke due to water getting in to it. And I was unable to charge it due to the charging circuit getting wet and failing.
So instead of buying a new shaver I decided to charge it using an old solar panel I had.
The modification was pretty straight forward.
Step 1: Items Needed
1 solar panel 3 volts
Some heat shrink.
Step 2: Wiring the Solar Panel
The first job I did was to solder 2 wires to my solar panel and check that I would get some volts out when it was in the sun.
I checked this using my multimeter set to volts.
When I was happy there was a voltage I used a little silicone sealant and sealed the contacts to stop moisture getting to them.
Step 3: Connecting the Base Unit to the Solar Panel
The next job was to figure out which was the + and - terminals on the base unit.
To do this I just used my multimeter and measured the voltage from the psu plugged in to the wall.
And as you can see I marked the base unit to make it easier to see.
Then I unplugged the wall charger.
Cut the wall chargers lead and wired the positive lead from the solar panel to the positive connector for the base unit.
And wired the negative lead from the solar panel to the negative lead of the base unit.
I sealed the wires using the heat shrink.
Then I checked I had a voltage at the base units contacts.
Step 4: Modifying the Shaver
The next job was to open the shaver and find out more about how it worked.
This is done by undoing the torx screws shown.
I was then able to see the batteries.
I lifted the batteries up so that I could get to the contacts and the PCB.
I soldered a diode to the positive terminal that would connect with the positive terminal on the base unit.
Make sure the diode is wired the correct way round. This can be checked with the multimeter. It will only allow current through in one direction.
On the back on the diode I attached a wire to the positive terminal of the battery.
And sleeved it.
Then I connected a wire between the negative charger contact and the negative of the battery as shown.
And reassembled the shaver.
Step 5: Testing
Testing was just a matter of putting the shaver in the base unit and putting the solar panel in the sun and checking that the voltage was getting to the battery.
Then I just put it back together and that's it.
Now I never have to worry about my shavers battery being flat.