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Topic: Cordless phone to battery charger - possible? (Read 1 time) previous topic - next topic

3Design

I have a damaged cordless phone that I want to use as a battery charger, doing as following:
- disassembly the phone from all parts, besides the base station (getting its power from the plug socket) and the display
- connect the charging unit via arduino to the display
- write a sketch which shows me on the display how much the batteries are charged, respectively when they are fully loaded
- use the device as well to charge AA batteries

Some data that might help (see also photos):
- device contains 3 NiMH rechargeable batteries type AAA, 1.2V, 850 mAh
- phone model: AEG Fame 400, 9V AC 350 mA
- when connected to the base station, the phone automatically loads the batteries

As my knowledge about battery charging devices is very limited; I'd like to know first of all if such a hack is possible.
What are the requirements for my projects? Parts I need to buy, etc.?

element74

Yes, it is definitely possible.
To charge different voltages, you would need power regulators with the appropriate reference voltages. I believe there are different methods required for charging Ni-Mh, Li, or Ni-Cd batteries. I don't know much about those, though. You could probably find them online.
Do you know what the specs of the display are?
And what data do you want to show on it?

3Design


Do you know what the specs of the display are?


No, this is the first time I use a display, so I don't know how and where to search.
I hope when disassembling it, I will find a labeling inside leading me to a datasheet.


And what data do you want to show on it?


I'm fine with simple data about how much the battery is already charged, e.g. a number between 0 and 100, where 0 means empty and 100 means full charge.
There has been a state of charge indication on the original display, but it is too rough (only three degrees of charged amount), and also might be rather complicate to trigger.

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