circuit for charging batteries in cordless Mouse from USB Port

[Andrey]

Hello All,

does anyone knows what would be a proper circuit to charge a pair of Ni MH
batteries (2.4 v) from USB in Cordless Mouse? I opened mine and found
resistor and a diode in series. Such circuit may offer some protection (from
overcurrent and voltage excess to USB) but I do not see how it satisfies
recuirements prescribed for Ni MH battery. My mouse is of cheap variety
"made in China" and folks there do not always follow proper design
practices. Looked up Motorola reference design for cordless mouse - they do
not discuss power arrangements at all there.

I would appreciate any wisdom on the subject.

Andrey

 

[Ian Stirling]

Hello All,

does anyone knows what would be a proper circuit to charge a pair of Ni MH
batteries (2.4 v) from USB in Cordless Mouse? I opened mine and found
resistor and a diode in series. Such circuit may offer some protection (from
overcurrent and voltage excess to USB) but I do not see how it satisfies
recuirements prescribed for Ni MH battery. My mouse is of cheap variety
"made in China" and folks there do not always follow proper design
practices. Looked up Motorola reference design for cordless mouse - they do
not discuss power arrangements at all there.

A resistor and a diode will be just fine.
If you only charge it until it's full (work out charge current, ...)
If you plug it in overnight, then you should adjust the resistor to
give a charge somewhere around C/20.
The 'right' solution would be to fit a proper battery charger
circuit, with delta-v detection.

 

[Andrey]

Hello Ian,

thank you for the advice. It gives me some confidence.

It is strange, I see your reply but I do not see my posting. Your reply
indicates that the posting was posted. How come other people could see it,
and I could not?

This would be a question to group administrator I guess. How to write to
him/her directly?

Sincerely,

Andrey

 

[John Woodgate]

I read in sci.electronics.design that Andrey <[email protected]>
wrote (in <[email protected]>) about 'circuit for
charging batteries in cordless Mouse from USB Port', on Tue, 28 Sep
2004:

It is strange, I see your reply but I do not see my posting. Your reply
indicates that the posting was posted. How come other people could see
it, and I could not?

It happens. Ask your ISP.

This would be a question to group administrator I guess. How to write to
him/her directly?

This is an unmoderated group. There is no administrator.