Charge 2 LIR2032's in series

[jpaytoncfd]

First off I have no experence building any IC's. I am hoping something exists already but I cant find anything. I am using 2 LIR2032 button cells in series mounted in a holder. I would like to be able to charge them in the holder because it is going to be sealed. Obviously I know that I need to have higher voltage. (its 4.2 volts to charge) so I need 8.4 volts. same 20mA. Right? I am hoping there is something or someone out there that already makes a charger for this purpous. or if there is a schematic for this that I could get someone to make for me. Oh and I want it to work off 12v DC. Maybe 110 AC too, not sure.

 

[Resqueline]

You'll also have to consider charge balancing, otherwise you run the risk of ruining the cell that reaches full charge first. So you'll need a center tap from the batteries.

 

[(*steve*)]

Are they rechargeable cells?

 

[jpaytoncfd]

They are rechargeable, LIR2032. I am trying to make a rechargeable petsafe battery. The battery is made of 2 CR2032's in a very small package. How would I do a center tap?

 

[nepow]

They are Lithium-ion button cells 3.6v @ 35mAh... the charge voltage = 4.2v constant and charge current = 17mA constant. I understand charge methods must be precisely controlled!! and balancing techniques can get quite involved. Maybe a good idea to search the web for data etc before progressing further. Kind Regards

 

[davenn]

I spent some time looking on google yesterday for youandcouldnt find any ccts for charging 2 in series. only chargers that had slots for 2 individual cells for charging.

Res's suggestion may be the best way to go ... hack one of those 2 cell chargers and modify the planned layout o your seriesed 2 cell battery pack

Dave