Power supply problems - need help and hints

[m2elena]

Hello guys, this is my first post here. Nice forum you got. Cheers.

So I have a question. Me and my friend are building a device here but we have problems with the power supply.
What we need is power supply between 4v and 6v. The thing is that space for power supply is very very very limited and I really mean it. It is only possible to build it from those very small rechargeable button cells (max diameter 7.9). I also would like to ask if it is possible to have only one connector for this power supply - I mean to plug power supply to pcb and to recharger with same connector? What connector should that be? Also can you point me to an online shop selling those types of button cells (we prefer those with high mAh).
I may sound a bit confused but I guess that's the way you think after many sleepless nights during last month.
Thank you guys in advance for your help and attention.

 

[stevez]

It would seem that you could deliver power to the device via one connector.

Questions that seem to be relevant:

A. Will the device be powered "on" while the battery is being charged?

B. Would you plan on having an on-board battery charge control circuit?

C. If the device is compact will heating during the charge cycle be a problem?

D. Can you run the device off the battery and apply power from the charger in parallel? That might not be the best for the battery but it's a way to get by. Note that you need enough control so as not to cause the battery to get extremely hot or explode. (my commercially made handheld transceiver is wired this way - mfr warns that constant application of external power can overcharge the on-board batteries.)

 

[penoy_balut]

put a diode between charger and the load, put a diode between the battery and the load and add a resistor to trickle charge the battery

 

[m2elena]

A. Will the device be powered "on" while the battery is being charged?

Device can be off, not a problem.

B. Would you plan on having an on-board battery charge control circuit?

There won't be charge control circuit on-board.

C. If the device is compact will heating during the charge cycle be a problem?

Device is compact but heating shouldn't be an issue in that case.

D. Can you run the device off the battery and apply power from the charger in parallel? That might not be the best for the battery but it's a way to get by. Note that you need enough control so as not to cause the battery to get extremely hot or explode. (my commercially made handheld transceiver is wired this way - mfr warns that constant application of external power can overcharge the on-board batteries.)

That is not an option.

So can you guys point me to specific battery models and connectors part numbers or anything that might help me? Where I can get a recharger as well?