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Replace a rechargable button cell with a supercap? In a camera.

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wilfred:
I have a digital camera that is getting on but I still like it. It is a Nikon P7000 and the camera has started losing the date and time as well as other settings when I remove the battery to recharge it.

I can't find much on this model but similar models seem to use a battery similar to one of these.
https://au.mouser.com/Seiko-Instruments/Power/Batteries/Coin-Cell-Battery/_/N-965wk?P=1z0y6z5Z1z0y70eZ1z0zp45Z1y8f1ho

I only use the camera occasionally in bursts and I only need the settings saved long enough to charge the battery. A few hours would be great but a day or two would be better.

Would a 0.22F 3.3V supercap be a suitable option for both retention time and as a replacement for a battery in a device originally designed to charge a battery?

I have some of these caps which is why I am specific. They also should be small enough to fit.

Until I open the camera (shudder) I don't know what exact battery it uses. I haven't found a service manual for the P7000 and other manuals for Nikon Coolpix camera don't list the battery replacement or part number.

Prehistoricman:
The camera may not use the internal battery to charge the backup battery. Are you sure the one you removed is rechargeable?
If it does though, then I see no issues. What's the maximum voltage of the main battery?

wilfred:
I haven't removed it yet but similar Nikon Coolpix cameras seem to use the rechargable button cells. I am just assuming mine is similar.

Looking at the datasheet here for a battery I found referenced in another teardown
https://www.sii.co.jp/en/me/datasheets/ms-rechargeable/ms414ge/

it says a charge/discharge cycle of 50 times for 100% discharge. So it is plausible the battery is dead. I want to avoid a repeat by using a supercap.

Mr Evil:
You'll have to measure the current drawn from the battery, and the minimum voltage that the camera needs, and work out if the supercapacitor can remain above that voltage for long enough at that current. 0.22F won't provide much current for a day though.

You'll also want to check that the charging circuit is compatible. If it's a simple 3.3V source connected to the battery through a resistor then it will be fine.

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