Electronics > Projects, Designs, and Technical Stuff
Help Choosing Battery Type
(1/3) > >>
don.r:
I am working on a battery backup circuit for my Sony XDR-S3HD radio here and I have been thinking my original choice of an 18650 may be overkill. Essentially, I need a battery that will basically sit there charging 24/7 and then be needed to provide about 10uA @ 2.7-3.3V for at least a few days (power outage situation). I am thinking maybe a supercap, NiMH or NiCd might be better here. I have the 18650 already (laptop salvage) along with a holder and 1S charging board but space is rather tight inside the radio and such a big battery screams overkill to me. I have lots of charging tap points from 3.3V to 11.5V most of which can provide at least 50mA for charging.
Pentoad:
I would go with the supercapacitor as leaving a lithium ion battery sitting at 4.2v all it's life is bad for it.
Siwastaja:
If you want to use li-ion, just float it at around 3.7V, halving the capacity. The lifetime will very likely be far over a decade.
don.r:
Excellent. Now what are the ramifications of installing a supercap wrt charging? I suspect I would I need to add a resistor to limit the charge current?

I see the 4.2V ones here: https://www.mouser.ca/ProductDetail/Vishay-BC-Components/MAL219691213E3?qs=sGAEpiMZZMuDCPMZUZ%252BYlxdFextp0taVAk4K2XCjS7c%3D
mzzj:

--- Quote from: Siwastaja on October 05, 2019, 05:34:20 pm ---If you want to use li-ion, just float it at around 3.7V, halving the capacity. The lifetime will very likely be far over a decade.

--- End quote ---
Heck, if you happen to get good li-ion it will last in OP's use for decade even without charging!

10uA, couple of days, only sometimes.

Tadiran XOL in AA size would provide back-up power  for  2400/88= 27 YEARS in case that the equipment is not plugged in. OP needed backup for couple of days  :-DD
http://www.tadiranbat.com/

Assume couple of days is 10 days per year, 10 years = 24mAh without ever charging the battery. 
 CR2430 anyone? Available in every third-world country, plenty of capacity for intended use, good self-life and cost 20 cents per piece.


Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod