I bought one of these and tried it out for the fairphone 5 battery. It seems to work okay. Charges to 85% like you said. It’s a max of 0.5A so it’s not that much current (you have to switch it to that since there is also 0.1A option). It takes around 10 hours to charge. Apparently Adafruit also sells a 1A version but haven’t tried it, and it has a different usb connector.
It’s hard to get the wires in there, you have to adjust the battery on table carefully so the end of battery kinda falls on the wires to make contact.
Update on this. I found the actual fp5 battery connector on aliexpress. They are all the same so you can shop around for a good deal, except it has to be the 7 pin 2mm one, not 2.5mm. https://www.aliexpress.us/item/3256807309500432.html
It’s called a male battery blade connector 7 pin 2mm pitch. It snaps into place for the fairphone 5 and it maintains connection. (The male connector goes into the female battery port.) I soldered the wires from the adafruit charger to the male connector and it works perfectly to plug into the fp5 battery
(Just because I finally got curious why this particular charger didn’t readily show up in force online when searching for its supposed brand + name.
While I had good experiences so far with a different type of cheap-o charger, just looking at the prices online I would make sure to have a fire extinguisher around, too, when using this .)
For users not reading or remembering the post above which I cited … words of caution:
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