Lithium polymer battery blues

December 14, 2022 6:55 AM

How risky is it to use a 3.7V lithium polymer battery with the plastic outer wrapping mistakenly removed?

The batteries look just like these listed on Amazon.it, but with slightly different info printed on the other side, except with slightly different information, and printed on the other side.

The spec on these include voltage, capacity, date of manaufacture and watt-hour rating:

- EP 851740
3.7V 500mAh
+ 20220721 1.85Wh

There's also a CE mark and a "don't throw in the bin" icon.

They came with a cheap novelty Christmas present which will probably be used once and never again, but the flight time on one battery is only 7 mins so it would be good to have both charged and ready to go, if safe (or as safe as these batteries can be.)

If unsafe, is wrapping in electrical insulating tape an option?

I'd just order a replacement (plus extras), but am struggling for an exact match in the UK. I understand polarity is crucial but am unsure how this is determined. Am nervous that the cables coming out of the battery appear in inverted positions in some similar product picutres. (Time is a factor – this is an early Christmas day celebration)

posted by nthdegx to Sports, Hobbies, & Recreation (6 answers total)

Just wrap it in electrical tape as you proposed.
posted by kschang at 7:44 AM on December 14, 2022 [2 favorites]

The yellow wrapping that indicates (limited) charge control built-in, or the silver bit?

If the former: not ideal, but less hazardous. You may have damaged some of the charge control components

If the latter: you are already on fire
posted by scruss at 8:11 AM on December 14, 2022 [1 favorite]

Response by poster: This was colourless totally see-through and shrinkwrap-eque but did have the battery specification printed on it
posted by nthdegx at 9:26 AM on December 14, 2022 [1 favorite]

Best answer: That yellow tape on the packaging is Kapton insulating tape. An electrical tape will perform the same function but is thicker and heavier, but I'd keep some kind of protection over whatever that is covering (probably the charge and monitor circuitry that scruss mentions)
posted by JoeZydeco at 1:17 PM on December 14, 2022

Best answer: These are the same batteries I have for a cheap drone that I mess about with indoors. Yes, just wrap it in a layer of PVC electrical tape. I've patched up one or two of mine after tearing the outer insulation, and it's fine.
posted by pipeski at 4:14 PM on December 14, 2022 [1 favorite]

Did these batteries come with a charger, or is there a charger you already use with these? If there's protection circuitry built-in, it may be more forgiving about how it accepts a charge, but I wouldn't necessarily expect to be able to charge it with some random DC power supply. You should be able to use a multimeter to tell which terminal is the positive and which is the negative if it isn't obvious.

Your mention of being unsure about polarity concerns me though; the problem with Lithium batteries is that they can fail with a quite energetic and difficult-to-extinguish fire, so you don't want to get it wrong.
posted by Aleyn at 8:29 PM on December 14, 2022 [1 favorite]