Would It Be Dangerous To Charge This Flashlight?

In My Humble Opinion
1

A couple of weeks ago I was eating at a local burger joint when out the window I noticed a light shining on the pavement in the road. It was next to the crosswalk I would take on the way home, so I thought I’d check it out if it was still there when I was done.

It was and it turned out to be a Cygolite Metro bicycle light. Its tough exterior got banged up by cars going by and the clamp used to attach it to a handlebar was toast but it looked like it managed to not get directly under someone’s tire. It was nicked and scraped but doesn’t appear dented at all. When I got home I noticed the outer part of light button was missing but I could still put my finger in the hole and hit the switch in there to turn it off and on.

They cost anywhere between $42 to $72 online and REI has the audacity of charging $109 for it. Even at the cheaper rate, which is a sale, I figured someone might be missing something that, for me, is kinda pricey. I put an ad on Craigslist but no one responded so I guess it’s mine now.

The light is very bright and steady (you can make it blink, too) and I could use it when I go walking in the dark but it has lithium-ion batteries and is charged via a USB port. The question is: dare I charge it? I know these batteries have been known to catch fire under certain circumstances. I imagine being banged around the way it had may cause it to do so. Or maybe not? I’m just not sure, so I turn to you, dear knowledgeable Dopers.

One other factor is that the intersection I found it in is undergoing work. The vehicles crossing it do so at only 10 or 20 MPH due to all the lumpy, bumpy temporary asphalt. It’s possible it didn’t get hit hard enough to bother the batteries at all. Maybe. What say you?

2

I’d say if the battery was shorted, it would have overheated already. It has enough power to light, so it has enough to cause a fire if it’s going to do that. I think you’re safe with charging it back up.

If you’re concerned, just don’t leave it sitting on or against flammable material. When you aren’t using it, keep it on something made of concrete or metal.

The problem wasn’t with all Li-Ion batteries, just some that were poorly designed for the uses to which they were put.

3

Is there any way you can charge it outside? At least the first time? USB wall wart on an extension cord would work. You don’t want to be near a cloud of burning Lithium if you can avoid it.

If it charges once it’ll probably be OK.

GaryM

4

Thank you for your answers, Saltire and GaryM. They make a lot of sense. I didn’t think that if the battery had shorted it would already be apparent. I realized after I had posted this last night that the flashlight doesn’t feel warm at all. A good sign!

I might try charging it outside the first time but that’ll have to wait for warmer weather. Our house is old and doesn’t have any exterior outlets. I won’t be using the flashlight often, so perhaps I’ll wait until a warm spell to run an extension cord from inside.