Test charging of L-ion battery that won't take a charge

I have 2 18 volt Ryobi L-ion batteries same age 1 takes a charge the other doesn't.

In a earlier thread it was mentioned that when a battery gets so low the charger won't charge it but if it is charged slightly the sensor in the charger may then pick up the trace current & charge the battery.

Well I am trying this idea out. I taped a long screw in contact with 1 terminal & a short screw in contact with the other so that the clamps from the charger would be spaced apart I reinforced the electrical tape holding the screws with a thick rubber band. So far the light on the battery is now indicating that there is some current in the cells. I am using a battery trickle charger that I use to keep my Bobcat battery up over the winter it senses the battery charge & turns off & on the sustain the proper charge on the battery. If this works it will make me very happy .

Sounds like a logical idea, but I would be really careful - If a Lithium Ion battery gets cranky, it simply catches fire. Ask the owners of the grounded Boeing Dreamliners. Ask the people who had a computer battery fail (I had two subject to manufacturer recall for overheating).

Charlie Plesums said:

Sounds like a logical idea, but I would be really careful - If a Lithium Ion battery gets cranky, it simply catches fire. Ask the owners of the grounded Boeing Dreamliners. Ask the people who had a computer battery fail (I had two subject to manufacturer recall for overheating).

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Charlie is 100% correct. Modern batteries are basically dangerous when they are out of spec. Li-ion isn't super bad, but when you start getting into Li-Po and Li-Fe batteries they can explode with little to no warning. Especially the hard cased tool batteries. With the stuff I use for R/C, the batteries will get "puffy" when they are taking a crap on you, can't tell with tools.

Most of the new batteries when the voltage drops too low, they are junk and are no longer charge-able. Most of the time there is a cut out in whatever the tool is that will shut it down once the cells are too low in voltage.

For me, I wouldn't do it. Well, I'd do it in the shop, because its insured and I need a career change. :lol: But, being homeless from a fire would suck.