Power Tool Battery Pack Comparisons

[Percival P. Cassidy]

A long time ago I asked here how to disassemble my Ryobi 18V Li-Ion battery pack that showed "charged" in the charger but did nothing. Many people simply said, "Get it rebuilt", but I didn't.

At long last I tried a little more brute force on it and got it apart, then tested each of the five cells individually; two are dead (milliVolts rather than 3.6V or so), so why did the charger indicate that it was charged? I'll try zapping each of those two cells with a 12V power source later, but I Googled the markings that I found on each cell

-- Samsung INR18650-13Q -- and came across the following site, which indicates that the battery packs from many different brands use these same cells, although the effective price per cell varies considerably from brand to brand

(about 2/3 way down the page)

Just $9.80 per cell for the Ryobi vs. $17.80 per cell for Craftsman. (The posting is a couple years old, so prices could have changed.)

And note the post further down that points out that the supposedly 19.2V Craftsman batteries use the same five 3.6V cells.

Perce

[Zigfroid]

Be careful, they can explode.

Li-Ion batteries deteriorate starting on the day they are manufactured, even while sitting on the shelf. My suspicions are that when you find 'new' batteries that are really really cheap, they may have been sitting on the shelf for awhile and the seller is trying to get rid of them since they have lost some of their capacity. I don't know how you tell which are the good batteries though and the cheap ones could very well be as good as the expensive ones since they may not be old but just on sale. For example, my oversize phone battery that cost $60 two years ago is now is listed at $17. Sale or old? My

*guess* is that you would have the best chance at a good battery by rebuilding your own battery with cells purchased from a high volume retailer.

[Ed Pawlowski]

Amazing how often things like that happen. Same exact sub assembly in different brand, but 100% to 500% difference in price. This explains why the rebuilders charge the same for say, a 14.4 volt pack no matter where it came from. Same guts.

As for the 19.2 volt pack, it is probably that for three seconds off the charger. Just like the 6 HP shop vacs and 5 hp table saws.

[Percival P. Cassidy]

One place on line sells these cells for $11 each. plus shipping, but I have no way of spot-welding them in place. I went to the local Batteries Plus to see what they would charge to replace those two cells but was informed that they don't do Li-Ion packs.

Perce