I have one of the early Ryobi 18V Li-Ion battery packs (I think it's
2.4Ah -- ten separate cells: five paralleled pairs), which the charger shows as full but the test button on the battery indicates low charge state (red glow rather than orange or green). I measure 18V across the terminals, and it drives a tool for several minutes but then will not do anything at all just a few minutes later.Any idea what could be going on here?
Perce
Internal resistance buildup due to age,
But with a high internal battery resistance, would the tool it's powering still run at full speed/power? For the short time that it does work, it performs well even with a circular saw in thick plywood.
Perce
Yup. You said 5 paralleled pairs. Think what happens if say four of those pairs have high internal resistance and one pair is good. You'll be able to get high current for a short time from the good pair, which will discharge way more rapidly under load than it would if all the pairs were good. As it discharges, it can no longer maintain the high current so the tool slows.
Ed
The tool does not slow with this battery. I make a couple of cuts, and then a few minutes later when I want to make another cut, there is nothing at all: it does not struggle to cut but simply does nothing; it appears to be totally dead.
Perce
It's worn out, not repairable. Buy a new one, or two.
-- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com
I am not so sure I would trust my tools with an after-market knock-off of dubious parentage and entirely unknown origin.
Peter Wieck Melrose Park, PA
To the OP: "Slowing down" vs "working one second and totally off the next" is a function of battery chemistry (and how the electronics handle state of charge). I've used Craftsmen and Ryobi tools for a long time. The older NiMH amd NiCd batteries would slow down but still be usable for that one last cut. However, the Li-ion batteries are designed to protect themselves from being overly discharged. If the voltage gets too low, the battery is disabled until it is recharged. As others have stated, yours sounds like it needs to be replaced.
Pat
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.