I've had a little Ryobi 3" trim saw for about 10 years, never had a problem
with the 12-V batteries.
"do_not_spam_me" wrote in message
om...
(Conase) wrote in message
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I have many tools with rechargable batteries.

The WORST I have bought to date has been the 12 volt Ryobi.

I've bought new B&D drills with 6 volt batteries from yard
sales for $5 that are still going strong 5-8 years later.

Which Ryobi 12V? Both are variable speed, but one has a single-ratio
gearbox while the other has a two-ratio gearbox and better bearings
and maybe gears. But I believe the battery packs are the same for
both.

I haven't noticed any differences in battery life when the charger is
smart and shuts off the current at full charge, but many drills that
use 9V or less don't have them, or they use a simple thermostat, and
either is a rough way to treat batteries.

It's usually best to not keep the batteries on the charger
continuously because even low-current overcharging can causes tiny
conductive whiskers between the plates of the cells and drain them.
This applies not only to cordless tools but to anything powered by
batteries, including phones and vacuum cleaners. Another reason that
cells overcharge is because some of them have developed reverse
polarity, so the charger doesn't know when to shut off. The only way
to prevent that is by occasionally measuring each cell (Ryobi and
DeWalt packs unscrew) and individually trickle charge any cell that
has reverse polarity (full charge not needed). Otherwise you can
charge an entire pack for a week and still not fix reversed cells.