On Sun, 25 Feb 2018 08:35:33 -0700, Brewster wrote:

On 2/24/18 4:13 PM, pyotr filipivich wrote:
Brewster on Sat, 24 Feb 2018 08:03:14 -0700 typed
in rec.woodworking the following:
On 2/22/18 7:48 PM, pyotr filipivich wrote:
Speaking of batteries

How does one go about testing to see if a second hand set of Ryobi
18v batteries are still "good"?
These are the green ones, I am not sure right now what type they
are (Lithium Ion, Ni-Cad, Auto-Cad, Alkaline, or Iron-Pyrite) but I am
not sure if they need replacing or not. I got them, and the charger,
and three tools at a thrift shop. "Guarenanteed not to rip, rot, rust
bust or throw dust - thirty feet or thirty seconds provided the
customer does not fool with them." {"Did you charge the batteries?"
Of course I charged the batteries!
"I told you not to fool with them!"

(OTOH, could be that I was over expecting how much use I could get
of a pair in the circ-saw cutting oak pallets.)

But anyway, testing procedures for batteries?

NiCads tend to get small shorts internally which causes them to
self-discharge at a faster rate. Fully charge the batteries and measure
the voltage. Wait a day or two and check the voltage again. Individual
cells that are failing will drop the voltage by 1.2 volts each.
If your second reading is lower by 1.2 volts or more, you probably have
dead/dying cells. They can be rebuilt, but the cost savings over new
batteries may not make economical sense.

Thanks. If I determine that the batteries are expired, I shall
replace them. I lack the time, space and talent to be rebuilding
batteries.



I have rebuilt battery packs on my own, but a RPITA since the cells are
really crammed in tight.

For rebuilding, I was referring to shops that do it (based on cell count)

i.e. http://freedombatteryrebuilds.com and others.

I had a set of old Milwaukee 14.4v NiCad packs rebuilt with NMH for
about 70% of new price (bonus extra power/run time with the chemistry
change)

I've had NiCd battery packs rebuilt, as well but haven't had good luck
with them. Another six or twelve months, for 70% of the original
price isn't worth the bother. Li batteries changed the whole game.