On 12/11/2015 12:59 PM, Jeff Liebermann wrote:

This battery pack does have connections from every between-cells
connection to the PC board, so I am assuming that this was supposed to
be part of the balancing circuitry.

I wasn't aware of that. Progress lurches forward, usually when I'm
not looking.

This might be of interest if you want to repair your battery pack:
"Cell Re-balance of Ryobi One+ 18V Li-ion Battery (130501002)"
https://www.ifixit.com/Guide/Cell+Re-balance+of+Ryobi+One%2B+18V+Li-ion+Battery+%28130501002%29/13286
"Rebuilding Ryobi 18v Batteries"
http://toolboyworld.com/eBay/Ryobi_Batt_Rebuild.htm
Looks like the balancing circuitry is in the battery pack, not the
charger.

I tried boosting the voltage of the low-voltage pair but without much
success so far. I don't really have a suitable power source.

When I plug that pack into a P117 charger, the red light flashes "for
ever" ("Testing"), but after a looong time changes to the slow flash
indicating "Defective." When I plug it into a P125 charger, I get the
"Charging" indication for just a minute or two, then it switches to
"Charged," but of course it isn't: that one pair of cells still shows
only in the mV range.

Perce