The plot thickens.. I had a 'virgin' 199C. Used it only with an original charger. The battery was dead, obviously, installed a new one. Worked fine. Concerning a concern from someone: the sense resistor value was spot on, so no chemical degradation or something... I then "refreshed" the battery. Worked fine, battery guage showed "full" afterwards.
I then had run down completely (untill it turned off). Had 3.5h+, so that's not too bad.
Plugged the charger back in in order not to send out the device with a depleted battery. This morning, the battery was hot (some 40C according to the NTC). Device still turned on, showed battery not full.
That was also the last time it turned on. The sense resistor is still fine, but it doesn't turn on with either battery or adapter.
Bleh. Can't sell them like this. Will need to dig a lot deeper.
That sucks. Lots of money in the balance with in even a dozen of those bad boys out of inventory. I wish I were a bit closer and could take a crack at one, just for fun.
Dumb question... have you tried a new replacement battery from Fluke? Maybe they have some form of doomsday countdown timer in the supervisor IC like some laptop batteries were alleged to have back in the day.
mnem
Like "unless you feed me a new original battery, you"re fucked"? Eh, wouldn't think so. Only batteries and NTC in the pack. And The Signal Path has made a LiOn mod for it, he didn't report any issues.
Kinda thinking it would be cheaper/easier converting them all to LiOn. Eh, well, supplies came in. Let's have some fun. To be continued.
*EDIT* Also: not excluding sending you one as an option. Shipping is, well cheaper, than blowing up two of these a week.
Oh, seriously, these have NiMH/NiCd packs in them...?
Hmmm... that old, the IR of the OEM pack may have gotten high enough that it just tanks immediately on power-on. I've had that before; where a pack seems to revive for a cycle or two, then one or more cells goes high IR and it's done.
And now that I think of it... your new aftermarket packs may have the inverse problem: low enough IR to be able to draw too much current from a charging circuit that isn't designed for modern high-current NiMH cells.
Hmmmm... I wonder if your units would work if you charged the new aftermarket packs completely from a bench supply before installing them...? But then... if a customer completely discharged the pack and it draws too much from the OEM charging circuit...
Well, that would explain the one you got back from your customer, tho. Another possibility is that the OEM pack has some form of OCP; maybe as simple as a Polyfuse. That could even be buried in the cell cluster...
mnem
*fulminating at the mind again*