Amanda Ripanykhazov wrote:
I am hoping this question isnt too basic for this forum but I am
trying to replace some rechargeable batteries (in a Roomba: I
understand that generally only one or two start malfunctioning over
time and that it is usually the same one). It MUST be easier than I am
finding it.

I can just about solder on a connection but these rechargeable C cells
(nickel metal hydride?
You sure they're not sub-C?
They're spot welded.
DO NOT SOLDER TO THE NEW BATTERIES. GET BATTERIES WITH TABS AND
SOLDER TO THE TABS.
Replace 'em ALL at once. Weak ones will be killed by the new ones.
"Not exactly, but that's the result."
I am pretty sure they aren't lithium!)
If you're gonna replace cells, shouldn't you be CERTAIN
what they are? Last thing you want is a robot running around
your floors ON FIRE!
always
seem to have some sort of electro-welded rectangular plate connecting
the batteries which wont come off with a normal soldering gun? Or do
I just have to apply an inordinate amount of heat at exactly the
position where the ;nick' seems to be in the plate? Given the amount
of heat I seem to have applied to it already with no effect
whatsoever, to me it seems that this might damage the cell?

Yes, it will.
Is there some trick to doing this

If you're gonna solder on batteries,
Wear safety glasses. Put 911 on speed dial.
Order up a whole set of tabbed cells to replace the ones
(actually ALL of them)
you ruin by overheating. Make sure you understand the charging
regimen so you can order the correct type of cells.

Now you're ready to ruin some new cells. Have at it.

OR,
you can take it back where you bought it and say, "fix it!"

please or am i supposed to use a
dremel wheel to cut the plates off, leaving just the electro-weld to
which I solder the wire for the new cell?