Tricky Dicky wrote:
Thanks TNP I will spend a bit of time wading through all the options on Aliexpress, seems to be quite a variety of costs and delivery charges.

Richard

There seems to be more to those than just pouch batteries
and glue.

"7.4v 2S Lipo Battery Repair" @ 3:52 minutes

https://www.youtube.com/watch?v=ziEcrK1b218

In the example here, the six pin chip looks like some
sort of protection device (measure cell voltage, disconnect
toy if pack is too low, disconnect pack if pack overheats).
I couldn't find an IC number, to locate a datasheet
with details of how it works.

http://www.bestechpower.com/upfilesn...1604283597.png

The (8 legged) dual MOSFET has the ability to disconnect the load,
when the controller wants it to. The notion of soldering
around the MOSFET -- that's like putting a penny in a
fuse socket :-/ Not a good idea particularly.

When you measure zero volts, it could be the MOSFET is
set to the disconnect state. The pack that measures 1.5V,
the protection has likely not triggered and it's still
open for business (even though too low to charge by an
intelligent charger).

Paul