I had a "Smudge" version of the Lumicycle 13.2v battery and smart charger. About a year ago it wasn't giving me a full nightride's worth using my HiD so I bought 11 Sanyo tagged 4/3A batteries and replaced the cells (putting the fuse and thyristor back in the same places). It's worked a treat up till last month. I bought a Lumi 3-Led light to go with it and it gives me more life than I needed.

We had a really cold night ride in the Lakes just before christmas, and when I charged it in the youth hostel, the charger indicated it was fully charged after only a short time, and the whole pack was really warm.

Now it doesn't hold a lot of charge (the volt indicator on my light goes from green to amber in about 10 mins, and red after an hour. It previously never went off green) and the pack gets warm after a short charge time.

I took the pack apart to see if it was just 1 cell that was getting hot, but charged it last night and they were all equally warm. When I separated out the thermistor, the charger still switched itself off after a short time.

What's up, and what can I do?

if you've continued to use it into the 'red' zone on your head unit you may have over-discharged the pack.
you'll need to get a meter on the individual cells and see what their nominal voltage is. i think this should identify which cell(s) is/are borked.

All the cells are reading the same voltage. I just spoke to the battery supplier and he's convinced me that Sanyo batteries can just die like that.

Doe anybody know if its possible to give Ni-MH cells a boost? Does discharge/recharge a few times work?

battery uni

may be something on here?