Originally Posted by roundturns
Had a pair of Hotronics installed last winter in a tight fit Atomic CS. Didn' t experience a fit compromise in toe box. Had to send one of the battery packs back at the end of the season as it wouldn't hold its charge. The shop I got them at said they have experienced failure with the charges as well as the battery packs but Hotronic fully warranties these problems. Hopefully, they will work well this year. They make a big difference in my comfort and enjoyment in cold weather, so for me they are worth their cost. I envy those of you that don't need them. The kid at the shop told me to be sure to let the charge completely run out before recharging which I wasn't doing.
Let the charge completely run out before recharging? That's bad advice. Almost certainlly the batteries were Lithium-Ion or Nickel Metal Hydride in which case the memory effect that your mentioning plays no role. Neither of these battery technologies build up cystaline structures on the cathode when not discharged fully, so they don't "learn" a new charge level since the chemical potential doesn't change.
Personally I use a boot heater (older Hotronic) since my feet naturally have poor circulation (even in a loose fitting hiking boot if I don't wear thick socks). I just replaced the crappy cells with Lithium Ion cells from www.batteryspace.com
and a $20 charger, haven't looked back since. The charge would easily last two days, but I prefer not to run the batteries down if I can avoid it since that will tend to degrade the chemistry more quickly. It's all about fighting entropy, and when Li-on or Ni-MH loose their charge they have no energy left to fight entropy (that's how batteries naturally discharge themselves after awhile, they're fighting entropy, though this is a big oversimplification).
The only time you'd want to fully discharge a Li-On is on a laptop or other more complex device, so the battery control circuitry can learn what the voltage discharge rate is when the potential starts hitting steep part of the curve. This doesn't play a role for Hotronics though since such circuitry would be horrendously expensive for a boot heater lol, unless you want to pay $300 for it, even according to their site:
"NiMH cells do NOT have “memory effect” and do NOT require fully discharging before fully recharging. "http://www.hotronic.com/products/fw/index_m3.html
In short, totally discharging your boot heaters should be avoided, though it's not the end of the world - especially if Hottronics will give you free new batteries