I use speleos Lithium batteries & Nova

my mate recently re-started caving after decades of not
I advised him to get the speleos Lithium batteries but with 14 led's 7 main bulb
which he did and is very pleased indeed.
We have just been to The Ardeche and used these lights.
Before he went i said he should buy a second Lithium battery as when they go out, they go out instantly with no warning
however they last for a very long time,
only on one trip did i have to change batteries 7 that was because i had forgotten to charge it.
He has tried to get a second Lithium from Bat products but tony who sold him the setup
says Speleos are being tardy at sending out more Lithiums.
I have just been on Speleos website,
they still do Lithium batteries but they do not "come up" when you press caving.
Are "they" indicating that caving is too tough for Lithiums?
Many people in M.C.G. use Speleos Lithium & Novas
Upper flood swallet exploration encouraged many to purchase this set up.

The sten and the Scurian are both Lithium.

Lithium is the future however it needs protection and circuit management so what we need are good quality products from the manufactures.

Scurian think protection for the batterys are very important even sticking them in an ally box on the back of the head.

There are some points you should not do with "Li" batteries:
1) don't deep discharge as the cell will be dead afterwards (3V/cell)
2) don't overcharge cells as they may explode
3) don't short-cut them (Li-Cells can provide very high currents) 
4) don't open them as this will result in a nice flame (Li-Ion are a bit more robust in my eyes, Li-Poly is usually only protected by a plastic foil),

a video about the disastrous features can be found here: http://www.autobloggreen.com/2007/08/29/video-dont-overcharge-your-lithium-batteries/

.... but 1)..3) are resolved with the protection circuits like in better notebook/mobile accus or in Scurion packs (don't know about Nova, Stenlight, Li-based mining lamps). Misused Li-Ion and Li-Poly happen to explode mostly in RC applications where you want highest currents (50 Amps) for your flight model going upwards like a rocket.

If Li-Ion caplamps shut off suddenly, it's the battery protection cutting in. That's rather sad - there is absolutely no reason why a bit of electronics shouldn't work out how much charge is left in the battery and dim the lamp before there's any need to shut down: mobiles manage to monitor the state of charge OK.

Downer said:

If Li-Ion caplamps shut off suddenly, it's the battery protection cutting in. That's rather sad - there is absolutely no reason why a bit of electronics shouldn't work out how much charge is left in the battery and dim the lamp before there's any need to shut down: mobiles manage to monitor the state of charge OK.

Click to expand...

Our current model of Li-ion lamp includes the charge protection circuit for the battery.

Also, if you are on main beam, then the beam flashes briefly every 5 seconds to let you know that you have about an hour left on main beam, and should swap to the pilot. Sufficient warning and gives you 2.5 hours or so notice of the cut-out

A lamp that just cuts out would be a bad thing....

Concerning the harsh cut-off made by any reasonable Li protection circuit:

Discharge voltage curve of a better Li accumulator is (as long as you have no high-current application like the RC guys) more or less linear until it is nearly empty. Thus, you can make a quite good estimation about the discharge state (Scurion does this in this way) and you could build a warning and/or a "throttle" which switches down to lower light level. No interference with any protection devices, so far.

At the end, however, the voltage of any Li-Chemistry will break down rather quickly (as we all like it from dry NiCd cells ), and if the protection circuit is well designed, it will cut off just a little bit before the voltage would do this. You will loose only few minutes of light; without this protection circuit you would similarly sit, these few minutes later, immediately in deepest darkness, because the voltage had really broken down, but then to irreversible battery death.

And I forgot.... unprotected (and therefore on short term often misused) accumulators of any chemistry are on long term a real safety risk as they will die earlier and often more unexpected. Accumulators which never get deeply discarged are more reliable.

an excellent link to information about battery technology (not only Li):
http://www.batteryuniversity.com/index.htm

Downer said:

If Li-Ion caplamps shut off suddenly, it's the battery protection cutting in. That's rather sad - there is absolutely no reason why a bit of electronics shouldn't work out how much charge is left in the battery and dim the lamp before there's any need to shut down: mobiles manage to monitor the state of charge OK.

Click to expand...

Scurion measures the remaining capacity (and displays it on the LED bar). If the pack is near empty, it gives you a warning and switches to continuously lower levels, extending remaining capacity. You have plenty of time (>10h) before the battery is completely empty.

- Martin

Martin Melzer said:

Downer said:

If Li-Ion caplamps shut off suddenly, it's the battery protection cutting in. That's rather sad - there is absolutely no reason why a bit of electronics shouldn't work out how much charge is left in the battery and dim the lamp before there's any need to shut down: mobiles manage to monitor the state of charge OK.

Click to expand...

Scurion measures the remaining capacity (and displays it on the LED bar). If the pack is near empty, it gives you a warning and switches to continuously lower levels, extending remaining capacity. You have plenty of time (>10h) before the battery is completely empty.

- Martin

Click to expand...

Do it right and you'd ALWAYS have 10 hours left

MatthiasM said:

And I forgot.... unprotected (and therefore on short term often misused) accumulators of any chemistry are on long term a real safety risk as they will die earlier and often more unexpected. Accumulators which never get deeply discarged are more reliable.

Click to expand...

Surely almost everybody does a burn-time test once in a while to avoid that? Or am I a total nerd? With a primary battery, I'd be more worried about forgetting how much time I'd already used - it is inevitable you sooner or later go caving with a battery that's nearly flat and a similar spare you've forgotten you used.

I meant, I take at least one spare accu pack with me and then I enjoy light until the protection circuit shuts off, then I change. Without protection circuit, I'd have to hit the best point before the accu itself makes cutoff by deep discharge.