Zener diode as rudimentary Li-Ion protection?

[meteor]

Just wondering if a Zener diode would work as a rudimentary Li-Ion "under-volt" protection device?


I have an older Kodak Pro digital camera for which I've cobbled together a few 2S Li-Ion packs. (stock pack is 6-cell 4/5A NiMh or NICd, and FYI, I've flown with Li-Ion and Li-Po for about 4 years now, and know the drill...)

The problem is that the camera will slowly drain a pack down to zero, even if it's turned off! I think it's to do with having a CF card in the slot...

With NiMh's this is not too big a deal (my first "re-pack" used KAN 950's!), but with Li-Ion this will kill the cells!


Can a Zener diode be used as a low-voltage "cut-off", or will there always be some residual drain? (anything over a few millamps is bad...)



Thanks.

[stu78]

Can't you just unplug the battery when you are finished?

The only way I can think to do it with zero current after cutoff is to use a relay, but this will increase current drain during the ON time.

Maybe others with more electronic knowledge can think of a better way.

Stuart

[coro]

Problem is more complex... voltage drop and so on. Look at this page, it is very nice design, resulting in microampere pack load and acceptable current passed by, hysteresis.. However, it looks quite complex on first touch? It is not in english, but circuit scheme and dps is international.
http://www.zajic.cz/odpojovac/odpojovac.htm

[AndyOne]

Meteor,

Look at...

http://pdfserv.maxim-ic.com/en/ds/MAX1665S-MAX1665X.pdf

This is the simplest LI-ion/poly protector device available, you could try scrounging some samples from Maxim if you can look like a bona-fide electronics business.

Andy.

[Minn.Man]

Look at the Smart BEC product and see if you could put your cam on the output of this device.

http://www.dimensionengineering.com/SmartBEC.htm