Columbus Ron

Can someone straighten me out.

I want to run an onboard receiver battery system that is regulated to 5.7 V. I want the security of loosing one cell and still having more than 4.8 V.

If I have a 5 cell NiCd and loose one cell will the pack still work and provide 4.8 V?

If I have a 5 cell NiMH and loose one cell will the pack still work and provide 4.8?

If I have a 3 cell Li-ion and loose one cell will the pack still work and provide 7.4 V?

If I have a 3 cell Li-Po and loose one cell will the pack still work and provide 7.4 V?

Thanks Ron

Flying Geezer

My Feedback: (14)

Just run a 5 cell pack and forget the regulator. Thousands of us are doing that with no problems. No regulator to bother with or have fail.

The full charge voltage of a 5 cell pack will not hurt your receiver and won't hurt your servos unless they specify 4.8 volts only.

JPMacG

My Feedback: (2)

What if a cell fails as an open circuit or high resistance? Would a redundant pack and switch be a better solution?

mrasmm

for that info check out red's site www.rcbatteryclinic.com he explains it all =)

oops =) I need to fix that info here is the direct link to visit, check that out and you should have your answer
http://www.rcbatteryclinic.com/parallel.html

I agree with geezer though, I've never seen an OC failure on a pack, although I've seen plenty of shorts. Usually the way they fail is they form stuff inside like in caves, the stalagtites and stalagmites and they grow together and eventually short out. Red can probably shed more light on this, but the only way I can think of right now really to fail in an OC situation is to have them drawing too many amps or getting too hot somehow and melting the solder that holds the packs together, or blowing apart the pack in a really extreme case, or maybe something like extreme vibration that gives the tabs or wires metal fatuige and the cunductors separate or something.

check out this page for more info on that
http://www.rcbatteryclinic.com/shorts.html

ps
sorry red, I dunno how to link to a specific page and keep it in the frame with the nice menu on the left =)

Flying Geezer

My Feedback: (14)

If a pack fails with an open cell then regulator or no regulator, the power is off. On large planes I use redundant 5 cell packs, on smaller craft I can't justify the space or weight.

Incidentally, cells rarely fail open, it's almost always shorted.