2 cell Lithium polymers as your receiver pack?

[Adam Glatt]

mike mueller wrote:

> Ok this has probably been discused but I never payed attention till 
> now. My question is can you use Li-poly's instead of Li ion's or 
> nicads? Would the regulators have to be different? What about 
> regulators over heating? How long would a 2 cell 1200 Li poly pack 
> last before needing a charge? Is this the way were headed? Thanks, Mike 
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If you run all or mostly digitals expect ~150mah per flight.

Never heard of a regulator over heating.  Due to bad combination of 
hard-mounted pipe and DZ and weak fuselage I was drawing 225mah per 
flight most of this year on a 7.4v ThunderPower 1950mah pack with a 4.8v 
regulator (with a heatsink), never had any problems.

If you charge them at too high voltage (i.e. in nicd mode, or any 
non-lithium charge mode) they will expand, and if they expand enough 
they will vent and stink and be toxic and possibly cause a fire, as by 
this point they are very hot.

Good: more capacity at lighter weight (though in the 1100mah range the 
constant weight of the regulator overcomes the weight/mah of the lipoly 
vs the nicd... so only existant at higher capacities). No self discharge.

Bad: dangerous and quick to be turn to garbage if mis-charged, more $$, 
requires a more expensive charger.

If anything, the Lipoly is good for more charges (atleast the Thunder 
Power ones are).

Lipolys only offer a clear advantage when they power the motor.  In 
everything else our batteries are already light, and you really have to 
weigh the pros and cons.  Though I should point out that in the > 
~1500mah range, the NiCds do become quite heavy and the lipolys offer a 
real weight saving. If you want NiCds and lots (12 flights on a charge) 
of flying you have to go with a smaller capacity and more than one pack.

BTW, Thunder Power is already producing batteries that make the one 
Shulman used in Poland look like old news =>

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