NIMH Batteries

"Free Flight 107" wrote

The reason for not using Li chemestry cells is concern for possible
overheating, bursting of cells, and resultant "Very Energetic" fire
from the release of the Lithium inside the cells.

The Li-ion and LiFe (A123) chemistries are also suseptable to these
events, but because of the steel cases, like NiCad & NiMh, will resist
abuse better than LiPoly. In actual practice they still use
specialized charging and balancing circuits, and usually over-
discharging circuits, esp. in consumer devices such as Laptops and
Cameras.

I have seen reports of burned LiPo and also some LiIo batteries and I would
not use them in my glider (apart from the LiPo in every PDA, Cellphone, MP3
Player, ....). But I have never heard of any A123 cells starting a fire, and
there are modelers who did some serious abuse testing.

BTW, I take issue with; "Both LiFePO4 series (of batteries) are
claimed to be able to be charged on most standard lead
acid chargers (set for AGM/GEL cells)", unless a complete set of
charging and balancing circuity is included in the package. And at the
prices quoted, they really should be!!

I have balancing tabs on my LiFe packs and use both, a standard lead acid
charger and a microprocessor controled charger / balancer combination.
Either way the individual cells stay pretty closely balanced.

If you want to know how some people (mis-)treat their A123 packs google for
"zip charging A123" ...

Michael