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Skipbreather · 6th October 2006, 15:16

Quote: (Originally Posted by jradomski)

A small correction..

There are many types of lithium cells.. The 3.6v type (LiSOCl2) has a predictable discharge curve, while the 1.5V types have a flat discharge curve then immediate failure.. At list a NiMH cell has some discernable voltage loss..

If you wanted to make a reasonable rechargeable pack use Li-Ion, these start with a Float voltage of 4.2v and decay down to 3.0v (can actually be drained to 2.4v but a rapid drop occurs around 3.0-3.5v (depends on discharge current, lower current draw means voltage stays higher further out before rapid drop) ), so a 2 cell Li-Ion pack would give some predictability

Hi Joe-

Thanks for the info re 1.5 V Lithums. I’ve always viewed them as sort of neither fish nor fowl and so have no actual experience w/ them. I’m genuinely curious about where you have used them & found them to be either cost efficient and/ or superior electrically to a quality AA alkaline. The packages make all sorts of claims, but I value your real world experience.

I looked closely at Li-Ion rechargeables when searching for a solution to 18 cell alkaline AA packs. The energy density & discharge characteristics are indeed the best of the commonly available technologies, but without exception all the sources I consulted referenced how fussy they are when charged- essentially do it right w/ a Li-Ion specific circuitry charger or risk a fire. The clincher for me turning to NiMH was how ugly a flood to the battery compartment would have been w/ Li-Ion. All rechargeables are nasty when shorted, but LI-Ion are particularly so.

Best,
Ken

6th October 2006, 15:16	#5 (permalink)
Skipbreather Reads fine print (mostly) Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet MK 15.X Home Build Join Date: Mar 2005 Location: Chicago, Illinois, USA Posts: 613	Re: Rechargeable battery packs for the Meg Quote: (Originally Posted by jradomski) A small correction.. There are many types of lithium cells.. The 3.6v type (LiSOCl2) has a predictable discharge curve, while the 1.5V types have a flat discharge curve then immediate failure.. At list a NiMH cell has some discernable voltage loss.. If you wanted to make a reasonable rechargeable pack use Li-Ion, these start with a Float voltage of 4.2v and decay down to 3.0v (can actually be drained to 2.4v but a rapid drop occurs around 3.0-3.5v (depends on discharge current, lower current draw means voltage stays higher further out before rapid drop) ), so a 2 cell Li-Ion pack would give some predictability Hi Joe- Thanks for the info re 1.5 V Lithums. I’ve always viewed them as sort of neither fish nor fowl and so have no actual experience w/ them. I’m genuinely curious about where you have used them & found them to be either cost efficient and/ or superior electrically to a quality AA alkaline. The packages make all sorts of claims, but I value your real world experience. I looked closely at Li-Ion rechargeables when searching for a solution to 18 cell alkaline AA packs. The energy density & discharge characteristics are indeed the best of the commonly available technologies, but without exception all the sources I consulted referenced how fussy they are when charged- essentially do it right w/ a Li-Ion specific circuitry charger or risk a fire. The clincher for me turning to NiMH was how ugly a flood to the battery compartment would have been w/ Li-Ion. All rechargeables are nasty when shorted, but LI-Ion are particularly so. Best, Ken
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