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Lithium-Sulfur Batteries
Submitted by AaronGreer on Sun, 2008-08-24 10:36.
The Clubhouse
I came across this interesting article today: Which led me to this site: Has anybody heard of these batteries being used in regular RC planes yet, or are they too new still? In any case, they look like they'll open even more possibilities for electric planes with longer flight times, etc. Discharge RateSubmitted by GHExiter on Tue, 2008-08-26 02:23.
The Li-S packs have improved on the number of deep charge cycles in the last four years according to Sion to 300 cycles, however for our applications I see the discharge rate as a bigger problem. Sion's most curent data sheet quotes a 2C discharge rate maximum for a 2.5 V cell where as the typical Li-Po gives at least a 12C on its 3.7 V cell. We tend to pull the capacity out of our cells pretty quick during a flying session. Linkage?Submitted by Matt Barnson on Tue, 2008-08-26 08:19.
Quote:
...Sion's most curent data sheet quotes a 2C discharge rate maximum for a 2.5 V cell... Do you happen to have a link to this? I didn't find one on their site. Quote:
...the typical Li-Po gives at least a 12C on its 3.7 V cell. My experience has been that modern 20C-30C LiPos have very low cycle life if discharged above a 12C sustained rate. I have been really disappointed. One brand of LiPo -- Common Sense R/C -- gave me over 300 cycles. None of the rest have, although my sole FlightPower 18C LiPo battery is impressive so far. 57 cycles and counting, and it is performing as if it's brand-new. --Matt B. Linkage EstablishedSubmitted by GHExiter on Tue, 2008-08-26 12:41.
Here is the link to Sion Power's latest data sheet for their Li-S batteries. |
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Number of recharges
The downside to these batteries, as far as I'm concerned, is the number of recharges.
See: http://www.infosyncworld.com/news/n/4941.html
Your average RC Lithium-Ion user gets around 100 cycles out of a pack due to our heavy usage pattern and the general quality of batteries. I'm not interested in paying top-dollar for a battery that's only going to give me 30 cycles before it poops out :)
Then again, if it's 30 cycles of double or triple the flight time, does it all equal out in the end?
I've really been enjoying the A123 M1 cells lately. They are safe, recharge very quickly (around 5-8 minutes), have great energy density compared to nickel-based batteries, and have superb cycle life (>1000 cycles). The only downside is that they weigh about 30% more than a Lithium-Polymer battery. I hear, though, that A123 Systems is researching a "bagged" version of their lithium nanophosphate cells. Using a plastic shell instead of aluminum (for the 2300) or steel (for the 1100) would bring the weight of A123-based batteries down substantially.