On Monday, April 2, 2018 at 7:16:45 PM UTC-4, wrote:
On Monday, April 2, 2018 at 4:29:49 PM UTC-4, Darryl Ramm wrote:
You may be better off using LiFePO4 batteries.

Well I've been wondering about that each time I buy a new SLA and still find that I cannot justify the much higher cost of the LiFePO4 batteries (5x to 10x, depending on size, brand, etc). The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.

This depends also on how much capacity you need vs. the weight and volume needed to hold the battery(ies) in the glider. In my case my modest needs, in warm weather, are usually met by one 4AH SLA, and I can also use a 12AH when I want spare capacity (or a bit of ballast :-). If I had a fancier computer, plus transponder and FLARM, then the picture might be different, since the LiFePO4 can be discharged more deeply without damage while the SLA should only be taken to about half-full (and even when I test them I stop at about 11.5V).

I just switched to lifepo4, got tired of killing SLA's. 5 to 10 times more expensive? Do you include the predicted lifetimes in that estimate? I paid $65 for my last 14 ah SLA and replaced it with lifepo4 for $130. So next year, or the year after, when I don't have to buy another SLA I'll be even? And I don't really have to worry about storage, running out of battery on a long flight, and the charge time is much less. With the new prices lifepo4 seems a no brainer to me. But I just bought it so we'll see.