SLA batteries and heat

Evan: I get good service (several years) out of the batteries that I take home between flights and charge right away (and then disconnect from the charger). The battery that died was the one I left in the trailer all summer. It was fairly old even before I used it for that purpose. I would have just assumed it died of old age. But, the club batteries died too. And they were only 1 year old, that's annoying. And I don't really know how often they were left in the gliders. (Nor how good are the club chargers that they get left on for long periods.)

If we were to switch from SLA to, e.g., LiFePO4 batteries (as you have), will they survive the heat for long? How long? They cost about 5 times as much... And the promised large number of "cycles" is irrelevant if they too die after a few years due to age alone. We only subject most batteries to dozens of cycles per year.

On Thursday, January 26, 2017 at 3:45:48 PM UTC-5, wrote:
Evan: I get good service (several years) out of the batteries that I take home between flights and charge right away (and then disconnect from the charger). The battery that died was the one I left in the trailer all summer. It was fairly old even before I used it for that purpose. I would have just assumed it died of old age. But, the club batteries died too. And they were only 1 year old, that's annoying. And I don't really know how often they were left in the gliders. (Nor how good are the club chargers that they get left on for long periods.)

If we were to switch from SLA to, e.g., LiFePO4 batteries (as you have), will they survive the heat for long? How long? They cost about 5 times as much... And the promised large number of "cycles" is irrelevant if they too die after a few years due to age alone. We only subject most batteries to dozens of cycles per year.

lol. Moshe, you are doing a nice job of highlighting all the short comings of SLA batteries. Are you sure you like them? :-)

I ran across some 20 year old Sonnenshein 7 AH SLA batteries this Summer that would run an LNav and a radio for 3 - 4 hours (if you weren't too chatty!). Those batteries were very obviously much better quality (and more expensive) than currently available cheap SLAs all of which seem to be made in China. "Modern" SLAs seem to die after 2 - 3 seasons no matter what. And of course there are many ways to kill them much faster.

I didn't switch to LFP for reasons of economy... although you're making the case here that the economy of SLA batteries in our club environment is pretty bad! I switched for reasons of reliability, useful capacity, cold weather performance, & fast charging. The light weight is nice too if wrestling a 12AH battery into an awkward space is something you have to do (and I do). Four full seasons on that battery now. I tested it after 3 full seasons and it tested at 12.05 AH.

I think the club gliders ought to be on LFP batteries too... but so far I have been over ruled by the upper valley cheapskates.

best,
Evan

In my previous LAK-17a I had a lot of electric doo-dads: ClearNav
Vario, Trig TT22 transponder, MicroAir 760 radio, TruTrak turn
indicator, MRX PCAS, Dell Streak 5, and my two SLA batteries were on
their last gasps at the end of a 6 hour flight. After switching to two
LiFePO4 batteries, I seldom, if ever, switched in the second battery.
They just last and last in service. I can't say anything for the
longevity since I sold the glider after two years with the lithium
batteries.

Now I have more electric goodies than before in my Stemme. Thank
goodness for the solar panels as a 9 AH SLA will only last about 2 hours
on a cloudy day and I don't like to use the engine battery to run
soaring goodies. Who knows - I might actually need to start the engine...

On 1/26/2017 3:04 PM, Tango Eight wrote:
On Thursday, January 26, 2017 at 3:45:48 PM UTC-5, wrote:
Evan: I get good service (several years) out of the batteries that I take home between flights and charge right away (and then disconnect from the charger). The battery that died was the one I left in the trailer all summer. It was fairly old even before I used it for that purpose. I would have just assumed it died of old age. But, the club batteries died too. And they were only 1 year old, that's annoying. And I don't really know how often they were left in the gliders. (Nor how good are the club chargers that they get left on for long periods.)

If we were to switch from SLA to, e.g., LiFePO4 batteries (as you have), will they survive the heat for long? How long? They cost about 5 times as much... And the promised large number of "cycles" is irrelevant if they too die after a few years due to age alone. We only subject most batteries to dozens of cycles per year.
lol. Moshe, you are doing a nice job of highlighting all the short comings of SLA batteries. Are you sure you like them? :-)

I ran across some 20 year old Sonnenshein 7 AH SLA batteries this Summer that would run an LNav and a radio for 3 - 4 hours (if you weren't too chatty!). Those batteries were very obviously much better quality (and more expensive) than currently available cheap SLAs all of which seem to be made in China. "Modern" SLAs seem to die after 2 - 3 seasons no matter what. And of course there are many ways to kill them much faster.

I didn't switch to LFP for reasons of economy... although you're making the case here that the economy of SLA batteries in our club environment is pretty bad! I switched for reasons of reliability, useful capacity, cold weather performance, & fast charging. The light weight is nice too if wrestling a 12AH battery into an awkward space is something you have to do (and I do). Four full seasons on that battery now. I tested it after 3 full seasons and it tested at 12.05 AH.

I think the club gliders ought to be on LFP batteries too... but so far I have been over ruled by the upper valley cheapskates.

best,
Evan


--
Dan, 5J

Excessive heat for any battery will shorten its life, some faster than others.
Overcharging is just another form of overheating, maybe you never felt a battery surface during a high rate charge.

Many years ago, dark ages of early NiCad use in RC cars, the goal was to charge a pack at a moderate rate until full, then top off a number of times just prior to a race. This made sure the pack was full and the heat reduced the internal resistance for max power.
Too much heat caused venting of the internal "stuff" which also reduced capacity.

Modern chemistries have varying levels of resistance to the negative effects of over charging/excessive heat. Think of hot LiPo batteries........