On Dec 4, 12:18*pm, ASM wrote:
Hi there,

Does anyone of you have any experience with LiFePO4 batteries in
sailplanes? I need to up my battery capacity, but have very limited
space in my ship. I read about them a bit, but ..... So, here are my
questions: is it worth buying this type of battery (they are quite
pricey), is the size comparable to sealed acid batteries (capacity to
size), any issues related to charging. Your input would be greatly
appreciated.

Jacek
Pasco, WA

Jacek,
The K2 10 Ah LiFePO4 battery (http://store.peakbattery.com/
12lfpba.html)
may be a great choice for sailplanes. It is in a standard 7 aH box so
it looks like the battery package you are used to. They have an
internal circuit board to protect from over charging, over
discharging, and it equalizes the individual cell charges when
charging it up. The flat discharge voltage curve means that more of
its capacity is available in a voltage range that your radio will
like. It is very light weight, and has a discharge cycle life of
2,000 cycles. The LiFePO4 chemistry seems to be about a safe as you
can get right now, combined with the internal circuit board, and a
fuse right off the battery,this battery seems to be a relatively safe
alternative to the standard SLA batteries. You will neet to buy a
charger made for this battery as the charging voltage is a little
different that what your SLA smart chargers are set up for. I have
heard of some people who now have two seasons on these batteries
without problems.

Now for the bad news. They are not FAA approved for use in aircraft.
Obtaining FAA approval is unlikely, as it is a very expensive process
to complete. All batteries are dangerous, this one included. Because
of its high energy density, and Lithium chemistry, this battery should
probably be considered more dangerous than your standard Sealed Lead
Acid Battery or "Gel Cell". It is definitly less dangerous than a
lithium battery pack that has a battery chemistry that supplies its
own oxidizer to the fire if the battery gets hot enough to ingite, and
does not have the proper protective circuits. It is expensive compared
to a single SLA battery, however if the 2,000 cycles is accurate, it
could end up being cheaper than using several SLA batteries in the
long run.

Should you use it in a sailplane? I can't answer that one for you.
Research the facts and you can reach your own conclusion, and assume a
level of risk you are personally comfortable with.