LifePO4 batteries for motorgliders - are we there yet?

At 00:40 05 January 2016, jfitch wrote:

Not a DG, but I have been using an LiFeP04 for the engine start battery
in
my ASH26E for a year now. While the engine start battery can power the
avionics, I have a separate (LiFePo4) battery for that. You need to find a
Li
battery that fits in the same spot, has charge/discharge/current
protections built in, and has a max discharge capacity sufficient to crank
the
starter reliably. I measured the ASH starter at 150 amps stall current and
100 or so while cranking. The battery I am using is a CTC LFP128198, rated
at
19.8 AH and 160 amps discharge for 30 seconds.
Beware of LFP batteries advertised for motorcycle or auto start which
will
say something like "20 AH equivalent" as these generally will deliver the
same high discharge current for a short time, but do not actually have
the
AH capacity to run instruments.=20

I have had no problem at all with the battery, and it cranks the engine
much better than the LA battery that it replaced, holding the voltage
about 3
volts higher during cranking.

Can you post a link to the factory approving data that authorizes the
switch from the SLA to LifePo4 batteries?

On Tuesday, January 5, 2016 at 11:00:07 AM UTC-8, soarin wrote:

Can you post a link to the factory approving data that authorizes the
switch from the SLA to LifePo4 batteries?

No. As with the hundreds of gliders using LFP batteries for instruments, it is a substitution made at the owner's discretion and rules interpretation. The SLA battery supplied by the factory is a hardware store battery, not TSO'd or otherwise qualified either. In the case of the ASH26E, the specific battery originally supplied is no longer available and has been already replaced several times.