On Thursday, April 16, 2015 at 8:04:05 AM UTC-7, Dan Marotta wrote:
A comment on lithium batteries since I have two in my glider and a
digital volt meter mounted on the panel...* I don't notice much
voltage drop as I did with lead batteries other than when I
transmit.* The data available for the batteries indicates a rapid
decline and shutoff when the battery is nearly spent.* I don't think
that's a problem since the shutoff voltage is around 9.6 volts and
your radio will quit transmitting before reaching that limit.



The reason I post this is because I was using a lithium powered
flashlight the other day while working on my car and, when the
battery reached it's limit, it simply shut off.* It was so sudden
that I thought the bulb had burned out.* No dimming as you're used
to with standard batteries.* Changing the bulb had no effect so I
swapped batteries with my drill and the light worked again.*
Charging the battery took less than an hour.




On 4/15/2015 11:27 PM, Paul Remde
wrote:


Hi,




I just added some new batteries to my web site tonight.* They have
been highly recommended to me by several sailplane pilots.




New - Bioenno Power Lithium Iron Phosphate LiFePO4 12V Glider
Batteries




- Enhanced cycle life - up to 2000 charge cycles! After 2000
charge cycles, the battery still holds 75-80% of its original
capacity.


- Lower weight - less than half the weight of lead-acid batteries!
If you are accustomed to using lead-acid batteries - you will be
shocked the first time you pick-up one of these batteries.


- Constant and stable discharge voltage - Lead-acid batteries
gradually lose voltage over time as they discharge - dropping
below 12V early-on. LiFePO4 batteries have a much more gradual
decrease in voltage until they are nearly fully discharged -
staying at 13+V for most of their discharge cycle - so they are
able to power your sailplane radio and instruments at higher
voltages for longer periods of time. Higher voltages assure
maximum transmit power from radios and transponders.




http://www.cumulus-soaring.com/bioenno.htm




Best Regards,




Paul Remde


Cumulus Soaring, Inc.





--

Dan Marotta

I was wondering about this characteristic myself, but don't! I bought a Stark Power LiFePo4 battery and ran it until it was discharged. The voltage declined very slowly over the first 8 hours or so, then more rapidly over about the next 2 hours before I shut it off at 11.9 V. This led me to conclude that a) mine will last for a very long flight and b) the decline in voltage gives plenty of warning that it is near the end.