Most small LiFePO4's are going to have a BMS (Battery Management System)
that disconnect the battery in event of excessive charging or
discharging, since they're hypersensitive to those events. That's what
you saw when the light went off instantly. If you were using an LED
flashlight, it has an active regulator to control the LED's. Which would
have hidden the voltage drop prior to cutoff. You can generally hear the
switching circuit put out RF noise if you hold it close to an AM radio.

-Dave


On Thu, 16 Apr 2015 09:04:01 -0600, 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.