On 11/26/2020 4:55 PM, AS wrote:

Good points, Eric.
I currently have room for and use two 12V LiFe batteries (K2) but I get low voltage warnings on my SN10b fairly early into the flight when keying the radio, a KTR72N. The batteries are only two seasons old. I may have some other, more power hungry equipment, like a Volkslogger functioning only as the GPS source, which may have a higher draw.
My goal is to get rid of the Volkslogger but in parallel, I was thinking about upgrading the batteries. However, that seems to be not as easy as cleaning up my panel.

Uli
'AS'


Uli, the SN10b should not complain until the voltage is below 12V. The
LiFePO4 batteries should hold well above that for a long time, if fully
charged to start with (check your charger?). I don't know what else is
in your panel, but with only vario, volkslogger, radio, flarm and SN10
it seems rather unlikely that the pair of K2s are already mostly
discharged "early into the flight". If the low voltage is only while
transmitting, check whether there is too much resistance between the
battery and where theSN10b (reporting the low voltage) and the radio
supply lines diverge. Too much resistance due to thin wires, bad fuse
contact, bad switch, etc. For a test (on the ground) you can run an
extra wire from the battery directly to the radio and see if that
changes the behavior. Remember that electricity flows in closed loops,
i.e., the problem may be in the negative (ground) side of the wiring.

For comparison, I use one 12AH LFP battery, running vario, computer,
flarm and radio, and it would easily last for 2 or even 3 long flights
on one charge. Note: I do not have a transponder, those are relatively
power hungry.