On Feb 4, 7:33*pm, JohnDeRosa wrote:
On Feb 4, 5:28*pm, Papa3 wrote:

According to the Becker manual, the 4201 Low Voltage warning (blinking of the display) kicks in when the supply voltage drops to 10.5. * I'm wondering if anyone has had a reason to independently check this out for accuracy. *Reason for the question is that my Becker seems to be indicating low voltage before it "should".

*I run two 12V 12AH SLA batteries (independent circuits) which I just load tested (thanks to the John DeRosa article in soaring). *The newer battery shows almost new performance (6.5 hours to terminal voltage under a 1.7A load). * The older one shows nearly 70%.

The average load in my glider is about 1.8A (Radio, Xponder, Clearnav and vario assuming 5% transmit and fairly frequent interrogation on the Xponder). * The radio frequently starts blinking after only a couple of hours.. * Nobody has complained about the transmit quality. *And yeah, I know the Becker has a built in volt meter. *I just never thought to turn it to that page when this happens.

Any thoughts?

P3

Sure seems like you should have enough power with 2x12AH batteries.
Yes, breakers can be a culprit as they are basically a tiny resistive
heater coil which, unfortunately, drops a significant voltage (lower
the amp rating, the higher the voltage drop!) - but you say you are
using fuses which is a dead short so zero volts drop. *But other
things can cause a drop in voltage like a loose connection or some
corrosion somewhere in the path between battery and avionics.
Transponders can be real power hogs if interrogated frequently as
yours is. *One suggestion is to have a separate battery for just the
transponder - and if that battery goes flat, then all the other
avionics will stay running.

As you surmise with your comment about the Becker voltmeter, the best
way to check if there is a true low voltage issue is to measure the
voltage at the avionics and then work backwards towards the battery
thought any connections, bus bars, switches and fuses.

Good luck. *And glad you made use of my article.

- John

Our club had the same problem, it was in the radio and Becker fixed it.