On Friday, May 21, 2021 at 11:48:21 AM UTC-7, Phoenix wrote:
On Friday, May 21, 2021 at 2:22:17 PM UTC-4, waremark wrote:
Or an LX Nav S10 or S100 - excellent vario with lots else, artificial horizon, battery backup, backup IGC logger
Would like for the "hole filler" to be able to accommodate a gear warning micro switch as the ship already has one installed.
More ideas?

I included an MGL BAT1 volt/ammeter in my 31Mi panel (http://www.mglavionics.co.za/Infinit...uals/BAT1.pdf). As I have a total glass panel (i.e. no pneumatic instruments) characterizing battery condition and state of charge was a high priority. I wasn't even sure what the total drain would be with my full panel operating. I am glad that I had this instrument added because using the voltmeter built into instruments like the LX9000 is problematic (it measures the voltage at the instrument, not the battery) and it does not measure current at all. I determined almost immediately that I would need an LFP battery for the avionics as my current drain was over 2 A and Pb batteries don't want to be discharged more than 50%. I was getting a Low Batt alert from the LX9000 after just 3 hr (your battery voltage drops immediately when drawing 2 A from it, so I was getting below 12 V after a few short hours). I have been using the Bioenno BLF-1220AS:
https://www.bioennopower.com/collect...abs-blf-1220as
It has a built-in Battery Management System (BMS) that protects against over-voltage charging and under-voltage drain. I also use a pair of these batteries as the donor batteries for the X2 charger mentioned below. I recharge the donor batteries with a pair of solar panels and a Bioenno MPPT solar charge controller for LFP batteries.

Occasionally, I would see the current drain jump up 0.6 A if I accidently bumped the fuel bag valve switch on, which was easy to do as it was right below the LX9000.

I also monitor the energy required to recharge the battery after the flight.. My battery charger, a Hitec AC/DC X2 (https://www.amazon.com/Hitec-RCD-Bla...1644506&sr=8-2) provides this information providing that there isn't a fault during charging (typically low DC input voltage), in which case it just displays a fault message. I want to know how much energy was put into the battery prior to the fault. So I use an independent battery monitor:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I double check that the battery is fully charged by comparing the analyzer's amp-hour reading to energy consumed during the flight (discharge rate times length of flight plus ground on time). I recently had a 7 hour flight and the energy to recharge the battery was 12 AHr (I flew with one instrument turned off). These figures agreed, so I an confident that I have a full charge in the battery.

This all adds up to quite an assemblage of equipment, but it ensures that I can properly charge my 31 batteries regardless of the availability of shore power:

2 50 W solar panels
1 Bioenno MPPT solar charge controller
2 Bioenno BLF-1220AS LFP donor batteries
1 Hitec X2 AC/DC Multicharger
1 GT Power RC 130A Power Analyzer Battery Consumption Performance Monitor
Associated connectors and cables

Can you get by without the BAT1? Probably so, but sooner or later something is going to go wrong and your battery may go dead at a most inopportune moment. I have to have 100% confidence in my battery condition. The engine battery can always be used in an emergency, but using it for an extended time can jeopardize your ability to restart the engine. Also, I have an available instrument hole should the need arise.

Tom