On Saturday, December 12, 2020 at 8:54:52 AM UTC-8, Paul Remde wrote:
Hi,

I've been asked a lot whether the new LXNAV Airdata Indicator has a built-in backup battery. It doesn't. I'm glad because I'm not a fan of built-in backup batteries. They sit in unused for many months and then charge for the glider's main battery - reducing the main battery's ability to power everything else.

I have 2 recommended solutions for making sure the LXNAV Airdata Indicator is available when you need it.
- Use redundant main batteries that you can easily switch between. I use a Battery1/OFF/Battery2 switch in our glider.
- Use a AA battery pack and change the batteries once a year.

The Goddard-Cable-S3-Backup-Sw-1 wiring harness includes a battery pack for 8 AA batteries. It has an ON/OFF/Backup panel-mountable switch for manually switching from main battery power to the AA backup batteries. It is compatible with the LXNAV S3 variometer, LXNAV ADI (Airdata Indicator), and LXNAV G-Meter. I just finished testing it with the ADI and it ran with the backlight at full brightness for 11+ hours. You can see details he
https://www.cumulus-soaring.com/stor...s3-backup-sw-1

Good Soaring,

Paul Remde
Cumulus Soaring, Inc.

There is certainly nothing inherently wrong with backup batteries; I ordered that option for my Garmin G5 PFD. The backup is a lithium battery that holds its charge well. Most importantly, I have vital flight data in the event of a main power failure.

Tom