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I have a Stratomaster Ultra Horizon and lately I am finding that some data/settings like the Hobbs meter and contrast are resetting at power on.
On researching this issue it appears that the internal battery which should last about ten years is going flat and needs replacing.
Apparently the battery is soldered to a board inside but this is only hearsay and before that I have to be able to get a replacement battery.
If anybody has ever performed this maintenance I would appreciate knowing how to get into the unit without breaking it and any other information you can offer.

Thanks in Advance

Hi Peter, I have replaced the battery in my Ultra Horizon. It's quite easy and wasn't soldered in on mine. I think you need to pull the instrument out of the panel which is just a matter of disconnecting 4 wires and the pitot and static hoses. There are 4 screws holding the back on. The battery is a button cell of a common type, CR2032, and easily accessible.

Peter

I replaced the battery in an older Ultra X (not XL). After removing the 4 screws holding the back cover on I found the battery glued inside the case with wires soldered on each side of the battery. Those wires were run and connected to the circuit board. Replacement was pretty simple. Just cut the wires off at the battery, buy a battery holder for a CR2032 battery and solder that onto the wires. This way you don't have to try and solder the wires to a new battery which can easily ruin it if it gets too hot. In order to make changing the battery in the future easier I mounted the battery holder to the outside of the EFIS on the back. That way I could swap the battery out without having to pull the instrument from the panel in the future. The battery holder I used was similar to this one:

http://www.allelectronics.com/item/bh-2 ... 0mm/1.html

Some of the later Ultra's had a holder built into the circuit board so you may not need to do any of the above other than just removing the back cover, popping the battery out and putting a new one in. If you really aren't comfortable doing the work you can always give MGL a call. I seem to remember them offering a service to replace the battery. Don't remember how much it was but it wasn't too expensive.

Keith
#554

Thanks very much, seems very straight forward heading for the airfield this morning to do the deed and then go for a fly.
How good does it get?

Might be worthwhile making a note of the internal settings, in case the memory gets wiped once the battery is removed.

Might be worthwhile making a note of the internal settings, in case the memory gets wiped once the battery is removed.

Crikey Phil, I wouldn't even know how to do that. When the battery went on mine it retained the flight log but just lost the date and time for flights from when the battery died. I didn't lose anything when I swapped the battery and just had to reset the date and time.

Peter

I never lost any settings either when I removed the battery on mine, but I think it is possible and I would be kicking myself if I had to drain the fuel tank to recalibrate the fuel level having not written down those numbers as an example.