Skyview back up battery

When I planned my skyview panel, I did not want a back up battery because I am VFR and did not think I needed the redundancey. I Started flying my 8A a month ago and don't like how I lose the screens during engine cranking and then have to wait for what seems like a long time for the screens to come back up to see my oil pressure. So I looked at the sky view back up battery, $180 each.

Has any one tried to roll your own on this? I have two screens so I need two batteries and just think 180 a piece for a 12 volt battery is a little steep. If you have, what battery did you end up with?

I am not sure that I have anything to add to your question except to say I have two screens as you do (SV10 inch). I have only one back up battery, only VFR. I start the engine on the pilot side, it stays on while starting, after the start I reach over and power the second screen. By the time I get to the runway or even before I get there, it is powered.

I know that if one SV dies, the co-pilot side will go away, but the one on the pilot side has the back up battery. All is good
Best to you
Dave

Remember the 'official' backup battery is designed to run the system for a couple of hours. If it is just for engine start you need a battery for 10 seconds. Whole lot less capacity.

I've heard that skyview units have two power leads that are diode isolated. If that's true you could make a simple aux circuit just for preventing brownouts upon startup. Battery could be small and cheap.

Take a look at this guys excellent writeup for more ideas.
http://www.myrv10.com/tips/electrical/N104CD_Aux_Batt/

SkyView does not have two diode isolated inputs. If you want to make your own backup, you'll need to do something outside to switch the power.

Do not use the built in battery charge leads. This is a lot more than "a 12V battery". This is a 3 cell, lithium ion battery with built in cell and pack protection for over charge, over current, short circuit, and more. The built in battery manager assumes this and will do bad things to any other battery chemistry or capacity. Remember, the $180 gets you a warranty on your SkyView and your battery.

Finally, if SkyView is rebooting during engine crank, you can probably solve this. SkyView stays operational down to 4.5V for 10 seconds (yes, really). In my airplane with 3 SkyViews, one doesn't have a battery and it doesn't generally reboot unless my starter battery is very low.

You might want to look at the gauge of all your wires, the size of your main battery, etc, and see if you can solve the issue which is that during crank SkyView is getting down to 4.5V.

Why have 2 backup batteries? Lose your electrical system then revert to one-screen Skyview system for finding an airport. Plenty of folks fly full time on a 1-screen Skyview like my RV12. I may add a second screen but not a second backup battery.

2 screens, 1 backup batt, DPDT panel switch connects batt to screen 1 or screen 2?

If you decide the risk of the battery backed-up screen failing at the same time the alternator has died and the main battery has run out of juice is unacceptable.