Back-up Battery Charging Source

[bendun]

Is the back-up battery charged by the EFIS system or from ship power?

Depending on the answer to the above, if I have 3 back-up batteries (1 per EFIS Screen) can they be powered by the same circuit?

I will be taking delivery of my AFS soon, but I am trying to configure my VPX-Pro and have run out of available pins. If the back-up batteries can all be powered by the same circuit then I will be saved!

[Rob Hickman]

Is the back-up battery charged by the EFIS system or from ship power?

Depending on the answer to the above, if I have 3 back-up batteries (1 per EFIS Screen) can they be powered by the same circuit?

I will be taking delivery of my AFS soon, but I am trying to configure my VPX-Pro and have run out of available pins. If the back-up batteries can all be powered by the same circuit then I will be saved!

The EFIS does not charge the backup battery.

[bendun]

Is there any reason why I should NOT wire all 3 to the same circuit on the VPX?

[Rob Hickman]

Is there any reason why I should NOT wire all 3 to the same circuit on the VPX?

If one shorts out it will take all three out.

[bendun]

If they did, won't I still have 3 fully charged batteries? You only get so many pins on a VPX-Pro and I don't have 3 extra to devote to charging batteries. From what I can gather, this is probably a pretty common dilemma for folks who want a "glass cockpit".

Rob, you are the Pro here, what would you do?

[Rob Hickman]

I would power the EFIS and battery charge circuit from the same VPX Power pin. The TCW battery charge can take 3 1/2 Amps and the EFIS is 3 1/2 Amps so it will need to be on a 8 amp circuit.

VPX Power Pin ---->------ EFIS Pin 1 + Pin 15
|
--- TCW Pin 1 + Pin 6