Quote:
Originally Posted by BoilermakerRV
Does the GAD 27 keep alive need to be powered from a separate battery? I'm struggling to understand how it can maintain voltage if the entire battery system is being pulled down by the starter. Big capacitors?
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Hello Michael,
No, the GAD 27 does not need to be powered from a separate battery.
The GAD 27 is designed to be connected to the same primary battery bus that is being used to start the engine. Even though the act of starting the engine may temporarily draw the bus voltage down below where some devices can continue to operate, the GAD 27 will condition that power and provide 12Vdc at up to 3.5A to several devices which you want to keep in operation through engine start.
For example, a common installation would be to wire primary power to power input 1 on PFD1, GSU 25, GEA 24, and the GAD 27. Next, the keep alive power output from the GAD 27 may be wired to the power 2 inputs on the PFD1 primary display, GSU 25 ADAHRS, and GEA 24 engine monitor.
When you turn on your primary bus, the PFD, ADAHRS, and engine monitor can come up running, and then when you start your engine, these devices will continue to run (automatically switch to using power input 2) when the voltage dips on power input 1.
This allows your PFD to stay running with engine information, your ADAHRS to either continue aligning or stay aligned, and allows your engine gauges to all operate before, during, and after engine start.
Best of all, it does all of this without a battery, so you don't have the long term maintenance requirements associated with a battery.
Let us know if you have additional questions.
Thanks,
Steve