GPUs - is there a best strategy/model to use?

I’m excited to now be a new cirrus owner - 2005 SR20 G2. I still have a lot to learn regarding the Avidyne and Garmin nav systems and presume that a GPU would be a benefit so I can do a little ‘live learning’ with them - powered up on the apron. As with a host of other choices for aircraft accessories out there, the type and capability of a GPU is full of options - and with cost in mind, this choice is one I want to be as informed on as I can be: Do you just get one that only powers the avionics? or one that has extra amp capacity? one that can work as a battery tender as well (are any extra electrical mods needed for that)? is it worth it to get one that can function to support starting ($$) ?

That is alot of questions - but humbly ask for anyone’s lived experience and/or recommendations.

thanks very much

Had this one for a few months. Happy so far. Nice to have one box for GPU and minder.

Welcome! Check the archives via the search function. You’ll find many people use the Marc Hanna built GPUs for their aircraft; I do.

GPUs are a great way to explore the avionics while on the ground without worrying about running the batteries down. Just be sure you understand how to operate it, and how to check that you are running off the GPU, not the batteries. In our model of G2 SR20, that means connecting the GPU and then turning on only the Bat1 switch, observing ~27volts.

Practically speaking, you probably won’t need to rely on a GPU to charge your aircraft batteries; if you happen to fully discharge your main battery, it’s best to either replace it, or charge it outside the aircraft via a normal battery charger.

In most other instances, say you’ve left the plane sitting for a month, a quick GPU connection, giving you time to update your databases, should be enough to restart the aircraft, which will then fully charge as you operate it.

There are some people who prefer to leave their aircraft on a trickle charger; this can be done, but requires installation of the charge connector; there is some concern that you could create a dangerous situation if your battery fluid levels drop below the minimum when connected to a trickle charger. Units like the Battery Minder, are supposed to be smart enough to avoid this.


I second the Marc Hannah built GPU. It will be your most cost effective option. I have a G1 SR20, and Marc’s GPU has served me well for avionics updates and familiarization while topping battery off. Thus far, I have not had a need for a trickle charger with weekly flying and periodic GPU top offs during avionics updates.


I also have a Marc Hanna built GPU, after two years I am extremely happy plus it is much cheaper than anything on the market.

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