Battery drain during flight plan load.

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bryanchatham
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Battery drain during flight plan load.

Post by bryanchatham »

New to the da-40 having come from cirrus. Can I fire up the avionics and put in a flight plan before starting or do I need to be concerned about battery usage. Let’s say five minutes tops. It would be great to get everything loaded and set before start up.


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Diamond_Dan
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Re: Battery drain during flight plan load.

Post by Diamond_Dan »

Welcome neighbor!
I leave my plane connected to a battery minder when it isn’t flying so for a database update or flight plan programming, battery drain isn’t an issue. That said, I haven’t had an issue running off battery for several minutes before startup when away from my hangar. With a slick start and electronic ignition, he plane fires up almost instantly.
I might encourage you to put your real tail number in your profile. The advice you get in this forum will be more valuable when folks can look up the vintage of your aircraft.
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alanhawse
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Re: Battery drain during flight plan load.

Post by alanhawse »

bryanchatham wrote: Sat Mar 11, 2023 8:08 pm New to the da-40 having come from cirrus. Can I fire up the avionics and put in a flight plan before starting or do I need to be concerned about battery usage. Let’s say five minutes tops. It would be great to get everything loaded and set before start up.


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I typically load the fllight plan when Im doing the mandatory engine warm up...

That being said I always upload it with foreflight via flight stream ... so that doesn't take to long.
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dmloftus
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Re: Battery drain during flight plan load.

Post by dmloftus »

The G1000 pulls close to 10 amps even before the Avionics bus is enabled, which is a huge load on the small battery. I certainly would not go over about 5 minutes. I, like Alan, load my flight plan while I am idling to warm up the engine. Not a big deal to have the engine idling if you own the plane as the impact to tach hours is negligible. If you are a renter paying $200 per Hobbs hour, it's probably a bit more expensive. Then again, you're not the one paying $750 for a new battery after excessive drainage ;-) Seriously, you're almost always better doing it with the engine running. If your flight plan is quite complex, you can always load it on the top Nav SD card ahead of time, which then takes seconds to load when you power up the aircraft. As Michael mentioned, you always have the option to power up the G1000 from the GPU plug if you want to operate the G1000 for an extended time without running the engine.
bryanchatham
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Re: Battery drain during flight plan load.

Post by bryanchatham »

10 amps. Wow. That is a lot. I did not realize you could use the top ssd slot. I will use that option. Thanks so much.
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CFIDave
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Re: Battery drain during flight plan load.

Post by CFIDave »

You're only burning 0.5 gallon/hour in a DA40NG with the engine at idle, and you need to let the engine warm up before takeoff anyway. So don't risk running down the battery by waiting to start the engine.
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Rich
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Re: Battery drain during flight plan load.

Post by Rich »

I don't feel comfortable sitting for extended periods with the engine running (with prop flailing, prop-wash blowing) in certain areas of airports. Crowded tiedown/hangar areas with uncontrolled foot traffic, for example. At some airports there aren't any good spots to be taking a long time with additional pre-flight procedures. This can include runup areas, which can be mere token spots with no good way to avoid blocking someone behind you that's ready to go.

GNS 530/430 boxes like mine are particularly limited, in that they have no native capacity to understand airways (or T-routes), though they do have all the necessary fixes, waypoints, and procedures. So for years, unless it was direct-to, entering the entirety of a flight plan was a particularly tedious operation. My technique back then was to only broadly enter the early, busy part of the route into the 530W and then refine it enroute (where ATC changes it anyway :)).

Now, with the Flighstream, popping a flight plan into my GNS units from Foreflight is a matter of seconds and therefore time is not a factor. If someone is with me I will sometimes have them do it while I taxi - my wife is completely familiar with the process. I happened to show this to my most recent safety pilot couple, who are fairly new PPL folks and they were amazed how cool this is. They own a Grumman Traveler with prehistoric avionics and added this capability to their gotta-have-it list when they undertake panel replacement.
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Johnrschaefer
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Re: Battery drain during flight plan load.

Post by Johnrschaefer »

I've never had a problem with battery drain in operating the avionics on the ground without the engine running. I try to avoid extended periods, but the time required to update databases (including forgetting for a while to turn off the master switch after I'm done) has not run down the battery. I also often turn on avionics & radios to get my IFR clearance and set up the flight plan in the GPS before engine start.

I do check battery voltage before I start, and find it is usually OK if the plane has been flown within the past week or so. Full disclosure, I have the ElectroAir electronic ignition and, apart from occasionally difficult hot starts, the engine always starts up with an absolute minimum of cranking, so there is not a lot of battery drain from starting a stubborn engine.
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MarkA
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Re: Battery drain during flight plan load.

Post by MarkA »

A couple of things to also note about starting off with a partially drained battery before a flight.

A brand-new Concord RG24-15M battery capacity is rated at 13.6 amp hours. The battery’s capacity determines how long the avionics operate if the alternator fails in flight. Since as Dave pointed out previously, the base G1000 with avionics master on consumes 10+ amps (more if you have other electrical equipment on) so it only takes a few minutes to deplete a significant portion of the battery’s total capacity.

Even if the battery is significantly below its full capacity either due to age or use, it will still show close to 24v and start the engine with no problem. However, taking off with a less than full capacity means you’ll have less time with functioning avionics if your alternator were to fail. It also may take a lot longer that you’d expect for the alternator to recharge the battery depending on how far it has been drained (like an hour or more).

In my case I have a BatteryMINDer connected in the hanger all the time including when I do G1000 database updates. I also start the engine to warm it up before entering the flight plan on the ramp.
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bryanchatham
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Re: Battery drain during flight plan load.

Post by bryanchatham »

Good point on voltage vs. amperage. I guess I should try to see how much discharge I am actually causing, then post start up, see how many amps are being drawn from the alternator as a measure of discharge. As other people have posted, I am trying to balance the risk/discomfort of sitting in the plane in the parking area with the engine running with people walking around and my head down twiddling knobs, with the impact on the plane's battery. It seems as though for a few minutes I should be OK, but I should check the amps once I start to see how much I drain the battery
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