Battery of default C172 Classic get flat way too fast

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ISSUE DESCRIPTION

When flying in network (vatsim, ivao, SI), like In real life (SEP pilot here), in controlled airports, we turn ON the avionics, tune the ATIS frequency and then contact the clearance for a first call and a Start-Up request.

All those steps are done with the battery ON and the engine is not powered yet.

In a real C172, the battery is drained after around 30 min of use without engine.

In FS (2024 but also 2020), the battery becomes flat much before and many times, I am in a situation in which I can’t startup after getting the clearance because the battery emptied ..

Would it be possible to have longer battery life span?

If not possible, is there another way to “reset/recharge “ the battery instead of restarting the flight? It is a very annoying issue, especially when flying in VR with a lot of VFR maps that have to be reset if the flight has to be started again..

Thank you

FREQUENCY OF ISSUE

Everytime I am on ground for more than 5-10 min with avionics ON.

REPRODUCTION STEPS

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YOUR SETTINGS

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MEDIA

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Are you referring to the C172 Classic or C172 G1000 or both ?

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Doesn’t work on all airports, but on some you can ask for a power cart once you have the avionics turned on, this obviously would be from the built in ATC and not from VATSIM etc.

In the past I have used FSUIPC to extend the battery life, but I am not sure if that still works in MSFS for that feature.

Does VATSIM penalize you for starting without clearance?? In my real world Saratoga I always started first before contacting ATC, the only exception was when I had to call a remote tower for IFR clearance on my cell phone. The IO-540 even at low idle was too noisy and back then my cell phone could not connect through the Bose headset.

If the engine state is not transmitted to the network, you could still ask for startup later.

1 Like
4

For a quick work around but I’m not 100% sure, if you use repair/refuel it may reset battery life.
It’s not mapped by default.

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https://docs.flightsimulator.com/html/Content_Configuration/SimObjects/Aircraft_SimO/system/electrical.htm

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Not in the US (not sure about everywhere else). I start before calling all the time.

If it’s cold outside, you might not have enough cranking amps after using the radios with the engine off. Not sure if the sim takes outside air temp into account for cranking.

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I don’t know if there is a penalty in VATSIM or IVAO for that, but it doesn’t really matter.

The battery life of a real Cessna is around 30 min. Why this can’t be changed in Flight Simulator?

I see this in the analog one (never fly with the G1000) since I don’t use it.

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Title updated with “Classic”.

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The 30 minutes can’t be applied globally, though, which leaves that unqualified. There’s usually an amp-hour rating tied to the battery and the more amps you’re drawing, the faster it will discharge. The starter draws/requires more than anything else, especially when the engine and battery are cold. Avionics generally draw quite a bit, especially when transmitting on radios.

So you could easily be a several minutes into operating lights and radios (especially transmitting) on the ground and get to the point where the engine won’t crank enough to turn over. No, it’s not instantaneous - there should be a bit of leeway. But I wouldn’t expect it to run on battery alone for 30 minutes and be still able to crank enough to start.

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That’s not the length of time it will remain charged enough to crank and start.

It shouldn’t take more than 2 minutes to get your clearance and start up.

2 Likes
11

By “drained” do you mean battery is not able to power the avionics anymore ? or which voltage do you expect the battery to be at after 30 minutes ?

Just did a test and after 30 minutes battery lowered from 24.5v to 11.7v (just avionics 1 was turned on). I don’t know if it is correct or voltage should be higher ?:

Screenshot (2116)
Screenshot (2116)1914×1032 180 KB

After 5-10 minutes the avionics turns OFF ?

1 Like
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Solid work! And those avionics include a pair of GNS which draw a bit.

To expand for the crowd: If we were able to pull breakers and/or switch some avionics off, we could prolong the battery life a bit. Some planes simulate this ability, others unfortunately don’t. Being able to shed the load by performing these actions in flight following an alternator failure is crucial. Some of that is what is meant by “study level” in the GA space (because there really isn’t a whole lot more depth for a 172; accuracy is a different story).

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That is how I remembered it, but it has been a few ages since I have last flown on VATSIM.:smiley:

In our real Saratoga we did spend a few dollars to change lights to LEDs where possible to reduce drain, you would not believe how much draw is caused by an old fashioned rotating beacon light. And as per regs of course that beacon must be on when you do anything inside of an aircraft :smirking_face:

And when we overhauled the avionics she did get a split avionics switch so that we could power up only the GNS530 initially and the rest would come later in those situations where we did need the avionics before engine start. In most cases, as I said I would start the IO-540 up first and let it warm up while I did the „official“ stuff. Back in the day for example KHND where we had a second hangar did not like aircraft sitting on the ground engines running for too long.

I only tried to help, with a suggestion for a workaround since I can‘t reprogram the Cessna for you. I will make sure not to do that again :smirking_face:

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Also for pc users.
FAUIP7
Amongst it many other excellent uses, is extend battery life.

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Crowd here… Thanks! –Redeye

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Doing some troubleshooting here - with the avionics on, no lights, and the engine off, I’m drawing 38 amps. Note I have the GTN750 and 650 installed.

Pulling the avionics 1 bus sheds about 16 amps and I lose the GTNs and ADF

Pulling the avionics 2 bus sheds 15 amps and I lose the autopilot

Interestingly, the turn coordinator isn’t firing up and isn’t affected by pulling the breaker. However, when I do so, it does shed 2 amps

Also, I think that despite having the TDS GTN overlaid still fires up the original instruments, which are hidden. Pulling the GPS breaker sheds 8-9 amps, but no change on the panel (GTNs stay active)

Cranking the starter adds about 75 amps initially, then down to a stable 40 or so. It also kills all my avionics right now (been sitting like this for about 10 mins.

I ran at a 25 amp load for a minute and lost about 0.42 volts

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Hello,

To clarify the TDS GTNXi MSFS 2024 Mod, the default GNS is not hidden, but completely removed from the configuration, so this should not cause the power issue.

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Weird. I believe what you’re saying, but yeah, pulling the GPS breaker definitely dropped the amperage with no ill effect on the GTN equipment. There’s some weirdness going on with the electrical system.

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Perhaps the issue is related to this bug:
https://devsupport.flightsimulator.com/t/su4-beta-random-circuits-trigger-on-and-off/17040/11

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Agree that the time would depends on the consumption and temperate obviously.. but even at cold weather , it doesn’t discharge in 5 min ( I fly IRL in Sweden) . If I am unable to startup the engine after hearing the ATIS and getting a clearance, there might be a problem somewhere in my C172.
If only there was a way to reinitiate the electrical system ( like xplane has) instead of restarting the flight