Connecting Ground Power will not turn over engine with drained battery - ED Forums
 


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Old 01-24-2020, 03:52 PM   #1
-0303-
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Default Connecting Ground Power will not turn over engine with drained battery

Quoting old thread:
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Originally Posted by BIGNEWY View Post
I would need to check or get a spitfire expert to comment, but my understanding was the ground power was just for the starter and radios and so on, it did not charge the onboard battery.
Ground Power is for starter, what I always assumed, makes perfect sense. But ...
I've noticed many times, engine refuse to turn over, battery seems low, after repairs. Connecting Ground Power doesn't help. So I did a simple experiment with P-51 and with Spitfire (Summer +20'C).

1) Spawn "Takeoff from runway" (This assured engine temp/oil pressure was up, no damaging engine by turning over cold)
2) Shut off magnetos (engine stops)
3) Spun the starter until battery drained (prop stopped moving)
4) Attached Ground Power and attempted to start.

P-51 started (as it should). Spitfire prop didn't turn over at all (voltmeter showed 5V (down from initial 14/15V), whatever that means *1)

If Ground Power is for starting, which again makes perfect sense, then this is a simple well defined bug. Ground Power should power the starter in an undamaged aeroplane.

*1) Would ground power really bypass the voltmeter? If it does, be that as it may, the important point here is that ground power doesn't power the starter.

Last edited by -0303-; 01-29-2020 at 10:45 AM.
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Old 01-29-2020, 09:03 AM   #2
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I made a video production to get more attention, sue me.

This bug seems simple and well defined. Spitfire doesn't get any "Ground Power".
Who cares, how often does one drain battery anyway? Often enough after repair (20%?) to be annoying when it can't start again. This *is* a bug, unless someone explains why it isn't.

Note (as final screen also says), I don't think Spitfire gets any ground power, not to starter, not to dash lamps, not anywhere.
Have tracks.


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Old 01-31-2020, 12:30 AM   #3
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I just had this experience with the P-51. Kept landing (and crashing/repairing a lot) on Carrier. It refused to start. Connected Ground Power and happiness ensued (it started).


Wish the Spitfire worked with Ground Power.

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Old 02-09-2020, 02:29 PM   #4
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Can someone confirm this?
It's very easy. Takes 30 min to drain battery. Make a starter HOTAS binding so you don't have to hold the key down.
Then connect ground Power and note that Spitfire does not get any power anywhere, not starter, not instrument lights.
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Old 02-09-2020, 05:05 PM   #5
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Nah, max time acceleration and left click is enough .

Can confirm, although I'm more puzzled by the fact that starter can go for so long. I seem to recall back in 1.2.xx times starter in the Mustang was overheating and faililng if used too long.
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Old 02-10-2020, 02:14 AM   #6
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Thanks. Ground Power not providing *any power* anywhere *is* a bug. Fishing for BIGNEWY to say REPORTED.
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Old 02-10-2020, 06:06 AM   #7
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Quote:
Ground Power not providing *any power* anywhere *is* a bug.

Would like to see the schematics before saying anything definite. It's possible that on some systems, there's a relay closing the GP circuit when it is powered by the battery after the latter has been switched on; however, whether such schemes were actually in use is debatable.

But the starter turning for 30 minutes without burning out? Now THAT's a bug for sure
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Old 02-10-2020, 06:52 AM   #8
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Quote:
Originally Posted by msalama View Post
Would like to see the schematics before saying anything definite. It's possible that on some systems, there's a relay closing the GP circuit when it is powered by the battery after the latter has been switched on; however, whether such schemes were actually in use is debatable.

But the starter turning for 30 minutes without burning out? Now THAT's a bug for sure
It is not spitfire uses 12 V but starter is 24 V so starter works at much lower power level then was designed.
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Old 02-10-2020, 07:42 AM   #9
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Quote:
much lower power level
Still not sure about that. How much current does it draw? How thick is the wiring? How hot does it get over time? What's the circuit resistance? Would really like to see some data, or at the very least, anecdotes supporting the claim of it being able to run for half an hour loaded.

Because it's not just the voltage in isolation. That only gives you a higher possible average power level if your circuit can handle the current for longer periods of time. Peaks are a different animal altogether.

But I'm not claiming anything. It's also entirely possible that the starter system can do this. I'd just like to see some data.
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Old 02-10-2020, 07:48 AM   #10
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Quote:
so starter works at much lower power level then was designed
All else being equal, it definitely does not. Quite the contrary. What happens if you replace a 6V power source with a 12V one and leave the circuit it feeds unchanged?
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