Main Battery Lasted Over 3.25 after Main Tie Trip

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Urquhart
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by Urquhart »

Good information to review
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Chris
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by Chris »

Chris B wrote:In a situation where the main &/or ESS breakers pop due to a depleted battery (see this related thread), one alternative would be to:
  1. Turn the BAT switch OFF
  2. Reset ESS/Main Tie breakers
  3. Periodically switch BAT ON for 10-15 sec (~ every 2 minutes?)
  4. Repeat step 3 until the indicated alternator output drops below ~30A
  5. At this point BAT can be left ON indefinitely
OTOH, if the ESS &/or Main Tie popped, or one was not careful with the BAT switch, things could get exciting...

Comments?
I was thinking along these same lines and came to the conclusion that steps (1) and (2) make sense as long as you're running enough RPMs to run the entire equipment stack. In the air it might get interesting as alternator output drops off during a descent to land, though. Step (3) sounds like a recipe for playing whack-a-mole with your circuit breaker panel, unless you can dial in the right RPM to charge the battery without exceeding the breaker limits. I don't think I'd mess with it in the air if everything was working fine off the ALT.
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Rich
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by Rich »

Chris B wrote:Thanks for the diagram, Rick. You might want to consider showing the values for a few key breakers. ESS & Main Tie come to mind. ;)

FWIW, the load budget helps illustrate why LED position/strobes are such a huge help on the electrical load. The position/strobe combination on my aircraft is <1A, vs. ~7A with conventional lights.

In a situation where the main &/or ESS breakers pop due to a depleted battery (see this related thread), one alternative would be to:
  1. Turn the BAT switch OFF
  2. Reset ESS/Main Tie breakers
  3. Periodically switch BAT ON for 10-15 sec (~ every 2 minutes?)
  4. Repeat step 3 until the indicated alternator output drops below ~30A
  5. At this point BAT can be left ON indefinitely
OTOH, if the ESS &/or Main Tie popped, or one was not careful with the BAT switch, things could get exciting...

Comments? :scratch:

I don't expect to repeat this experience, but it would be nice to have a backup plan if I screw-up again... :oops:

Chris
When my battery got run way down a couple of years ago I found the way to get it back up without popping the breaker was just run it on the ground for awhile at an RPM that supplied about 35 amps. After about 10 minutes of this, I could run it up to redline without popping said breaker.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by kevingab »

Rick wrote:I have been carrying the attached diagram in my DA40 for many years (actually, I had a KAP140-version before, but then updated it). Thankfully, I have never needed to reference it in flight (yet), but I have always thought it might help me sort through what to do with an electrical problem. I would be interested in any comments or corrections from the other experts within...
DA40 Electrical Diagram.pdf
Rick,

Very helpful. Thank you. Helped me understand what Steve was saying.

Thanks to all!

Kevin
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Chris B
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by Chris B »

Rich wrote:When my battery got run way down a couple of years ago I found the way to get it back up without popping the breaker was just run it on the ground for awhile at an RPM that supplied about 35 amps. After about 10 minutes of this, I could run it up to redline without popping said breaker.
From personal experience, I know that this works great on the ground. :oops:

But the bad scenario is being over widespread IMC (or worse, in IMC!). There it doesn't work so well. ;)

Chris
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by Charbie »

Gentlemen, I experienced the same issues yesterday after a repeated hot start event. Eventually the engine started and I was able to return on a 40 minute flight but the main tie breaker tripped and the low voltage annunciation was on the entire trip. Repeated attempts to reset the breaker were ineffective. The battery is being charged over night to see if there are other issues. So just to ensure I understand this thread correctly.
1. Depleted battery from repeated attempts to hot start the engine.
2. Alternator trying to charge a depleted battery while running all avionics causes the main tie to trip.
3. If these issues go away after a fully charged battery I should be good. I will fly a number of circuits and check the data logger to see if everything is ok.

The 10 year prop overhaul is due in the spring and I will install a new alternator /belt then.
By the way, going forward, I will use the flooded engine start procedure after one hot start attempt.
It was the procedure that started the engine after flooding it.

I would appreciate any feedback. Thanks.
2007 DA40 XL , CZBA, Burlington, Ontario, Canada
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by CFIDave »

An alternative solution to a depleted DA40 battery popping breakers (e.g., after a hot start):

Run the engine on the ground at *low* RPM for a few minutes, setting RPM with the throttle just high enough that the alternator output stays below 25 Amps. The alternator won't provide full amperage at lower RPMs. As amps drawn by the depleted battery go down, gradually increase RPM with more throttle to again stay below 25 amps.

After about 10-15 minutes as the battery charges you'll be able to increase throttle to run-up RPM (where the alternator can provide full output) without popping any circuit breakers. Then it's safe to go flying.
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by Rich »

CFIDave wrote:An alternative solution to a depleted DA40 battery popping breakers (e.g., after a hot start):

Run the engine on the ground at *low* RPM for a few minutes, setting RPM with the throttle just high enough that the alternator output stays below 25 Amps. The alternator won't provide full amperage at lower RPMs. As amps drawn by the depleted battery go down, gradually increase RPM with more throttle to again stay below 25 amps.

After about 10-15 minutes as the battery charges you'll be able to increase throttle to run-up RPM (where the alternator can provide full output) without popping any circuit breakers. Then it's safe to go flying.
This is basically correct (been there, done that) BUT not if you're launching into IMC. You need to understand that the battery is not really fully charged and won't be able to power the electronics very long should it be needed.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by ihfanjv »

CFIDave wrote:An alternative solution to a depleted DA40 battery popping breakers (e.g., after a hot start):

Run the engine on the ground at *low* RPM for a few minutes, setting RPM with the throttle just high enough that the alternator output stays below 25 Amps. The alternator won't provide full amperage at lower RPMs. As amps drawn by the depleted battery go down, gradually increase RPM with more throttle to again stay below 25 amps.

After about 10-15 minutes as the battery charges you'll be able to increase throttle to run-up RPM (where the alternator can provide full output) without popping any circuit breakers. Then it's safe to go flying.
This is the correct procedure.

Someone should come up with a fix so that a perfectly functioning alternator and a low but not fried battery does not trip the breaker (and also deal with the high output alternator tripping the breaker issue).
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Re: Main Battery Lasted Over 3.25 after Main Tie Trip

Post by CFIDave »

What I was trying to say was that you need to be able to do a run-up without popping circuit breakers before *any* flying.

We could get into an interesting separate discussion of how fully charged your battery needs to be to fly a DA40 in IMC. If you have an older battery (e.g. more than 3 years old), fly in winter cold, and/or have to crank your engine awhile to get it started, you're not going to have access to full rated battery capacity even without any malfunctions or popped circuit breakers.

As someone who had a DA42 alternator fail when flying IFR, I really appreciated having twin engines each with its own alternator so I didn't have to rely on battery backup.
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