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Ovation 3 Rapid No 1 battery discharge.

Jack Russell

By Jack Russell
in Modern Mooney Discussion

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Jack Russell Apprentice

Jack Russell

Posted
Posted

Have Ovation 3GX. Battery  1 seems to be rapidly discharging when using battery 2?
 

Story: Battery 1 found completely discharged after a flight. Was fine when checked prior. Used Battery 2 during flight. We recharged battery 1 and all good for next couple of flights. On subsequent start up battery 1 would not turn engine. So presumed battery dead and replaced with new Concorde unit. All good on next flight and charging normally. On next  flight new battery 1 checked out OK and was charging normally but I switched to battery 2 for the flight. Everything still seemed normal. However on arrival new battery 1 found completely dead. Any ideas?

atpdave Contributor

atpdave

Posted
Posted
23 hours ago, Cruiser said:

[...]

Everything else in the plane is common to both batteries. 

Not exactly.  Cabin lights (and Hobbs meter) are fed from Battery 1 only.  Don't know whether this plane has the fuses or the circuit breaker mini panel in the tailcone.  If Battery 1 is excessively discharged you will get a huge charging current from the alternator if Battery 1 is selected or a blown charging fuse/tripped CB if Battery 2 is selected.  If the plane is flown mainly during the day the cabin lights might not be noticed.  I've heard this kills battery 1 in these models from time to time.

M20S Driver Experienced

M20S Driver

Posted
Posted
1 hour ago, atpdave said:

Not exactly.  Cabin lights (and Hobbs meter) are fed from Battery 1 only.  Don't know whether this plane has the fuses or the circuit breaker mini panel in the tailcone.  If Battery 1 is excessively discharged you will get a huge charging current from the alternator if Battery 1 is selected or a blown charging fuse/tripped CB if Battery 2 is selected.  If the plane is flown mainly during the day the cabin lights might not be noticed.  I've heard this kills battery 1 in these models from time to time.

I completely agree.  The cabin light switch is poorly designed and could easily be turned on by bumping into it.   I lost a battery (1) before I made it a part of my final check before locking the door.

Jack Russell Apprentice

Jack Russell

Posted
  • Author
Posted
8 hours ago, rgpilot said:

Did you actually check the battery or just found that it did not respond when switch was moved to battery one?

Yes, it was down to 6.9 volts. I think problem might be elsewhere. I hope I have not cooked a new battery as well.

  • 3 weeks later...
Jack Russell Apprentice

Jack Russell

Posted
  • Author
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On 12/4/2021 at 1:40 PM, M20S Driver said:

I completely agree.  The cabin light switch is poorly designed and could easily be turned on by bumping into it.   I lost a battery (1) before I made it a part of my final check before locking the door.

Thankyou very much for this…. I think I might have a very red face. The interior lighting system is completely mad and has probably caught me out big time. 5 lights and 6 switches in various places around the aircraft, some apparently going through the battery master switch, some directly connected to No1 battery without going through the battery master. The result being that it’s possible to leave a light on, discharging battery No 1, with the battery master off.  I think this may well be what happened initially. The problem then is, as per the POH, the battery must be removed and recharged properly because it will not recharge from the alternator. The POH is a little vague on that but that seems to be the case)?) I think that may well be why I saw large charging currents from the alternator but without realising No 1 battery was probably not charging but then I stupidly concluded something else had discharged it. The advice  I was getting was that the battery had probably failed or it might be the relay stuck. Well, I got a new battery but I found that went flat too (I’m guessing I hadn’t noticed a light still on, so it would have done exactly the same discharge.) and a Mooneyspacer very kindly got me an unobtainium relay and shipped it to me. Meanwhile I started to think about the posts here on the interior lights… so I played around with the switches, making sure everything was off, took the bulbs out to make sure and found the luggage area has a separate light with a strange hidden switch I didn’t even know about. I got the the original battery No1 recharged and tested on a proper approved aircraft battery charger, refitted it and needless the say, it’s all been fine since. (So far)

Thanks very much for all of the advice and especially the incredibly kind member who obtained and sent me the relay. I guess the lesson learned is think about the simple things first. At least I now have a spare battery I’m almost bound to need sooner or later and an unobtainium relay! 

  • Like 3
carusoam Grand Master

carusoam

Posted
Posted

The baggage compartment light catches many new owners off guard…

The reading lights for the back seaters catches many parents off guard…

Somebody at Mooney thought leaving these circuits live after the master is shut off was a good idea…

The more recent Mooneys have an auto-shut off circuit to help with this situation… iirc.

An MSer has also designed a circuit to do this as well…

The real hint… Battery #1 supports all of the live circuits… memory functions for all the electronics….  Check to see if everything survived the low voltage status…. Most new stuff has less volatile memory…

Thanks for sharing the follow-up…

-a-

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