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  #1  
Old 07-12-2013, 07:06 AM
newt's Avatar
newt newt is offline
 
Join Date: Jan 2011
Location: Sydney, Australia
Posts: 370
Default Cold morning starts with Odyssey batteries

I have a Skytec light weight starter on an O-320 160hp carbed engine. Odyssey PC625 battery.

I don't usually have any trouble starting, as long as the battery is in good condition. I push the red knob in, hit the fuel pump until the pressure gets into the bottom of the green, crack the throttle, and crank. Usually starts after 3-4 blades.

I replaced the battery last year, so it should be in good nic.

However-- I've always had this problem, where if I don't fly it for more than about 2 weeks, its ability to crank its way past the first compression stroke is very hit and miss, especially if it's cold outside. I don't know enough about the Odyssey battery chemistry to know whether that's normal behaviour, or whether I have a very very slow electrical discharge somewhere in the system when everything has shut down.

It's rarely a real problem because I usually fly every week or so, so it's unusual for it to be idle for more than 2 weeks; and if it is, I put it on the charger for 20 minutes during my preflight inspection anyway.

But I'm still curious about whether there's some current leakage somewhere that's slowly, ever so slowly, draining my battery. I know batteries don't hold their charge forever, but how much decrease is "right" for these AGM's?

Can anyone reset my expectations? Is it normal for a PC625 that's left idle for 2 or 3 weeks to have trouble turning over a 160hp Lycoming on a 50 degF morning?

- mark
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  #2  
Old 07-12-2013, 07:51 AM
humptybump humptybump is offline
 
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Location: USA
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Default

Mark - I dont have your answer but I will follow this thread because, "its ability to crank its way past the first compression stroke" is an everyday problem for me. I've changed batteries and no difference. I have a different starter. I will be testing the solenoid the next time the cowl comes off.

Good luck and I'll be lurking.
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  #3  
Old 07-12-2013, 08:13 AM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
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Default

The type of starter is a factor. The older non-wire wound units require more amps and have a greater voltage drop. Typically an Odyssey will spin the engine very briskly with the latest wire wound starters like from B&C or the Sky-Tec NL series. A wire wound starter is recommended for electronic ignition, the voltage drop is less than with older magnet starters and will help the EI to not loose its brain during start.

Another factor is parasite load on the battery. If there are any keep alive items, they will deplete the battery in a couple weeks.

Corroded cables and/or connections could be a factor.

Finally, the 625 does not have the umph of the 680 - but it should do the job better than you describe.
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  #4  
Old 07-12-2013, 10:21 AM
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flyboy1963 flyboy1963 is offline
 
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Location: Lake Country, B.C. Canada
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Default is it luck? or science?...or???

I had a 2006 concord in my bird with an 0-320 and Delco 'classic' starter. Never a problem starting, even in winter ( outdoors, below freezing) after sitting not flying for 4 months.
seemed after 6 years, it was gradually losing some stored voltage capacity, so as a precaution, replaced it with an Odyssey 925, which fit in the same bracket as the typical Concorde RG-25 or Odyssey 680, just on it's side.
Now it cranks much faster, so hopefully that means it will also have more reserve in winter if I screw up and flood it!
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Last edited by flyboy1963 : 07-12-2013 at 10:24 AM.
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  #5  
Old 07-12-2013, 11:12 AM
rv9aviator rv9aviator is offline
 
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Location: Arkansas
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I have a B&C Starter on my 0-320 150HP and a 680 battery. It starts fine in cold weather and hot. No problems turning the engine over at all.
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  #6  
Old 07-12-2013, 12:31 PM
Rupester Rupester is offline
 
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Location: Mahomet, Illinois
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Default Me too ...

... Like Jim Wright said.
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  #7  
Old 07-12-2013, 05:57 PM
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newt newt is offline
 
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I'm starting to wonder if the PC625 is undersized.

- mark
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  #8  
Old 07-12-2013, 06:25 PM
Acrophil Acrophil is offline
 
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Location: GA
Posts: 50
Default Starting

I started the AEIO-540 in my Extra 300 with an Odessy PC -680 for three years. B&C starter. Cold or hot. No issues. Charged at 14.5 volts and it was going strong when I sold it. Also started the 525 HP Dart motor in my V8 motorcycle with a 680. Same deal. No issues. Needs a high charge rate. Got one in the Rv-7A with injected 180. No .........

Phil
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  #9  
Old 07-12-2013, 06:31 PM
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ccsmith51 ccsmith51 is offline
 
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Location: Orlando, FL
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I have an O-360 with a wood Sterba prop, a Landoll starter, and a 680. I had starting issues and thought it was the battery. Sometimes I could not get past the compression stroke. I was told part of the problem was the light prop. Even leaving the battery on the trickle charger when it was colder outside was not enough.

I replaced the battery but the problem persisted. I then removed, cleaned, and reattached every connection from the battery to the starter. I found that there was quite a bit of corrosion which would have made the problem worse.

I also found that the braided ground strap from the firewall through-bolt to the engine was a bit on the light side. So I replaced that with a 4-0 welding cable.

Finally, I replaced the Landoll starter with a Sky-Tec 149-NL.

Since that time I have not had an issue starting, even in colder weather. I'm not sure which issue caused the most problems, probably the bad connections and the ground strap. The battery is working fine on the Panther prototype, so I think that really wasn't part of the problem.

YMMV,
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Last edited by ccsmith51 : 07-12-2013 at 06:56 PM. Reason: Spelling (again....)
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  #10  
Old 07-12-2013, 09:08 PM
rv9aviator rv9aviator is offline
 
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I just noticed you have a PC 625. I have a PC 680 so I wasn't comparing apples to apples.
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