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Cold morning starts with Odyssey batteries

newt

Well Known Member
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
 
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.
 
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.
 
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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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.:)
 
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
 
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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I don't know the battery you have, but the PC680 comes with a steel case. I have had two batteries over ten years and to keep them going I removed the steel case. It seems to get them going better in cold conditions, and by cold I mean 4 or 5deg C. The case is only held in place with silicon sealer.
 
The PC625 is a bit smaller than the PC680. It's in a black PVC case.

Based on the responses here I'm forming the view that it's just a small battery with perhaps a bit less grunt than required.

Most of the rest of you have PC680s, a little bit bigger, a little bit heavier.

- mark
 
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