Battery goes dead

[pierre smith]

Mornin' everybody,
We have 8 hours on 33PL but after the airplane sits a few days, the battery, an Oddysey, gets weaker and weaker and won't crank the engine. It's two years old but sat for most of that time while we built the Sojourner. There is nothing on to draw current, not even a memory wire for the radios. What gives? After it starts and the alternator is turned on the voltmeter goes to 14 volts from 12.
Regards, Pierre

[robertahegy]

It's possible that you may have just gotten a bad battery. It happens. I have had my Odyssey PC680 for about 2.5 years and it is still doing well, even in cold weather.

Check for a draw, if you haven't yet, by taking the negative lead off the battery and placing a test light (12V bulb) between the lead and the battery post. Don't use a voltmeter. They will read the potential and give a false indication. Current flow will be indicated better by a lit lightbulb. If the bulb lights up, start disconnecting devices until it goes out. When the bulb goes out, you have found the source of your current draw causing your battery to go dead.

The 14V indication says the alternator is producing some power, but possibly not full power. Generally, alternators are all or nothing kind of animals. But, it could also be the problem. Once you get the engine running, load the alternator by turning on a lot of devices and see that the voltage remains in the 14V area. This will tell you if the output is still OK.

Hope this helps,

Roberta

[szicree]

Roberta's trick is defiintely the first move. I had an old MG that was doing the same thing until I discovered that the trunk light wasn't going out when the trunk lid closed. The lightbulb trick worked great.

Steve Zicree
RV4 finishing

[hevansrv7a]

I once experienced a whole series of Delco alternators with a bad diode in the internal voltage regulator. The only solution was to put on a battery disconnect. In your case, the master switch should have done it, but be sure.

[az_gila]

From the Odyssey web site....

"Longer storage life - Unlike conventional batteries that need to be recharged every six to twelve weeks, the ODYSSEY? battery, when fully charged , can be stored for up to 2 years at room temperature (25?C, 77?F). At lower temperatures, storage times will be even longer."

Pierrre, where your batteries possibly exposed to high temperatures during the 2 year storage time?

gil in Tucson.... where batteries don't last long....:^)

[gmcjetpilot]

You need a minimum of 14.3 volts to charge. The charge range is 14.3 to 14.9V. (15 volts max). If you don't get the full charge voltage it will charge slightly but will never deep charge. Read the technical document that came with it or check their web site.



Also by the way 1.5 amp trickle charges will NOT fully charge an Odyssey battery.

Cheers George

[pierre smith]

Thanks guys,
Yes Gil, we see 100 deg temps here in the summer (328'MSL) and even tho' my hangar is insulated, it still gets HOT. I didn't realize that those temps would be hard on an Oddysey.
Pierre

[Bryan Wood]

Hi Pierre,

My battery acts very much like yours. They seem to be sensative to cold temps and just don't want to turn the engine over. With these symtoms I ordered a new battery from Van's and installed it with the same results. After trying just about every test that I could think of I called AeroSport who built my engine and talked to Bart about it. He said that the Skytec starter is most likely the cause because of its design pulls more current than traditional starters and the battery just can't take it. My choice was to replace the starter with one weighing several pounds more, and vague memories are recalling 6lbs. Since I used a Hartzell C/S I just couldn't afford the weight so the choice was to just live with it. Now on cold mornings the starter will just simply not turn the prop through. To compensate I've kind of learned a technique of using the starter to kind of "Slap" the prop against the compression stroke and on about the third try it will always fire. It never feels good to be away from home on a cold morning and wonder if it will start, but it always does. I'll be watching this thread along with you to see if anybody has come up with a cure that we are not aware of yet. Short of using two batteries in Parallel, or replacing the starter I just don't know what to do either.

Good luck, and let us know what you find.
Bryan 9A

[robertahegy]

I have a Skytec starter in my 7A (0-360 A1A) with Hartzell and PC680 Odyssey battery. I haven't had any cold weather starting problems, at least down to 20 deg. F. I use Aeroshell 15W50 oil year around. Perhaps a heavy weight oil might be the problem in cold weather.

Roberta

[Bryan Wood]

You might be on to something Roberta. I don't use multi vis because of the generally mild climate here in CA. The starter is much better when the engine is warm. As for the starter, well it is also used to turn 0-540s over with no problems usually. ????

Bryan 9A