Starting Battery Power Question
 

I was reading another thread about alternator and battery power issues and it got me to thinking about my own battery power situation when starting. I keep a battery minder hooked up to the aircraft when I'm not flying. However, when I attempt an engine start it barely turns the first time. I then engage a second time and it usually starts. I bought the airplane two years ago from the original builder and it's always been slow to crank. I have an Odessey battery and just wonder if the battery is nearing its life expectancy.

When I check battery voltage with my tester it reads around 13.4 volts but does drop down to around 12.6 volts or lower if I've been playing with the avionics equipment. I'm wondering if maybe the lead from the battery to the starter might be undersized? Any ideas?

It will only read 13.4 volts if you've just removed it from the charger. Wait an hour (or give it a brief load-turn on your master for a few seconds) and then measure. Full voltage should be around 12.8 volts. If you turn on the avionics (a few amps or so) and the voltage rapidly (a few minutes) drops down to 12.2 or less, then you have lost a substantial amount of the nominal battery capacity.

Read the Odyssey instructions for float charger voltage. They are very specific, too low or too high will result in long term loss of capacity.

That's not right. First, I would check the age of the battery. Some people use them for up to seven years, but I change mine (B&C 100-1) every three years whether it needs it or not. Is there a way you can hook a voltmeter across the battery during cranking?

You want at least #2 AWG battery cable.

How old is the Odyssey?

If the battery is healthy you won't need a trickle charger if the plane is flown every month or so. Trickle chargers have been known to kill the PC680--these batteries maintain voltage for a long time without charging between flights.

12.6-ish is in the normal range for a good battery. But if the trickle charger has been in use long-term the battery may have been compromised.

Jim - I had a very similar experience on my bought 7A and PC680. Sometimes wouldn't get past the compression stroke on initial start - would come off the starter, pause, and crank again to start. Would do this more times than not. Bought a new starter and no issues after that. Also stopped using my tender due to reading here on the board - have always used them on my motorcycles - and had no issues whatsoever. Although there weren't many times that I would go longer than several days between flights.

Terminals
 

+1

Check the terminals on the fat wires. It should take more than 900 lbs to pull the cable out of the terminal. My bad boy was on the + battery terminal.

If you decide on a new battery, consider the EarthX900. 10 lbs lighter and spins the prop like crazy! It will lighten your wallet as well.

My PC-680 came with the kit in 2010. Still going strong (probably just jinxed myself) and its never been on a trickle charger. More fun way to keep it charged is to fly it at least once a month, although mine has gone more than that a couple of times. My (second) Ducati charges it at about 13.9.

Thanks everyone
 

The VAF family will always provide good answers. I will check my battery capacity by turning things on and see how long it takes for the voltage to drop. I will also check to see if my battery cable is at least 2AWG in size and stop using the battery minder to test the battery's ability to hold a charge. If any of these checks give me reason to question the battery I will replace it.

I'm Not sold on the idea of the Earth X900. Not only is it expensive but it's also lithium ion technology and with hover boards catching on fire, cell phones catching on fire, and Boeing having trouble several years ago with battery fires; it just doesn't seem worth the risk. Few things are more scary than an inflight electrical fire. I know that for a fact from my USAF days.

A new PC 680 is relatively inexpensive compared to having battery problems on "the road."

12.8 volts is normal for a fully charged Odyssey, not the normal 12.6 for a flooded cell battery.
But what you need to know for your problem is what is the voltage at the starter while cranking. It should be north of 10 volts. If it's low, check again at the battery while cranking. If it comes up more than a few tenths of a volt you have a high resistance problem between the battery and starter. If it doesn't you have a battery problem.
You can rejuvenate an odyssey by draining down to 10 volts through a head light bulb, measure the time it takes to get to 10 volts. Recharge now with an approved odyssey charger, let it sit 10 hours or so and repeat. If the time to drain to 10 volts increases repeat the cycle. If it doesn't increase buy a new one.
I'm rejuvenating the one out of my Cozy now, it will go in the mower when done because I don't like being stuck away from home, but the procedure works. I've got the drain time from 2.5 hrs to almost 4 hours with the above procedure.
I've come to believe these odysseys need a ground charge from time to time as all the approved chargers have an extended "saturation" charge mode of several hours. If you only fly an hour or so this may not be enough charge time, buts that's just my thinking on it.
I just bought the Ctek approved charger with the new battery. I'll keep an eye on my battery voltage going forward and maybe give it a monthly charge to keep it topped off. If it's not up at 12.8 it's not fully charged and this will reduce the life of the battery.
Tim Andres

Head to Harbor Freight with a 20% off coupon and purchase a Battery Load Tester.

If it tests good, then check cable size and all fittings. also, check the ground cable and path the same way.