Need help diagnosing EI starting problem

[cccjbr6]

Please help us diagnose an interesting problem starting the plane. We have a RV-6A with an IO360. We run a two screen Garmin G3X, a VPX Pro, an Electroair EI and regular mag, and a one year old PC680 battery and a 3 hour Aux battery. The EI is wired directly to the main battery. We keep the battery plugged into the Odyssey charger/conditioner when it is on the ground. We have never had any difficulty starting the plane in the three years we have had the EI.

It was in the low 40s. Turning the AUX battery on (master still off) did nothing. Usually the PFD comes on line. With the master on and the EI and mag both turned on we attempted a normal cold start. The MFD went blank.
The starter turned fine but the engine would not fire. We turned the EI off and tried starting on the mag only. It started normally.

Once the engine was running we tested the Aux battery- it worked just fine when we shut off the Main battery. During the mag check it ran fine on the EI.

A few hours later on the return trip it did the same thing again. Both batteries read normal voltage on the VPX. Any thoughts?

[lr172]

The giveaway is the EFIS dropping out. Cold weather starting is MUCH harder on the battery and often shows any weakness in the system. your voltage is likely dropping below the critical level for running your EI and EFIS during the cranking. It could be weakness in the battery or in various parts of your delilvery system to the starter or both. The increased current required by the starter, along with the batteries reduced ability to deliver current due the cold is allowing voltage to drop below levels seen in warmer temps during the cranking. Batteries lose delivery efficiency in a linear fashion with lowering temps.

Typical troubleshooting. Contacts, connections, grounds, etc. You can also put a volt meter in the starting circuit to observe and confirm the voltage drop.

Many threads here discussing troubleshooting.

The brown out or voltage fluctuating above and below critical likely caused the EI software to do something wierd that prevented starting and explains why it started without it.

Larry

[FasGlas]

I believe the ElectroAir needs 9 volt minimum to fire the plugs. You are obviously going below this voltage while trying to start your plane. If you find nothing wrong with the wiring, connections or solenoid you can try starting with minimum avionics or replace the battery. I run dual ElectroAir's and never have a problem starting but I have almost nothing energized while starting. Once the engine fires I turn on the EFIS's, Radio's, Alt, etc. I also don't like to spike my avionics.

[erich weaver]

Originally Posted by lr172

your voltage is likely dropping below the critical level for running your EI and EFIS during the cranking

Exactly.

Why are you using the battery charger after every flight? If you fly with any regularity at all, your alternator will keep the battery completely charged, just like your car. While I do not know the reason why, there are numerous reports of failing batteries that are left on their chargers continuously between flights.

Try a new battery or at least do a capacity test on your existing one. Knowing the resting voltage by itself is not enough.

Erich

[Tom Martin]

Try starting while using your auxiliary battery to power the electronic ignition. After start you can run the ignition as it is normally used.
I also wonder about the charging after every flight. Not necessary and not recommended by Odessey.
Checks all your main ground connections

I was having starting issues with my ei this year and it turned out to be a fault with the 13 year old circuit board.

[cccjbr6]

Originally Posted by erich weaver

Exactly.

Why are you using the battery charger after every flight? If you fly with any regularity at all, your alternator will keep the battery completely charged, just like your car. While I do not know the reason why, there are numerous reports of failing batteries that are left on their chargers continuously between flights.

Try a new battery or at least do a capacity test on your existing one. Knowing the resting voltage by itself is not enough.

Erich

Between flights we keep the battery on the Odyssey Ultimizer charger (OMAX-25A-1B) recommended for the PC680. The manual for the charger says it can be left connected indefinitely without harming the battery.

[Toobuilder]

There is plenty of evidence that suggests you do not need to keep a battery tender plugged in to keep an Odyssey battery happy. I treat mine like a car - in other words zero maintenance aside from flying - and I get good service.

With that said, what is the voltage delivered to your EI while the starter is grinding away? That's the first thing you need to find and that will lead you to the solution.

[Bavafa]

There has been many reports of poor performance with the newer Odyssey PC680 batteries. My Odyssey that I purchased in 2008 is still going strong and always kept it on a trickle charger with no issues but many have reported issues with no clear indication as what causes a short life in these batteries.

Like others have said, I would replace or barrow another battery to see if the problem goes away.

[lr172]

Originally Posted by Bavafa

There has been many reports of poor performance with the newer Odyssey PC680 batteries. My Odyssey that I purchased in 2008 is still going strong and always kept it on a trickle charger with no issues but many have reported issues with no clear indication as what causes a short life in these batteries.

Like others have said, I would replace or barrow another battery to see if the problem goes away.

Charger type/brand has a lot to do with this issue, so not surprising that some find it to be ok. Using a charger that is not designed for floating an SLA battery has been shown to significantly reduce battery life on SLA's. Most "battery tenders" are designed for flodded lead acid batteries and not Sealed Lead Acid or AGM batteries, which are different and don't take well to floating. The odyssey charger doesn't float like a battery tender, it shuts off once charged and begins charging again when the voltage level drops. That is a good sign that odyssey doesn't believe long term floating is a good idea for their batteries.

Larry