Thread: Battery a energy killer?

Hello CT friends,

last week I had a very mysterious experience with our CTSW. During flight the voltage dropped below 12 V and the Dynon EMS popped up a warning. My first thought was the landing light, but it was switched off. While checking the landing light, the voltage dropped even further. The next thought was the generator. Does it deliver loading current? It did. The Amperemeter showed 16 Amps with a plus sign!! Wow. So much charging? To verify this, I pulled the generator plug and the amperemeter fell down to -3 Ampere while the voltage fell down to 10 Volts. So the generator seems to work well. After this, I switched off the transponder, radio, pushed the generator plug back in and took my way home. The flight to my home base took about 30 minutes and during this time, the voltage dropped down to 6 Volt while the charging current displayed at about 18 Ampere.

What the heck was this??

Back on ground I checked the capacitor, the battery and the cables. Nothing seemed to be wrong. The battery was empty but it recovered well, after a short charging period with an external charger.

After that, I took another flight for about 45 mins and all worked as expected. The battery regained its health.

Spooky, isnt it?

My conclusion after studying the wiring diagram: If the Dynon shows positive Ampere, energy goes from the generator to the battery. If the voltage is low anyhow, there must be something wrong with the battery. Even if it seems to work normal after this incident. So I ordered a new Hawker and hope that this will chase away my energy eating ghost.

Other ideas?

Markus

It is your ground wires. Under the cowl up by the battery, regulator and even up the firewall a little further are all grounding wires. Whether you think these are tight or not put a wrench on them. Especially tighten the one or two that go through the fire wall. It comes out on the back side of the fire wall right behind the right instrument panel. There is a cluster of ground wires on a bolt or grounding block back there. make sure those screws or bolts are tight. If it is the bolt, back off on the top locking nut and then tighten the bottom one. Once the grounds are back to snug your issue should go away. 98% of of the funny electrical readings that pop up out of no where are poor grounds found at these locations.
It should take about 15-20 minutes to tighten all these.

Hello Roger,

thank you very much for your answer. I like your competent and knowledge-based postings at this forum very much and have learned quite a lot from your posts.

This time, I am quite sure, that the ground wires are not involved because of two reasons:

1. If the ground wires are failing to contact, you have a problem because of increasing resistors. At thie described incident, our CTSW had more current than normal which indicates lower resistors than normal.

2. Our CTSW had the same problem with fluctuating gauges like others some time ago. I rewired the ground scheme and installed a star-shaped grounding scheme which works very well since about one year. If you like, I will take some pictures of the new wiring.

Greetings from Germany

Markus

Hi Markus,

I'm very curious, so lets us know when you find the problem.

Hi Folks,

after changing the battery, the problem disappeared. A little unsureness remains to me, because the problem disappeard right after the flight with the incident, when the old battery was in place.

I will check the old battery with my AccuMaster and run some charge/discharge cycles with it. Hopefully I will find the clue.

@Roger: Due to the grounding discussion, I posted my solution HERE

Kind regards

Markus

Due to further investigation, some news on this topic arrived:

1. The problem occured once more, even with the new battery.
2. The old battery is in perfect shape (several charge/discharge cycles)
3. The focus is now at the ignition switch.

The pilot, which had the same error the last time reported, that an unusal key position attracted his eye. He said, the ignition key was closer to the "start"-position than to the "1+2"-position. After pushing the key back to the "1+2"-position, voltage raised up and the current fell down to 0-3 Amps.

I wonder, if it is possible, the starter runs for such a long time without getting damaged? If this is true, at my flight home, the starter would have run for at least 30 minutes.

Greetings

Markus