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Resolved IBBS IN USE warning message on Garmin G3X

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Forums Chief Pilot
Staff member
Oct 31, 1996
Type aircraft owned
Carbon Cub FX-3
Base airport
For those that may have seen my videos over the past few months may have noticed a flashing, then later steady, IBBS in use message on my G3X. This started last December, six months ago. I inquired with CubCrafters support and later Garmin g3xpert and the symptom typically reflects something bad in the sensor wire path between the IBBS battery behind the right forward panel and the GEA24 pin 41 is the one CubCrafters used. I initially mixed up the ignition backup battery with the IBBS battery but Pete caught me and steered me back on the right path.

Over the past six months I removed the right forward panel multiple times checking for corrosion or something causing a bad connection. CubCrafters said they've seen this once before and they noticed white "corrosion" on the wire. I did not see this. I then wanted to check the GEA24 side but that is extremely difficult to access as the wire connectors are on the forward side and of course cleanly zip tied. I wasn't sure how I'd even get the four screws holding down the GEA24 removed as it's so tight in there but I later found a setup that worked in the tools I had. I got two of the connectors removed after dangling the GEA24 down the forward side of the tray, no luck, all looked good and reassembled. No change!

This has been one of those grueling situations but you want to find it. After discussing further with Pete from CubCrafters I asked about flying with the IBBS off. He informed me the XCub's don't even have IBBS so yeah, that's fine, and in fact that would be a good test as there are several paths that could have a problem and by flying with the IBBS off you would get a red X on one of the three component areas if there was a wiring problem. So I did, and no failures observed, so still back to head scratching.

During my condition inspection a few weeks ago I wanted to give this another very very thorough look. I figured out how to get the GEA24 connectors off without removing the GEA24 from the tray and also pin pointed pin 41 on the appropriate connector which I think was p244 if I recall. It looked fine but I still cleaned out the connector and used compressed air to blow it out. Did same thing on the battery side.

This past weekend flew several hours to/from a fly-in and noticed my IBBS voltage while flying was 12.4. @Tsquared was flying so I asked him what his was showing and it was 13.7. Obviously I'm not getting a charge feed to the IBBS, something is wrong or the battery is defective. The other batteries (starter and ign backup) are showing 13.7 so they're getting a charge and I also just had it on the battery tender for a week.

Off to shoot another email to CubCrafters as to what could be the cause of the 12.4V on the IBBS battery and why is it not charging. Sadly Pete is out of the office and it seems like support is a one man show so I'd have to wait until the end of the month for Pete to return and catch up before getting help from the CubCrafters support side.

In the mean time I started googling IBBS battery not charging or something along that line and learned that the IBBS circuit breaker only breaks the charge circuit, if that is not good then the battery won't charge. Okay, interesting. It does not disconnect the IBBS as that is controlled by the IBBS toggle switch itself at the top of the panel, another lesson learned as to how this circuit really works. I got access to a wiring diagram and got educated on all of this and headed back to the plane.

I got under the panel with a light and started looking around and sure enough like a damn snake ready to attack I see a wire hanging by itself right above the IBBS circuit breaker area. Voila! And a few months ago I found a screw on the floor, which of course I saved. Yep, the screw that holds the ring connector to the breaker came out and this cable disconnected. I pulled the GDU off giving me easy access to secure the wire back to the breaker and long story longer IT WORKS! It is charging and the IBBS IN USE is finally gone.

One other lesson learned from my studies is that the IBBS battery only charges when MASTER is ON. So a battery tender won't charge the IBBS battery and the only way to verify it is charging is to connect your power source (tender, charger, etc.) and have IBBS and MASTER ON. Sure enough I'm showing up to 13.2 in about 30 minutes.

If only I could have known this six months ago! This has been a non stop hunt and epically painful at that. So easy to reconnect this wire.

So what was triggering IBBS IN USE to be intermittent and later staying on if the sensor wire was in fact properly intact? I think what triggers the IBBS IN USE is when the IBBS battery gets below a certain voltage. I'm actually surprised after all this time it was still able to maintain 12.4V's.

I thought maybe my 5 months of traveling in my motorhome and the IBBS battery not getting a charge may be an issue so I learned that TCW (maker of the IBBS battery) offers a ground charger for extended non use. Ironically I ordered one (and it shipped) about two hours prior to solving this very long dilemma. Not bad to have as I do travel months at a time. Will be nice to keep the battery in top shape.

So here is the wire that was disconnected. It was hanging just above the breaker but I pulled it away to get a picture. The question that comes to mind is should we, as owners, be checking these breaker screws to ensure they are torqued or tight? The vibration in these planes certainly warrants inspections as such, so hope not only self but others can learn from this painful but educational saga.