IBBS - confessional

[Andy]

I was at the hangar and loaded a new G3X database but didn't fly. That broke the normal routine and I managed to leave the hangar without turning off IBBS. It was a week before I found out and the IBBS battery did not seem to take any charge on a 1 hour flight. IBBS voltage did not rise above 7 V.

I spoke with TCW and had my fears confirmed. The battery is too deeply discharged for the charge controller to enable charging. Only fix is to replace the internal battery pack.

The good news, if there is any to be found, is that TCW now allows experimental IBBS owners to change the battery pack themselves. The manual I have on file says IBBS must be returned for battery change.

[ceslaw]

I was at the hangar and loaded a new G3X database but didn't fly. That broke the normal routine and I managed to leave the hangar without turning off IBBS. It was a week before I found out and the IBBS battery did not seem to take any charge on a 1 hour flight. IBBS voltage did not rise above 7 V.

I spoke with TCW and had my fears confirmed. The battery is too deeply discharged for the charge controller to enable charging. Only fix is to replace the internal battery pack.

The good news, if there is any to be found, is that TCW now allows experimental IBBS owners to change the battery pack themselves. The manual I have on file says IBBS must be returned for battery change.

Don't be too hard on your self. I did exactly the same thing. Replacing the battery was straightforward. Hasn't happened again. Yet.

[Andy]

Don't be too hard on your self. I did exactly the same thing. Replacing the battery was straightforward. Hasn't happened again. Yet.

The cost of replacing the battery pack is insignificant compared to the annual cost of insurance. However, I was surprised that the IBBS did not self isolate to prevent its own destruction. I asked Bob at TCW about this and he explained there was a design compromise between getting the maximum possible time out of the IBBS in a real emergency use and protecting the batttery pack against deep and unrecoverable discharge.

Thanks for sharing that you made the same mistake. Maybe our talking about it will save someone else.

[olympiashorts]

I know "someone else" that did something similar and ended up making a big sign on the hangar door with this and a couple other checklist items like: "Flight Plan Closed?", "CO Monitor Off?" etc... I'm told that this list keeps getting longer.

[Rick Bosshardt]

Andy,
Im in the same club, and had to do the same fix.
I havnt forgotten since!

[Andy]

I checked the data log for this accidental IBBS discharge event. Start IBBS volts was 12.5 and log ended after 1 hour 56 minutes with IBBS volts 8.2.

An intentional IBBS discharge test I had run May 2022 was manually terminated after 2 hours 33 minutes with start volts 12.6 and end volts 12.0.

It appears that the IBBS battery had deteriorated significantly in the last 2 years.