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.

[ceslaw]

Good information.

Wonder if replacing the IBBS battery at regular intervals should be considered?

[Andy]

Good information.

Wonder if replacing the IBBS battery at regular intervals should be considered?

I think a periodic discharge test would be prudent and TCM recommends that.

"Battery life depends strongly on many factors including operating and storage temperature, number of discharge cycles and depth of discharge. The battery capacity should be checked at least annually for suitable back-up power operation of the connected equipment. When the battery capacity no longer meets the operating criteria of the aircraft it must be replaced."

I would only change the battery if the test showed significant loss of capacity not just based on calendar time. (That's what I do with the emergency ignition battery.)

[Andy]

"Instructions for Continued Airworthiness:
On at least an annual basis the endurance capability of the IBBS system shall be confirmed and compared against the back-up endurance required for the connected equipment. As an alternate to these tests, the IBBS unit may be returned to TCW Technologies for a loaded endurance test, contact TCW Technologies, LLC. for details.
Procedure for endurance testing All applications except electronic ignition systems
1) Turn off the Aircraft Master Switch
2) Turn on the Back-up Power Master Switch
3) Turn on all equipment connected to and supplied with back-up power from the IBBS product.
4) Measure and record at least the following information: The time until the first piece of connected equipment no longer functions or the time until the output of back-up power supply voltage drops to 9.5 volts. AVOID allowing the back-up battery voltage to fall below 9 volts.
5) After completing the endurance test, recharge the IBBS product by operating the system with the Aircraft Master Switch in the ON position for up to two hours. This may be accomplished by operating the aircraft in conditions known to not require back-up poweror by powering the aircraft system on a suitable ground power source as described in the section: Ground Base Recharging.
6) Record the results of the endurance testing in the aircraft logbook.
7) If the IBBS no longer meets the endurance testing requirement, the back-up battery may need replacement

For CC aircraft IBBS ON MASTER OFF and monitor IBBS voltage to ensure it does not drop below 9.5 V. I think stopping the test at 12 V is probably enough to see the trend.