Solution to Boeing 787 Aircraft Lithium Batteries
Over the years, I’ve discovered problems with aircraft circuit breakers and lithium batteries. The Follow Post Goes into the Possible Cause of Damage to the Lithium Batteries on the Boeing 787 Aircraft
As a result, I believe my procedure will isolate your problem.
First, I’ve used a lithium batteries in my test instrument, Bartol mag probe, 80,000 to date. Several years ago, I had a problem with lithium battery failures which reached a high of 50%. The batteries would overheat and fail. After intense testing, I isolated the problem. Sudden loading caused battery damage and the battery did not recover. Now, battery damage isn’t even a consideration. Just to satisfy my curiosity, I tested circuit breakers using a current generator to establish the point of disengagement, which should agree with the circuit breakers specifications. I was shocked when I discovered that all the circuit breakers disengaged at more than the indicated value. In addition, the response time was slow. Of course, what would happen if the response time was fast? This time is critical on aircraft. Too fast would cause disengagement of components used to control engine or flight controls. I’m sure, redundant systems are included on all aircraft but this problem could also exist in the backup system. Slow circuit breaker response time can result in wire damage, which could also cause adjacent wire damage in a wiring harness.
I’m a firm believer in lithium batteries. I’ve concluded exhaustive tests on the lithium batteries I use in the mag probe test instrument. For example, -80°F to +160°F, in a Bell jar at one times 10 to the minus fifth torr. A shock test of +70°F to -20°F in 5 min. No problems were encountered.
Here’s my procedure for locating your problem. Please see the attached diagram.
Circuit breakers typically don’t disengage when a sharp current spike occurs. However, if the bottom of the current spike is wide enough, the circuit breaker will disengage. If current spike one and two occur at the same time, the current drain on the battery will be seen as the sum of the two. However, circuit breaker one and two may not disengage. All this will be random, therefore it’s necessary to use a current graph and store into memory. Observing the graph should identify which load is causing the battery problem.
I’m in the process of designing a new circuit breaker that will overcome the spike problem without sacrificing safety.
Best Regards, Bob Bartol
Bartol Research (208) 866-7895
