If Boeing were forced to replace the batteries in the Dreamliner, that rigorous testing would be a fresh problem.
The redesign is much smaller than the extensive testing that would go on, that would be time consuming. Wed be talking about months. Many months.
The new one on the right looks to be a simple open box (no top cover) - gotta wonder why it isn't in a flame-proof steel box that would help prevent fire. Perhaps better that than an explosion.
Interesting. I wonder if aircraft testing included a scenario that simulated a ‘fully-loaded’ stress test over a long period of time..in other words, having every appliance turned on in the kitchens, cockpit, not to mention all the music ports, movies and computer users, etc.
A power source, like a battery (meaning multiple cells), without the means to shut down the individual cells via a fuse or switch is simply asking for trouble.
Some batteries are safer than others like the good old, heavy, lead acid batteries in our cars but these newer batteries are KNOWN to overheat and to build a battery in a mission critical application like an aircraft is beyond stupid. From laptops to electric cars and now airplanes it should be obvious to anyone who knows which direction electrons actually flow, you need protective devices at the cell level.
Most people don’t understand this mess. Anything — ANYTHING — that is installed in an aircraft as equipment, has to be tested and paper-worked to death. It’s weight and effect on the CG envelope has to be discovered and then allowed per FAA regs. All — ALL — ops and maintenance manuals must be approved by the FAA and then supplied to all users. The supplier has to be officially blessed by the FAA and no — NO — non-approved device or part can be used or even mentioned. The part supplier has to undergo the equivalent of a military TS background check. The legal liability assumed by a supplier and builder is open-ended. You cannot add a four-pound GPS to your Cessna’s panel without a complete rework of the airplane’s paperwork. Then, after all that, there is public perception. Boeing is in deep trouble. So is the current battery supplier. Law suits will be ongoing for the next 15 years. The Lockheed L-188 Electra suffered four crashes before it was discovered that engine mounts were failing. It never recovered, although the Navy bought it as the P-3 with wing re-working.
Computer design is a tool. It is no replacement for human experience. The 787 relies on too much on technology, and not enough on basic aircraft design. Trying to squeeze every ounce of weight and inch of space has come back to haunt them.
“....which is indicative of a design problem”
They were designed to last for the life of the aircraft, so technically, there is no design problem.
It sounds like Boeing is covering their butts.
I've been using these batteries for almost 10 years and when the batteries are manufactured, the nominal voltage is 3.7 volts per cell. The maximum per cell voltage in a fully charged state for a properly charged battery is 4.2 volts.
The only time they go into a thermal runaway state is when they are charged to a state above 4.2V per cell or if they are discharged at a rate higher than their designed to deliver.
In both cases (over-charge and over-discharge) they will develop internal shorts which trigger the thermal runaway.
I've never heard of a Li-Ion battery going into a thermal runaway all by itself.
One of the unique features of Li-Ion batteries is the ability to wire them in series and parallel at the same time. This allows the batteries to be formed into packs that deliver a higher voltage and capacity. When wired in parallel, each cell must be balanced before or during the charging process to ensure that each cell's voltage never rises above 4.2 volts.
If one cell resting voltage is higher than those of the rest of the pack, and each cell's voltage is not monitored during charge or if all the cells in a pack are not balanced with each other before charging, then it's possible to over-charge a single cell above it's maximum rated voltage, which will trigger a thermal runaway.
Once a cell goes into thermal runaway it can trigger other cells.
Why not just get a windmill from a wind farm bolted to the undercarriage. Voila! No toxic lithium and no overheating battery.
The batteries really don’t power anything unless ground power or on board generator power is not available. They are back-up/auxiliary power only.
“In the case of the 787, two 32-volt lithium-ion primary batteries provide power as key elements of the aircraft’s more-electric architecture. The main battery, located forward in the electric/electronic (E/E) equipment bay below the cabin floor by the front passenger doors, provides power for aircraft start-up, ground operations such as refueling and towing, and acts as backup power for the electrically actuated brake system. It can also assist the second battery, located in the aft E/E bay, in starting up the auxiliary power unit (APU) and, in the event of a power failure, energizes essential flight instruments in the flight deck until the drop-down ram air turbine spools up.
The battery that caught fire on the Japan Airlines 787 in Boston was the second main battery. This unit’s primary purpose is to electrically start the APU when neither of the engines is running and the aircraft is not connected to external ground power. In this case, the battery energizes the righthand of the two starter/generators connected to the APU. The aft battery also provides another minor role, namely to power navigation lights during battery-only towing operations.”
Now all they have to do is figure out why the windshield cracked ad the fuel leaked.
didn’t they learn from klinton and flight 800?
I heard the other day that lithium batteries are not allowed as cargo on aircraft after a crash that was thought to have been caused by a number of such batteries having caught fire.