Actually, it depends on how they are installed, if they are securely attached to the
ECV in protective housing that prevents short circuits, then it would be allowed, but extra check in time and advance notice to the airline must be provided. If the batteries are removable they would not be allowed.
I just checked TSAs website on it, the rules are complex, so you would want to double check to make sure the vehicle fully complies with both FAA regulations and any riles imposed by the airline.
TSA is not the place to check. The FAA actually governs this particular issue. The Hubs works for a major airline, and deals with the FAA daily, and can quote all this stuff literally chapter & verse - and he does every.single.time.I.fly.anywhere LOL.
You are absolutely correct about how complex these rules are, and to confuse matters even more, when there is a "housing" for the batteries, each airline gets to have it's say as to how they will handle it - what (for example) American Airlines has no problem with, Delta may refuse to carry, United may refuse but Southwest will allow. Some airlines will allow *some* devices in the hold with lithium-ion batteries, but not others, and often the call is made by a gate agent, the pilot, or a flight attendant, so it can vary widely from airline to airline, flight to flight, airport to airport. Some airlines require that
all lithium ion batteries fly in the cabin, regardless of any housing that may be present to protect the battery. As a courtesy, when I fly, I always bring both of my batteries into the cabin, in a single bag, and before I take my seat I notify the Sr FA exactly where I will be stowing that bag. (Sometimes, they will move it to a special compartment (depends on the aircraft & pilot request) but most of the time they prefer for it to be directly overhead in the bins.
Because it can vary so widely, just flying one carrier, let alone multiple airlines, that's why I recommend staying within the FAA's guidelines, especially when it comes to lithium-ion batteries, as they are *very* specific. And always contact your airline, let them know specifically the make and model of your device, and then arrive at the airport early - and be prepared to remove the batteries from your device if you bump up against a gate agent who is having a bad day. (And yes, the TSA will allow a small toolkit with screwdrivers and pliers; I keep my tools packed in a pocket in my battery bag)
Here's the FAA's verbiage, copied and pasted (emphasis is mine):
Wheelchairs and mobility devices with lithium ion batteries, normal design, battery installed
Electric wheelchair, mobility scooter
Lithium metal (non-rechargeable lithium) batteries are forbidden with these devices.
The battery may remain installed only if it is securely attached to the mobility device, the battery housing provides protection from damage, and the terminals are protected from short circuit. The battery cables may remain connected only if the device is protected from accidental activation. For complete passenger instructions contact your airline. Advance arrangements and extra check-in time may be necessary.
See: 49 CFR 175.10(a)(17)
Electric wheelchair, mobility scooter
This description is for a wheelchair or mobility device that does not have a protective housing for its lithium ion battery. Lithium ion battery size is limited to 300 watt hours (Wh) or 25 grams equivalent lithium content (ELC). One spare battery not exceeding 300 Wh or two spare batteries not exceeding 160 Wh (13.5 grams ELC) each may be carried in carry-on baggage.
Lithium metal (non-rechargeable lithium) batteries are forbidden with these devices.
Lithium ion batteries must be removed from this type of mobility device and battery terminals protected from short circuit. The lithium ion batteries must be carried in carry-on baggage only. The passenger must advise the airline of the battery location. The airline must notify the Pilot-in-command of the battery location in the cabin.
For complete passenger instructions contact your airline. Advance arrangements and extra check-in time may be necessary.
Though allowable, airlines may not be able to accommodate the folded-up wheelchair/device in the passenger cabin. The device, with batteries removed, may travel as checked baggage.
See 49 CFR 175.10(a)(17) for additional requirements and conditions.
And again - all of the above is strictly about lithium-ion batteries. Different battery chemistries have different rules & regs. So, someone using an SLA battery may never have to think twice about this stuff. And because of consumer devices with exploding lithium-ion batteries like hover boards, vape pens and cell phones, it's made traveling with a lithium-ion powered personal mobility device more difficult and confusing. I hate that, because Li-ion batteries are great for our devices; they last longer, recharge (relatively) quickly, and don't have the "memory effect" that you can see develop with older battery chemistries.
BUT - to get back to my original question regarding the Triple Lindy LOL - we still don't know what kind of battery chemistry the Triple Lindy has (although thanks to the OP, we do know that it carries 2 each 45
amp batteries, but we don't know the
watts, which is the measurement that the FAA and the airlines use). This is the sticker from one of my batteries; with the volts & the amps, it's possible to calculate the watts:
According to Walker's page, the batteries are "made in the US" which leads me to believe that they are SLA or similar. There are two battery cases under the seat that hold what will probably be something about the size of a standard car battery in each compartment. Typically, Li-ion batteries large enough to power a device the size of the Triple Lindy are made overseas.
I think I may have just answered my own question...!