My takeaway from this thread is that wheelchair batteries are appallingly small in physical size. The compartment must be, too. This seriously limits energy storage and the distance you can enjoy. I had hoped the compartment would be able to hold "a car battery", something like 15 inches wide, 12 deep, 12 high. To me moving that much weight around, and over typical bumps like door thresholds, should have an energy source with more "overhead" and torque. IMO the batteries are killing themselves early by being overstressed-- giving too much current for their sizes under peak use (accelerating up hills).
I know scooters have size constraints-- they have to fit through doors, obviously, and rotate within a small circle. But they should be able to find the room.
You're absolutely correct regarding battery size being the challenge, but there's more going on here that you don't know about. Issues that I didn't explain (but should have). I'll explain those issues now.
Class 3 mobility scooters and E-Wheelchairs are large, powerful, outdoor mobility scooters and E-wheelchairs. They have large size, heavy powerful batteries and motors, and large tires. The have lots of range. They're made for outdoor use, and are too large for practical use indoors, and way too large and heavy to load into a car trunk when traveling in a car.
Class 2 mobility scooters and E-Wheelchairs are small, nimble, indoor, mobility scooters and E-wheelchairs. They have small size, light small batteries and motors, and small tires. They have less range. They're made for indoor use, and lack the battery size and tire size needed for practical use outdoors. Range limited to 6-15 blocks using stock OEM batteries. The good thing about Class 2 scooters is they're small enough to work well indoors, and small and light enough to load into a car trunk for traveling.
Class 2 scooters easily disassemble into 4 or 5 parts (no tools required). This allows storage of parts in car trunk. The scooter parts easily reassemble (no tools required). It only takes my cousin about 3 min to disassemble my class 2 scooter and store it it my Buick Park Ave trunk (with room to spare for groceries in it's wide and deep trunk). It takes him about 4 minutes to take it out of trunk and reassemble it.
Two companies (that I know of) have made a few models of Class 2 that are medium size scooters with medium size batteries (U1) and medium size tires. Those medium size class 2 scooters are an attempt to make a do-it-all scooter that's good indoors and outdoors.
My medium size scooter is one of these. It's clumsy and a tight fit indoors, but is marginally usable indoors. IRL city driving range with stock OEM batteries (MK AGM) was 2 miles, but the batteries only lasted 1 year. Using Powersonic PDC this scooter has IRL city driving 8 miles range and lasts me 3-5 years.
So a Class 2 medium size scooters are a struggle indoors due to being larger than ideal indoors. Possible to load into a very large car trunk, but a struggle for anyone who's not a very fit man. For most people the range is only 2 miles with stock batteries, but I solved that issue by using PDC batteries and getting 8 miles range, though I rarely drive farther than 2-3 miles.
But we're getting sidetracked from normal size (small) class 2 scooters, which are the small enough to be good indoors and reasonably easy to load into a car trunk. Those scooters are what you need indoors, but their tire size, battery size, and range outdoors is lousy with stock tires and stock batteries.
I own Golden Buzzaround XLS-HD mobility scooter, and a Golden Buzzaround EX mobility scooter. One is a small Class 2. The other is a medium size Class 2.
By upgrading my class 2 small scooter (Golden Buzzaround XLS-HD) tires from 7 inch foam filled tires to 8" foam filled tire in front, and 10" peneumatic tires in rear, it then had a softer ride and could drive over obstacles much more easily. However, the range was only 1 miles with the original OEM batteries (size half U1). The OEM batteries were MK AGM 20AH batteries. I tested half a dozen brands and models of batteries until I tried Powersonic PDC 21AH. With PDC batteries the range is now 4-5 miles. That's quite good for small batteries.
My small scooter is still ideal indoors, and now it's also pretty good outdoors. That's very useful because I usually drive outdoors to go to doctor appt. The exam rooms are small. So a small scooter is ideal. I often drive scooter to go shopping or into a restaurant. A small scooter is ideal.
When my cousin takes me places in my car, he greatly appreciates taking my small scooter instead of my medium size scooter. It's easier for him to lift the small scooters parts into and out of car trunk. It's also easier to fit them into trunk. He puts scooter seat on back seat of car. The rest in trunk.
So that was a very long explanation of why small mobility scooters with small batteries exist and why they're more desirable for indoor use and for putting in a car.
I can't just drive a huge class 3 scooter into a doctor office exam room or into a restaurant, grocery store, or doctor office. That would be like riding a bull into a china shop. I need a small, nimble class 2 scooter for those indoor places and I need it to have the range to get me from home to doctor office (across town) or grocery store (halfway across town) or restaurants, and then get me home again.
When it's warm or hot and not raining drive myself on my scooter to appointments, shopping, restaurants on my class 2 small scooter with "half U1" size batteries. When it's cold or raining, my cousin loads my class 2 small scooter into car trunk and me into front passenger seat and takes me to my appointment. So my small scooter is our preferred scooter, even though it has less range than my medium size scooter.
Thanks to PDC (half U1) 21AH batteries having increased my small scooter's range from 1 mile to 4-5 miles, my small scooter now has plenty of range for my needs because I rarely travel farther than 3 miles.
Just FYI- PDC U1 35AH batteries increased my medium size scooter's range from 2 miles to 8 miles. However, I typically only need to travel up to 3 miles (or less). So I take my small scooter these days because it fits inside stores, restaurants, and medical offices so well. So I rarely use my medium size scooter these days.
P.S. - "Half U1" is slang for a size of small battery that's physically about half as wide as a U1 battery. I put it in quotes because it's slang and not an official name. "Half U1" batteries are 12V and depending on brand and model are typically rated with 20hr capacity of 18AH or 20AH. The PDC I use is 21AH.
CSB EVH is rated 24AH, but due to having a slightly higher internal resistance (slightly less efficient internal energy transfer) it performs-delivers slightly less AH capacity at 8hrs and less than 8 hrs. For small mobility scooters and E-wheelchairs it's the 1hr AH capacity that matters because realistically, a small scooter has small batteries. If they're good small batteries they can drive you at full throttle for about 1 hr. Then they need to rest and cool for 1-2 hours, then recharge.
can be okay, look into LTO cells, even used cells (SCiB series, Plannano e.g. for extreme C rates). Otherworldly in several regards.