Funny you should use that example. I was talking to a cave diver just in the last couple of days who has been using a Suex and wants more capacity because he was able to do one dive and came out with 39% battery. He wanted to do a second similar dive in the same day, but could not without charging his scooter up in between dives.
Charging a scooter in between cave dives can be problematic - unless you have a generator and bring it with you...
I am not trained in Cave DPV use (yet). But, I suspect that a scooter with a range of 5 miles means you can really only penetrate 1.7 miles or so. 1/3 in, 1/3 out, 1/3 in reserve. I suspect there are plenty of cave DPVers who either want to penetrate further than that on one dive, or want to do more than one dive per day to more than, say, 1 mile. 5000 feet (i.e. 1 mile) in a cave is not THAT far. I am only a baby cave diver and I have swam (no DPV) 8000 feet (total) in one dive. Swimming that took 4 hours. But, with a scooter, a 1 mile penetration and back out is (I'm guessing) a dive that is well less than 2 hours. So, definitely something a person might want to do more than once per day.
Also, several experienced scooterers have remarked to me how nice (convenient) it is to have a scooter with enough capacity that they can use it for a whole weekend (or more) without having to charge it.
Some people like to dive and also camp at or near their dive site. They probably wouldn't have the ability to charge a scooter at all.
Ultiimately, yes, we do have scooters now that (arguably) don't really need more range. The Genesis 3.2 (17 mile range) and Seacraft Ghost (20 miles) are examples. But, those scooters are heavy. The G3.2 is 50#. My personal experience is that a 50# scooter can be a real pain in the butt in a lot of situations.
A scooter with the same range as a G3.2 that was 15 - 20 # lighter (by virtue of having half the batteries with double the capacity) as well as 10+ inches (25+ cm) shorter would be a huge benefit. Being able to charge 5X faster would also be a big benefit - to SOME few folks.
Be glad you're coming into this at a time when you think 50lbs is a heavy scooter, 10years ago it was a true luxury to have a scooter that was that light but the other issue with them getting lighter is that they are all twitchy. Too much power, not enough stability for cruising for 9000ft. A UV26 is far more comfortable than a Genesis for long hauls like that because it weighs twice as much. Torque reducing fins are relatively new in the space in the last 5 years, but even with those the lack of mass makes them twitchy when going for long cruises.
Things like the Anker Solix F2000, Ecoflow Delta Pro, etc. are all perfectly reasonable ways to recharge a dpv from a car, and people are far more likely to pay $2k for something like that which can recharge those dpv's about twice from a normal dive vs. paying an extra $2k for a bigger battery just so they don't have to charge. People ask for it, they want it, but they don't put their money where their mouth is when it comes time to actually purchase them.
Anyone actually going 9000ft into a cave has a backup dpv with them for safety. May only be one for the team, but you definitely have at least one spare, and I don't know anyone who would do a pair of 9k ft penetrations in a day. 9k total is fine, I do that fairly regularly if I want some trigger time in Ginnie or JB, but one the way out with the flow you aren't using a third in and a third out anyway.
Either way, the quantity of people actually doing those dives who would be interested in a dpv like that are extremely few and there is not enough of a ROI for the manufacturers to bother investing in that technology to sell a dozen of those units a year, just not enough money to bother with. If the cells come out and you can drop them into something like a Warpcore then great, but I think it will be another 5 years before anything truly major happens in the DPV world, too much volatility right now.
Also regarding charge rates, remember this. Standard wall outlet, 15a@120v=1800w, 90% efficiency on the charger=1600w coming out of it, probably 95% efficiency of actually charging the batteries means 1500w going in, but still needs absorption so a 2kwh battery still needs a full hour to charge just limited by the wall outlet. Practically though most try to limit input wattage from a standard wall outlet to about 1200w absolute max because it's rare that it is the only device on that circuit so you don't want to max it out, so that comes out roughly to 1000w going into the pack at a max but that's where the balance comes into play. You have a dpv, your buddy has a dpv, if you're doing a pair of big dives you probably used the backup dpv to keep it cycling, so now you have 3 dpv's trying to charge so do you put one of them on and charge for 2 hours then have to cycle them out or do you put them all on a 200w charger so you can charge all three of them and your canister lights all on the same circuit? That's most of why the chargers are so small.
Pumping that much power into a pack is also going to generate a lot of heat, EV batteries are actively cooled, DPV's are not so the charge rates are going to be limited by how much of that heat can escape. Just talking about the practicality of charging these things wicked quick, 1-2hr charge rate is certainly quite fast and attainable to deal with on a SIT
