Bill, then to add to all this, there's something hasn't even been mentioned (I believe):
Battery thermal management on swappable packs! In order to keep a high performance as most regular EVs nowadays do, they must include the ability to relatively quickly and efficiently warm up or cool down the pack. On a fixed pack this creates no additional complications other than a good, efficient and capable AC/heat pump for heating and cooling. Then with the least efficient PTC heater element only for heating. I remember a few years back, someone from Ample (https://ample.com) reached out to me about a possible opportunity to join their team. At the time, they had the idea of creating individual small battery packs or actually small modules that could fit almost any type of already existing EVs original battery pack location (kind of like filling that original space with smaller standard size Lego bricks). So with a special EV retrofit (which I immediately thought it wouldn't be a simple one) they would be able to fit their own standard size modules, perform the swap considerably quickly (automated) and operate the EV as smoothly and as originally possible. Without asking much how they were dealing with the high voltage wiring, my most intriguing question was how they were providing thermal management (mostly cooling) to all of the modules while at the EV. The engineer went silent for a moment and almost ended up telling me without really telling me that they haven't figured that out yet. I know there are already liquid quick disconnects for the automotive market, but these are not cheap parts and these are not designed for robotic fully automated processes nor high cycle rate. Same thing applies for the high voltage connectors. The amount of stress due to shock and vibration every single part of a car suffers during its lifetime is huge. You need to rely on complex, accurate and very robust robotic systems to swap these heavy packs and these must be able to operate under a wide range of temperature and humidity conditions. Then at the swapping station, for every additional spare battery pack awaiting a new customer, the robotic system must grow within space of reach increasing the complexity of the system. Also, when usability times are low (idle) of the swapping station; it would be really really bad to keep all these packs fully charged waiting for customers while the battery self-degrades by sitting for long times at high SoC. Marco Gaxiola On Fri, Mar 21, 2025 at 8:49 PM Bill Dube via EV <ev@lists.evdl.org> wrote: > Sketched on a napkin, battery swapping seems like it will work. The > logistics and the technical details are difficult to overcome. It is > never going to happen. Never. > > >>>> Battery management electronics <<< > > The BMS is often divided between portions that reside on each cell, > portions that reside on each module, and a portion that remains attached > to the car. The connections between these BMS modules must be addressed, > as well as the history they contain. > > During charge, you must connect to the BMS and hold whatever new > historical data the pack transfers, and update the car with that data > when you return the pack. You have to do this for multiple brands and > models. > > >>>> Pack ownership and pack maintenance <<<< > > Who owns the pack? Who is responsible for maintaining the pack > while it is being charged, and after it is returned to the vehicle? > > When something goes amiss during the removal, changing, or > installation, who is responsible and how exactly is it dealt with? Will > a loaner pack or car be provided? > > >>>>>>>>>>>>> > > As you can see, this gets very complicated both legally and > technically. It is _FAR_ simpler to connect a fat cable to the car for a > few minutes to transfer a batch of electrons than it is to remove and > replace a bunch of fasteners, disconnect and reconnect several > connectors, then negotiate with the car computer and the pack computer > about the health of all the cells. > > Simply negotiating with the electronics in all brands of cars and > trucks to simply enable a fast charge is complicated enough. I put my > head in my hands thinking about how impossible it would be to negotiate > the swapping of battery packs over all car models. The mind boggles.... > > Bill D. > > On 3/22/2025 12:57 PM, EV List Lackey via EV wrote: > > On 21 Mar 2025 at 17:07, Lee Hart via EV wrote: > > > >> Given human nature, I suspect that battery swapping only works for a > rented or > >> leased EV. > > I think it could work for an owned EV with a leased battery. > > > > The Better Place model was similar to battery leasing. You owned the car > > and Better Place owned the battery. Effectively, you paid them by the km > > you drove. > > > > IMO, something like Better Place could still work if EV batteries were > > sufficiently standardized, and if the scheme were sufficiently > capitalized > > this time round. > > > > That said, I could be wrong, but I don't think it will happen. Aside > from > > the standardization problem, DCFC has nearly caught up with battery > swapping > > in speed. It's also tough for me to imagine an automated battery swapping > > depot that would cost less than DCFC per vehicle served. > > > > David Roden, EVDL moderator & general lackey > > > > To reach me, don't reply to this message; I won't get it. Use my > > offlist address here : http://evdl.org/help/index.html#supt > > > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > > First Law of Bicycling: No matter which way you ride, > > it's uphill and against the wind. > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > > _______________________________________________ > > Address messages to ev@lists.evdl.org > > No other addresses in TO and CC fields > > HELP: http://www.evdl.org/help/ > > > > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > > -- Marco Gaxiola -------------- next part -------------- An HTML attachment was scrubbed... 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