4 ms·

Fitting a battery won't be an issue in larger RVs. Look at a c class, you can use the entire underside. So you have way more space than even the a semi tractor

Fitting a battery won't be an issue in larger RVs. Look at a c class, you can use the entire underside. So you have way more space than even the a semi tractor has. The skateboard design of evs should work great in RV. More space, lower center of gravity, more storage. You can probably take the base battery I'm the platform and strap an additional range extension battery in the back, that would likely be a lot more upgradeable, and just charge the driving battery with the extension battery for more range. Or you could choose between an extension battery or an ice generator / range extender, or have both.

dredmorbius 4y ago
Matching the battery size to the necessary capacity is a probable issue, especially where GVW and drag coefficient increase. In the case of tractor-trailers, effective range remains on the order of single-digit miles / km, though I suspect keeping total vehicle weight within limits is a major part of that as well. Yes, the undercarriage affords a large potential battery storage volume, but that's not the only consideration. Range-extending battery trailers is a concept I've been suggesting for a number of years --- that would apply to standard passenger vehicles as well, and would also make for shorter charge-stops as the entire trailer could be swapped out. Battery condition and the usual issues of distributed / common ownership would of course be factors.
- AtlasBarfed 4y ago
  I had precisely the same idea. The range extending trailer can be ICE generator, hydrogen-whatever color fuel cell, batteries. Precharged for fast swap. Common ownership is not that hard, they are for range extension, so you have a network of swap sites where you swap the trailer you rented. I don't understand what you mean by the single-digit miles/km. I know demonstrations in EV land are to be viewed with skepticism, but Tesla did demo a near-megawatt Tesla semi tractor that took a full gross weight load 500 miles. Granted that was a flatbed trailer with some concrete barriers so presumably better aerodynamics. An RV made from the Tesla semi as a platform doesn't need to haul anywhere near that amount of weight, doesn't have the problematic boundary between tractor and trailer (it will be one vehicle, not towing an RV). So one would expect a megawatt-sized tesla tractor as a platform, then about 12-20,000 more pounds for the RV portion... that is WAY underneath an 80,000 GVM even if the tractor is 20-30,000 lbs alone. So if a Tesla semi-derived RV has better aerodynamics that then overall tractor-trailer demonstration, that implies 600-700 miles range if the RV is half of 80,000lbs from the demonstration. What am I missing?
  - dredmorbius 4y ago
    Largely agreed on trailers. Re: electrified overland cargo. I'm not fully current on details, but my understandings are that: - High range usually occurs at low speed and over carefully-selected (e.g., flat) routes. There was a bus range-record set a while back which involved a stripped empty bus running at about 20 kph / 13 mph constant speed. Problem being of course that this is almost the precise opposite of a typical operation cycle especially for urban transit. Commute transit (with its dual morning/evening cycle) or intercity (presuming reasonable range) might be viable. Trolly busses which draw current from fixed infrastructure remain the presently viable electrification option, though perhaps with a small onboard battery capacity to move between conductor segments. - High-load electrified cargo seems to be based on moving loads consistently downhill while relying on electrified traction for the return, unloaded, uphill segment. I'm aware of a quarry which operates such vehicles, and proposals for lumber shipments. These are effectively gravity powered with regenerative braking and electric storage. Again, a special use case. - I vaguely recall a European trial using an EV cargo lorry for short-haul deliveries on the order of 4--6 km, which is where my "single-digit" range comment comes from. Not turning up a reference, though I believe that was by either Volvo or BMW. - Gross vehicle weight is a major constraint for trucking, cuts directly into revenue-generating cargo margins (literally, load that pays), and remains a critical concern for EVs. Again, private passenger vehicles which already have a poor payload/vehicle mass ratio are an easy problem to solve here, and despite that, passenger EVs run heavy compared to ICE vehicles. For either mass transit or cargo freight, where payload mass is far higher relative to vehicle mass, there's far less latitude. - Aerodynamics are the other concern. Drag increases with the square of speed, and options are for low-profile high-mass loads (e.g., flatbeds and plate-steel or concrete barriers), or low-mass high-profile loads (consumer electronics, light bulk materials, etc.). Each run into issues with cargo. And with all that, there's what EV-based overland non-tracked cargo competes with: rail, trolly-bus or trolly-truck designs, barge or shipping traffic (where available), etc. In particular, there's been remarkably little R&D in the conventional rail sector best I can tell (outside high-speed rail). It seems to me that there ought to be considerable opportunity for much greater efficiencies in flexible, dynamic, trainset assembly and re-routing, which would provide for the efficienies of rail transport (energy consumption reduced by a factor of 5x or more per tonne/km) without the consequent challenges of battery-based transport. (This is presuming freight rail is electrified, itself a point in which the US is notably lagging.) Rail is efficient in terms of energy but not flexibility. Melding that efficiency with the flexibility of last-mile delivery (or last 50-mile delivery) afforded by conventional trucks seems to me a real game-changer. It seems odd that nobody seems to be working on this. Large logistics operators (Amazon, WalMart, UPS, FedEx, possibly existing rail or trucking organisations) might be potential candidates, but again, there's nothing that I'm aware of.

dredmorbius 4y ago

Matching the battery size to the necessary capacity is a probable issue, especially where GVW and drag coefficient increase. In the case of tractor-trailers, effective range remains on the order of single-digit miles / km, though I suspect keeping total vehicle weight within limits is a major part of that as well. Yes, the undercarriage affords a large potential battery storage volume, but that's not the only consideration. Range-extending battery trailers is a concept I've been suggesting for a number of years --- that would apply to standard passenger vehicles as well, and would also make for shorter charge-stops as the entire trailer could be swapped out. Battery condition and the usual issues of distributed / common ownership would of course be factors.

AtlasBarfed 4y ago
I had precisely the same idea. The range extending trailer can be ICE generator, hydrogen-whatever color fuel cell, batteries. Precharged for fast swap. Common ownership is not that hard, they are for range extension, so you have a network of swap sites where you swap the trailer you rented. I don't understand what you mean by the single-digit miles/km. I know demonstrations in EV land are to be viewed with skepticism, but Tesla did demo a near-megawatt Tesla semi tractor that took a full gross weight load 500 miles. Granted that was a flatbed trailer with some concrete barriers so presumably better aerodynamics. An RV made from the Tesla semi as a platform doesn't need to haul anywhere near that amount of weight, doesn't have the problematic boundary between tractor and trailer (it will be one vehicle, not towing an RV). So one would expect a megawatt-sized tesla tractor as a platform, then about 12-20,000 more pounds for the RV portion... that is WAY underneath an 80,000 GVM even if the tractor is 20-30,000 lbs alone. So if a Tesla semi-derived RV has better aerodynamics that then overall tractor-trailer demonstration, that implies 600-700 miles range if the RV is half of 80,000lbs from the demonstration. What am I missing?
- dredmorbius 4y ago
  Largely agreed on trailers. Re: electrified overland cargo. I'm not fully current on details, but my understandings are that: - High range usually occurs at low speed and over carefully-selected (e.g., flat) routes. There was a bus range-record set a while back which involved a stripped empty bus running at about 20 kph / 13 mph constant speed. Problem being of course that this is almost the precise opposite of a typical operation cycle especially for urban transit. Commute transit (with its dual morning/evening cycle) or intercity (presuming reasonable range) might be viable. Trolly busses which draw current from fixed infrastructure remain the presently viable electrification option, though perhaps with a small onboard battery capacity to move between conductor segments. - High-load electrified cargo seems to be based on moving loads consistently downhill while relying on electrified traction for the return, unloaded, uphill segment. I'm aware of a quarry which operates such vehicles, and proposals for lumber shipments. These are effectively gravity powered with regenerative braking and electric storage. Again, a special use case. - I vaguely recall a European trial using an EV cargo lorry for short-haul deliveries on the order of 4--6 km, which is where my "single-digit" range comment comes from. Not turning up a reference, though I believe that was by either Volvo or BMW. - Gross vehicle weight is a major constraint for trucking, cuts directly into revenue-generating cargo margins (literally, load that pays), and remains a critical concern for EVs. Again, private passenger vehicles which already have a poor payload/vehicle mass ratio are an easy problem to solve here, and despite that, passenger EVs run heavy compared to ICE vehicles. For either mass transit or cargo freight, where payload mass is far higher relative to vehicle mass, there's far less latitude. - Aerodynamics are the other concern. Drag increases with the square of speed, and options are for low-profile high-mass loads (e.g., flatbeds and plate-steel or concrete barriers), or low-mass high-profile loads (consumer electronics, light bulk materials, etc.). Each run into issues with cargo. And with all that, there's what EV-based overland non-tracked cargo competes with: rail, trolly-bus or trolly-truck designs, barge or shipping traffic (where available), etc. In particular, there's been remarkably little R&D in the conventional rail sector best I can tell (outside high-speed rail). It seems to me that there ought to be considerable opportunity for much greater efficiencies in flexible, dynamic, trainset assembly and re-routing, which would provide for the efficienies of rail transport (energy consumption reduced by a factor of 5x or more per tonne/km) without the consequent challenges of battery-based transport. (This is presuming freight rail is electrified, itself a point in which the US is notably lagging.) Rail is efficient in terms of energy but not flexibility. Melding that efficiency with the flexibility of last-mile delivery (or last 50-mile delivery) afforded by conventional trucks seems to me a real game-changer. It seems odd that nobody seems to be working on this. Large logistics operators (Amazon, WalMart, UPS, FedEx, possibly existing rail or trucking organisations) might be potential candidates, but again, there's nothing that I'm aware of.