Is ev technology advanced enough yet to convert a 4 ton vehicle at reasonable cost – diy electric car forums gas pain

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I am an active member of a group of classic motorhome (RV) enthusiasts in the UK. These vans are Mercedes based 1985 to 1995, rear wheel drive. Classic Mercedes 5 cylinder diesels producing 95hp. The vans weigh between 3.5 and 4.5 tons fully loaded. I estimate that the engine and gearbox weighs about a ton – maybe a bit less, and without the engine and gearbox, there would be quite a decent size void up front.

In terms of range around 50 miles would be OK, obviously the more the merrier. Campsites over here generally have 6, 10 or 12 amp 240v supplies, plus there are the normal recharge points starting to appear for production EVs – Nissan leaf etc …

There would also be space for some sort of gasoline generator, and solar panels on the roof, but I doubt you could get more than about 500w of solar, assuming the sun shines. However there are plenty of retired folk who would just stay in one place until they had a charge to move on! The requirements for an RV would be quite a bit less than those for a commercial delivery vehicle with a defined duty cycle. With diesel costing $6 a gallon over here, present costs are around 40c a mile.

So far my basic thinking has led me to think that the engine and gearbox could be removed and replaced by a DC traction motor directly connected to the propshaft. I have read that these motors will also generate power through Regenerative Braking. But then there is the matter of the vehicle’s other systems – in particular the servo systems for the brakes and steering, which are driven by the fanbelt. Could these be retained and driven by a modified system using power take off, or even by a motor with a through drive shaft to the front as well as to the rear propshaft?

I have a reasonable grasp of the technology involved, but where I am completely clueless is the area of cost. I know prices are coming down as the technology become more mainstream, but I still have no idea on the cost per kw, the motors, and the ancillary systems required to do such a conversion.

Medium-duty trucks are actually a decent target for electrification, because there is usually space to mount batteries (but perhaps not in an RV, which uses under-floor space for tanks and other services), because fuel consumption is high (so there is motivation to convert) and because performance expectations are usually moderate. That means that many thousands of electric trucks and buses of this size have been built (normally based on vehicles that are usually sold with a diesel engine) and so motors and other hardware are available.

In a recent thread – RV Project – suitable hardware was discussed. This was about a series hybrid, but as far as the motor and controller are concerned that’s the same as straight battery-electric. Note that in that discussion existing production motors for medium-duty trucks were dismissed as unavailable… but they certainly exist and if you can find one (used), you have a suitable motor.

The main challenge, as discussed in other recent RV EV threads, is that electric vehicles are best suited to service in which they return to a charging station at the end of each day… and for many RV users, that is the exact opposite of how they travel.

But then there is the matter of the vehicle’s other systems – in particular the servo systems for the brakes and steering, which are driven by the fanbelt. Could these be retained and driven by a modified system using power take off, or even by a motor with a through drive shaft to the front as well as to the rear propshaft?

I don’t know why so many people want to drive these accessories from the traction motor, and thus have no accessory power when stopped (that should be fun for the steering boost when parking) and force the accessory systems to vary speed in proportion to road speed. No production EV does this – they use separate electric motors to drive each accessory when required and at a suitable speed. Even the forklifts that people get their motors from for EV conversion projects use one motor (or two) to drive the wheels and a separate motor to drive the hydraulic pump… and maybe another one for steering.

The currently practical method to electrically power steering in a custom installation is an inline unit which installs in the steering column, although it is also reasonable to use an electrically-driven pump with the existing hydraulic power steering (using a pump from one of the many non-electric production cars which were built with electro-hydraulic power steering).