Humping a Smart?

Darkspeed · June 17, 2015, 12:32:28 PM

I was passed by a class C humping a 2000lb Smart 451 on the rear sideways.
The Smart was about two feet off the ground on an elevated platform.
The idea of not towing is interesting especially if it were a Electric Smart that was being charged by the solar panels on the bus in transit.

https://www.google.com/search?tbm=isch&sa=1&q=smart+car+rv&oq=smart+car+rv

Iceni John · June 17, 2015, 12:48:44 PM

Quote from: Darkspeed on June 17, 2015, 12:32:28 PM
The idea of not towing is interesting especially if it were a Electric Smart that was being charged by the solar panels on the bus in transit.

Unfortunately there's no way that the amount of PV panels you could fit on even a 45' bus's roof will do much to recharge an EV. I'm guessing you could fit no more than about 3kW of panels, and that's only if you had no roof A/Cs or vents. 3kW is the equivalent of only about 4 horsepower! I don't know what the charging requirements are for even a small EV, but I suspect its batteries will need a lot more than that.

Folk look at my bus with eight big grid-tie panels on the roof, then they ask me if my bus is powered by solar? It would take more than 800 such panels to produce what my Detroit makes, then if you factor in the system inefficiencies you would need maybe 1,000 panels!

It would make more sense to charge an onboard EV from the engine's alternator while driving, just like some folk run A/Cs or water heaters from their alternators. Or if you towed a hybrid four-down, wouldn't it recharge itself just as if it were using its regenerative braking?

John

Lostranger · June 17, 2015, 01:08:15 PM

Isn't a Smart longer than 102"?

Darkspeed · June 17, 2015, 01:28:24 PM

Quote from: Iceni John on June 17, 2015, 12:48:44 PM
Unfortunately there's no way that the amount of PV panels you could fit on even a 45' bus's roof will do much to recharge an EV.

Depends on how often you drove it..

The Smart 450 is 98.4 in and the new 451 is 106.1 but people seem to be carrying the 451 without getting busted.

Darkspeed · June 17, 2015, 01:30:16 PM

John do you have any good photos of your 2kw solar system? Would like to see how you arranged them.

Iceni John · June 17, 2015, 03:12:04 PM

Quote from: Darkspeed on June 17, 2015, 01:30:16 PM
John do you have any good photos of your 2kw solar system? Would like to see how you arranged them.

Sorry, no photos! However there's a video on YouTube of all us Crown hooligans during our annual get-together as we left to create a smog cloud over the high desert - take that, CARB: https://www.youtube.com/watch?v=d-1nMvB8aYw Mine's the third bus, the loud one! You can see how I did them - I built a central walkway between my two roof hatches, and from that are hinged individual support frames for each panel that can be stowed down against the roof for travel (as the video shows), or raised up to face the sun better. This way I can have half the panels down against the roof at 21 degrees (the ideal angle for Southern California fixed arrays!), and the other half raised up to horizontal, or up 21 degrees,, or up 33 degrees, or up 45 degrees (i.e. Summer, Spring/Fall or Winter angles). The entire walkway and support frames are made from 6061 and 6063 aluminum, and all fasteners are stainless. Each array of panels feeds its own charge controller through its own combiner box and breakers, and each CC charges one of the two separate banks of house batteries. These two banks can be combined to minimize Peukert effects, or run separately through Schottky diode isolators to prevent one bank back-feeding into the other. Both banks feed the inverter(s) and a DC load center for the house DC loads. My intention is to be entirely self-sufficient for house power from the solar panels, with the generator or shore power for emergencies only. There's also space for two solar water-heating panels at the back, so I hope to rarely if ever heat water with propane. With 2kW of PV panels I could actually heat water in the Suburban water heater by its electric heating element from the inverter!

It's been a lot of work to get to this point, but it will be worth it when it's all up and running. Now I've just got to paint the bus and build the interior, easy in comparison to what I've done so far!

John

scott332 · June 17, 2015, 04:56:06 PM

Wow, 2000 lbs hanging off of the back of an RV IMHO is a terrible idea. The stress on the rear frame when it hits a bump at 50 MPH would be tremendous. I've seen golf carts hanging off of the back of RV's and it looked like the lift was going to fall off with the RV just sitting still.

Tikvah · June 17, 2015, 05:01:32 PM

Darkspeed · June 17, 2015, 06:33:26 PM

Quote from: Iceni John on June 17, 2015, 03:12:04 PM
Sorry, no photos! However there's a video on YouTube of all us Crown hooligans during our annual get-together as we left to create a smog cloud over the high desert - take that, CARB: https://www.youtube.com/watch?v=d-1nMvB8aYw Mine's the third bus, the loud one! You can see how I did them - I built a central walkway between my two roof hatches, and from that are hinged individual support frames for each panel that can be stowed down against the roof for travel (as the video shows), or raised up to face the sun better. This way I can have half the panels down against the roof at 21 degrees (the ideal angle for Southern California fixed arrays!), and the other half raised up to horizontal, or up 21 degrees,, or up 33 degrees, or up 45 degrees (i.e. Summer, Spring/Fall or Winter angles). The entire walkway and support frames are made from 6061 and 6063 aluminum, and all fasteners are stainless. Each array of panels feeds its own charge controller through its own combiner box and breakers, and each CC charges one of the two separate banks of house batteries. These two banks can be combined to minimize Peukert effects, or run separately through Schottky diode isolators to prevent one bank back-feeding into the other. Both banks feed the inverter(s) and a DC load center for the house DC loads. My intention is to be entirely self-sufficient for house power from the solar panels, with the generator or shore power for emergencies only. There's also space for two solar water-heating panels at the back, so I hope to rarely if ever heat water with propane. With 2kW of PV panels I could actually heat water in the Suburban water heater by its electric heating element from the inverter!

It's been a lot of work to get to this point, but it will be worth it when it's all up and running. Now I've just got to paint the bus and build the interior, easy in comparison to what I've done so far!

John

Ahh very cool!

Darkspeed · June 17, 2015, 06:36:14 PM

Quote from: scott332 on June 17, 2015, 04:56:06 PM
Wow, 2000 lbs hanging off of the back of an RV IMHO is a terrible idea. The stress on the rear frame when it hits a bump at 50 MPH would be tremendous. I've seen golf carts hanging off of the back of RV's and it looked like the lift was going to fall off with the RV just sitting still.

As a good engineer once said" It's all just math and metal.."
An OEM frame I would say yes, you would need to do some custom frame work to make it safe.

bevans6 · June 18, 2015, 12:44:57 PM

Some people mount them on a slant so they are legal, put them cross-wise on ramps in front of the fifth wheel on big truck.

Brian

Darkspeed · June 18, 2015, 03:17:55 PM

The more I look at this the more interesting it is as I was planning on getting an electric Smart anyway.
I wonder what body part the Smart 451 would have to sacrifice to meet the length limit... glances at grinder...
I am in the process of lowering the floor in my 4106 8" inches which entails a custom steel subframe connecting the front and rear suspension boxes.
It would not be much more work to continue it beyond the rear suspension angle up over the engine and exit the rear body just below the rear window.
Connecting down to the rear bumper ( custom bumper and engine cradle ) would allow for a very safe rear deck connection point, even a rear deck that could fold up when not in use.
The idea of charging a EV Smart from the bus in transit is very attractive for me.
May have to see if i can rent a EV Smart for a few days to do a little testing.

RoyJ · June 18, 2015, 11:18:14 PM

Quote from: scott332 on June 17, 2015, 04:56:06 PM
Wow, 2000 lbs hanging off of the back of an RV IMHO is a terrible idea. The stress on the rear frame when it hits a bump at 50 MPH would be tremendous. I've seen golf carts hanging off of the back of RV's and it looked like the lift was going to fall off with the RV just sitting still.

I would never do that on monocoque chassis, light duty RV, or any rear engine vehicle in general. A monocoque chassis is not designed for concentrated load, RVs are overloaded to begin with, and most rear engine coaches are near axle capacity in the back.

However, if I had a heavy duty truck conversion, or a front engine school bus, then I wouldn't worry much, as long as the carrier is acting as a frame extension, and the over hang is not too long.

If you think about those school buses with super long rear overhang - get 10 big guys in the very back, and you have the equivalent of a smart car handing off the back. Same as a box truck with a 2000 lbs pallet loaded in the very back. Again, all about the attachment points to the frame.