I was thinking the same thing. It could be a homebrew job, like some college engineering program that’s studying the efficiency of electric cars, and wants to build their own test equipment.
I love it. The Rabbit Hole just goes deeper.
But as posted by others, there are no other “high efficiency” measures taken–no aero dams, no removal of mirrors, and the hack-job of this set-up is literally taped on with no regard for drag or aerodynamics.
So I’m left to the conclusion they totally have no clue what they are doing or we are super uninformed as to what they are doing.
Again, this is fun!
Who says they’re trying to make the car more efficient? Maybe someone wants to measure the car’s performance in its stock configuration, either to confirm the manufacturer’s claims or as a baseline before they make modifications.
That pulley setup would have some impact on what they’re measuring, but hopefully not much. What would be the least impactful way to independently measure the performance of an electric car?
Hey man no defense from me! Are we agreeing that someone has some* really sensitive metric equipment* that dutifully measures such* data which can be literally taped to the back of a car*? It’s so loosey-goosey that it’s just bananas, right? I mean TAPE.
…TAPE.
Or to run a small refrigeration unit rather than cooling the whole car. There could be several uses like this, essentially using the wheel like a power take off on a farm tractor. That might make the fact that he’s driving an electric car a red herring. The tube seems to be capped, otherwise I would be more inclined to the notion that it’s a vent tube, and he’s carrying something in the car that he wants actively vented. Of course, if he’s carrying some odd piece of equipment in the trunk that he needs the jury rigged PTO for, the Bolt is an odd choice. I know somebody who has one, and the passenger compartment is generous for a small car, but the cargo area is tiny.
Getting the speed & odometer info through the OBD-II port. It won’t be perfectly accurate because the readings depend on exact tire size, but that’s true for the pulley contraption as well.
given the apparent filler tube - is he turning an all-electric Bolt into a Volt, and has a gas-powered generator in the trunk to extend his range?
If this were to charge the Bolt while being towed, couldn’t you just turn the car on before towing and be done with it? As far as the car knows it would be coasting downhill and doing the regenerative braking on its own.
If that’s what it’s for then wouldn’t you remove the chain for normal driving?
it would depend if the car will regen when in Neutral. and leaving it in Neutral can be tricky depending on manufacturer; a lot of (all?) cars with shift-by-wire will automatically go into Park if you open the door.
Perhaps, and that may need a traditional battery and charging circuit.
This discussion indicates the Bolt should not be towed with all 4 wheels on the ground.
It would be much easier to run an electrical (motor driven) refrigeration unit powered by the car’s electrical system. Installing a high power inverter is very common among EV/PHEV enthusiasts, e.g. to use the EV as a backup power source for a house.
ETA: That link is for a wiring to an external inverter, but the principle is the same. It shouldn’t be too difficult to run the wires to the back of the car and mount an inverter there.
That Reddit thread is now locked and marked “solved”, but skimming through it, I don’t see a solution.
It’s not “clearly” an alternator just because it has a V belt pulley. You can stick a V pulley on anything that you wanted to drive off the wheel. It could just as easily be some kind of pump, or compressor. Maybe its a pump that sprays liquid from the tube sticking out the back.
Or it could be an electric motor. The fact that it is red behind the cover makes me think motor.
Maybe he’s spraying Holy Water on all the cars that he passes.
The most likely explanation is that it is an alternator hooked-up to charge the car as it is being towed behind an RV.
The compressor explanation doesn’t make sense as the pulley on the compressor would be much larger than what is pictured. At 60 mph, the wheels would be doing about 800 rpm. At 50, more like 650 rpm. From the posted photo, I would guess the pitch diameter of the drive pulley was 5 times that of the smaller pulley, so the whatever-it-is would be turning around 4000 rpm, well within the operating range of an automotive alternator, but much too fast for an standard automotive A/C compressor.
The motor explanation doesn’t make sense, either, since the Bolt already has a much more effective solution to turning the wheels with a motor.
Most of the reasons given for the whatever-it-is not being used to charge the car while being towed seems to based on it being easier/cheaper/more effective to just wire it into the electrical system of the RV, which is probably true. However, what if the owner owns the Bolt, but only rents an RV when he needs to. He wouldn’t want to modify the RV in any way or it would cost him. With this gizmo, he can use a different tow vehicle every day and would have no problems.
Unless someone can come up with an explanation that makes more sense that it being an alternator to charge the batteries while being towed, my guess would be that is exactly what it is for. Occam’s razor and all that.
But why would this be needed? That part doesn’t make sense. Towing a car should not require the towed car to receive power. Also a 12V alternator is not going to do much to recharge a EV.
So Occam would also shave that one off too with his razor.