Charging while moving?

[Oba]

Yes, of course, 10kW is plenty for extending range. A trip length of 600 miles could be accomplished at 50mph over 12 hours, allowing the battery to receive 12 hours * 10kW = 120kWh ADDITIONAL power during that time.

80kWh plus 120kWh = 200kWh

At 333 wattHours (heck, you could have the heater blasting at 50mph), you'll get the job done... easily. Make sure your consumption calculations include the drag from a trailer.

The challenges that I see are:

1) Need high quality charger(s) like those produced by Brusa. I recommend the liquid cooled ones over the air cooled ones. Relying on "homemade", poorly engineered chargers with questionable reliably seems like folly. Like the Tesla onboard chargers, liquid cooling for continuous duty in high summer temperatures is best.

2) Need a high quality junction box between the traction battery and inverter.

3) Need a safe method to connect and disconnect high voltage from trailer. Please don't suggest an Anderson connector!

4) Need a safe method to ensure no over voltage of the main traction battery

 

[green1]

Please don't suggest an Anderson connector!

Out of curiosity, could you expand on that a bit? They have connectors rated up to 450 Amps at 600 Volts, seems to me that would be plenty?
They also have sealed waterproof connectors rated as high as 310 Amps at 600 Volts

 

[Cyberax]

Out of curiosity, could you expand on that a bit? They have connectors rated up to 450 Amps at 600 Volts, seems to me that would be plenty?
They also have sealed waterproof connectors rated as high as 310 Amps at 600 Volts

Anderson connectors by themselves are fine if you connect only de-energized circuits. Using them for a live 400V wire is not a good idea (arcing looks cool but can ruin your whole day). So we'll add a contactor after the connector to make sure that the HVDC circuit is fully de-energized before the disconnect.

I looked at Brusa but so far the "homemade" charger looks better - it has a voltage-following mode with cutoffs at low (circuit disconnect) and high (battery overcharge) voltages. And for 12kW we can get away with air cooling, its efficiency is 95% so the dissipated power will be about 500W.

 

[green1]

Anderson connectors by themselves are fine if you connect only de-energized circuits. Using them for a live 400V wire is not a good idea (arcing looks cool but can ruin your whole day). So we'll add a contactor after the connector to make sure that the HVDC circuit is fully de-energized before the disconnect.

I looked at Brusa but so far the "homemade" charger looks better - it has a voltage-following mode with cutoffs at low (circuit disconnect) and high (battery overcharge) voltages. And for 12kW we can get away with air cooling, its efficiency is 95% so the dissipated power will be about 500W.

The Anderson connectors were rated for hot plugging up to 100A though I do agree that deenergizing is always a good idea.

 

[kennybobby]

...
I looked at Brusa but so far the "homemade" charger looks better - it has a voltage-following mode with cutoffs at low (circuit disconnect) and high (battery overcharge) voltages. And for 12kW we can get away with air cooling, its efficiency is 95% so the dissipated power will be about 500W.

Nearly 3,000 posts with lots of discussi'n and cussin' related to the 'homemade' charger by the diy electric car folks, who want to believe that this charger is the real thing, but in the words of Billy Joel it's just a fantasy.

10kW / 60A DIY charger open source design - DIY Electric Car Forums

 

[Cyberax]

Nearly 3,000 posts with lots of discussi'n and cussin' related to the 'homemade' charger by the diy electric car folks, who want to believe that this charger is the real thing, but in the words of Billy Joel it's just a fantasy.

I was referring to: Electric Motor Werks, Inc. - SmartCharge-12000 - a 12kW Universal Voltage EV Charger - Fully Assembled Tested which looks kinda "homemade".

 

[Ingineer]

According to this page: Electric Motor Werks, Inc. - Electric Motor Werks, Inc.
Only the IsoCharge-20000 is Galvanically isolated. The non-galvanically isolated chargers will cause problems on a Tesla, and are dangerous.

 

[Cyberax]

According to this page: Electric Motor Werks, Inc. - Electric Motor Werks, Inc.
Only the IsoCharge-20000 is Galvanically isolated. The non-galvanically isolated chargers will cause problems on a Tesla, and are dangerous.

Yes, I spoke with the company's representative. The newer models are all isolated, but this isn't reflected on the site yet.

 

[xinen]

so great!

 

[wk057]

The problem is going to be the BMS not agreeing with the inverter. The car isn't going to understand where the additional power is coming from and why the inverter demand is higher than the battery output. A load could be explained away, since the car probably doesn't care about additional load on the HV side of things if it is within reason (usage by the DC-DC, A/C compressor, heater, etc)... but there is nothing the can cause a charge on the DC side under normal conditions while moving besides the inverter during regen.

I could be wrong, but I'd be willing to bet that even if you got everything wired up perfectly that the car is going to freak out when you start pumping power in and power measured at the shunt inside the pack on the BMS is less than the power being used, or even negative.

Then again, maybe the car will just be happy about it. At best, it will work, but will screw up range and power consumption calculations. The car may even still shutdown at 0 miles or whatever since it's pulled what it thought was a full charge from the pack.

Who knows. You should be the guinea pig. But, my money is still on this failing pretty miserably without some kind of software hacks.

 

[RichardL]

So here is something seriously scary - a converted 1970 Beetle, to become a 'pusher trailer'!

From the person who encountered this masterpiece - 'The reason i say it's ... scary is because you have a VW motor and trans (in 4th gear) held at WOT (Wide Open Throttle) behind you with no dead-man switch. To stop the car, you have to now brake not only the car you are pushing, but also against a motor at WOT. It's a ready-made law suit on wheels'

 

[Cyberax]

Who knows. You should be the guinea pig. But, my money is still on this failing pretty miserably without some kind of software hacks.

I'm still waiting for a high-power charge controller. But we did make a test with our low-power controller on a dynamometer. It appears to work correctly, the car just ignores the extra input. Battery calculations are predictably screwed.

 

[AudubonB]

So here is something seriously scary - a converted 1970 Beetle, to become a 'pusher trailer'! From the person who encountered this masterpiece - 'The reason i say it's ... scary is because you have a VW motor and trans (in 4th gear) held at WOT (Wide Open Throttle) behind you with no dead-man switch. To stop the car, you have to now brake not only the car you are pushing, but also against a motor at WOT. It's a ready-made law suit on wheels'

There have been approximately zero times in my life I have felt compelled to report others' expected actions to some authority. The physics of what that picture shows ends that streak of mine. Mr. I Own A White ____?___ With California Plate ¿¿¿ 7XFY264 ????? needs a visit, quickly, from CHP or someone similar. Except the photo strongly suggests he's in Washington....

That contraption is a clear and present absolute danger to any vehicle nearby. I don't care two hoots for what happens to the operator.

 

[HankLloydRight]

I'm not sure I even get the point of that.

So to stop the contraption, he has to park the SUV while the VM motor is still at WOT and jump out to shut it off? Either the tires are spinning or the trans or clutch is burning up.

Does his SUV need help climbing some impossible mountain?

 

[EVenthusiast]

The point of that you can drive the RAV4 EV long distance if you really need to. There is tons of more info on this trailer, I believe Tony Williams used it as well (in fact, I thought that was his RAV4 EV).

I think I like Ingineer's LEAF trailer/implementation the most.

 

[AudubonB]

So you're saying it is not a pusher; rather it is only a generator, that charges the vehicle's batteries in the fashion that this thread's OP was desiring? If so that makes a large difference. If not,........

 

[HankLloydRight]

So you're saying it is not a pusher; rather it is only a generator, that charges the vehicle's batteries in the fashion that this thread's OP was desiring? If so that makes a large difference. If not,........

Yeah, huge difference there. Pusher or charger -- which is it?

Also, it's not obvious that the SUV is a RAV4-EV in the photo (at least to me).

 

[RichardL]

This is in Washington - here is how it works (it is simply pushing - no other connection to the car except the tow hitch):

What he says he does is stops on the shoulder of the on-ramp. He walks back and puts the contraption in 4th gear. Then pulls away under electric power which pop-starts the motor in 4th at WOT. By 35mph or so it begins to get in the power curve of the air-cooled motor and pushes his EV. When he stops, it just bogs and stalls the motor

Remember this is a 1970 Beetle motor - so hardly enough power to 'spin the wheels'

 

[wk057]

With some relatively minor safety features added that would probably be a clever contraption. As it stands now I think it's a bit crazy and unsafe, though. At a minimum he should have the throttle or electrical kill of the contraption tied in with the brakes of the RAV4. Would be pretty simple considering the brake light trailer hook up would be in the back already. At least something to prevent that thing from pushing itself out and around from the back of the vehicle in an emergency situation. For example, hit the brakes and it cuts the plugs off on the VW engine, release the brakes and it just pop starts it again. At least that way it wouldn't be pushing against the RAV4 in an unsafe manner in an emergency situation.

*shrugs*

 

[arnolddeleon]

Yeah, huge difference there. Pusher or charger -- which is it?

Also, it's not obvious that the SUV is a RAV4-EV in the photo (at least to me).

Oh it is definitely a RAV4-EV.

From what I know of Tony Williams he would never do anything like this particular push trailer.

This was also discussed in the in the RAV4-EV forums: Toyota Rav4 EV Forum View topic - Trailer range extender

arnold