Charging off of Truck's 220 outlet

[JBee]

The Model 3/S/X use a dedicated 12 volt battery for powering of the onboard electronics, even though have 12v DC to charge that battery from the main battery.

For high and irregular current draws, they will need some means of supplying that power on-demand at the proper voltage.

Imagine that you have a load that uses 3 cells and suddenly changes to need 200 cells. The charger cannot anticipate the load.

So my guess is, pending some ingenious solution, another battery or supercapacitor.

Which works when you have the entire grid as a sink, but taking one half of the circuit would unbalance a charger being run in reverse, no?

An bi-directional inverter charger can do voltage, current and frequency matching on the fly. In fact any solar inverter needs to do this to "follow the grid" otherwise it would be disconnected by the protection circuits. I'd imagine they'd tap the main battery, and not use another battery that can't be used for driving, for any significant loads (over 500W) and not use the 12V circuit for that. In an effort to reduce complexity and cost, I'd imagine that both the battery charger and inverter, and potentially even the solar regulator are integrated into one unit for the CT. That way all power flows can be managed as required.

As for "balancing" I'm assuming that means load balancing across the inverter circuits? That shouldn't be required with a split phase setup.

Technically, if they wanted to, which they won't, they could even integrate a MIG/TIG/MMA/Plasma along with a high current DC charger into the same system. You could then weld and cut steel straight on the CT! I think I saw someone add a CNC router/cutter/3D printer to the truck bed somewhere. Make that a MIG 3D printer with CNC so it's a car that makes a car...reproductive technology!

(Welder/alternator/generator for ICE: http://www.unipower.com.au/download/Unipower185_Brochure.pdf)

 

[SeminoleFSU]

The Model 3/S/X use a dedicated 12 volt battery for powering of the onboard electronics, even though have 12v DC to charge that battery from the main battery.

For high and irregular current draws, they will need some means of supplying that power on-demand at the proper voltage.

Imagine that you have a load that uses 3 cells and suddenly changes to need 200 cells. The charger cannot anticipate the load.

So my guess is, pending some ingenious solution, another battery or supercapacitor.

I like the option Jack speculates on here:

 

[SeminoleFSU]

An bi-directional inverter charger can do voltage, current and frequency matching on the fly. In fact any solar inverter needs to do this to "follow the grid" otherwise it would be disconnected by the protection circuits. I'd imagine they'd tap the main battery, and not use another battery that can't be used for driving, for any significant loads (over 500W) and not use the 12V circuit for that. In an effort to reduce complexity and cost, I'd imagine that both the battery charger and inverter, and potentially even the solar regulator are integrated into one unit for the CT. That way all power flows can be managed as required.

As for "balancing" I'm assuming that means load balancing across the inverter circuits? That shouldn't be required with a split phase setup.

Technically, if they wanted to, which they won't, they could even integrate a MIG/TIG/MMA/Plasma along with a high current DC charger into the same system. You could then weld and cut steel straight on the CT! I think I saw someone add a CNC router/cutter/3D printer to the truck bed somewhere. Make that a MIG 3D printer with CNC so it's a car that makes a car...reproductive technology!

(Welder/alternator/generator for ICE: http://www.unipower.com.au/download/Unipower185_Brochure.pdf)

Jack thinks the Model 3 charger/inverter is the ticket

 

[user212_nr]

I like the option Jack speculates on here:

Links a 2 hour long video.

 

[JBee]

A timestamp would be helpful for the video.

 

[SeminoleFSU]

Links a 2 hour long video.

The whole thing is informative, but the M3 power control unit discussion starts 16m in. Jack is a slowish talker so bump the speed to 1.25

Cliff notes version:
The model 3 power control unit could in theory be used to power the 240v and 120v plugs in the bed. It has a capability of up to 10kw. Using the 240v plug in the bed with a 14-50 extension cord into your 14-50 house plug could allow you to backfeed the panel in your house. Interlock strongly encouraged. This would be a really cool temporary home battery backup

 

[israndy]

That's just what I posted in this thread previously. Just need software from Tesla to bless the whole contraption.

One of the guys in my EV group took the charger for the Model 3 apart and noticed that the circuit could easily be reversed in software. Instead of taking 220v and using it to produce DC to charge the battery it could take DC from the battery and create AC at the plugs, it would require some sort of [outlet] hardware to be plugged into the car's charge-port

I did send a link to Jack's Vlog to the guy in the group who couldn't believe he had to watch 2 hours of Jack droning on to get to the tiny nugget of Jack agreeing that it could work.

 

[mspohr]

That's just what I posted in this thread previously. Just need software from Tesla to bless the whole contraption.

I did send a link to Jack's Vlog to the guy in the group who couldn't believe he had to watch 2 hours of Jack droning on to get to the tiny nugget of Jack agreeing that it could work.

Jack had that insight a few years ago and implemented it on a Chinese inverter to provide bidirectional power flow.
Jack is brilliant but tends to ramble slowly. I usually watch him at 2x speed.

 

[JBee]

Nothing special about using a h-bridge inverter bidirectionally for battery charging and 240V output. Reprogramming someone elses hardware MCU can be however, as these are mostly unrecoverable machine code.

The real question is why Tesla hasn't done it before.

I've said this previously, but grid defection is real and it won't be long before electricity network providers close shop, and we'll be charging our EV's to run our houses, as well as to drive them. At some point it will be more cost effective to drive electricity between locations than run it over a powerline. It might sound crazy, but its already so in rural locations. RE like solar is a distributed system anyway, so why put solar where there is no load and run a cable? Solar can be at the same location as the load. Accordingly, our dependence on networks will diminish, meaning they won't be profitable. Most already aren't that have a high RE penetration. Having household power supply on a EV is a must.

 

[mspohr]

Nothing special about using a h-bridge inverter bidirectionally for battery charging and 240V output. Reprogramming someone elses hardware MCU can be however, as these are mostly unrecoverable machine code.

The real question is why Tesla hasn't done it before.

I've said this previously, but grid defection is real and it won't be long before electricity network providers close shop, and we'll be charging our EV's to run our houses, as well as to drive them. At some point it will be more cost effective to drive electricity between locations than run it over a powerline. It might sound crazy, but its already so in rural locations. RE like solar is a distributed system anyway, so why put solar where there is no load and run a cable? Solar can be at the same location as the load. Accordingly, our dependence on networks will diminish, meaning they won't be profitable. Most already aren't that have a high RE penetration. Having household power supply on a EV is a must.

Of course you still need to accommodate winter/summer variation.
Summer I generate 60 kWh/day and use 30. Winter it's the reverse.

 

[JBee]

Of course you still need to accommodate winter/summer variation.
Summer I generate 60 kWh/day and use 30. Winter it's the reverse.

What size solar do you have? 7-10kW? Thats a fair bit of consumption overall. We average 15kWh a day during the summer, with A/C, and under 20kWh during the winter with heating using A/C. But its a mild climate here.

If the consumption is from heating and cooling then most of that can be reduced by adding insulation. Whatever heat you don't gain or lose you also don't have to make. It is obviously critical to reduce overall consumption first and then produce what you need. Houses are predominately consumers of energy for heat generation or removal, most consuming 60-70% of their energy budget for doing that. A fridge does 10% of that by itself, and the main reason is they leak heat like a siff because of their poor insulation, and sideways opening door.

You are right that in winter solar production is lower, and typically that period requires more energy. It's common to have to add energy in the winter, and this is where EV energy distribution is required most, so they can bring in energy from another RE source that needs to be larger scale and centralised to be affordable.

The main issue preventing households from going off-grid with batteries is cost of storage, and alternate supply when solarsolidarity is low.
A CT offers a very large battery bank and comes with a free car attached to move it and you as well. So it makes financial sense to operate them like that.

 

[Ben W]

One of the guys in my EV group took the charger for the Model 3 apart and noticed that the circuit could easily be reversed in software. Instead of taking 220v and using it to produce DC to charge the battery it could take DC from the battery and create AC at the plugs, it would require some sort of hardware to be plugged into the car's charge port, someplace to allow things to be plugged into the car.

I’d buy a Powerwall in a heartbeat if my Tesla could trickle-charge it in an emergency (extended power outage). Also, I imagine a constant-current connection from Tesla to Powerwall (say 2kW or 5kW) would be a lot easier than full direct V2G.

 

[JBee]

I’d buy a Powerwall in a heartbeat if my Tesla could trickle-charge it in an emergency (extended power outage). Also, I imagine a constant-current connection from Tesla to Powerwall (say 2kW or 5kW) would be a lot easier than full direct V2G.

With a CT you can do that straight out if you plug in the Powerwall to the 240V output.

But I completely agree that Tesla needs to integrate the devices a bit better. Powerwall should have a EV charger interface, as well as a secondary 240V input source connection integrated, or as a additional charger/off-grid box. I don't think a DC charger will happen with Powerwall, but going over AC is fine at those power levels. The other item that is missing is a solar charger/regulator, which should really be in the powerwall as well, and charge the batteries via DC. Dunno what marketing issue got rid of the DC powerwall, but maybe it's time to bring it back and just keep everything in the DC domain. In an ideal world we'd have DC household appliances as well, seeing that many already are running DC and are converting AC to run.

But in general, we really need to try to get rid of AC in the households and significantly improve household efficiency first.

 

[Cosmacelf]

Tesla used to have a DC interfaced powerwall (but not for direct car charging), but got rid of it because it was harder to integrate.

 

[JBee]

@Cosmacelf
I know, but I still wasn't that happy about it. :-(

We need a more integrated solution that is end to end. It just seems to make sense if solar, batteries and even PM motors are DC. I'm expecting a proliferation of DC appliances using batteries instead of cabled 240V, similar to whats happened to hand power tools. At some point batteries will be good enough to "cut the cord" for good. I'm not sure where cabled AC has a place in that era.

 

[israndy]

When DC is at different potentials, the current flow can be enormous, converting the cables to filaments that melt the insulation and cause dead shorts. With AC you can convert the potential to whatever is needed to best move the electricity around. Also, DC has tremendous line losses to heat, the cord size ends up needing to be extremely thick, like the high power orange cables in your car. Extremely expensive cables.

The AC cables in your walls end up being not much thicker than lamp cord, yet carry great potential. When I wired my solar, because I had micro-inverters that converted the solar DC to AC on the roof, I was able to run 12 gauge wires down from the roof, instead of the thick DC cables that would have been required to run the length of my home.

Nikola Tesla was right!

 

[JBee]

I'm a big Nikola fan but HVDC transmission network is a thing and works out cheaper than AC:
High-voltage direct current - Wikipedia

Also DC to DC potential voltage conversion is equally as trivial as DC to AC with modern "transformerless" switchmode power supplies. Each conversion has losses too, which can be avoided with DC only, especially if solar is the energy source.

But my argument is to not have a transmission or distribution network at all, neither DC or AC, as they are becoming a waste of resources (poor time of use) and batteries will become better suited for using energy, especially so in household appliances and portable devices.

So instead of having wall sockets and wall wiring you'd have fast chargers and each device has replaceable batteries instead. (Think cordless power tool kit). If you do your numbers you'll see that the savings in wiring alone nearly pay for the devices you need. There is precedent for this if you look at the evolution of wired telephones and current mobile phone technology. Expect batteries to mobilise any energy consumer as their prices come down. Who still wants to plug in a cable nowadays? That's so last millennium!

For that matter, we are finally slowly edging closer to Nikolas dream of free wireless power for all...just in a long winded, roundabout way!

 

[JBee]

For those that didn't bother to read the link I posted:
"HVDC requires less conductor per unit distance than an AC line, as there is no need to support three phases and there is no skin effect."

(Many off shore renewables use HVDC)

 

[mspohr]

I'm a big Nikola fan but HVDC transmission network is a thing and works out cheaper than AC:
High-voltage direct current - Wikipedia

Also DC to DC potential voltage conversion is equally as trivial as DC to AC with modern "transformerless" switchmode power supplies. Each conversion has losses too, which can be avoided with DC only, especially if solar is the energy source.

But my argument is to not have a transmission or distribution network at all, neither DC or AC, as they are becoming a waste of resources (poor time of use) and batteries will become better suited for using energy, especially so in household appliances and portable devices.

So instead of having wall sockets and wall wiring you'd have fast chargers and each device has replaceable batteries instead. (Think cordless power tool kit). If you do your numbers you'll see that the savings in wiring alone nearly pay for the devices you need. There is precedent for this if you look at the evolution of wired telephones and current mobile phone technology. Expect batteries to mobilise any energy consumer as their prices come down. Who still wants to plug in a cable nowadays? That's so last millennium!

For that matter, we are finally slowly edging closer to Nikolas dream of free wireless power for all...just in a long winded, roundabout way!

I just don't think a DC only system will work. All of my battery powered devices need to be charged at a wall outlet so so savings in wiring. Lots of appliances require much more power than batteries can supply.
As far a gridless goes. Seasonal variation would require me to truck power out all summer and truck it in all winter. No home battery could carry my 3 MWh summer surplus to the winter.

 

[JBee]

@mspohr
How much power do use for HVAC heating and cooling? Because none of that should ever be stored in batteries. Water is much cheaper and better as a inter-seasonal store thermal mass.

As for wiring what devices do you have that actually need 240V or 110V to run?