Charging the Roadster

[JRP3]

NEMA 14-50 seems to be the dominant cable choice for home brew 220V EV chargers in the US...

As a side note those plugs are really hard to unplug. Since it's a right angle plug there isn't a large barrel to grab onto and the contacts have a large surface area and grab tightly. I usually have to use a screwdriver to pry them apart, after shutting off the circuit breaker of course :biggrin:

 

[dpeilow]

I've just thought of a way of halving the charge time of the Roadster when you are away from home...

In the UK, at least, domestic circuits are 32 Amp rings - one for downstairs and one for up (or sometime front and back of the house).

A double socket (like the one Clarkson plugs into on the TG film) can output up to 26A. Therefore, a Y-shaped charging lead could draw 26A and get the charge time down to ~8 hours. As long as there are not different phases across the sockets in a given location (I think this is now banned, anyway) then this is possible.

Could this be done on other systems?

 

[graham]

I have often thought that the Roadster should have 2 plugs. One normal charging plug like they have today, but a separate plug that one could use in parallel, if you had a second circuit available. While I doubt it is feasible to have two 70 amp circuits to charge the car, I think it would be reasonable to have one high powered charge going into the main plug to recharge the batteries, and a second minor circuit just to run the cooling system. This would allow for a faster charge overall.

 

[vfx]

I always thought they should have two plugs -one on each side. As it is the driver's side is opposite any curbside charging station.

 

[malcolm]

I always thought they should have two plugs -one on each side. As it is the driver's side is opposite any curbside charging station.

That takes me back....

http://www.teslamotorsclub.com/tesla-roadster/259-two-evs.html

 

[vfx]

That takes me back....

http://www.teslamotorsclub.com/tesla-roadster/259-two-evs.html

My brain does not go back that far

Anyway, we have to rehash all subjects every year or so.

Turnover, yaknow.

 

[malcolm]

Anyway, we have to rehash all subjects every year or so.

I'm right with you on that one :biggrin:

Making both cables retractable would be an interesting challenge.

 

[ToddLa]

Using two 110v plugs to charge Tesla

I have often thought that the Roadster should have 2 plugs. One normal charging plug like they have today, but a separate plug that one could use in parallel, if you had a second circuit available. While I doubt it is feasible to have two 70 amp circuits to charge the car, I think it would be reasonable to have one high powered charge going into the main plug to recharge the batteries, and a second minor circuit just to run the cooling system. This would allow for a faster charge overall.

Has anyone heard of this company, 220 240 Volts from 110 120 Volt Outlets - Catalog & Pricing, they appear to make a product that would be useful for recharging on the road.

 

[TEG]

Yes, I think that Tesla has likely built their own devices like that to let you grab both phases from different outlets in different parts of the building. The problem is a typical 120v circuit still only has maybe a 15 or 20amp breaker/fuse so you still aren't all the way there.
If the 70amp@220v takes 3.5 hours to full charge,
and a "level 2" 32amp@240v takes 8+ hours, then the
"two into 1" <15amp@240v would take around 16 hours to fully charge a roadster.
It still beats the ~30+ hours you would need with a conventional 120VAC outlet, but is still a bit on the slow side compared to a real "dryer/range/welder/RV" outlet with a higher amperage breaker.

 

[dpeilow]

I guess similar topics have been covered before, but my thoughts were to cover situations where you are away from the home charger. I thought if you make a Y cable where the plugs are on the same phase, it just in parallel and doubling the available current.

I suppose it wouldn't be too hard to make a box that takes 2 or more inputs and rectifies various currents or phases into a single coherent supply (1 or 3 phase) for the car.


I've been told the car can take a three phase supply. As we know that the home charger just provides a few safety interlocks (smoke detector etc), could this function not be moved to the car? That way (as I've suggested above), any high power supply could be used (63 or 125A, etc).

 

[TEG]

I guess similar topics have been covered before, but my thoughts were to cover situations where you are away from the home charger. I thought if you make a Y cable where the plugs are on the same phase, it just in parallel and doubling the available current.

OK, so I think we are contemplating 2 different types of "Y cable" arrangements. The one in the link provided has an indicator light to show when you have plugged into both phases of a split phase US supply and gives you 240V (at probably 15 or 20 amp max due to circuit breaker).

What I think you are mentioning is just to halve the load across two breakers. In the US that would possibly provide 120VAC@~40amp which would result in similar recharge times. *But*, it isn't friendly to the street transformers to pull unbalanced high load current from one side of the split phase like that. Also, you have no way to have an indicator light to see if you are on two breakers or not. So you could plug into two different outlets and end up finding out (by blowing a breaker or fuse) that they are actually wired on the same circuit.

I am talking about a US situation. Things would be a bit different in the UK.

 

[Tdave]

Yes, I think that Tesla has likely built their own devices like that to let you grab both phases from different outlets in different parts of the building. The problem is a typical 120v circuit still only has maybe a 15 or 20amp breaker/fuse so you still aren't all the way there.
If the 70amp@220v takes 3.5 hours to full charge,
and a "level 2" 32amp@240v takes 8+ hours, then the
"two into 1" <15amp@240v would take around 16 hours to fully charge a roadster.
It still beats the ~30+ hours you would need with a conventional 120VAC outlet, but is still a bit on the slow side compared to a real "dryer/range/welder/RV" outlet with a higher amperage breaker.

Then how about a 4-into-1? Each goes to a different 120v breaker, 2 from one phase and 2 from the other. It's balanced and would provide 30amp@240v.

Four standard heavy duty extension cords could be used as the 4 inputs. The custom piece is the converter box with a short 4 foot monster cord to car. When visiting a friend's house this would be the only piece we'd have to transport with us.

 

[TEG]

Then how about a 4-into-1? Each goes to a different 120v breaker, 2 from one phase and 2 from the other. It's balanced and would provide 30amp@240v.

Four standard heavy duty extension cords could be used as the 4 inputs. The custom piece is the converter box with a short 4 foot monster cord to car. When visiting a friend's house this would be the only piece we'd have to transport with us.

Sounds like a plan! Tell them to turn everything else off because you are going to use all the power their house can provide!

But, how to quickly figure out which outlets are on different breakers?
Better have a wiring diagram handy.

 

[Tdave]

New condition of my friendship ... I'll visit you only if you install a 240v dryer outlet in your garage.

 

[TEG]

New condition of my friendship ... I'll visit you only if you install a 240v dryer outlet in your garage.

I have a NEMA 14-50 in my driveway. Come on over and leave your Tesla!

 

[vfx]

]Tell your friend that you would be happy to set the charger to kick on at 2 in the morning while you sleep in his guest room.

 

[bobw]

You'll need to take something like an Amprobe Circuit Breaker Finder when you visit your friends. You can leave them with an accurate diagram showing which sockets are on which breakers.

I think it might fit in a Roadster's trunk.

 

[WarpedOne]

Such a scheme would only give the roadster new name: "Tesla roadster brakes your house". It may be academically interesting to think about it but it is a WOMBAT.

 

[malcolm]

Meanwhile, down at the slower, cheaper end....

Newride: recharge points

Good news, but is my power renewable? | Danny's Contentment

Several London Boroughs and locations elsewhere in the UK are using these recharging points from Elektromotive:

http://www.elektromotive.com/html/elektrobay_instructions.php

If we assume that city driving is likely to be at about 30-40mph then one of these units could recharge the Roadster at the rate of about 17 miles of range per hour. A 9 til 5 recharge in an office parking bay would give enough time to gain an extra 24 kWh. That's not far off half a "tank" for the Roadster.

 

[vfx]

VP19 at a charge point in central London:

I get it now. The charge port is on the other side of the pond!