120 vac Level 1 Charger

If you are handy, you can build your own portable charger, it will be capable of L1 or L2, up to 7.2KW (30A J-1772 cabling), cost is under $500 to build one. This would charge your PiP from 240 in 1.5 hours, or from 120 in 3 hours, it will also be capable of working with your next real EV, such as a Leaf, Tesla, a Focus EV, etc. see the projects site:

http://code.google.com/p/open-evse/

 

Page 79 of the Owner's Manual states:

 

Even if you did, just for the EVSE you'd need something like 10 gauge extension cord, which I believe is rated for 15 amps. Adding an electric heater to the mix would likely overload the extension cord and be a fire hazard.

It seems Chevy recommends against using an extension cord but gives guidelines if it must be done. Toyota's wording is much more straight forward against its use, it seems.

 

Charging a car is different, its a "continous load", for anything over 75', you should upsize the wire gauge, meaning for 75' or 100', you should go with a 10awg cord. There is also voltage drop on such long cords, that's the main reason to upsize the wire gauge.

The reason Toyota recomends AGAINST using extension cords is, anything before the EVSE may not be GFCI protected, and using a 75' or 100' cord outdoors in the elements without a GFCI protecting most of it is a bad idea.

 

i am going to do the same thing, but i'm in a garage and there's no chance of having the cord stolen at work because i'm parked right outside my office. i don't see a problem with it, the statement in the manual is just cya.

 

if 14 gauge is sufficient for in home, in wall 15 amp circuit, why would an extension cord be any different. what you really need is a table to calculate your loss over the total run from circuit breaker to evse. then you'll know what size in wall cable and what size extension cord. if you run 12 ga. in wall and 12 ga. extension, you'll be fine. if you have 14 ga. in wall, not sure about extension without table, but even 14 ga. may be fine. and if the extension is plugged into gfci, you're covered.

 

electrician2.com Wire Size calculator

13A continuous load calculates out to 12AWG wiring, check yourself.

Extensions cords are different because they are not solid copper conductors (stranded), they also use different insulation than in wall wiring, there are many different factors other than the conductor sizing.

Do whatever you want, if you burn up the built in 3.3KW charger, Toyota is not likely to cover it under warranty.

 

isn't toyota's requirement simply a dedicated 15amp circuit with gfci? do they spec 12 ga wire?

 

The thickness of the wire is important due to internal losses within the wire. If the wire is to thin, than a big load will heat up the wire and also cause a drop in voltage.

There is a formula to calculate this, but this is for European units:

U(%)=(100 x cable length x power)/(56 x cable thickness x U x U)

56=copper
38=aluminium

It goes like this. U(%) is a Voltage drop in percent. If your voltage at the beginning of the wire is 200V, then at 10% Voltage drop, the Voltage at the end of the wire will be 180V.

Cable length is in meters.
Power is in Watts.
Cable thickness unit is in mm2 (as in milimeters squared).

For example. I have a 100 meters long wire, 230V (EU) Voltage at the beginning of the wire, a 1.5mm2 thick copper cable and a 2kW power demand.

The formula goes like this:

U(%)=(100 x 100m x 2000W)/(56 x 1.5 x 230V x 230V)
U(%)= 4.5%

That means that the voltage drop will be 4.5%, which equates to final Voltage at the end of the wire at 220V. The other 10 Volts is a loss. This loss is generated as heat, so 10V * (2000W/230V = 8.7A) = 78Watts of loss.

These 78Watts will heat up the wire. If the Power demand is higher, the voltage drop is even higher and a power loss is even bigger.

If you want to use the above formula to calculate your needs, you can use any online conversion tool to make a conversion from feets to meters and from your Gauge wire to mm2 thickness.

I live an apartment block and I have a 60 meters wire down to my -2nd floor of underground garage from my apartment. The cable is 5mm2 thick. I have a 25A Circuit breaker at the beginning and at the end of the wire. I also have ground fault protection at the end of the wire.

 

Do you have a pointer to someone selling the legrand charger? A
quick search didn't show me any online.

 

thank you andy, that all makes sense and sounds like the best way to do it. what i don't understand is, toyota specifies (if i'm not mistaken) a 15 amp dedicated circuit. in the u.s., most residences have 14 ga. wire supplied by 15 amp breaker. i'm sure if the distance was extremely far,using your formula, 12 ga. would be used. but as far as the 14 ga. is concerned, the breaker is supposed to trip if there is too much draw and the wire should not heat up if it doesn't.

 

I don't know exactly, how think (in mm2) are 12 ga. and 14 ga., but 1.5mm2 thick and very long cable can have a considerable voltage drop at high loads and that's not good for the device at the end of the wire. In case of a charger, it can result in a higher current being drawn to meet the constant power demand and that could lead to charger overheating (due to higher currents) or even circuit breaker tripping.
It can also lead to considerable warming of the wire. I've witnessed first hand, when my Vectrix and a Tazzari Zero were both charging on a single 1.5mm2 wire, 230V, 16A breaker, getting the wire very warm. My Vectrix draws 7.5A, Zero also around that number, so we were on the edge of tripping the breaker. The wire was very warm to touch. The minute, when my Vectrix reached 90% SOC and dropped power draw to 500W, the wire became cold again. And that was on a cold autumn evening.
Danger of heating is also very different if the wire is laid in the ground or above the ground. 1.5mm2 is ok for 16A when laid in the ground, but only for 10A when above the ground.