Help with charging solution

[KNVB]

I have a MS on order and trying to come up with a charging solution. Having trouble getting an answer that I like from Tesla and my electrician.

Here are the relevant facts:

1. My detached garage is >24 feet away from the closest edge of my house (so a 24' TWC on the house won't work).
2. I have a 100 Amp electrical panel
3. I have a crawl space, so electricity can be run under the house.
4. Between the edge of the house and the garage there is a deck, artificial turf and pavers.

The electrician's idea was to run a new 240 line out to the garage. In addition, because I only have 100 Amps, he would put in a new sub-panel with an on/off switch to allow me to use either the TWC or my A/C, so as not to overload the circuit panel. He told me upgrading to 200 Amps would be quite costly because the wires are underground and then I would have to dig up the sidewalk/concrete, etc (an even if I did upgrade to 200 amps, I still have to get the power to the garage). The quote was $5,000 without the cost to replace the deck/turf/pavers, which I imagine will be another several thousand dollars. There is a reasonable chance that I move in the next year or two as well, so I don't want to drop a ton of money into something that I won't get a lot of use from.

My suggestion (being a novice) was to put a 240 outlet on the back of my house and then use an extension cord to run to the garage (like this one:
Amazon.com: Camco 55195 50 AMP 30' Extension Cord with PowerGrip Handle: Automotive

The electrician thought that the city permit people wouldn't agree to let this install happen. I am trying to reach out to the city, but that is not an easy process.

The Tesla charging person thought that this wasn't a great idea because a 50 Amp extension cord could potentially send more electricity to the car that I have left on the panel (the electrician calculated that I could use 15 amps to charge). He said that human error could create problems. My understanding is that I could manually set the car to charge at 15 amps overnight and then I wouldn't run into a problem.

Any advice would be greatly appreciated.

 

[LuPapa]

Do you have to put the car in the garage to charge ? Could you park it closer without being in the garage ?

 

[LuPapa]

Also have you called your electric utility and asked how much for them to install a 2nd meter in the garage? They install meters every day. Their price for a new meter may be a lot less than trying to bridge off your house.

 

[KNVB]

Can't park in the driveway, because it is a shared driveway. I could park in front of my house, but then I would have to have some sort of charger between the sidewalk and the street. Not sure how to do that.

Doesn't the meter just measure how much electricity I use? Not sure how this would help (sorry if I misunderstood, I am not too savvy with these things).

 

[182RG]

15 amps. Not much to work with.

Cheap solution, NEMA 6-15 outlet in a weather proof box on the back of the house. 30' NEMA 6-15 outdoor rated extension cord. Tesla NEMA 6-15 adapter. 240V, 15 amps. Not sure why you would have a permit problem for an outlet. They don't need to know the use case.

More optimal, 15 amp circuit to a sub-panel inside garage with a NEMA 6-15 outlet for the TWC, with a NEMA 6-15 plug wired on...or direct wire TWC. 240V, 15 amps.

If it were me, I'd upgrade the service to 200 amps, and put a 100 amp sub-panel in the garage. But, I get the cost of investment and the potential to move.

 

[KNVB]

Thanks 182RG!

The optimal solution is basically what the electrician wanted to do. But at $20-30,000 that is pretty steep.......

 

[LuPapa]

Doesn't the meter just measure how much electricity I use? Not sure how this would help (sorry if I misunderstood, I am not too savvy with these things).

The meter sits on your house between the street (utility) and your electrical panel. It is what is connected to the utility and is the end point of their connection to you. They own the connection from the street to the meter. They own the meter.

Call them and ask if they will install another meter and the connection from the street. Many customers have detached garages and a separate meter.

If they can run an overhead line instead of buried it is super cheap. Even if they have to dig it might be cheaper than upgrading to 200amp service and when you sell it could be a plus to have power in the garage for the buyer. So not a loss of investment.

 

[KNVB]

LuPapa - I have electricity in the garage already, just not a meter. The outlets in the garage are just the standard 5-15 socket though. Do you think that getting them to run the wire overhead would still work? Would that bring another 100 Amps to the garage?

 

[LuPapa]

LuPapa - I have electricity in the garage already, just not a meter. The outlets in the garage are just the standard 5-15 socket though. Do you think that getting them to run the wire overhead would still work? Would that bring another 100 Amps to the garage?

It's worth a call. They benefit from the fact that you will be buying more electricity and adding an additional meter with an overhead wire is painless for the utility.

Are you a PG&E customer ? They show their estimates and lot of explanation online. Of course each site is different.


Building and Renovation Services - Project Cost Range | PG&E

 

[dmsail]

Here's a sort of kludgy option. If you have 120 V outlets in your garage that are on separate branches you can double the voltage to 240 V using a suitable box (Steambrite). That would give you 6 - 10 miles of range per hour of charging which might be enough depending on you daily driving needs. If you only have a single branch in your garage you might be able to run 120 V on another branch from your house via an extension cord into the doubling box. These doubling boxes have two requirements: the two separate inputs are on separate circuits and neither is GFCI-protected.

 

[dmsail]

Here's the link:

Power Joiner Step Up Inverter Electric Car Charger Converts Dual 20amp 120volt Outlets To 240volt

I know it seems a little pricey for such a simple box but they have done all the engineering and construction for you. I have had a circuit breaker fail in my box and I just ordered a replacement off Amazon and replaced it myself. I carry a couple of breakers as spares for long road trips.

You need to set the charging current in the car to not exceed the amperage of the breakers in the doubling box (16 A) and if one or both of the 120 V circuits is 15 A, then you will be limited to 12 A charging.

 

[Tazman]

I have the setup you describe. 240v outlet, 3 prong to 4 prong adapter, 50 foot extension cord, weatherproof rv outlet outside of the house. Car is manually dialed back to 20 amps. Works like a charm though I still try to watch it each time it starts charging to make sure it hasn't lost the setting. I only caught it going higher one time and I can't recall if that was after a software update or if I had screwed it up.

This can work for about $100 bucks but be careful on the amps and using adapters can be dangerous if someone ever plugs something else in.

 

[arnolddeleon]

Simplest/cheapest options. Make the existing circuit to the garage dedicated if it is not already. Should be relatively easy since the garage is separate so there has be a dedicated line going to and the house the can be intercepted. You get charge at 12A 120V, not much, but might be enough for your daily drives.

If you are lucky there are two circuits, one for the lighting and one for outlets. If that's the case then you might be able to convert the outlet circuit to a dedicated 15 or 20A 240V circuit without pulling any new wiress. You can't turn it in a regular NEMA socket (this will involve repurposing/remarking the neutral to second hot, might not be allowed these days, don't know if the codes now prohibit labeling the white as hot). If the wires are the right size then you can charge at 16A 240V, if not then you get 12A at 240V. You will need smart/creative electrician who will be willing to solve the problem in a way that makes likely makes them less money.

arnold