Should I get a Model 3 Performance? Charging concerns.

[rentien]

Should I get a Model 3 Performance? Thanks in advance to anyone who reads and responds to my long post.

If anyone sees something I have left out in my research, please help to point it out to me! I'd really like to make this work.

Background:
So I rented a Model 3 Performance back in 2019. I have always been a fan. I want a model 3.

My issues are:
My garage is currently wired with one 120V/15A line from the breaker. I measured the plug in the garage to measure the wire size, it is 14 AWG. (Measured the wire at ~1.62mm). This means I cannot upgrade the breaker beyond 15A, safely. Taking into account the little chest fridge I have in there, my calculations show that: 1800W minus an assumed 200W for the fridge, and not taking into account the garage door since it doesn't open often, I have 1600 W left over.

This means I can only charge at 120V/13A IF the breaker does not trip from the garage door opening. If it does, I will have to decrease the charging amperage.

I have received quotes to install 240V from one Tesla recommended vendor in the area, of $4-$7K. The garage is not connected to my condo physically but the power in there ultimately comes from the breaker in my condo.

Assuming 75% efficiency, I get 1170W charging going to the car.

If I charge off peak on the EV2A PG&E scheme (still charging at partial peak) I can charge from 9 PM to 8AM when I leave for work. That gets 11 hours of charging a night.

This nets me around 15-16% charge to the battery.

My commute is 84 miles round trip, which comes out to 33% charge. (Calculated by ABRP).

I do have 6.6 kW (20 mi/hr) charging at work, however it is often taken by other tesla owners, so getting that is hit or miss.

If I want to keep charge between 75% and 30%, then I have to charge once every 2 days at work in order to stay above 30%.

I would like to avoid super charging if possible to prolong battery life.

The only alternative options I have thought of, is to charge during peak hours, or supercharge whenever I cannot get charging at work.

Does anyone think this is just too much of a hectic corner situation to own a Tesla? Have I missed anything that would make this easier?

 

[brkaus]

I guess the only question I would ask is if it would be possible to put in smaller 240v (say 20a/240v) for a lower cost. But if you have a single wire to the garage currently, the cost isn't in wire, it's probably in digging and/or routing the wire.

Agree w/ most of what you have written. I personally wouldn't worry about super charging and battery life. I would worry about supercharging and my personal time.

How much of a chance do you really have at getting the charger at work? If you get there a but early would that make it more reliable? Do you know the other users and can communicate and make sure people unplug once they are done?

Not sure what I would do in your situation. the work is the wildcard. With 84 miles a day and a 15a/120v circuit I'd probably pass, but the work charging makes it possible IMHO.

 

[agsqwe]

Trickle charging is limited to 12A and that 84 miles can be more like 40%.
However I see little problem charging to 100% on weekend and occasional use of supercharger if nearby. You sure you're not overthinking it?

 

[bruce4000]

Also, code limits you to 80% of the full rating since it is continuous use.

 

[ElectricIAC]

You will be lucky to pull 9-10A consistently (less if there’s considerable voltage sag) and it may still trip the breaker when the compressor for the fridge kicks on.

4-7K is outrageous to install a 240 and wall connector.

 

[Black306]

Unless you’re willing to cough up the money to get a 240v circuit for charging, not worth it IMO. One of the biggest benefits to an EV is the ability to charge at home. If your specific use-case makes it difficult for a regular daily routine, forget about it.

Plus, a Performance is only good at upper SoCs. If you’re going to be regularly under 60% SoC, I’d suggest just getting a regular 3 or an LR. Power drop off is dramatic at lower SoCs.

 

[The_Observer]

If you are able to move the fridge away from the garage outlet/breaker and have it dedicated for your vehicle, you can also consider converting the current 15amp/120v breaker to 240v/15amps with a 6-15 outlet.

That shouldn't cost a lot, and you will go from 3mph charging on 120v/15a to 11mph charging on 240v/15a (according on Tesla's website), which is alot better.

 

[rentien]

I guess the only question I would ask is if it would be possible to put in smaller 240v (say 20a/240v) for a lower cost. But if you have a single wire to the garage currently, the cost isn't in wire, it's probably in digging and/or routing the wire.

Agree w/ most of what you have written. I personally wouldn't worry about super charging and battery life. I would worry about supercharging and my personal time.

How much of a chance do you really have at getting the charger at work? If you get there a but early would that make it more reliable? Do you know the other users and can communicate and make sure people unplug once they are done?

Not sure what I would do in your situation. the work is the wildcard. With 84 miles a day and a 15a/120v circuit I'd probably pass, but the work charging makes it possible IMHO.

Yeah, personal time is also a thing. My job is... super busy and one of the original benefits to me, was to not go to gas stations but always charge at work.

Yeah, I talked to an electrician and he said I would probably have to replace the pipe the wire goes in, to put bigger wire to do any form of 240V charging.

For charging at work, I would have to get there before 8 maybe latest 8:30 am. Also, I could charge after people get off the chargers, but sometimes people just leave their cars on the charger.

Thanks for the response.

 

[rentien]

Also, code limits you to 80% of the full rating since it is continuous use.

Yep, that's factored in. I think 14 AWG can handle 20A but 80% if 15A, so I plan to use right up to that 15A.

Breaker is only rated for 15A though so not sure if breaker will consistently break if I run at say... 14.8A. I wouldn't want to put a 20A breaker on the circuit either though.

 

[rentien]

If you are able to move the fridge away from the garage outlet/breaker and have it dedicated for your vehicle, you can also consider converting the current 15amp/120v breaker to 240v/15amps with a 6-15 outlet.

That shouldn't cost a lot, and you will go from 3mph charging on 120v/15a to 11mph charging on 240v/15a (according on Tesla's website), which is alot better.

Wait, is this possible on 14 AWG wire?

If this is possible this sounds totally a workable solution. If I could do this on existing 14 AWG wire, and just change to connect 240 to the current wire, change the breaker and plus and be done.

I will look into this.

 

[mswlogo]

Is your 15A (14/2) circuit in conduit?

If it is, you can probably upgrade to a 12/3 for very little money. I think that the largest wire in a 1/2” conduit.

Get an electrician out there first hand and get options. You don’t need 60A 240 and that might be what Tesla is estimating.

By just upgrading to 12/3 you can run full 12A / 240V for charging. And put Fridge on one Hot and Garage door on the other hot and I suspect nothing will trip.

Technically EV charging is suppose to be a dedicated circuit. You could do 16A 120V on one hot for charging and door opener/fridge in the other hot. But 12A 240V will be much faster charging.

You also can’t safely dial any amperage you want. You can in the car but that’s not safe or sustainable. You want the system to automatically guarantee not trip any breakers without you intervening to help it along.

I’d also seriously consider a Model 3 LR for max efficiency and range.

 

[rentien]

Does it not work to limit the amperage right there on the charging screen?

Any draw back to this? I thought the purpose of that amperage setting was specifically for my situation.

 

[rentien]

Is your 15A (14/2) circuit in conduit?

If it is, you can probably upgrade to a 12/3 for very little money. I think that the largest wire in a 1/2” conduit.

Get an electrician out there first hand and get options. You don’t need 60A 240 and that might be what Tesla is estimating.

By just upgrading to 12/3 you can run full 12A / 240V for charging. And put Fridge on one Hot and Garage door on the other hot and I suspect nothing will trip.

Technically EV charging is suppose to be a dedicated circuit. You could do 16A 120V on one hot for charging and door opener/fridge in the other hot. But 12A 240V will be much faster charging.

You also can’t safely dial any amperage you want. You can in the car but that’s not safe or sustainable. You want the system to automatically guarantee not trip any breakers without you intervening to help it along.

I’d also seriously consider a Model 3 LR for max efficiency and range.

Thanks for your response.

Can you clarify what “in conduit” means? I don’t fully understand all this electrical verbiage.

 

[The_Observer]

Wait, is this possible on 14 AWG wire?

If this is possible this sounds totally a workable solution. If I could do this on existing 14 AWG wire, and just change to connect 240 to the current wire, change the breaker and plus and be done.

I will look into this.

Voltage shouldn't matter in this scenario, wire gauge determines how much amps it can handle.

14 gauge should be good for 15 amps, with 12 amps continuous.

I could be wrong, but it's something you can consider talking to an electrician about this and see if it's safe to do so. In theory and wire size rating, this should be fine.

 

[RandyS]

My observation about work charging is that even if you miss getting one of the work chargers when you arrive, there is usually turnover at lunchtime as people leave to run errands or get food. So you should be able to get a charger at lunch and charge for the rest of the day...

Another thing that newbies sometimes do is underestimate the car's consumption. The car is always using energy, even when not driving. Some of the setting choices you make on the screen will save some of that energy (Sentry mode uses 1 mile of range for every hour, for example), but the bottom line is that the car will probably use more energy than you think (when driving and not driving)...

Agree with seeing if you can upgrade the 14 ga. wire to 12 ga. to your garage (it should be easy if it runs inside a conduit from your panel to the garage, but not so easy if it is Romex type wire that can't be pulled out and replaced with the larger wire).

In addition, here's a safety recommendation: Assuming that the outlet(s) in your garage are more than a few years old, and since you'll be charging at Level 1 speed for many hours per day (pretty close to full load with your frig., etc.), I would replace all the 120v outlets with commercial grade ones and specifically DON'T use the backstab connections since the springs loosen over time and can cause overheating at high current levels (DO use the screw connections, which are better). Since you probably don't know how the wire comes from the panel and in what order it feeds the outlets in the garage (since the wire is probably daisy-chained), I would replace all of the outlets...

Otherwise, rock on!!!

 

[jjrandorin]

My commute is 84 miles round trip, which comes out to 33% charge.

You got a lot of info already, and I know you say you calculated with ABRP.... but if your commute is 84 "real" miles going to work, that is going to use between 85 and like 120 "tesla miles". My commute is 80 miles round trip, and I have a 2018 model 3 performance.

Its going to be higher in the winter (even what passes for winter in CA) and if it rains. If its raining and in the 50s outside and windy, you will probably use 120 or so "Tesla miles" (miles off the range meter).

 

[bruce4000]

Does it not work to limit the amperage right there on the charging screen?

Any draw back to this? I thought the purpose of that amperage setting was specifically for my situation.

I use this feature to limit current and has worked fine.

 

[mswlogo]

Thanks for your response.

Can you clarify what “in conduit” means? I don’t fully understand all this electrical verbiage.

It’s either underground cable or it’s in a pipe. If it’s in a pipe it can usually be replaced with slightly higher gauge wire without digging.

 

[brkaus]

Yeah, personal time is also a thing. My job is... super busy and one of the original benefits to me, was to not go to gas stations but always charge at work.

Yeah, I talked to an electrician and he said I would probably have to replace the pipe the wire goes in, to put bigger wire to do any form of 240V charging.

For charging at work, I would have to get there before 8 maybe latest 8:30 am. Also, I could charge after people get off the chargers, but sometimes people just leave their cars on the charger.

Thanks for the response.

If it’s in pipe (conduit) I would ask what is the largest (if any) 240v circuit that could be retrofitted. Even a 15a 240v circuit would be ok for your situation (imho).

But you still need 120v in the garage, so that would mean a sub-panel and I’m not sure they even do that on a 20a circuit.

I assume the conduit is buried? What is the distance? Where is the main panel located relative to the conduit? (Inside/outside/etc).

5K isn’t crazy if there is a lot of digging, upgrade main panel, and add a sub panel.

You might also ask what it would cost if you did your own digging (or sub-contract it yourself). There are a lot less surprises priced in if the trench is exposed and ready.

 

[srs5694]

Does it not work to limit the amperage right there on the charging screen?

Any draw back to this? I thought the purpose of that amperage setting was specifically for my situation.

Yes, you can limit the charge amperage from the screen of the Tesla, and it should "stick" to the value you set in a specific geographic location; however, the car's GPS is sometimes off, so it might not be 100% accurate. It'd be better to get a plug for the Mobile Connector that limits the rate, but I've never heard of one that will limit 120v charging to less than 12A. (These plugs include a chip that encodes how many amps the Mobile Connector can draw. There are third parties that sell some variants that Tesla doesn't sell.)

More broadly, I've seen some good suggestions in this thread. I particularly like the one of converting your 120v line to 240v; however, other electrical devices in the garage, including the garage door opener and lights, may need to work on 240v if you do that, unless they're on a separate circuit. Another idea I had is that you can supplement your at-home charging with various types of public charging. You've already mentioned workplace charging, but there are other types of public charging. In my area, many supermarkets, malls, parks, libraries, and other locations have public Level 2 charging available; and DC fast charging is starting to appear at more locations, too. In your situation, I would strongly recommend buying Tesla's new CCS1 adapter (or a third-party alternative), since this will enable you to DC fast charge at more locations. As you say, minimizing DC fast charging is best for the battery; but I wouldn't worry about doing a DC fast charge once or twice a month, if that's what it takes in your situation. Between your limited home charging options, your work charging options, and local DC fast charging, you should be OK. It won't be quite optimal, but it will be OK.

There's also the possibility of just biting the bullet and paying the $4-$7K for a new dedicated 240v line to the garage. That is definitely a lot of money, but it will increase the value of your property, particularly as EVs become more common.