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Chevy Bolt L1 EVSE (Wall plug) to trickle charge MY.

Hey all,

I just took delivery of my MYLR in solid black and it's exceeded all my expectations so far. I have a question regarding charging:

I live in an apartment and my parking spot is in a garage which (luckily) is directly below my balcony where I have a regular 120v wall outlet. The Tesla mobile connector is (not so luckily) ~5ft shy of reaching and don't have a way to install a L2 charger in the garage or move parking spots. Even though it is slow, L1 would do for now and I have two options:

Option 1. Use a >5ft extension cord + Tesla mobile connector (~20ft).
Option 2. Use the Chevy Bolt's OEM L1 Wall charger (~25 ft) + J1772 to Tesla adapter.

Is there an objectively better option? If option 1 is better, is there a specific extension cord I should be using?

Thanks!
 
Hey all,

I just took delivery of my MYLR in solid black and it's exceeded all my expectations so far. I have a question regarding charging:

I live in an apartment and my parking spot is in a garage which (luckily) is directly below my balcony where I have a regular 120v wall outlet. The Tesla mobile connector is (not so luckily) ~5ft shy of reaching and don't have a way to install a L2 charger in the garage or move parking spots. Even though it is slow, L1 would do for now and I have two options:

Option 1. Use a >5ft extension cord + Tesla mobile connector (~20ft).
Option 2. Use the Chevy Bolt's OEM L1 Wall charger (~25 ft) + J1772 to Tesla adapter.

Is there an objectively better option? If option 1 is better, is there a specific extension cord I should be using?

Thanks!
You are fine using Option 2. It will be slow with 120V no matter which one you use.
 

jcanoe

Active Member
Oct 2, 2020
4,399
4,582
Maryland
Option 2 will be fine. Know that if you lock the Tesla Model Y then someone cannot remove/steal the SAE J1772 adapter but they can remove the J1772 charging connector from the adapter. (If this is a concern there is a locking ring you can purchase on eBay, Etsy that prevents removing the J1772 connector when the Tesla is locked.)

The Tesla defaults to 120V/12A for Level 1 charging (the Chevy Bolt defaults to 120V/8A.) You will have to lower the maximum charging amperage on the Tesla charging screen if you need to limit charging to 8A.) I'm not certain if the Tesla Model Y will remember the charging amperage setting for this location.

Sentry Mode provides some peace of mind when your Tesla vehicle is parked but the Tesla vehicle uses about 10X more power when Sentry Mode is active versus the Tesla vehicle entering Sleep Mode. The power drain with Sentry Mode left on at your Home Location is ~230W. This is significant since you are only able to charge at a maximum of 1.4kW when charging at 120V and 12A, even less (960W) when charging at 120V and 8A. When the Tesla vehicle enters Sleep Mode when parked the power drain is only ~25W.
 
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Twiglett

Single pedal driver
Oct 3, 2014
3,238
3,476
Austin
These guys do a J1772 "lock"

If you're going to extension cord route, make sure to get a decent one, I tried a cheapo extension and got weird errors and even slower charge speeds ;)
 
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Option 2 will be fine. Know that if you lock the Tesla Model Y then someone cannot remove/steal the SAE J1772 adapter but they can remove the J1772 charging connector from the adapter. (If this is a concern there is a locking ring you can purchase on eBay, Etsy that prevents removing the J1772 connector when the Tesla is locked.)

The Tesla defaults to 120V/12A for Level 1 charging (the Chevy Bolt defaults to 120V/8A.) You will have to lower the maximum charging amperage on the Tesla charging screen if you need to limit charging to 8A.) I'm not certain if the Tesla Model Y will remember the charging amperage setting for this location.

Sentry Mode provides some peace of mind when your Tesla vehicle is parked but the Tesla vehicle uses about 10X more power when Sentry Mode is active versus the Tesla vehicle entering Sleep Mode. The power drain with Sentry Mode left on at your Home Location is ~230W. This is significant since you are only able to charge at a maximum of 1.4kW when charging at 120V and 12A, even less (960W) when charging at 120V and 8A. When the Tesla vehicle enters Sleep Mode when parked the power drain is only ~25W.
Awesome, I just had a chance to check out the locking rings, I don't think it will be an issue since my parking spot is pretty hidden but you never know. I also have a 3D printer so I can print my own and give it a try.

Good to know on the charging amperage, I'll need to look into the "memory" on my MY for this specific location. And yes, I've read that Sentry mode does drain the battery quite a bit but didn't have numbers so thanks for adding them here. I'd leave Sentry mode ON for sure if I were going away on longer trips and the trickle charge will at least help by not letting the battery get too low.

Thanks for the useful response!
 
These guys do a J1772 "lock"

If you're going to extension cord route, make sure to get a decent one, I tried a cheapo extension and got weird errors and even slower charge speeds ;)
Thanks for the heads up, sounds like I'll be using the Bolt EVSE for now but good to know in the future in case my setup needs to change. 👍
 
This may help -
Thanks for this - I'm charging a Prius Prime over a 100' 12 AWG extension cable; at first the voltage dropped down to 105, but I took advantage of the fact that my outlet is on a 20A breaker (and 10 AWG supply wire), and replaced the outlet and the cable ends with NEMA 5-20 plugs and receptacles, as well as using this as an excuse to cut about 10' of slack cable off. My voltage at 12A load is now 113V, which, given the demo, means my MY (when it arrives) shouldn't have any trouble.

That said, I'm curious what will happen if I use a 5-20 adapter and try to charge at 16A. Will I see enough additional voltage drop for the car to reduce the current?
 

andaconda

Member
Apr 3, 2021
443
263
S.W. Montana
That said, I'm curious what will happen if I use a 5-20 adapter and try to charge at 16A. Will I see enough additional voltage drop for the car to reduce the current?
I have a 100' 12awg extension cord that is rated a 15 amps. I think if you pushed your "90 ft" cord to 16a it would put it in a dangerous situation. Most likely it would over heat. I wouldn't take the risk.
 

jcanoe

Active Member
Oct 2, 2020
4,399
4,582
Maryland
We can't know what will happen over time to the extension cord (especially the end connectors) if you draw 16A for an extended period. You might want to pick up a hand held digital thermometer sold on Amazon. These start at under $20 and will show you in an instant the temperature of the receptacle, plug, cord and any interconnects.

https://www.amazon.com/gp/product/B07XG3P7R9/
 
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We can't know what will happen over time to the extension cord (especially the end connectors) if you draw 16A for an extended period. You might want to pick up a hand held digital thermometer sold on Amazon. These start at under $20 and will show you in an instant the temperature of the receptacle, plug, cord and any interconnects.

https://www.amazon.com/gp/product/B07XG3P7R9

After a bit more research, I decided to order a 10/3 AWG 100' cable, and I'll take the existing one (putting a 5-15 plug back onto it) and keep it in the frunk for emergencies.

One thing I'm wondering is if it makes sense to take the existing 12/3 cord and cut if in half, so that I don't need to use the full length if I don't have to. Is the reduced resistance I'd see worth the trouble? And if I then used both halves together, would the junction plug/receptacle add too much resistance to get the full 12A?
 

jcanoe

Active Member
Oct 2, 2020
4,399
4,582
Maryland
After a bit more research, I decided to order a 10/3 AWG 100' cable, and I'll take the existing one (putting a 5-15 plug back onto it) and keep it in the frunk for emergencies.

One thing I'm wondering is if it makes sense to take the existing 12/3 cord and cut if in half, so that I don't need to use the full length if I don't have to. Is the reduced resistance I'd see worth the trouble? And if I then used both halves together, would the junction plug/receptacle add too much resistance to get the full 12A?
Extension cords are inexpensive enough that I would purchase a 25 ft 12/3 cord and a 50 ft 12/3 cord. That way you have a 120V extension cord of an appropriate length and gauge for any reasonable application.
 
Following up on my own post here; I've run a 10/3 cable in place of the 12/3 I had before, cut the same amount of excess slack, and attached the 5-20 cable ends. My EDD is still a month away, so I can't test 16A yet, but at 12A my voltage drop is from 121.5 to 114.5 - 7.0 volts total, for .583 ohms of total resistance. With 33% more current, this would drop 9.3V to 112.2V, which I'd hope won't trigger the car to lower the amperage. Does anyone know what the threshold actually is?
 

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