Car charged at higher amps than set. Blew out my fuse box

[InigoMontoya]

I awoke to a fully charged Tesla 3, but no power in half the house. This house was built in 1963 and probably still has the original electrical panel with screw-in fuses and four cartridge fuses - 60 amps. Two of the 60 amp fuses blew and melted/burned some of the panel. It has to be replaced.
Although I had set the Tesla max. charging amps to 22 at home, my car apparently changed it to 32 amps.

How can I make sure that my car never pulls more than 22 amps when charging at home?

 

[Tam]

I awoke to a fully charged Tesla 3, but no power in half the house. This house was built in 1963 and probably still has the original electrical panel with screw-in fuses and four cartridge fuses - 60 amps. Two of the 60 amp fuses blew and melted/burned some of the panel. It has to be replaced.
Although I had set the Tesla max. charging amps to 22 at home, my car apparently changed it to 32 amps.

How can I make sure that my car never pulls more than 22 amps when charging at home?

You didn't describe your charging setup.

1) If you use Mobile Connector, the car will never go beyond the adapter that you bought.

If you bought a 14-50 adapter, the car might try to go up to as high as 40A and blow your fuses if somehow your preset 22 Amperes were not honored due to a reset after a firmware update, GPS/Location error/reset, or some other reasons.

If you bought a 6-20 adapter, the car does not go beyond 16A.

If you bought a 10-30 or 14-30 adapter, the car does not go beyond 24A.


2) If you use a High Power Wall Connector, I think you can set up the maximum Amperes allowable so that it would ignore the car's demand for a higher Amperes that you set up in the Wall Connector.

 

[Sophias_dad]

If you have an HPWC, you should set it as if you have a 30 amp breaker(which will keep the car from using more than 24 amps), or 20 amp breaker(which will keep the car from using more than 16 amps.

A similar thing can be done with the UMC, but you need to change the outlet to a 14-30 or 6-20 and get the appropriate UMC adapter. The adapter tells the UMC what its allowed to draw.

I >really< hope when your panel is replaced they use a circuit breaker main! Get it upgraded to 100, 125, or 150 if you can.

 

[mswlogo]

Never rely on the car for setting max amp, ever. Neither Tesla or car is to blame here. Either use the correct plug or wall connector.

If you only have 60 Amp service I highly suspect 30 Amp circuit (charge at 24 A) is way to high. Max you might go is 20 Amp circuit (240V) and a charge rate of 16A (as suggested above). But even that might be to much.

 

[RayK]

How can I make sure that my car never pulls more than 22 amps when charging at home?

Use one of the 20A NEMA adapters from Tesla; 5-20 (120V - 5MPH rate) or 6-20 (240V - 15MPH rate). Both will automatically limit the mobile connector to a maximum of 16A. If you are using a 30A adapter (10-30, 14-30), then the mobile connector will use 24A as a maximum, exceeding your desire of 22A. In that situation you can manually set the charge current lower and the car is supposed to remember that value. However, if it's a matter of a charge current being more than 22A causing damage (like your blown fuses), then I would not use anything larger than a 20A NEMA adapter until you can get a qualified electrician to look at your panel and run a load analysis to see what you can reserve for your charging.

If you are using a Wall Connector, then there is a way to set the maximum current but I believe it's either 16A or 24A. Consult your installation / operation manual (Gen2 and Gen3 are done differently).

 

[jjrandorin]

I awoke to a fully charged Tesla 3, but no power in half the house. This house was built in 1963 and probably still has the original electrical panel with screw-in fuses and four cartridge fuses - 60 amps. Two of the 60 amp fuses blew and melted/burned some of the panel. It has to be replaced.
Although I had set the Tesla max. charging amps to 22 at home, my car apparently changed it to 32 amps.

How can I make sure that my car never pulls more than 22 amps when charging at home?

Depending on the car to set the amps = problem waiting to happen (as you found out). No one should ever depend on "setting the amps in the car or the app" as the proper way to ensure the car does not charge at a higher amperage / speed than its set to.

You obviously have the wrong outlet installed because it wasnt safe, and you are now trying to blame the car for it instead of whomever it was that installed the outlet.

To answer your question, you should have installed an outlet and breaker that would not provide more power than was safe for your connection, whatever that is. If your wiring / home can only take a 240v 20 amp charge rate, then you should put in an outlet that wont provide more than that. This is not the fault of the car, its the fault of the outlet, and whoever wired it to provide more power than was safe for your home.

 

[ucmndd]

How can I make sure that my car never pulls more than 22 amps when charging at home?

Install an appropriate charging circuit and use the correct outlet/breaker/adapter that can’t possibly overdraw what your service can provide. The car should never be relied on to enforce this, ever.

 

[3sr+buyer]

You didn't describe your charging setup.

1) If you use Mobile Connector, the car will never go beyond the adapter that you bought.

If you bought a 14-50 adapter, the car might try to go up to as high as 40A and blow your fuses if somehow your preset 22 Amperes were not honored due to a reset after a firmware update, GPS/Location error/reset, or some other reasons.

The mobile connector does not go above 32A, since a 14-50 or 6-50 outlet can be on a 40A circuit.

But since the OP needs a new panel anyway, time to upgrade to one with sufficient capacity, and install / upgrade the circuit to the garage as needed.

 

[rwiegand]

To answer your question, you should have installed an outlet and breaker that would not provide more power than was safe for your connection, whatever that is. If your wiring / home can only take a 240v 20 amp charge rate, then you should put in an outlet that wont provide more than that. This is not the fault of the car, its the fault of the outlet, and whoever wired it to provide more power than was safe for your home.

There is no such thing that I'm aware of as a outlet that limits current draw. In the OP's case the fuse(s) protecting the circuit blew, which is exactly what is supposed to happen in an overcurrent situation. Just because you've installed a "15 A" outlet doesn't mean your hair dryer won't try to pull 20 or a dead short 1000 amps. The outlet has no way of knowing what's on the other end of the plug. All that's in there, at least in the US, is a piece of metal to bridge the incoming wire to the prong of a plug. The fuse or the circuit breaker is the only thing that's there to protect the wiring and limit current.

If the car provides an option to set a maximum charging current it is completely reasonable to expect it to work, and would be a much better/safer option than relying on detecting what physical outlet might be in use. People have wired up all kinds of weird combinations of outlets and wires over the last 100 years.

 

[InigoMontoya]

Thanks for the replies.
A few details. I use the mobile charger provided with the car and a Gen 2 NEMA Adaptor 10-30 to plug into the clothes dryer outlet. I only charge after midnight to take advantage of off-peak rates and avoid conflict with the dryer.
I rent so I don't want to put much money into the house. It looks like we'll get a new circuit breaker box to replace the antiquated screw-in fuse box. I hope that helps.
When I bought the car, I had an electrician look at my set-up and he est. $5,000 to set up for Tesla's wall charger. I decided to use the mobile charger and see what happens. It has worked amazingly well with only a few exceptions, like burning up the fuse box. oops

 

[InigoMontoya]

You didn't describe your charging setup.

1) If you use Mobile Connector, the car will never go beyond the adapter that you bought.

If you bought a 14-50 adapter, the car might try to go up to as high as 40A and blow your fuses if somehow your preset 22 Amperes were not honored due to a reset after a firmware update, GPS/Location error/reset, or some other reasons.

If you bought a 6-20 adapter, the car does not go beyond 16A.

If you bought a 10-30 or 14-30 adapter, the car does not go beyond 24A.


2) If you use a High Power Wall Connector, I think you can set up the maximum Amperes allowable so that it would ignore the car's demand for a higher Amperes that you set up in the Wall Connector.

I use a 10-30 adaptor.

 

[InigoMontoya]

There is no such thing that I'm aware of as a outlet that limits current draw. In the OP's case the fuse(s) protecting the circuit blew, which is exactly what is supposed to happen in an overcurrent situation. Just because you've installed a "15 A" outlet doesn't mean your hair dryer won't try to pull 20 or a dead short 1000 amps. The outlet has no way of knowing what's on the other end of the plug. All that's in there, at least in the US, is a piece of metal to bridge the incoming wire to the prong of a plug. The fuse or the circuit breaker is the only thing that's there to protect the wiring and limit current.

If the car provides an option to set a maximum charging current it is completely reasonable to expect it to work, and would be a much better/safer option than relying on detecting what physical outlet might be in use. People have wired up all kinds of weird combinations of outlets and wires over the last 100 years.

Thanks. It looks like the car switched to 32 Amps at a Super Charger and kept that setting at my home, despite me setting it for 24 amps.

 

[appleguru]

Thanks. It looks like the car switched to 32 Amps at a Super Charger and kept that setting at my home, despite me setting it for 24 amps.

Shouldn’t be possible with a tesla 10-30 adapter… unless you’re saying your mobile connector has a NEMA 14-50 plug on it and you made/bought your own 10-30 adapter?

 

[ucmndd]

Thanks. It looks like the car switched to 32 Amps at a Super Charger and kept that setting at my home, despite me setting it for 24 amps.

This is not possible. The car will never draw more than 24 amps from a mobile connector with a properly functioning 10-30 adapter installed.

I think your presumption that the car charging at 32 amps caused this is not correct. It seems more likely your ancient panel just took a dump under high continuous load after 70 odd years.

 

[rwiegand]

I used to have those old 60A cartridge fuses. If you run them close to capacity for an extended period of time they will heat up and degrade. They char at the ends first and then crumble when you go to pull them out. I'm kind of liking the explanation of degradation under extended near-capacity load.

A modern disconnect with circuit breakers is a really good idea.

 

[3sr+buyer]

Thanks for the replies.
A few details. I use the mobile charger provided with the car and a Gen 2 NEMA Adaptor 10-30 to plug into the clothes dryer outlet.

Isn't the 10-30 adapter supposed to cause the mobile connector to limit charging to 80% of the presumed circuit capacity (i.e. 24A for the presumed 30A circuit behind the 10-30 receptacle)?

Whatever the lower of what the EVSE (mobile connector) and car say should be what the charging speed will be. I.e. if the EVSE says 24A and the car says 32A, the charging speed will be 24A.

Of course, if the old panel and fuses were in poor condition, maybe even 24A was enough to burn them out.

 

[Gauss Guzzler]

If you're using Tesla's 10-30 pigtail then the mobile charger will be hard-limited to 24A. There's no possible workaround.
If you tricked it into charging at 32A by using some generic illegal adapter designed to bypass the safety limits, then the fuse would have blown.

What most likely happened is that your fuses/terminals were old/corroded/loose which caused them to overheat even though you were charging at an appropriate and safe current of 24A.

 

[InigoMontoya]

Update: The landlord hired an electrician friend of his to replace a few parts on the old fuse box. The electrician said to me and I presume my landlord that I should not charge the Tesla at home. Should I accept this or fight it?

 

[InigoMontoya]

If you're using Tesla's 10-30 pigtail then the mobile charger will be hard-limited to 24A. There's no possible workaround.
If you tricked it into charging at 32A by using some generic illegal adapter designed to bypass the safety limits, then the fuse would have blown.

What most likely happened is that your fuses/terminals were old/corroded/loose which caused them to overheat even though you were charging at an appropriate and safe current of 24A.

I bought the 10-30 adaptor from Tesla. Apparently 24A is too much here.

 

[jjrandorin]

Update: The landlord hired an electrician friend of his to replace a few parts on the old fuse box. The electrician said to me and I presume my landlord that I should not charge the Tesla at home. Should I accept this or fight it?

You also mentioned:

I rent so I don't want to put much money into the house.

I am not a lawyer (not even close) but I am not sure how you can "fight" this, so to speak. You rent the home, and presumably the landlord is the owner of the property. It seems to me that, they would be within their rights to say to you:

===============
"It appears that a subject matter expert (electrician) has determined that the home does not currently support electric vehicle charging. If you would like to charge here, this is the list of upgrades to the electrical system that will need to be made. Since this will be in support of you charging your car, if you desire this, you will need to bear this cost. Let me know how you would like to proceed".
==============

(or something like that)

Your only recourse at that point would seem to be to either (1) pay for upgrades (which if extensive doesnt make much sense at a property you rent, (2), Not charge there and deal with finding charging, or (3) not charge there and deal with finding charging, then move to someplace that supports charging.

Like I said, not a lawyer or anything like that at all, it just seems to me that the owner of the property gets to dictate how repairs or upgrades get done as long as there are no code violations, so not sure how much "fighting" you can do here.