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"Charge Current" keeps changing back to 40A

im having a weird problem in my condo garage where my breakers from the garage charger keeps getting tripped up. ive had this setup for years now with no problems so not sure what the issue is. i live on the 5th floor, with no new major appliances or any new power needs.

anyhow, my management company suggested i change the settings on the vehicle to charge at 20amps max vs the standard 40amps.

how do you change the charging amps limits and make it stay? on my car, it defaults to 40 amps on the "charge current" area. i change it to 20 amps, and when i check back later, often its back to 40amp. is there a way to keep it at 20 amp max permanently?
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,838
9,861
Boise, ID
how do you change the charging amps limits and make it stay? on my car, it defaults to 40 amps on the "charge current" area. i change it to 20 amps, and when i check back later, often its back to 40amp. is there a way to keep it at 20 amp max permanently?
Well, a couple of conditions for this to work that people sometimes forget. One person in another thread said, "I change the amps and then plug in" It won't store the setting if you are changing the amps while you are not charging. It only stores it if charging is currently going on.

Also, it tags it to that GPS location, which works if it has a good handle on detecting where the car is. What is the situation with the parking at your condo garage? Do you have one fixed parking space, or do you frequently have to park in different places within that general area? If you're in a few places, it probably is not recognizing the "location" when you are back there the next day.

Or, if it's deep in a parking structure, I wonder if it just can't get good enough GPS signal to lock down the location well, so it's not logging the setting to that place very well.
 
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mswlogo

Well-Known Member
Aug 27, 2018
7,535
6,991
MA, NH
im having a weird problem in my condo garage where my breakers from the garage charger keeps getting tripped up. ive had this setup for years now with no problems so not sure what the issue is. i live on the 5th floor, with no new major appliances or any new power needs.

anyhow, my management company suggested i change the settings on the vehicle to charge at 20amps max vs the standard 40amps.

how do you change the charging amps limits and make it stay? on my car, it defaults to 40 amps on the "charge current" area. i change it to 20 amps, and when i check back later, often its back to 40amp. is there a way to keep it at 20 amp max permanently?

Your real problem is that you should not depend on lowering the amps in your car to not trip a breaker. That is problem #1. Fine for a temporary work around.

You need to get to the bottom of why it's tripping. Could be just a bad breaker. Breaker might be heating up and false tripping. Might never have been installed correctly.

Get it looked at and find out why.

Could be as simple as Wall Connector set wrong.

What Size Breaker is getting tripped?
 
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Rocky_H

Well-Known Member
Feb 19, 2015
7,838
9,861
Boise, ID
so maybe i need to change the amperage when im charging?
That's a given. It won't ever remember the setting if you're moving it around while it isn't charging.

yes, i have one fixed spot that is mine. however, no signal gets down there. so in order to get tesla updates, i need to go to street level.
Then this is more of the secondary concern. It does have to be set while charging, but it's possible it might not remember it if the location isn't known very well.
 
Interesting... I was pretty sure it did not matter if you were charging or not; you should be able to dial back the current then plug it in. I suggest setting it to 20A, plug it in, but don't leave until it has ramped up. This will confirm whether or not you can set it before plugging in.
Not having a GPS signal could be an issue for when you leave and come back.

If it starts charging at 20A then increases by itself to 40A, I only have one explanation, but it's a bit of a long shot.

I created an adapter to plug my 40A UMC into a 30A outlet (away from home), then dialed back the current to 24A. One time when I went to check on it, the car had detected a charging problem and "reduced" the charging current by 25% to 30A. This is the only time I have ever seen the car increase current when I set it lower.
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
6,861
13,466
Springfield, VA
If charging at 40 amps trips your breaker, I recommend reducing the charge rate in steps until you find a suitable level. No reason to cut it down to 20 amps if it will charge fine at 30 or 32.

Regarding your conversation with Tesla Support, it’s absolutely fine to change the charge rate while it is charging.

Question: how many amps is your circuit breaker? If it’s a 40 amp breaker, you should set the car to a maximum of 32 amps.

Since this is the Model S forum, I suspect you’re charging with a Gen 1 UMC on a NEMA 14-50 receptacle hooked up to a 40 amp breaker. The car will try to default to 40 amps since it expects that receptacle type to be on a 50 amp breaker. This would explain the breaker trips since you’re exceeding the 80% sustained load rule.
 
OP indicated this setup has not changed in years, but breaker started tripping.

A few more ideas come to mind.
Possibly the breaker is bad, tripping with less load than it should. Replace breaker. (Electrician recommended.)
Possibly a bad connection somewhere, make sure the wiring's tight on the breaker. (Electrician recommended.)
Clean the contacts on the charge port and charger connector.
And on the conspiracy side, make sure nobody is tapping into your circuit stealing electricity from you.

Still, the car should not increase current after it ramps up charging.
 
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MorrisonHiker

Well-Known Member
Moderator
Mar 8, 2015
10,551
10,578
Colorado
Interesting... I was pretty sure it did not matter if you were charging or not; you should be able to dial back the current then plug it in.
You don't have to be charging. You need to be at the location where you will be charging. If you change it while you are elsewhere, it will remember the amps for that location, not your home location.
 
brass guy---thanks for your advice. im sort of trying to fix this issue without spending money, therefore havent hired an electrician yet. ill try cleaning the contact points. and ill be on the lookout for the culprit on the conspiracy theory!!!
big earl ---ill have to check on the amps of the breaker. its in a storage room that i cant assess easily. ive already bothered management enough with having to turn the breaker on. will look next time. but yes, thats my plan, to lower the amps until there is no problem. ill try and adjust to 30 to see if that stays put.
 
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The advise to set the current to lower amperage while plugged in does not conflict with the Tesla advise to not change while charging. Just because the car is plugged in doesn't mean it is charging.
That said I suspect the person you spoke to at Tesla is clueless.

I think the breaker is old and weak or the wire is loose at the breaker causing heat.
 

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