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Charging limited to 24 amps - 2016 S

Hi all,

Anyone have any thoughts on this? I searched and see a lot of PCS issues, but that looks to be more related Model 3/Y.

I generally charge in my garage using the mobile connector and until recently pulled consistent 32 amps. Recently I have noticed that when initially plugged in, it’s showing the max amps as 24 but when it actually begins to charge it will show 23/32 or 24/32. I think I can rule out the mobile connector and outlet because just last week I had a Gen 3 wall charger installed and I’m getting the same result.

In the meantime, I have manually turned it down to 24 amp max.

Thanks
 

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Can you raise the amps to 32? The car will reduce the current in an attempt to continue charging if it detects a voltage drop. I would try raising the amps to 32 and monitor the voltage as it starts charging.

What is the max amperage setting on your HPWC?
I tried raising it manually. As soon as I hit 26 it drops itself back down to 23.

HPWC is max 32, 40 amp breaker.
 
What does your voltage read at the different amp settings? I see it says 244v @ 24A which is fine. I'm wondering if it's unusually high and then drops to 244. In my experience charging and seeing voltage droop, I started at 230v and then dropped to 223v before the car lowered the amps from 40 to 30. 250v home service is high, but not unheard of.
 
I'm stumped so far. Perhaps try another L2 charger outside of your home and see if you can replicate the issue? If the problem persists, I'd suspect something in your car, but typically you'd get a warning or error of some type if the current was reduced due to a problem in the car's charger.
 

Rocky_H

Well-Known Member
Feb 19, 2015
8,569
11,119
Boise, ID
You could have a failing module in your onboard charger, similar to what's happening in larger numbers to the 3/Y.
Well, I thought that just briefly, but ruled it out.
Your onboard charger is made up of two 24 amp boards.
But it's not. They aren't 24A each. That's why the only two sized onboard charger options are either 32A or 48A. 24A isn't a unit that goes into those. The internal modules in the chargers are 16A each, with either two of them or three of them. And with those failures, it will usually just quit and cause a loss of 16A, rather than half working, which could show 24A.

So I am going to concur with @beatle 's suspicion. If the car's safety reduction gets kicked in from a voltage drop, it will reduce to 3/4 of what it was trying to use. So seeing 24A out of 32A is a normal indicator of that. Being above 240V, though, looks like that's really good. I have seen a few cases of someone's house or neighborhood having some other big device kick on suddenly, which craters the system voltage for a second, and that kicks in the car's voltage drop sensor. But if the 30A public charging station is still having the car stuck at 23 or 24A, that doesn't seem to work either. I'm about out of ideas.
 

ucmndd

Well-Known Member
Mar 10, 2016
9,445
18,339
California
But it's not. They aren't 24A each. That's why the only two sized onboard charger options are either 32A or 48A. 24A isn't a unit that goes into those. The internal modules in the chargers are 16A each, with either two of them or three of them. And with those failures, it will usually just quit and cause a loss of 16A, rather than half working, which could show 24A.
In post-refresh 2016s, the onboard charger options were 48 amps (two internal modules) or 72 amps (3 internal modules).

At some point in the future that did change, after the high amperage charger option was discontinued, but OPs onboard charger definitely uses 24 amp modules.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
8,569
11,119
Boise, ID
In post-refresh 2016s, the onboard charger options were 48 amps (two internal modules) or 72 amps (3 internal modules).

At some point in the future that did change, after the high amperage charger option was discontinued, but OPs onboard charger definitely uses 24 amp modules.
Oh, sorry. I forgot we were talking about the previous generation chargers with the 48/72 versions. Yes, you're right--24A pieces. OK, I'm going to change my guess to yours now.
 
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ucmndd

Well-Known Member
Mar 10, 2016
9,445
18,339
California
Thanks for the insight…and I’m guessing this is not part of the battery warranty?

It’s not. The onboard charger in your generation Model S is under the rear seat and not part of the HV battery enclosure.

There are some pending arbitration cases on the 3/Y side trying to make the case that because PCS components are housed inside the battery enclosure on those cars they should be covered by the 8 year battery warranty, but Tesla so far maintains otherwise and has not indicated any willingness to entertain that loophole.
 
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