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Charging issue

Charging issue

Sorry, just taken delivery of my Model 3, and so new to the forum, and I'm not sure how to search the forum to see if my problem is answered in previous posts.
I'm home charging and manage a rate of 25-20 ml/hr. After about 2 hours this drops to 6 ml/hr. The only way I can get back to the higher rate is to unplug from car and charger unit, then plug back in. I've tried stopping and re-starting charging without unplugging, but that doesn't work. Can anyone advise?
Thanks

derotam | 20 september 2019

Is there any error that shows on the screen in the car? When it goes down do you get any kind of notification from the Tesla app on your phone?

Are there any red lights on the mobile connector when the charge rate goes down?

It could be just about anything at this point without more info.

donharvey2323 | 20 september 2019

Are you using the charger that came with the car or something else?

d.sharma | 20 september 2019

No warnings nor notifications, no red lights. After it happened the first time, I've kept an eye on the app. Three time I've charged and it's happened each time. I'm using the cable supplied by Tesla and the charge point (eon) was installed by a Tesla recommended electrician, Thanks

TeslaTap.com | 20 september 2019

The drop off may be normal. As the car gets near 100% the charging rate drops. These charts show the taper for connected to a Supercharger, but the same thing happens with a home charger, but it's flat for the lower 90% or so: https://teslatap.com/articles/supercharger-superguide/#tapered

Tronguy | 20 september 2019

@d.sharma: Sorry to rag on you like this, but: You've got a new car. Read The Manual. I can kind of tell that you haven't, quite.
Look: A Tesla has a maximum charge rate. With a Supercharger, with the car at 20% or so of charge, at 150 kW one can get around 600 Miles of Charge per Hour (Call this MoCpH). That works until one is up around 50% of full charge at which point the car slows down the charge rate to keep the battery from overheating and becoming damaged. By the time it's at 80% the rate of charge is a lot less, I think around 80 MoCpH. (I forget, others will correct me, I'm sure.)
So: I charge at 250V@48A which results in a rate of 45 MoCpH. I'm pretty sure the car gets to the 90% of full charge that I routinely charge to at that 45 MoCpH rate. Going higher than that.. the max rate slows 'way down as one approaches 100% of full charge.
So, you're seeing a significant slow-down. I therefore deduce that you're charging to 100%. And this is why I know you haven't read the manual: The Manual, information on-line, and any number of the people here in the forum will tell you that routinely charging to 100% is a bad idea:
1. It wears out the battery.
2. You don't get any regen braking until the state of charge has dropped some percent.
3. The Manual says to go to 100% _only_ if one is about to go on a long trip.

I charge to 90%; Elon has said that's OK, but there's any number of the maddened crowd around here who will rush in and state that 80% or even 70% is better, for various arguments about battery longevity.

Finally: Was this really a Tesla-certified electrician? While there are people with Chargepoint wall connectors (they're not chargers: The charger is in the car, the box on the wall simply supplies 250 VAC and tells the car how much current it can supply, maximum. The car decides how much current to draw.), they're not wildly popular around here, mainly because a Tesla Wall Connector costs $500 and can do up to 100A with the right breakers. (Mind you, like I said, it's the car that decides what current to draw: SR cars do up to 32A max; LR and up can do up to 48A; and there's variants of the Model S that can do 100A). But the Chargepoints are either (a) less current or (b) more expensive than the TWC for the same current. So: sure about that electrician?

d.sharma | 21 september 2019

I read the manual more than any other - knowing that owning an electric car is very different. From the very first charge I set to 80%, largely for the regen braking. If this was simply a tail off as the battery reaches full charge, why would it happen at 50% charge, and be resolved by unplugging & re-plugging.

kevin_rf | 21 september 2019

Trying to diagnose over the internet without the full details is difficult, if not impossible.

Remember the car monitors the input voltage and will adjust the rate accordingly if there is an issue with your setup.

For instance if you are using the NEMA 14-50 adapter that come with the mobil kit, this may indicate something is not kosher with the outlet you are plugging into and it is getting very hot due to a loose connection. Or you have a ground issue. Actually dropping to 6mph sounds like one of the 2 phase 240v legs is dropping out.

I would get the wiring inspected.

Information that would be helpful:
What are you charging with, mobile kit, wall connector/charger and brand?
Outlet type?
Size of the breaker in the breaker box?
Are you using an extension cord?
What is the voltage and current you are seeing in the car when you start charging?
What is the voltage and current you see when the event occurs?
What is the light pattern on the charger port, the mobile connector?
Is anything getting hot or smoking?

Four instance the NEMA 14-50 should be reading about 240v 32amps 30ish mph while charging. 24-25mph indicates low voltage or current limiting right out of the gate. When at 6mph if a phase dropped out, it might read something like 120v 20ish amps. Will the car even allow that, it just error out?

Get that wiring inspected.

peter.watson51 | 21 september 2019

I wonder if it could be that electrical circuit. Is the receptacle NEMA 14-50? When you first plug the car in, take note of the Voltage as well as the current??

d.sharma | 21 september 2019

Thanks Kevin, that's helpful. I was trying to figure out where to start: connector, lead or car - sound like I need to look at the electrics first. I did contact the installer on Thursday and I'm waiting for them to get back to me. It has reached up to 30 mph when first plugged in: 240v & 32A, current drops off when the rate slows, but I think the voltage stays the same. Nothing feels hot when I unplug. It sounds about right that pehaps the car is protectively dropping the current because of a build up of something that is released when the lead's unplugged. I presume the installer would have checked the house's wiring was OK for the wall connector - but shouldn't presume anything!
I'm not using an extensionI'll look to get more detail next time: light patterns etc. It's an EO Mini Pro connector using a Type 2 connector.
I'll see if I can access a public charger to see if this is associated with any problems to try and isolate the issue to the home unit.
Thanks again

rob | 21 september 2019

It could be as simple as the air conditioner coming on. When I charge my car at work I get about 22 mph. But if it gets hot, the AC will come on and the charge rate will drop to about 5-6mph.

kevin_rf | 21 september 2019

Based on what I can find on the eo mini pro, I assume you are in the UK.

There are some significant differences between the US and UK charging setup. Specifically, it sounds like the Type 2 is an UK Ev specific equivalent of what we in the US use the NEMA 14-50 for.

So one would assume you are going from the car to the eo mini pro with the Tesla type 2 cable. So, no adapters in between.

I like the idea of trying a different charging location, and seeing if it repeats.

d.sharma | 21 september 2019

Thanks Rob, charging in the evening, so it's cool - no overheating problems in Scotland! Thanks again Kevin. If I get to the bottom of things I'll post again for others. Can I ask how you find posts - there doesn't appear to a search function on the forum?