any reason why a new 12A outlet in a garage keeps tripping, and why is my Amps keep changing after supercharging

[drtimhill]

How many years of 'inefficient' charging will it take before it equals the installation cost of a dedicated 240V line, breaker and Tesla WC?

As of course you realize there are way too many variables to generalize. First there is how much you drive every day, then there is the cost of electricity in your area (and what times of day you charge). There is also the cost of installation (cost me $500), which varies a LOT depending on local needs. Finally, of course, there is the convenience aspect .. is is worthwhile convenience having faster home charging even if there is some additional outlay?

And btw the “inefficiency” here is not small .. I’ve forgotten the actual numbers (there are many threads here discussing this) but with a cold battery you may not get ANY charging for quite some time after plugging the car in. We’re talking DOUBLE the electricity costs in some cases.

 

[jjrandorin]

I haven't done the numbers, but an educated guess is probably thousands of days. The inefficiencies aren't that bad. They may even be less than your water heater inefficiencies.

Wouldnt it depend on the cost of electricity where the car is (since it keeps the car awake)? Where I am, for example, it could be the difference between charging during super off peak rates and having the car charge during peak rates.

its not much different than running Sentry mode all the time (both keep the car awake).

 

[davewill]

The mobile connector limits the car to 12a on a standard wall plug, so the idea the supercharging set the car to a "high amperage" really makes no sense.

 

[Cosmacelf]

Let’s see. A years worth of charging to go 12,000 miles at say an efficiency of 0.3 kWh per mile is 3,600 kWh of energy needed. Charging overhead is 0.5 kW while charging (500 watts).

Let try charging at 48A/240V (60A breaker). That's 11.5 kW, but 0.5 kW is overhead, so only 11 kW goes into the car. 3,600 kWh / 11 kW = 327 hours of charging. My current super off peak rate is around $0.14/kWh now, so that's 327 * 11.5 * .14 = $526 of electricity for a year's worth of driving.

Charging at 12A/120V only gives you 1.4 kW of power, but 0.5 kW is overhead, so you are putting in 0.9 kWh every hour. To get 3,600 kWh, you charge for 3600 / 0.9 = 4000 hours. Now, only 6 hours out of 24 are super off peak, the rest is a mixture of peak and semi-peak. But you'll for sure be charging for all 6 hours of super off peak, and then a mix. So let's say 34% charging at $0.14 and 66% charging at $0.40. These are roughly correct for California.

So 4,000 hours at 1.4 kW * (.34*0.14 + .66*.40) = $1,745 in electric costs for one year of charging.

In other words, if you drive 12,000 miles in CA with time of use rates, you'll end up spending an extra $1,219 charging from a 15A receptacle rather than charging from a 60A breaker Wall Charger.

 

[DuncanM]

Let’s see. A years worth of charging to go 12,000 miles at say an efficiency of 0.3 kWh per mile is 3,600 kWh of energy needed. Charging overhead is 0.5 kW while charging (500 watts).

Let try charging at 48A/240V (60A breaker). That's 11.5 kW, but 0.5 kW is overhead, so only 11 kW goes into the car. 3,600 kWh / 11 kW = 327 hours of charging. My current super off peak rate is around $0.14/kWh now, so that's 327 * 11.5 * .14 = $526 of electricity for a year's worth of driving.

Charging at 12A/120V only gives you 1.4 kW of power, but 0.5 kW is overhead, so you are putting in 0.9 kWh every hour. To get 3,600 kWh, you charge for 3600 / 0.9 = 4000 hours. Now, only 6 hours out of 24 are super off peak, the rest is a mixture of peak and semi-peak. But you'll for sure be charging for all 6 hours of super off peak, and then a mix. So let's say 34% charging at $0.14 and 66% charging at $0.40. These are roughly correct for California.

So 4,000 hours at 1.4 kW * (.34*0.14 + .66*.40) = $1,745 in electric costs for one year of charging.

In other words, if you drive 12,000 miles in CA with time of use rates, you'll end up spending an extra $1,219 charging from a 15A receptacle rather than charging from a 60A breaker Wall Charger.

I get about 1.2% SOC per hour increase whilst charging my M3 RWD at ~8A/110v in our condo so I know that the charging overhead is somewhat less than 500w and my estimate is about 250-300w

My M3 has a max L2 charge rate of 7.6kw at 240v/32a but it would be about 6.7kw in the condo because it's 208v.

3600kw/365 = 9.9kw/day

For me, with a fixed rate at 10 cents/kw I would need ~15hrs of charging vs 1.5hours so about 4kw (13.5H X ~300W) lost per day to overhead or about $150/yr at 10 cents/kwh versus an install cost of a dedicated 208v line and TWC of ~$3000.
~1,5 hours charging at
(15 - 1.5) = 13.5 hours difference at 8a/110v = ~4kw lost to overhead

7 hours difference at 12a/~120v (house) = ~2kw/day lost

~4.5 hours difference at 16a/~120v (house = ~1.4kw/day lost

~2 hours per day difference at 16a/240v = 600w/day lost

 

[Cosmacelf]

I get about 1.2% SOC per hour increase whilst charging my M3 RWD at ~8A/110v in our condo so I know that the charging overhead is somewhat less than 500w and my estimate is about 250-300w

My M3 has a max L2 charge rate of 7.6kw at 240v/32a but it would be about 6.7kw in the condo because it's 208v.

3600kw/365 = 9.9kw/day

For me, with a fixed rate at 10 cents/kw I would need ~15hrs of charging vs 1.5hours so about 4kw (13.5H X ~300W) lost per day to overhead or about $150/yr at 10 cents/kwh versus an install cost of a dedicated 208v line and TWC of ~$3000.
~1,5 hours charging at
(15 - 1.5) = 13.5 hours difference at 8a/110v = ~4kw lost to overhead

7 hours difference at 12a/~120v (house) = ~2kw/day lost

~4.5 hours difference at 16a/~120v (house = ~1.4kw/day lost

~2 hours per day difference at 16a/240v = 600w/day lost

Ah, BC Hydro, CDN$0.10/ kWh fixed throughout the day? Luxury!

 

[DuncanM]

Ah, BC Hydro, CDN$0.10/ kWh fixed throughout the day? Luxury!

BC Hydro is floating the idea of 5cents/kw off peak charging for house owners, in exchange for ~15 cents peak time charging:

The new rate we've applied for is an optional time-use-rate for residential customers.

With this rate, you'll still be billed for your total electricity use in a billing period at the existing two-tier residential rate. Then, you'll get a credit of 5 cents per kilowatt hour (kWh) for electricity used overnight (11 p.m. to 7 a.m.) and you'll be charged an additional 5 cents per kWh for electricity used during the on-peak peak period (4 to 9 p.m.). No credit or additional charge will be applied to usage during the off-peak period (7 a.m. to 4 p.m. and 9 to 11 p.m.)

This proposed rate could help you save on electricity costs if you shift some of your usage to off-peak periods. It's particularly beneficial to those who charge an EV at home and can charge overnight. You could also save money by shifting other household usage outside of the peak period, such as laundry and dishwashing. Current rate design activities

 

[ewoodrick]

Let’s see. A years worth of charging to go 12,000 miles at say an efficiency of 0.3 kWh per mile is 3,600 kWh of energy needed. Charging overhead is 0.5 kW while charging (500 watts).

Let try charging at 48A/240V (60A breaker). That's 11.5 kW, but 0.5 kW is overhead, so only 11 kW goes into the car. 3,600 kWh / 11 kW = 327 hours of charging. My current super off peak rate is around $0.14/kWh now, so that's 327 * 11.5 * .14 = $526 of electricity for a year's worth of driving.

Charging at 12A/120V only gives you 1.4 kW of power, but 0.5 kW is overhead, so you are putting in 0.9 kWh every hour. To get 3,600 kWh, you charge for 3600 / 0.9 = 4000 hours. Now, only 6 hours out of 24 are super off peak, the rest is a mixture of peak and semi-peak. But you'll for sure be charging for all 6 hours of super off peak, and then a mix. So let's say 34% charging at $0.14 and 66% charging at $0.40. These are roughly correct for California.

So 4,000 hours at 1.4 kW * (.34*0.14 + .66*.40) = $1,745 in electric costs for one year of charging.

In other words, if you drive 12,000 miles in CA with time of use rates, you'll end up spending an extra $1,219 charging from a 15A receptacle rather than charging from a 60A breaker Wall Charger.

The car NEVER uses electricity when not charging? I'm pretty sure that mine does. Your calculations don't seem to include that. So the 0.5 kWh that you only assume is used when the car is actively charging may not be quite right.
You also seem to think that the overhead is consistent. I don't believe that it is. Depending on the battery temperature, the fans can run at different speeds or be off.

And at my HIGHEST rate, for 4,000 kWH (~12,000 miles) I'd ONLY pay $640. (sure, I didn't include the inefficiencies here, but then again, my winter rate is half that much). Not sure how I can save anywhere near $1,200.

 

[ewoodrick]

BC Hydro is floating the idea of 5cents/kw off peak charging for house owners, in exchange for ~15 cents peak time charging:

I'd recommend running away from the rate, unless it is ONLY for EV charging and not whole house.
The amount that you are going to save when your existing is only $0.10 just isn't going to be worth it.

 

[@heist80]

the local tesla and highly rated electrician company charges $1400 to install a tesla wall charger (including parts supposedly)

factor that into the fact i may be here 1 year only as a renter, 2 years tops. 3 years highly unlikely but possible. so then i would have to either leave it here or take it with me which will cost another $300-500 for an electrician to come back out and disconnect it then re-install it in the new home. i can tell you that charging during off peak is no more than 12c per hour, and i get 6mph charging.

now do the math is it still worth it? hell no.

 

[@heist80]

The mobile connector limits the car to 12a on a standard wall plug, so the idea the supercharging set the car to a "high amperage" really makes no sense.

which is the point of the thread. i'm trying to figure out why it happened.

it kept trying to charge at 25amps or something and kept tripping. when i manually dropped the amps down to 5amps it stopped tripping, then i manually took it up to 12a and it charged fine. but a few days later out of nowhere it tripped again. the great mystery has yet to be solved, i have a guy who was supposed to come out yesterday to take a look at it but he never even called.

and last night i charged it for 5 hours then right before i hit 89% charge out of nowhere the thing trips again, then kept tripping over and over. so i left it alone. today i plugged it up and like magic it is charging fine. maybe it just gets too hot and then trips? but the weird thing is that it seems to always happen at night, like around 8-10pm where the tripping issues happen.

ah 1st world problems

looking back wish i would have gotten into being an electrician or AC guy, it would have saved me a fortune in $$$ but also saved a lot of hassle

 

[jjrandorin]

and last night i charged it for 5 hours then right before i hit 89% charge out of nowhere the thing trips again, then kept tripping over and over. so i left it alone. today i plugged it up and like magic it is charging fine.

This particular symptom is fairly characteristic of something overheating, especially the "charged for 5 hours, then trips, then kept tripping". Nothing about that sounds normal, or safe actually. I certainly wouldnt be just plugging it back in later, but I also have a healthy respect for the fact that electrical problems can burn down a house.

 

[@heist80]

This particular symptom is fairly characteristic of something overheating, especially the "charged for 5 hours, then trips, then kept tripping". Nothing about that sounds normal, or safe actually. I certainly wouldnt be just plugging it back in later, but I also have a healthy respect for the fact that electrical problems can burn down a house.

so my house is gonna burn down now?

you sound like those oil loving boomers who keep claiming how dangerous tesla's are and how they blow up and all that.

good advice on not plugging it in. i merely did it to see what would happen. but no i didn't just leave it plugged in and then go to sleep

as i said earlier, the guy is supposed to come out and look at it. if/when i get an answer i will share it.

 

[jjrandorin]

so my house is gonna burn down now?

you sound like those oil loving boomers who keep claiming how dangerous tesla's are and how they blow up and all that.

good advice on not plugging it in. i merely did it to see what would happen. but no i didn't just leave it plugged in and then go to sleep

as i said earlier, the guy is supposed to come out and look at it. if/when i get an answer i will share it.

People normalize electricity all the time, by "plugging in" even when there is evidence they shouldnt (like a breaker tripping multiple times). I am not sure where you got I am saying teslas are dangerous, I have 2 of them, tesla solar and tesla powerwalls in my garage. I AM saying though, that plugging into a shared circut isnt necessarily a good idea... ESPECIALLY when its telling you that something is wrong by repeatedly tripping.

Electrical problems are the cause of a lot of house fires, yes. if you want to take that risk go ahead, but know that you ARE taking a risk, especially because the symptoms are telling you there is a problem.

In any case, since you seem to want to lash out at people who are simply trying to give you advice, I will just wish you good luck.

 

[davewill]

it kept trying to charge at 25amps or something ...

What I'm saying is that I simply don't believe that. That particular observation is incompatible with everything we've ever seen happen when charging Teslas using a mobile connector with the standard 5-15 adapter. What does happen sometimes is that people will see the car is set to a higher amperage before plugging the cable in, which makes sense because the car has no way to know what amperage is available before you plug it in, and report that. Once you're actually plugged in and charging, it will be limited to 12a.

What seems obvious is that your outlet isn't really capable of supporting 12a 120v charging, and you need to determine what the issue is before using it any more. It could be other appliances on the circuit, it could be poor connections, it could be a subpar or worn outlet, or some other issue. Ignore it at your own peril.

 

[ucmndd]

it kept trying to charge at 25amps or something.

No, it didn’t. Your conclusion that what you’re experiencing is in any way related to supercharging or the car trying to draw more than 12 amps is nonsense.

 

[ewoodrick]

so my house is gonna burn down now?

you sound like those oil loving boomers who keep claiming how dangerous tesla's are and how they blow up and all that.

good advice on not plugging it in. i merely did it to see what would happen. but no i didn't just leave it plugged in and then go to sleep

as i said earlier, the guy is supposed to come out and look at it. if/when i get an answer i will share it.

The answer is absolutely, positively, yes.

Ever heard of a small space heater burning a house down? I hope so, since they do kill many people each year.

That's EXACTLY what this is, except that you are talking about something pulling a LOT more current.

A loose wire can easily spark and catch the wall on fire. A wire can have problems, something as simple as an accidental nail piercing the wire that changes the resistance and can become a hot spot that becomes hot enough to cause combustion.

It's not a boomer thing, it's scientific fact that's easy to show and prove.

Remember that space heater that I just talked about? Know how it works? It has a wire that is too small to carry the load and is just on the verge of melting. That's exactly what can happen behind the walls.