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Only 198 volts on nema 14-50. Yikes!?
- Thread starter DavidM34Me
- Start date
#6 wire is supposed to be OK for up to 100 ft. The most important thing is for the connections at the breaker and the outlet to be perfect and break-ass tight. Also the $50 Hubbell type 14-50 outlets with the double V clamps are necessary instead of the screw clamps on the $9 Levitron types. With lower voltage as long as there are no bad connection hot spots the car will just charge a little slower. At 32 amps all these wires get warm but they shouldn't get hot.
Electrical engineer here: I've glimpsed through the thread and saw you live in an apartment building? There were a few jobs where we designed a 3-phase 120/208V service for apartments because of elevator requirements. This meant that each apartment was served 120/208V single phase power which may be what you have going on as well. If so, you have nothing to worry about and complaining won't get them to change your service voltage.
Changing the service is such a big deal I wouldn't even bother asking about the cost (let alone complaining). I would ask an electrician about installing a 208-to-240 step-up transformer between the panel and the charger, though. The transformer itself is probably under $500. If you do look into either option, I'll be interested to hear how it goes.
gilscales
Banned
Like this?
Larson Electronics - 1 Phase Buck & Boost Step-Up Transformer - 208V Primary - 240V Secondary at 46.8 Amps - 50/60Hz
Interesting that there is no information on the efficiency of this unit.
It's an autotransformer, it's going to be 98-99% efficient. Careful that you do not exceed 80% loading on the primary side if anyone does go the transformer route.
If you're going to go through that much effort though, why not just step up to a big boy voltage like 277Vac?
Here's my car charging at 277Vac. Using a NEMA 14-30 to 7-30 pigtail.
ucmndd
Well-Known Member
It does actually... if it detects too large a voltage drop it automatically backs off the current by 25%.
Good point re stepping up to 277 instead of just 240.
Read this first though. Seems like some conditions apply.
Info from Tesla - 277v feed to Wall Connector (HPWC) - Which Cars Support It
Also: before you spend too much time/money on this, consider that charging 15-30% faster at home doesn't necessarily provide a real benefit. Depending on your driving patterns you might have only two charging scenarios: 1) overnight/top-up, which is already fast enough; 2) in a hurry, the extra 15-30% still isn't enough, you need a supercharger / DC charger anyway.
Read this first though. Seems like some conditions apply.
Info from Tesla - 277v feed to Wall Connector (HPWC) - Which Cars Support It
Also: before you spend too much time/money on this, consider that charging 15-30% faster at home doesn't necessarily provide a real benefit. Depending on your driving patterns you might have only two charging scenarios: 1) overnight/top-up, which is already fast enough; 2) in a hurry, the extra 15-30% still isn't enough, you need a supercharger / DC charger anyway.
I do not think that using step-up transformer is a good idea: the cost of transformer ($500?) will never paid off, couple miles per hour speed up will not make much of a difference, involving extra element to something what should be as simple as possible does not make it more reliable, higher amperage load on probably already weak line, additional loses in the transformer itself (do not forget that very powerful transformers have effectiveness of 95-98% with optimal load, less powerful has usually less effectiveness), additional terminals, wires and so on. How often OP have to full charge overnight? As OP already said, he is on 208V line, so there are no any issues really.
So update on my situation:
When I plug in my car, it starts at 6/6 amps out of a total of 32 amps. Around 203-204V.
After a few minutes it gets going and goes to its max of 32/32 amps. The volts drop to around 192-193.
After a few minutes it drops to 16/16 amps at 198 volts where it remains for the rest of the charge.
I cannot get back up to 32 amps.
What the heck is going on? I am unable to charge at the maximum amps for more than a few minutes before it auto drops to 16/16 amps!
When I plug in my car, it starts at 6/6 amps out of a total of 32 amps. Around 203-204V.
After a few minutes it gets going and goes to its max of 32/32 amps. The volts drop to around 192-193.
After a few minutes it drops to 16/16 amps at 198 volts where it remains for the rest of the charge.
I cannot get back up to 32 amps.
What the heck is going on? I am unable to charge at the maximum amps for more than a few minutes before it auto drops to 16/16 amps!
You've definitely got something else going on. A 32A load on #6 wire, 120' away should only have a drop of 3.4V or 1.6% so you are losing a good deal more than that. My thought is that your car is seeing this large drop and limiting your charging. You should definitely have the electrician come by and check it out.
It looks like the voltage drops too low, so software limits the current.
The run is about 300-400 feet (I live in a condo and am estimating, I looked again today).
I turned on Tesla app notifications and about every hour I am getting a “charge interrupted” notification.
When I check the app it says 0/16 amps and after a few minutes ramps back up to 16 amps.
Really bizarre. I live in a condo and these are free commercial chargers like ChargePoint. I hope it won’t damage my car.
I do not think that software is smart enough to know that you on a 208V line and deal with it as if you were on a 240V line. So, in reality the drop is about 5-6V which is fine, but software does not think so. Try to limit current to 24A or find the maximum amperage what software still allow you to charge with, it could be still good enough for you.
I thought you were the OP when I did my numbers, being on the Chargepoint is different. I'd have to know your wire size and amp load on the charge point to tell you if it's where it needs to be. I am fairly positive you won't have damage to your car, but something about that install is not right.
I have heard recently that the stalls that can charge 2 cars require two separate circuits. If you don't supply it with two, when a second car plugs in the output cuts in half. Maybe that's the issue?
The system that detects voltage fluctuations (and responds by limiting current) must be aware of the incoming voltage. That's one reason why it starts low and ramps up. If it weren't smart enough to know whether the initial/nominal voltage was 208 or 240, it would be useless for detecting voltage fluctuations on a 240 circuit.
El0n it sounds like your car's "too much voltage drop" threshold is around 11V, which agrees with my "max 10V" guess above. If you're hitting this, I agree with mmiketa, something isn't right.
Can you tell what size the wire is? I'd expect #2 for a 400 foot feed, or #4 for a 300 foot feed, assuming it's a dedicated circuit for a single 32A charger. #6 would be too small, and would probably cause what you're seeing.
El0n it sounds like your car's "too much voltage drop" threshold is around 11V, which agrees with my "max 10V" guess above. If you're hitting this, I agree with mmiketa, something isn't right.
Can you tell what size the wire is? I'd expect #2 for a 400 foot feed, or #4 for a 300 foot feed, assuming it's a dedicated circuit for a single 32A charger. #6 would be too small, and would probably cause what you're seeing.
It sounds like the issue for El0n is that this is a load sharing charger, and someone else is using the other charging station, or there is some other load on the circuit. El0n is not on NEMA 14-50, they are using a commercial EV charger.
It's probably not the car that is limiting the current. The car does not drop to 50% right away when Vsag is too large, it tries 25% first. Could also be a time of day setup, maybe the charger limits current depending on how much electricity costs.
Regardless, this isn't going to damage your car, so I wouldn't worry about it too much.
It's probably not the car that is limiting the current. The car does not drop to 50% right away when Vsag is too large, it tries 25% first. Could also be a time of day setup, maybe the charger limits current depending on how much electricity costs.
Regardless, this isn't going to damage your car, so I wouldn't worry about it too much.
It’s a residential charging station. I wouldn’t even know how to contact an electrician nor is it my responsibility to do so - but if anyone thinks this is dangerous I will for sure contact the manager.
If the only issue is a “slower” charge - then I don’t mind as I plug it in overnight and don’t care much for the speed. Rather have it trickle in overnight than charge super fast and be done at midnight and then sit around.
Are you guys certain this won’t damage my car? Or just assuming it won’t?
If the only issue is a “slower” charge - then I don’t mind as I plug it in overnight and don’t care much for the speed. Rather have it trickle in overnight than charge super fast and be done at midnight and then sit around.
Are you guys certain this won’t damage my car? Or just assuming it won’t?
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