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Fair enough. I'll install a 14-50 outlet as a temporary measure. The 6-50 seemed better, but from what I'm hearing, those adapters are currently backordered. Thanks, Scott!
pilotSteve
Active Member
My HPWC is powered by a 100A breaker in my garage's 125A panel. The only significant other loads on this panel are two heat pumps.
I've not observed any problems with the HPs or garage lights, etc. No dimming or anything like that. However as my HPWC ramps up toward 80A the voltage drops from 240 to 232 and charges max at 79/80 amps, which is 18kW, not the full 20kW I would like. My electrician suggested I call the power company to check the transformer and feed.
Came out today and tested my (underground) service which is served along with one or two other houses by a 75kVA (I believe thats what he said). He measured "normal" loads with a tester and said voltage was good at 120 per leg.
So then I said I would crank up the HPWC. He attached current camps on the underground main feeds and saw about 17A load from the house. As the HPWC ramped up to 79A he started stuttering whoa whoa whoa and noted total load was now 95A which corresponds perfectly to 17+79. Both on the Tesla and on his meter the voltage had dropped to about 231-233 VAC.
Utility guy's assessment is that I may need a separate meter/feed for the garage. He felt the transformer was very adequate size but that my underground feed wires might be undersized. (I have a large house with two 200A panels and the 125A panel for the garage). He is going to ask the utility company engineers what they think.
The only anomalous behavior I see anywhere is the voltage drop when charging and the HPWC (probably smartly) limiting to 79A/18kW.
Any comments? Should I be concerned or not?
I've not observed any problems with the HPs or garage lights, etc. No dimming or anything like that. However as my HPWC ramps up toward 80A the voltage drops from 240 to 232 and charges max at 79/80 amps, which is 18kW, not the full 20kW I would like. My electrician suggested I call the power company to check the transformer and feed.
Came out today and tested my (underground) service which is served along with one or two other houses by a 75kVA (I believe thats what he said). He measured "normal" loads with a tester and said voltage was good at 120 per leg.
So then I said I would crank up the HPWC. He attached current camps on the underground main feeds and saw about 17A load from the house. As the HPWC ramped up to 79A he started stuttering whoa whoa whoa and noted total load was now 95A which corresponds perfectly to 17+79. Both on the Tesla and on his meter the voltage had dropped to about 231-233 VAC.
Utility guy's assessment is that I may need a separate meter/feed for the garage. He felt the transformer was very adequate size but that my underground feed wires might be undersized. (I have a large house with two 200A panels and the 125A panel for the garage). He is going to ask the utility company engineers what they think.
The only anomalous behavior I see anywhere is the voltage drop when charging and the HPWC (probably smartly) limiting to 79A/18kW.
Any comments? Should I be concerned or not?
I have almost exactly the same setup with the exception of a 200 amp subpanel. I have the same drop almost 246 to 235 v. I asked FlasherZ what he thought of the drop in a pm, and this is his answer so he does not have to post again:
It's tolerable. Usually you try to keep it under 3%, but at 4.5% it's nothing I would worry too much about.
The HPWC uses very premium 105 deg C, #6 wire rated for 80A continuous operation. This generates just over 1% drop across its 25 ft.
The remaining 3% drop could be attributable to a long run from the subpanel. If that's close, then we look at how far your transformer is and what your main service size is (and its cabling). If that's close, then we start looking at the loading on the transformer that would raise its resistance.
Either way, I wouldn't worry at all unless we start to go over 5-6%.
It's tolerable. Usually you try to keep it under 3%, but at 4.5% it's nothing I would worry too much about.
The HPWC uses very premium 105 deg C, #6 wire rated for 80A continuous operation. This generates just over 1% drop across its 25 ft.
The remaining 3% drop could be attributable to a long run from the subpanel. If that's close, then we look at how far your transformer is and what your main service size is (and its cabling). If that's close, then we start looking at the loading on the transformer that would raise its resistance.
Either way, I wouldn't worry at all unless we start to go over 5-6%.
pilotSteve
Active Member
Lloyd - can you get the full 80A/20kW charge from your HPWC? Mine always stops at 79A (out of 80) and 18kW. I assumed amps were being limited by the HPWC noticing the voltage drop. 79A@232V is 18.3kW, while 80A@240V would be 19.2kW. Rounding notwithstanding I thought some people had posted photos showing 20kW.
It's pretty normal for PoCo's to undersize cables and transformers, they're permitted to by the PUC as they've standardized on 200A service minimums, etc. Voltage drops on large cables really don't become a concern until your loads begin to reach the maximums, and since that's rare, it's not too much of an issue.
One word of advice to you: be sure you check out what the power company's responsibilities are in this case. My PoCo charges $34/month for an extra meter. My PoCo is also responsible for the cabling from their transformer to my meter. So if they try to pressure you for an additional meter service, be sure you ask about impact to your bills. If they'll give you a second meter for free, it might be a way to alleviate it, but if they want to charge, tell them just to make the existing cable bigger.
Just to share some more from Lloyd's calculation, when I add up the voltage drops for his transformer-to-service-panel, service-panel-to-subpanel, subpanel-to-HPWC, and HPWC-to-car spans, I get exactly (within .1%) what he's seeing. Unless you're seeing voltage sagging below 228V, I wouldn't worry.
I still do not have my HPWC, and since I do not have twin chargers, I was only really buying it for convenience and looks.
I only plug in a couple of times a week at home, so it's really not $1200's worth (plus shipping!) of inconvenience. On the assumption they'll eventually sell the UMC (for $500 I think I read?), has anyone succeeded in cancelling their HPWC order?
I only plug in a couple of times a week at home, so it's really not $1200's worth (plus shipping!) of inconvenience. On the assumption they'll eventually sell the UMC (for $500 I think I read?), has anyone succeeded in cancelling their HPWC order?
Hank42
Legacy Supporter
pilotSteve
Active Member
Thank you FlasherZ for the advice and calculations. Makes good sense to me, I feel the PoCo guy was over reacting a bit.
I believe 4.3 toned down the draw just slightly as there were some reports of fuses blowing internally in the HPWC that had to be replaced. I see the Amps stay mainly at 79 but bouncing occasionally on 80. It is due to the voltage drop and is fully normal. 18 kw is still a ton on power!! I believe that what you are seeing is correct and proper.
Hank42
Legacy Supporter
There really is not much to it. I think the OpenEVSE is on par, if not superior in several aspects.
lolachampcar
Well-Known Member
Darren,
I am using the contacts for scale and I think the 100 amp inductive load contractor I used for my OpenEVSE is as big as the HPWC! Ooooops, I think I got carried away.
I am using the contacts for scale and I think the 100 amp inductive load contractor I used for my OpenEVSE is as big as the HPWC! Ooooops, I think I got carried away.
From a flexibility standpoint, the OpenEVSE has some superiority because of its intelligence, you could put any number of features in it to present charge current under different circumstances.
However, in true Aluminum EVSE fashion (think "Iron Chef"), the scores are more than just that.
The charge port opening button gets a big advantage IMO, and the styling to match gets a point or two.I received the tracking number for my HPWC. It will be delivered in Anchorage tomorrow (3/29). So, the 48 hour window within vehicle delivery was accurate. I'm surprised. My S is currently cruising (or being barged) home...
Wow, that's really surprising. I guess Tesla really isn't sending the HPWC's in any kind of logical sequence. Oh well, NEMA 6-50 is working just fine for now.
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