HPWC Charge handle temperature @ 80 amps

[Cottonwood]

Be aware that you can't rely on an IR thermometer to tell you the temperature of a black surface. Its emissivity is calibrated at 0.95 (which is about what an opaque white surface is.) To get around this, you can use a small amount of tip-ex or white correction fluid on the point you want to measure.

I beg to differ. You want black, not white.

0.95 emissivity is what you get with a good, black, opaque, non-reflective object, like black masking tape. For better accuracy, put some black masking tape on the object. The flat, black surface of the HPWC handle is probably pretty good, but the reflective, metallic parts are really bad for an IR temperature measurement. Also, distance spot ratio is really important. For an inexpensive IR Thermometers with a distance spot ratio of 8:1, you need to be 4" away to get a 0.5" diameter measurement spot.

From IR Thermometers & Pyrometers - Omega.com:

One way to determine emissivity experimentally is by comparing the radiation thermometer measurement of a target with the simultaneous measurement obtained using a thermocouple or RTD. The difference in readings is due to the emissivity, which is, of course, less than one. For temperatures up to 500°F (260°C) emissivity values can be determined experimentally by putting a piece of black masking tape on the target surface. Using a radiation pyrometer set for an emissivity of 0.95, measure the temperature of the tape surface (allowing time for it to gain thermal equilibrium). Then measure the temperature of the target surface without the tape. The difference in readings determines the actual value for the target emissivity.​

 

[tom66]

I do thermal testing at work, we use white tip-ex.

Actually come to think of it, it's more because we know the emissivity of white paint, rather than the emissivity of black rubber/plastic. It's a lot more dependable. (We used to use specialist thermal correction fluid, but came to realise tip-ex was basically the same stuff at a tenth the price.)

 

[Cottonwood]

I do thermal testing at work, we use white tip-ex.

Actually come to think of it, it's more because we know the emissivity of white paint, rather than the emissivity of black rubber/plastic. It's a lot more dependable. (We used to use specialist thermal correction fluid, but came to realise tip-ex was basically the same stuff at a tenth the price.)

I agree that a known emissivity is the key, but I have always been taught that dark and non-reflective got you closer to the 0.95 built into most units. What emissivity do you use for the "tip-ex" and how big a patch do you paint?

 

[Lloyd]

Well that does sound useful - and just cheap enough that I would probably impulse buy one if I saw one in an electronics store (or Canadian Tire for those who know it). Sounds like I have the perfect excuse to buy one now - and some "White out"/"Tipex" - assuming one can actually still buy that stuff.

Amazon.com: Nubee® Temperature Gun Non-contact Infrared Thermometer w/ Laser Sight: Kitchen Dining

 

[tom66]

I agree that a known emissivity is the key, but I have always been taught that dark and non-reflective got you closer to the 0.95 built into most units. What emissivity do you use for the "tip-ex" and how big a patch do you paint?

We use 0.95.

 

[SarahsDad]

Heh. Another case of awesome if not somewhat spooky Tesla service. I posted my 190 degree HPWC cable pix above at 10:30 last night.
Got an unsolicited call from the service center today, wants to send a tech out tomorrow (Saturday) to see if it needs to be replaced.
Stalker-esque but pretty damn good service.

 

[SarahsDad]

...and a Ranger came by the house yesterday, confirmed the overheating cable, switched out for a new cable, and now max temps only around 120-130F. Awesome service.

 

[redi]

I had to unplug mid-charge to depart for a mission and found the handle/cable area hot, and measured it at 135F while charging at 51A (in-car setting). My garage ambient temp is 80F. The rest of the cable was not hot at all, neither was the HPWC on the wall or the breaker. I usually don't run my HPWC at 80A, although it is configured to support that and is on a 100A CB.

Tesla has a ranger coming next week to replace the cable.

What is the "normal" peak handle temp for most folks running 80A?

Thanks. Sorry to zombie-up the thread.

 

[FlasherZ]

I had to unplug mid-charge to depart for a mission and found the handle/cable area hot, and measured it at 135F while charging at 51A (in-car setting). My garage ambient temp is 80F. The rest of the cable was not hot at all, neither was the HPWC on the wall or the breaker. I usually don't run my HPWC at 80A, although it is configured to support that and is on a 100A CB.

Tesla has a ranger coming next week to replace the cable.

What is the "normal" peak handle temp for most folks running 80A?

Thanks. Sorry to zombie-up the thread.

Tesla told me they expect max temp to be 140, anything more and it needs to be cleaned/replaced.

 

[islandbayy]

I've hit 180+ *F at Superchargers.

I think I did narrow it down to Charge Port, or possibly my charge port is going flaky and not working right due to the extreme temps it has been being fed.

 

[redi]

135F at 51A is hot enought that I would be a little leery to crank it up to 80A. A few weeks ago the Supercharger handle was warm, but not any worse than it is now.

I am packing my thermal gun for the next XC trip.

 

[spentan]

Has this been resolved? I just got a HPWC last week and had it wired up.

Will be charging at 80A, so wanna make sure that I don't get burnt haha

 

[FlasherZ]

Has this been resolved? I just got a HPWC last week and had it wired up.

Will be charging at 80A, so wanna make sure that I don't get burnt haha

New HPWC's typically don't have this problem. After a while, the contacts seem to get loose and/or dirty and the temp goes up.

 

[Khatsalano]

I have duals and an HPWC from February 2015. Yup, it will get warm at 40A-64A. It will get hot at 80A. It's not hand-burning hot, but it definitely enough to surprise you the first time. If you mind it for comfort grip reasons, stop charge and wait 60 seconds to unplug. It cools quickly.

Even supercharger handles get hot too if you unplug around 50-70% SOC from a 10-20% SOC since it's still at a very high charge rate.

- K

 

[AmpedRealtor]

My service center says that hot HPWC cords and handles are perfectly normal. In fact, they get so hot here in Arizona that the Tesla Gallery in Scottsdale will not allow anyone to charge at their HPWC after hours due to this issue. A Tesla employee must be the one plugging/unplugging the HPWC for liability reasons, at least that's what they told me. Hot handles at 80A seem to be the norm, and the unit is operating as designed.

 

[davewill]

... A Tesla employee must be the one plugging/unplugging the HPWC for liability reasons, at least that's what they told me. ...

What a brain dead comment on their part. They sell these for people's homes. It is supposed to be OK so long as you burn yourself at home?

 

[Lloyd]

The real reason from other sales sites is that the HPWC's are also used for charging the demo cars. Owners were plugging in and the demo cars were having a hard time getting charged for test drives. Employees from Tesla wanted to go home, and they had to stay and wait for an owner to unplug so the demo car would be charged for a test drive in the morning. I was told it was easier for them just to take over the HPWC's and regulate who charged.

 

[AmpedRealtor]

What a brain dead comment on their part. They sell these for people's homes. It is supposed to be OK so long as you burn yourself at home?

It sounds like someone complained and made a stink about it, I can't think of any other reason why they would have this policy. It makes no sense, to me anyway, why an HPWC should sit idle after hours just because some douche complained about the hot handle.

 

[ERP]

Its really not surprising the cable gets so hot. Tesla is pushing the limits of the wiring at 80 amps and has given us all electrical space heaters in our garage. The size of the wire inside the power cable is 6 awg, and 80 amps is right at the recommended limit of constant draw. With some quick calculations from this handy site (http://photovoltaic-software.com/DC_AC_drop_voltage_energy_losses_calculator.php) the wasted energy in just the 25 ft cable is ~130 watts.

It disappointing that the cable is so wasteful, especially in the summer when my garage does not need the extra heat. But when you figure out the cost you can see why Tesla didn't opt for larger wiring.

I charge an average of 1 hour a day at 240 volts and 80 amps. Each month that translates to 4.1 kWh of wasted electricity, and at my current electrical rate it costs me $0.42 to heat the cable. Before I finished this calculation I was considering shortening the power cable by 15 ft to reduce energy waste and to tidy up that garage since I do not need 25 ft to reach the charge port. This would save me 83 watts and a whopping $0.26 a month. So I see why Tesla kept their cost down by minimizing the wire gauge, the wasted energy simply doesn't cost much. 2 gauge wire would cut the loss in half but costs 4-6 times more per ft.

I used my Seek thermal camera attachment to take these pictures.

 

[redi]

135F at 51A is hot enought that I would be a little leery to crank it up to 80A. A few weeks ago the Supercharger handle was warm, but not any worse than it is now.

I am packing my thermal gun for the next XC trip.

My HPWC cable was replaced thanks to the good folks at Tesla. At 80A the handle/cable junction area could get to about 160F after ~~10 minutes charging in a 85F garage. The new cable gets to 105F-106F at that same place at 80A, farther down the cable a couple feet it gets to 120F. A good fix. Keeping an eye (and thermal gun) on it for a while. And will probably not normally charge > 52A unless I feel the need to hurry the charge.