Chevy Bolt EV Forum banner

1 - 20 of 27 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Hi, all:

Newbie here - new to the Forum, new to EVs, new to the Bolt, and new to my new AV TurboDX 32A home charging station just installed today and using for the first time tonight to charge my Bolt from 63% battery to 100%.

I've noticed the following: The wall charger unit is warm (blue light blinking slowly, as expected). The cable from the unit to the charge port is warm. The Bolt itself in the vicinity of the chargeport is warm. From the charging stats, it seems the car pulled around 25 to 30 amps at the beginning, but has slowed down as it reaches full charge. Some fan inside the car cycles on and off slowly - otherwise, no odd noise. No unusual notices from the car display. Charge time is around 3-3/4 hours which seems about right. All of this seems normal as far as I can tell.

My question for the more experienced here is that the 40A breaker (on an unused 50A circuit for an electric range in a 200A panel) is almost too hot to touch. I don't know what the temperature is, but I can't lay my palm across the exposed face of the breaker plastic body for more than 10 secs without it being too uncomfortable to continue. There is no hot or burning smell - no vibration or buzz. It is just hot.

Is this normal? The breaker temperature has not increased while I've been watching it tonight. If anything, the temps seems to be moderating a bit as the car pulls less and less current toward full.

Thanks for any advice you can all provide. Just looking to know if I need to call the electrician back out.

PS: If this question has already been answered, feel free to direct me to the right discussion.

PPS: What a great car! It is like the diff between a rotary phone and a smartphone. Not likely to buy a gasoline car ever again.
 

·
Registered
Joined
·
2,364 Posts
googled that number. 90F per UL.

Also googled that 140F is temp that someone can touch up to 5 seconds.

I'd get someone to look at the torque on your breaker connectors. Other issue that can happen is the breaker is not making good contact on the bus bar. Wrong matching breaker. Make sure you have the same manufacturer of the breaker as the power center.
 

·
Registered
Joined
·
49 Posts
The acceptable operating temperature of a circuit breaker is defined by UL in the UL489 standard (June 2011), which is listed below.
  • Terminations for standard rated breakers: UL 489 Paragraph 7.1.4.2.2 says the temperature rise on a wiring terminal at a point to which the insulation of a wire is brought up as in actual service shall not exceed 50°C (90°F).
  • Terminations for 100% rated breakers: UL489 Paragraph 7.1.4.3.3 says the temperature rise on the termination shall not exceed 60 deg. C (108 deg. F).
  • Handles, knobs and other user surfaces: UL489 Paragraph 7.1.4.1.6 says the maximum temperature on handles, knobs, and other surfaces subject to user contact during normal operation shall not exceed 60°C (140°F) on metallic and 85°C (185°F) on nonmetallic surfaces.
The circuit breakers in my house have nonmetallic faces/trip levers, so they fall under the 85C (185F) catagory. This info was taken from a Schneider Electric FAQ webpage.
 

·
Registered
Joined
·
102 Posts
I'm no expert...so that's out of the way...is this a separate subpanel with a 40A breaker attached to a 50A breaker in your main panel? Could be cable size from the main to that 40A breaker. Could be cable length for that size and desired power draw between the main and 40A breaker.
 

·
Registered
Joined
·
456 Posts
I'd suggest
a) tighten the screws in the buss inside the box, after removing the panel cover. Use a screwdriver with some tape around the shaft, to avoid big fat sparks,
b) then replace the breaker. It probably won't cost over $15, and should be a plug-n-play replacement. It should never be hot to the touch.
 

·
Registered
Joined
·
69 Posts
Should not run that hot. Breakers are cheap. Replace it.
 

·
Registered
Joined
·
2,560 Posts
I'm all for self repair. That said, turn the main breaker off when servicing the 50a breaker. Don't rely on tape and a steady hand to keep you from a shock...

I recently figured I'd try to replace a fan switch with a timed switch with the breaker on. That was an illuminating experience.

Yes, you'll have to reset the time on the microwave and the coffee pot.
 

·
Registered
Joined
·
622 Posts
You've gotten lots of good advice in this thread already and yes that's way too hot. I also concur with red point if you're not an electrician you should never be working on a panel live.

It is very common for the screw connections on the circuit breakers to the wire to actually back themselves out overtime with temperature cycling. It is excellent preventive maintenance to turn a panel off and run down every screw terminal with the screwdriver retorquing all the connections.

As already stated it could also be the interface between the breaker in the bus bar.

A common diagnostic tool in an electrician's tool box is a thermal camera, you point it at sockets, electrical connections, and breaker boxes, and look for problem spots that are high temperature.
 

·
Registered
Joined
·
94 Posts

·
Registered
Joined
·
49 Posts
Very informative article, but it seems to have a few improper temp conversions.

50°C = 122°F, not 90°F
60°C = 140°F, not 108°F
That part of the table refers to temperature rise above ambient, not absolute temperature. Try subtracting 32F from your numbers.
 

·
Registered
Joined
·
238 Posts
My 32A L2 charger specifies that it needs a 50A breaker. If it was my house, I'd replace the 40A breaker with a 50 and make sure #8 wire is run all the way. That's the way mine is wired and I've checked everything from the charge cord to the breaker and nothing is beyond just barely warm.

Mike
 

·
Registered
Joined
·
102 Posts
MikeyBolt
From what I've gathered, it's because there isn't a 40A outlet. 40A should be fine for the 80% rule. Just that to match the 50A outlet.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #15
Thanks to all for your replies - really appreciate the info. After I posted about the hot breaker, I got a notification that the charge cycle had ended so I went out to the garage. Surprise! The car had started a battery conditioning cycle. I'm sure I don't have to tell you: that is a surprise when it first happens. This sophisticated, quiet, clean, modern device suddenly turns into a shop vac! Anyway, it only lasted for 10 mins or so with the fan noise decreasing throughout. When finished, the charger stopped blinking and things were back to normal. I will say that the garage was noticeably warmer after charging & conditioning finished.

On the breaker topic: Seems that it should not be that hot, but also from the Schneider info, a temp rise of 60 degF (from 80 to 140) is within the specs for the breaker if I understand the data. My neighbor has a Tesla so I've asked him if his breaker gets warm/hot while charging (didn't know). I've also asked one of the execs in my company who has a Bolt if that happens on his charger unit. This should confirm what MikeyBolt says - that the circuit should not be hot while charging. Anyone else done the touch test while charging?

Btw, Duke installed a digital meter earlier this year. I looked online and could see that the unit was pulling 6-7 kW during those hours it was charging. I also realized that my AC unit was running fully during that period. The ganged 40A breaker for the AC is right across from the charger breakers at the top of the box. Next time, I'll see if they are warm although it seems from online that the compressor will not pull as much current as the charger.

I will ask the electrician to come back out and inspect the circuit given your advice and will report back.

Thanks again for the info.
 

·
Registered
Joined
·
102 Posts
Again...no expert here...interesting bit about the AC on at the same time. So then there's your service capacity like 100A? 200A? What's the main total shut-off breaker number? Then panel capacity. Is the AC breaker also warm?
 

·
Registered
Joined
·
4 Posts
I had an unused 40A breaker in my pannel that I used for my OpenEVSE. It got hot. I also discovered that my 40A stove breaker was hot. Two breakers latter, all is fine. I took the bad breakers apart and the internal contacts we burnt in both units. They were both a disaster waiting to happen.
 

·
Registered
Joined
·
472 Posts
... I took the bad breakers apart and the internal contacts were burnt in both units. They were both a disaster waiting to happen.
Similar here. Running two 15 amp portable heaters tripped a 100 amp subpanel's main breaker. The breaker was ugly inside, badly corroded and the springs that open the contacts were badly rusted.

Disaster averted. That barn subpanel will eventually host an EVSE.
 

·
Registered
Joined
·
236 Posts
I have a JuiceBox Pro 40 on a 50 amp breaker. After a little while on full load (237 V, 32 A) the breaker is slightly warm. I wouldn't say hot by any stretch, maybe slightly above body temp.
 
1 - 20 of 27 Posts
About this Discussion
26 Replies
19 Participants
bww129
Chevy Bolt EV Forum
We’re the Largest Chevy Bolt EV Online Community and Owner's Club. Join to discuss sport mode, reviews, battery range and charging!
Full Forum Listing
Top