Charging in the rain

Patrick W · May 8, 2015

So there I was at the local supercharger last evening. Standing in the rain in a puddle of water and reaching for the supercharger cable. About then I had this mental image of me acting as a conductor for 400 volts and 100 amps.

All went well of course, but I am curious, has anyone ever heard any cautions about supercharging in the rain?

jerry33 · May 8, 2015

No current will flow unless there is a connection though the pilot circuit, and then the car tells the Supercharger what to do, so there's no electricity flowing until it's properly plugged in.

spottyq · May 8, 2015

It's not 100A, it is 330A.

But like jerry33 said, a supercharger is quite secure. You would have to try very hard in order to get electrocuted.

Patrick W · May 8, 2015

Thanks folks. Guess I'll have to find something else to worry about.

mattmass · May 8, 2015

This is something I've been wondering about quite bit, but not for supercharging. How have people's experience been with their UMC in the rain?

DavidB · May 8, 2015

Unfortunately, unless you do get shocked, you will probably have no indication of how close you came to being a statistic.

When I have felt that I can shield the UMC plugs (both ends) from a mild rain, I have gone ahead and charged my car. In heavy rains, I wait. Far better to wait than to risk death.

Zythryn · May 8, 2015

DavidB said:
Unfortunately, unless you do get shocked, you will probably have no indication of how close you came to being a statistic.

When I have felt that I can shield the UMC plugs (both ends) from a mild rain, I have gone ahead and charged my car. In heavy rains, I wait. Far better to wait than to risk death.

The car side is protected just as much with either charge plug.
If the wall side of the UMC were being rained on and it was not an outdoor rated cover, I wouldn't charge.

Twiglett · May 8, 2015

I remember seeing a video of one EVSE manufacturer dropping an operational unit into a bucket of water

FlasherZ · May 8, 2015

I would recommend being far more careful with that NEMA 14-50 plug while standing on rain-soaked ground. 50A circuits aren't required to have GFI capability, for various reasons. That's what has driven the NEC 2014 clarification that EVSE's plugged into a 240V outlet must be "fastened in place" - the idea was to make them only "semi-portable", not completely portable.

So if you're holding one of those outside prongs when you plug it in, you're not going to like it.

scaesare · May 8, 2015

The Mobile Connector User Guide includes the following warnings:

UMC Guide said:
Do not use the Mobile Connector when either you, the vehicle or the Mobile Connector is exposed to severe rain, snow, electrical storm or other inclement weather.

Protect the Mobile Connector from moisture, water and foreign objects at all times. If any exist or appear to have damaged or corroded the Mobile Connector, do not use the Mobile Connector.

If rain falls during charging, do not allow rainwater to run along the length of cable and wet the electrical outlet or charging port.

If the electrical outlet is submerged in water or covered in snow, do not insert the Mobile Connector’s plug. If, in this situation, the Mobile Connector’s plug is already plugged in and needs to
be unplugged, first turn off the breaker and then unplug the Mobile Connector’s plug.

That latter one speaks to FlasherZ's comments, which I also agree with.

Interestingly the HPWC Guide contains the first two warnings, but omits the one about rainwater running along the cable to the charge port.

The manual also lists a Type 3R enclosure rating for the HPWC (approved for outdoors). The HPWC box itself is rubberized and the cover is gasketed. I wonder if that rating implies any suitability for use by the charge connector itself.

The UMC Guide has no ratings I can find, other than being UL listed & FCC approved. The body of the UMC itself also only lists UL compliance, if memory serves.

Obviously the supercharger cabinets themselves are weather proof, and the Supercharging Page has this to say:

Supercharging Page said:
Does weather affect Supercharging?
The Supercharger will operate normally in all conditions, but might reduce power slightly in very extreme weather conditions.

Is it okay to Supercharge in the rain and snow?
Model S is designed to charge in inclement weather including rain and snow. Charging times may vary in extreme climate conditions.

However the exterior interface of the connector on all 3 devices look similar in terms of weather protection... I wonder if they are gasketed differently internally somehow...

Cyclone · May 8, 2015

There is a MythBusters episode about the "exploding water heater". They wanted to see the destructive force of the water heater. But in order to test this, they have to circumvent a number of safety features. Essentially, it became nearly impossible to have a "catastrophic failure" of a water heater vs. a simple, non-life-threatening failure. I would imagine the Supercharges are designed to the same or better standard!

jeff_adams · May 8, 2015

Would wearing a rubber glove while plugging or unplugging offer any protection? I only ask because I saw someone doing that in the snow when charging their car and I was curious.

FlasherZ · May 8, 2015

jeff_adams said:
Would wearing a rubber glove while plugging or unplugging offer any protection? I only ask because I saw someone doing that in the snow when charging their car and I was curious.

Depends on the thickness of the rubber and whether the glove is wet.

For the most part you really don't have to worry as long as you're not holding the prongs of the adapter as you insert it into the outlet.

The car coupling end of the charger is protected against ground fault, so no need to worry there.

tom66 · May 8, 2015

When you plug into a supercharger, you'll hear several sets of clicks. One side is the car, and the other side is the charger itself (maybe hidden inside the charger cabinet.) These are DC contactors which completely isolate the cable from the charging system until it is ready to begin.

The charger will only connect to the car when the connection is made and the handshake is complete.

The locking pin prevents the cable being removed (this is also to avoid arcing issues which would occur if the cable was removed during charging.) If the cable is removed, the charge process must be stopped. If the locking pin failed, I presume either the car would refuse to charge (it will be able to detect the pin being retracted or broken) or if it did start charging, the arcing event occuring during retraction, and sudden reduction in charge current, would trip a fault.

The cable itself is doubly insulated with very thick insulation, and the connector will be waterproof as it is permanently exposed in most supercharger stations.

Nothing to worry about there...

Twiglett · May 8, 2015

I knew I'd seen it somewhere

http://insideevs.com/electric-motor...-bucket-challenge-schneider-bosch-next-video/

scaesare · May 8, 2015

tom66 said:
When you plug into a supercharger, you'll hear several sets of clicks. One side is the car, and the other side is the charger itself (maybe hidden inside the charger cabinet.) These are DC contactors which completely isolate the cable from the charging system until it is ready to begin.

The charger will only connect to the car when the connection is made and the handshake is complete.

The locking pin prevents the cable being removed (this is also to avoid arcing issues which would occur if the cable was removed during charging.) If the cable is removed, the charge process must be stopped. If the locking pin failed, I presume either the car would refuse to charge (it will be able to detect the pin being retracted or broken) or if it did start charging, the arcing event occuring during retraction, and sudden reduction in charge current, would trip a fault.

The cable itself is doubly insulated with very thick insulation, and the connector will be waterproof as it is permanently exposed in most supercharger stations.

Nothing to worry about there...

All of this is much the same with a HPWC: the handshake must complete, there's a set of contactors in the HPWC that must close, the car's contactors must close, the connector is locked in to place while current is flowing, the insulation is appropriately rated for outdoor use and the voltage the cable will carry, etc...

Yet the actual outside shape and design of the plastic connector head is practically identical... for instance the Supercharger connector does not have an extra o-ring or seal on the outside. Yet the HPWC warns against allowing rainwater to "run along the length of cable and wet the ...charging port." and the Superchargers do not.

brianman · May 8, 2015

spottyq said:
You would have to try very hard in order to get electrocuted.

Please don't reply with "challenge accepted".

Todd Burch · May 8, 2015

Those rain-related warnings are for the NEMA 14-50 outlet end of the UMC, which as FlasherZ mentioned are not GFCI protected (in fact you don't want them to be). The NEMA 14-50 plug end is of course always live whenever the breaker is on, so fiddling around there in wet conditions can be bad.

But using the UMC-end (where it plugs into the car) is fine, as others have said. This end is not live unless the car and UMC handshake and both agree that the connection is complete.

Having said that, since I am smart enough to be terrified of electricity, I'm not going to go touching my tongue to the prongs inside the end that plugs into the car, even though I know they're not energized when not plugged into the car

.

scaesare · May 9, 2015

Todd Burch said:
Those rain-related warnings are for the NEMA 14-50 outlet end of the UMC, which as FlasherZ mentioned are not GFCI protected (in fact you don't want them to be). The NEMA 14-50 plug end is of course always live whenever the breaker is on, so fiddling around there in wet conditions can be bad.

But using the UMC-end (where it plugs into the car) is fine, as others have said. This end is not live unless the car and UMC handshake and both agree that the connection is complete.

Having said that, since I am smart enough to be terrified of electricity, I'm not going to go touching my tongue to the prongs inside the end that plugs into the car, even though I know they're not energized when not plugged into the car .

I believe that's incorrect. Look at the exact quote I copied from the HPWC manual:

HPWC Guide said:
If rain falls during charging, do not allow rainwater to run along the length of cable and wet the electrical outlet or charging port.

Look at the parts I bolded. They discuss both the outlet (i.e. the 14-50) as well as the charging port,

jerry33 · May 9, 2015

scaesare said:
I believe that's incorrect. Look at the exact quote I copied from the HPWC manual:

Originally Posted by HPWC Guide
If rain falls during charging, do not allow rainwater to run along the length of cable and wet the electrical outlet or charging port.

Click to expand...

Look at the parts I bolded. They discuss both the outlet (i.e. the 14-50) as well as the charging port,

True, but it's obvious that the 14-50 side will be far more sensitive to rain than the charge port location. What's needed is a cover for the charge port and handle. It could be attached with velcro over the charge cable and the top could be tucked into the hatch. Had the door been designed with a horizontal rather than vertical hinge, it would work as a cover. There doesn't need to be much, just enough to keep most of the rain off the handle.

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