charge [rate] drops by 50% on a NEMA 14-50 plug

[@heist80]

had 2 electricians install a NEMA 14-50 outside my garage. first guy did a crap job then ghosted me after i paid him $600. so had to get a 2nd guy come out who had to clean up the 1st guys mess and spent another $300. anyway long story short when i charge its is about 34mph, but halfway through the charge or thereabouts it mysteriously drops to 17mph.

anyone have this happen to them? what could be wrong? is it something dangerous?

 

[LoudMusic]

Sounds like the car is observing voltage sag and dropping current draw in order to compensate. The charging screen should show you the volts and amps while charging and not charging. Check and let us know what it sees. While not charging it should be within about 5 volts of 240v. While charging it will likely go down, but shouldn't dramatic. If it is, the car will lower the amps in order to compensate.

Also with it on the outside of the garage in Florida it could just be overheating and dropping current draw in order to cool back down. Check the cord and mobile connector box. They can be warm to the touch but you should be able to grasp it indefinitely. If it's too warm to hold onto then it's way too warm.

 

[Sophias_dad]

While not charging it should be within about 5 volts of 240v

Make that 12V (5%). The car doesn't actually care much about the start voltage, but rather how much it goes down as the current goes up.

Hate to be the "Leviton" guy, but given the poor experience with the first electrician, did you specify and did (s)he install an outlet better than a Leviton?

 

[@heist80]

Sounds like the car is observing voltage sag and dropping current draw in order to compensate. The charging screen should show you the volts and amps while charging and not charging. Check and let us know what it sees. While not charging it should be within about 5 volts of 240v. While charging it will likely go down, but shouldn't dramatic. If it is, the car will lower the amps in order to compensate.

Also with it on the outside of the garage in Florida it could just be overheating and dropping current draw in order to cool back down. Check the cord and mobile connector box. They can be warm to the touch but you should be able to grasp it indefinitely. If it's too warm to hold onto then it's way too warm.

yes the voltage drops.

so this is normal in the FL heat?

not a situation where i need a 3rd electrician out?

 

[Rocky_H]

yes the voltage drops.

so this is normal in the FL heat?

not a situation where i need a 3rd electrician out?

That's not a solid answer yet because of the outstanding questions: What did it show on the display? How much did it drop? What did the amps show as it was running versus what it dropped to?

 

[@heist80]

That's not a solid answer yet because of the outstanding questions: What did it show on the display? How much did it drop? What did the amps show as it was running versus what it dropped to?

i will take a look next time and track it

 

[jackmott]

Does the mobile charger have a blinking red T when this happens?

 

[@heist80]

Does the mobile charger have a blinking red T when this happens?

not that i have noticed. but i could be wrong

 

[jackmott]

not that i have noticed. but i could be wrong

Check that next time, that indicates it detected a hot plug and reduced charging rate as a result. It is a common issue. Not sure if due to faulty sensor or 14-50 plugs that are set up badly. You could split the difference by manually setting the amps to 24, so at least you get that instead of 16 amps.

 

[3sr+buyer]

If the plug head detects too much heat, then it will signal the car to drop the charging amperage.

If your outlet setup is marginal, this may occur more often during warmer weather (i.e. the extra heat may not cross the "too hot" threshold in cooler weather, but may during warmer weather).

Two likely causes of extra heat:

• Wires are not properly clamped to the outlet. This is not a problem if installed correctly, but outlet with screw-down clamps are easier to install poorly. Screw-down clamps are found on the Leviton 14-50 and 6-50 outlets as well as the Bryant 6-50 outlet, but the Bryant 14-50 outlet has are more mistake-resistant method of clamping the wires.
• Outlet contacts do not fully contact the plug blades. This is a design problem with the Leviton 14-50 and 6-50 outlets, where the contacts are only about half of the length of the plug blade holes.

While the first issue can be avoided with careful installation, the second issue requires replacing the outlet.