Occasional use charger nearly started a garage fire

[jadnashuanh]

I prefer the receptacles with a back clamp. BTW, you should always try to go around the screw clockwise if you use the screws. I do not prefer the back stab connection - the spring tension on that can get weak after some uses when you're maxing out the current capacity, making the next use less secure.

 

[barrychan]

The charging rate is somewhat linear - not quite, but close enough for a WAG. I do not remember the 'steps' on max, medium, low on the US level 1EVSE, but would probably not even bother running it on low unless there was just no other place to plug it in and that circuit needed to share its power with a common breaker. In the USA, a 'typical' 110vac receptacle is protected by a 15A circuit, but it needn't be dedicated to one purpose. The largest 110vac receptacle commonly found is a 20A one, but not as often in residential situations. To get more power, you need to generally go up to a 240vac circuit, and those tend to be dedicated to a specific appliance. US code requires the 80% rule, so on a 15A circuit, the most you can use continually is 12A, or 80%. Something plugged in for more than 3-hours, triggers that rule, one often ignored when using something like space heaters, sometimes, to the operator's peril. Intermittent use at up to the max is allowed, but not continuous use of more than 3-hours.

So if i am unsure about all of the above and use max to charge and the worst could happen is pop the breaker right and i will know that i can't use max on that outlet?

 

[justanotherdrunk]

The charging rate is somewhat linear - not quite, but close enough for a WAG. I do not remember the 'steps' on max, medium, low on the US level 1EVSE, but would probably not even bother running it on low unless there was just no other place to plug it in and that circuit needed to share its power with a common breaker. In the USA, a 'typical' 110vac receptacle is protected by a 15A circuit, but it needn't be dedicated to one purpose. The largest 110vac receptacle commonly found is a 20A one, but not as often in residential situations. To get more power, you need to generally go up to a 240vac circuit, and those tend to be dedicated to a specific appliance. US code requires the 80% rule, so on a 15A circuit, the most you can use continually is 12A, or 80%. Something plugged in for more than 3-hours, triggers that rule, one often ignored when using something like space heaters, sometimes, to the operator's peril. Intermittent use at up to the max is allowed, but not continuous use of more than 3-hours.

So if i am unsure about all of the above and use max to charge and the worst could happen is pop the breaker right and i will know that i can't use max on that outlet?

the breaker did not save me

i was headed for a fire

 

[jadnashuanh]

You can solder electronic components with a 10W soldering iron (not pipe...too much gets lost with the pipe as a heat sink). At full tilt, the OUC is pulling 1440W - PLENTY of power to overheat a poor connection which acts like a heating element. There are two ways a receptacle may have a high resistance connection (well, three, if you count aluminum wiring): a loose connection where the wires are connected, or worn out plug contacts that have lost their spring, and therefore no longer tight. That usually happens because you ran something that maxed it out and left it there for too long, and the heat generated causes the metal to lose its temper (and spring). Over time, if you did not tighten the wire properly, the heating/cooling can cause the connection to loosen. Lots of people think it's simple...there's more to it than they think!

If the circuit you are using is NOT being used by anything else, AND, you don't have a deficient or defective connection or device, you should be able to use the max setting on the vehicle. BUT, if it needs to share its power with something else, if the total of what is being powered - the car and whatever, is over the 15A circuit, you will pop the breaker. Note, it is okay to use a 15A receptacle and feed it with a 20A circuit, but it is still possible to overload the total circuit, but not from a single device (you can't plug a 20A cord into a 15A receptacle - a 20A receptacle has an additional slot, looking like a T to accommodate either a 15A plug or a 20A one).

So, the easiest thing is to shut off the circuit breaker and see what else may no longer work! If there's nothing, you should be able to use it at max. But, there could be lots of light fixtures, and when off, no problem, but start turning them on, and it becomes a problem, or maybe the garage door opener...no problem until you run it.

 

[barrychan]

You can solder electronic components with a 10W soldering iron (not pipe...too much gets lost with the pipe as a heat sink). At full tilt, the OUC is pulling 1440W - PLENTY of power to overheat a poor connection which acts like a heating element. There are two ways a receptacle may have a high resistance connection (well, three, if you count aluminum wiring): a loose connection where the wires are connected, or worn out plug contacts that have lost their spring, and therefore no longer tight. That usually happens because you ran something that maxed it out and left it there for too long, and the heat generated causes the metal to lose its temper (and spring). Over time, if you did not tighten the wire properly, the heating/cooling can cause the connection to loosen. Lots of people think it's simple...there's more to it than they think!

If the circuit you are using is NOT being used by anything else, AND, you don't have a deficient or defective connection or device, you should be able to use the max setting on the vehicle. BUT, if it needs to share its power with something else, if the total of what is being powered - the car and whatever, is over the 15A circuit, you will pop the breaker. Note, it is okay to use a 15A receptacle and feed it with a 20A circuit, but it is still possible to overload the total circuit, but not from a single device (you can't plug a 20A cord into a 15A receptacle - a 20A receptacle has an additional slot, looking like a T to accommodate either a 15A plug or a 20A one).

So, the easiest thing is to shut off the circuit breaker and see what else may no longer work! If there's nothing, you should be able to use it at max. But, there could be lots of light fixtures, and when off, no problem, but start turning them on, and it becomes a problem, or maybe the garage door opener...no problem until you run it.

Thanks, very informative, so i did put on max to charge a couple days ago and it charged approx. 10 km in an hour, i did feel the receptacle a little warm on the plate but not hot, is it normal?

 

[jadnashuanh]

Thanks, very informative, so i did put on max to charge a couple days ago and it charged approx. 10 km in an hour, i did feel the receptacle a little warm on the plate but not hot, is it normal?

Slightly warm shouldn't be an issue, it should not get hot. If the plug doesn't get gripped well by the receptacle, you may want to spring for a new one, and I'd not use the cheapest ones out there...I like the commercial rated ones. Those have better contacts and last longer. They look the same, but you'll be able to tell the difference when you plug something in...it really grips the plug. You can buy a builder's special receptacle for maybe $0.50 in bulk - guess what they builder puts in. A good commercial rated one is more like $4 or so...it won't break the bank, and is a better device. Loose connections act like a resistor or heating element and are best to be avoided! Cheap receptacles wear out fast when used at max current over longer timeframes. WOrk fine to power a table lamp, though, so many people never notice.

 

[SSi3]

Here's my OUC setup, I built myself a heavy duty 20ft extension cord from 14 gauge industrial grade wire and high quality male/female ends. Since my garage does not have a wall outlet close to the passenger side of the car, I'm using the ceiling outlet instead. And now I have an extension cord to bring along on trips in case I can't get close enough to a 120 outlet.

(Sorry I can't seem to get OneDrive to let me insert images)
https://onedrive.live.com/redir?resid=3c26bde8ab3f1dcd!5838&authkey=!AIacCr6bsOPg5RU&ithint=album,

Maybe someday we'll install an L2, but our commute is short and we charge while we sleep... plus there are 3 free L2's in my neighbourhood that I can always run the car over to if we need a quicker charge.

 

[barrychan]

So you have zero issue with the extension and that's good to know

I like the wheel where the cord goes.

 

[jadnashuanh]

14g wire would be the absolute minimum wire gauge you should consider for an extension cord for the OUC...personally, I would want a 12g one. Adding two more spring-loaded sets of contacts will increase the overall resistance, and, as mentioned, using high quality plug and socket is highly recommended, too.

There is a general recommendation to never use an extension cord with high power devices. In the case of the EVSE, those extra connections may disrupt the balance of the power flow and cause it to report a power fault, and shut down. Certainly doesn't always happen, and maybe never will if the cord is maintained in very good shape. And, while not huge, there is resistance in the wiring which decreases the power available to the device and results in heat generation.

A good safety practice...never leave the extension cord coiled up when you are using it - it will heat up. If you want to coil it at all during use, you can coil it in a figure-8 which cancels the magnetic field buildup and therefore the heat. Coiling the wire creates an inductor. This isn't a big deal on lower power devices, but is important once you start to deal with higher powered ones.

The resistance of 20' of 14g wire is about 0.05 ohms, and with 120vac in, you'll lose about 0.6 volts at the EVSE under load (none in an open circuit). 20' of 12g wire, you'd lose about 0.38vac. Power=volts*amps, so at .6volts*12amps, you'd lose 6W as heat in the extension cord. With a 12g wire, .38*12=4.6W. Those are watts not going into the vehicle, but you still have to pay for them. Considering that the extra set of plug/socket will have more resistance than that, you'd lose even more. Also part of the reason why you do not want to keep the wire coiled up as it concentrates that heat AND raises the resistance even more.

Most people do not understand the implications of not following the recommendations. Most of the time, it isn't a problem, safety or functional, but not always.

Personally, I'd have them install a dedicated 20A receptacle where it would then reach the vehicle with the supplied cord. You could get by with a 15A one, but the added flexibility may come in handy some day. You could eventually end up putting in a 20A/240vac receptacle there by just changing the socket and circuit breaker and then use one of the smaller plug-in level 2 EVSEs out there (would be limited to 16A based on the 80% rule, but 16A*240 verses 12A*120, you'd have nearly 3x more power available AND the car is more efficient at charging at 240vac than 120 - it's harder to make nearly 400vdc from 120vac than it is from 240vac, and you lose in efficiency).

 

[Blue20]

Here's my OUC setup, I built myself a heavy duty 20ft extension cord from 14 gauge industrial grade wire and high quality male/female ends. Since my garage does not have a wall outlet close to the passenger side of the car, I'm using the ceiling outlet instead. And now I have an extension cord to bring along on trips in case I can't get close enough to a 120 outlet.

(Sorry I can't seem to get OneDrive to let me insert images)
https://onedrive.live.com/redir?resid=3c26bde8ab3f1dcd!5838&authkey=!AIacCr6bsOPg5RU&ithint=album,

Maybe someday we'll install an L2, but our commute is short and we charge while we sleep... plus there are 3 free L2's in my neighbourhood that I can always run the car over to if we need a quicker charge.

Besides what has been mentioned already, you are sure it is cooper wire, right? Aluminum will need bigger wire.

Also your OUC is sharing the same outlet as the garage door opener. You may want to check the size of the breaker on this run. My guess is a 15A. The OUC will draw 12A, when the i3 is set to Max Power. (http://www.mybmwi3.com/forum/viewtopic.php?p=24478#p24478) As EVSE is a continuous load, you need to add 25% on top. i.e. calculate using 15A. While you are charging at Max and someone open the door, the breaker will trip. (it better be, otherwise you have a bigger problem)

A quick and dirty fix is to lower your 110v charging to Reduced. You can never be too safe.

 

[justanotherdrunk]

I now use the reduced charge car setting permanently

The current is limited to ~8 amps vs ~12 on max

The plug is completely cool

It works with my schedule and charging needs

 

[SSi3]

Yes my wiring is copper, all good there. The outlet is very new and unused.

The garage is on its own dedicated 15A circuit with twinned wiring for the long run from the house. The garage door opener is rarely if ever used when the OUC is charging, but I will confirm the amperage draw when it's opening.

As for the gauge of the extension wire, the electrical company I bought it from said that would work just fine for a 12A draw. It's been working fine and if there is any loss due to the longer run it's very minimal.

I expect BMW doesn't recommend the use of an extension cord because most people have a sketchy old Chinese made orange cable that's been in their garage for years getting used for weed wackers and shop-vacs with worn out connections.

 

[barrychan]

I now use the reduced charge car setting permanently

The current is limited to ~8 amps vs ~12 on max

The plug is completely cool

It works with my schedule and charging needs

Yes i switched to reduced charge as well, better safe than sorry and sleep better while its being charged.