Bosch Level 2 EVSE Charging too fast?

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tkdbrusco

Well-known member
Joined
Sep 7, 2014
Messages
510
Hi. I have a 2015 Leaf S. I installed a Bosch level 2 (30AMP) charger on an existing 220v dryer line I wasn't using. Put in a new Nema socket and bought a Nema cable. The breaker is connected to two existing 20AMP circuits. It seems like when plugged in, my leaf is charging much faster than the dash indicates is should take with the 6.6kw onboard charger. I started charging last night with 41% and after about 1:50 of charging had 98% charge? The dash indicator said it would take 4:00 with 6.6kw. My question is whether I did something wrong with the wiring that is allowing it to charge too fast or if there is some miscalculation with the dash indicator? I realize that the final few percent take longer than the rest of the charge, but I just want to make sure I'm not doing something wrong. I'm heard that the dash indicator isn't that accurate and I assume that the car itself is limiting the incoming charge at 6.6kwh.
 
I think the dash indicator is a worse case scenario and probably calculates it for say 15-amp Level 2 chargers and not the 30-amp like the Bosch is.
 
tkdbrusco said:
Hi. I have a 2015 Leaf S. I installed a Bosch level 2 (30AMP) charger on an existing 220v dryer line I wasn't using. Put in a new Nema socket and bought a Nema cable. The breaker is connected to two existing 20AMP circuits. It seems like when plugged in, my leaf is charging much faster than the dash indicates is should take with the 6.6kw onboard charger. I started charging last night with 41% and after about 1:50 of charging had 98% charge? The dash indicator said it would take 4:00 with 6.6kw. My question is whether I did something wrong with the wiring that is allowing it to charge too fast or if there is some miscalculation with the dash indicator? I realize that the final few percent take longer than the rest of the charge, but I just want to make sure I'm not doing something wrong. I'm heard that the dash indicator isn't that accurate and I assume that the car itself is limiting the incoming charge at 6.6kwh.


That unit should be on a 40A circuit not a 20A circuit. If it is on a 20A breaker it is a hazard. A 30A unit must be on a 40A circuit with proper wire size to match. Your dryer outlet is only rated for 24A max if done properly and you say it has a 20A breaker so it is only rated for 16A.
 
EVDRIVER said:
tkdbrusco said:
Hi. I have a 2015 Leaf S. I installed a Bosch level 2 (30AMP) charger on an existing 220v dryer line I wasn't using. Put in a new Nema socket and bought a Nema cable. The breaker is connected to two existing 20AMP circuits. It seems like when plugged in, my leaf is charging much faster than the dash indicates is should take with the 6.6kw onboard charger. I started charging last night with 41% and after about 1:50 of charging had 98% charge? The dash indicator said it would take 4:00 with 6.6kw. My question is whether I did something wrong with the wiring that is allowing it to charge too fast or if there is some miscalculation with the dash indicator? I realize that the final few percent take longer than the rest of the charge, but I just want to make sure I'm not doing something wrong. I'm heard that the dash indicator isn't that accurate and I assume that the car itself is limiting the incoming charge at 6.6kwh.


That unit should be on a 40A circuit not a 20A circuit. If it is on a 20A breaker it is a hazard. A 30A unit must be on a 40A circuit with proper wire size to match. Your dryer outlet is only rated for 24A max if done properly and you say it has a 20A breaker so it is only rated for 16A.

The unit is on a 40A circuit. The dryer line was on two connected 20A breakers. I'm assuming all is well with the circuit since it was wired for a 220v dryer plug. I swapped out the old receptacle for a NEMA 14-50. My concern is not so much the wiring just that the charge rate was faster than the dash indicated it would be.
 
Be careful now. 2) 20 amp breakers do not make 40 amps. The same current flows through both of them. (series not parallel) This is because both wires of a 240 volt circuit are hot relative to ground. If either wire shorts to ground, an overload condition could result, so each wire needs overload protection. A proper circuit for your charger would include a 2 pole common trip circuit breaker (one breaker tripping also turns the other off) and 8 gauge wire.

Hopefully this is what you have. Good luck with your project.
 
johnrhansen said:
Be careful now. 2) 20 amp breakers do not make 40 amps. The same current flows through both of them. (series not parallel) This is because both wires of a 240 volt circuit are hot relative to ground. If either wire shorts to ground, an overload condition could result, so each wire needs overload protection. A proper circuit for your charger would include a 2 pole common trip circuit breaker (one breaker tripping also turns the other off) and 8 gauge wire.

Hopefully this is what you have. Good luck with your project.

The circuit is definitely a 2 pole common trip circuit breaker. They are connected together at the breaker box and if one trips, the other will as well. So I think I'm good there. I'm assuming the wire is 8 gauge since that is code in CA for 30A, which I think is what a standard 240v dryer plug requires. It may be worth it though to take the outlet back out and double check the wire gauge as this may be the only potential issue based on what you're saying.
 
tkdbrusco said:
johnrhansen said:
Be careful now. 2) 20 amp breakers do not make 40 amps. The same current flows through both of them. (series not parallel) This is because both wires of a 240 volt circuit are hot relative to ground. If either wire shorts to ground, an overload condition could result, so each wire needs overload protection. A proper circuit for your charger would include a 2 pole common trip circuit breaker (one breaker tripping also turns the other off) and 8 gauge wire.

Hopefully this is what you have. Good luck with your project.

The circuit is definitely a 2 pole common trip circuit breaker. They are connected together at the breaker box and if one trips, the other will as well. So I think I'm good there. I'm assuming the wire is 8 gauge since that is code in CA for 30A, which I think is what a standard 240v dryer plug requires. It may be worth it though to take the outlet back out and double check the wire gauge as this may be the only potential issue based on what you're saying.

Each of your 2 Circuit Breakers need to be 40Amp rated. 20Amp + 20Amp will not work... you need 40Amp and 40 Amp for the two hot wires
 
TomT is right; there's no way you can make the car draw more than 6.6 kW. And tuanies post reminds me that the charge time estimates would change significantly when I used my L1 charger instead of the L2. If you've just started using this circuit and were using a different charge rate before, the time estimate should change to something more realistic after a charge or two. It still always overestimates by about 25 minutes, but it's consistent. This is observed on a 2011 car, and come to think of it, the firmware updates may have made all this behave differently.
 
tkdbrusco said:
The unit is on a 40A circuit. The dryer line was on two connected 20A breakers. I'm assuming all is well with the circuit since it was wired for a 220v dryer plug. I swapped out the old receptacle for a NEMA 14-50. My concern is not so much the wiring just that the charge rate was faster than the dash indicated it would be.
You best get an licensed electrician to review the work and then get a permit from the city.
Do this before you worry anything about charging speed.
 
As others have pointed out, you have a 20A circuit. The dual breaker is for both 120V circuits. Combined you get 240V at 20A.
 
"I swapped out the old receptacle for a NEMA 14-50."

Not a good choice for a 40A breaker circuit.

"Put in a new Nema socket and bought a Nema cable."

If the EVSE is not hardwired, most likely it's only outputting 25 amps and not 30 amps
via a cable, i.e. most cable EVSEs only charge at 25 amps versus a wall mounted EVSE
which typically outputs 30 amps.
 
Thanks everyone for the helpful replies. I spoke to a contractor who is connecting me with his electrician. He seems to think that all is well with the exception of possibly the wiring from the breaker to the receptacle. The breakers are (2) tandem connected 30A breakers which he says are likely OK, but may be replaced as well with a single 40A or higher. The wiring, which may be 10gauge as opposed to the required 8gauge may be the only thing that needs to be replaced. In the meantime I'll be trickle charging at night and only using the Bosch level 2 in the AM for the hour or so before I leave the house, alleviating the uncertainty of it being running while I'm sleeping upstairs. He says that since the run of wire is very short (about 6ft) from breaker to plug, it's probably not going to be an issue but better safe than sorry.
 
I thought you guys might like to know that I had an electrician come out and he actually said that if it was his house, he would leave it as is. He said that even though the code calls for #8 wire as opposed to #10, due to the short length of the run (approx 8 feet), and the fact that the EVSE is only drawing about 5 Watts more than my dryer was, he said it probably wasn't worth the hassle of swapping out the wire. That being said, I'm still leaning toward having the wire swapped out with #8 and I already ordered a new 2-pole 40A breaker to swap the 30A with. If he thinks its fine, it probably is, but the codes exist for a reason.
 
the length of the wire matters for just one concern. Voltage drop. With a short run, this is not a concern. What is a concern is the heating of the wire as a result of the current flowing through it. Length makes no difference. A short wire gets just as hot as a long one, there's just more wire to get hot in a longer wire. If the insulation of the wire is rated for a higher temperature, and it doesn't run next to any flammable materials, and has sufficient free air around it so that it keeps cool, fine. But no one knows what is going on inside your wall.
 
tkdbrusco said:
I thought you guys might like to know that I had an electrician come out and he actually said that if it was his house, he would leave it as is. He said that even though the code calls for #8 wire as opposed to #10, due to the short length of the run (approx 8 feet), and the fact that the EVSE is only drawing about 5 Watts more than my dryer was, he said it probably wasn't worth the hassle of swapping out the wire. That being said, I'm still leaning toward having the wire swapped out with #8 and I already ordered a new 2-pole 40A breaker to swap the 30A with. If he thinks its fine, it probably is, but the codes exist for a reason.
Of course the LEAF doesn't draw the full 30a that the EVSE is capable of. That's why it's only drawing about what your dryer did...and the dryer doesn't draw that for an extended time, just for ten or so minutes at a stretch. It might get a lot hotter if a different car draws a full 30a for hours. The circuit is supposed to be rated for 40a. Since the wire is so short, there should be no hassle in changing it out for the right gauge.
 
The difference is duty cycle. EVSE is considered continuous, dryer is not.

BTW for 8' just pull new #6 wire on a new circuit and stop sharing with the dryer.
 
Yeah I thought about just pulling #6 for the hell of it, but I doubt I would need any more than a 30A charger no matter what Car I buy in the future. Even though its a short run, its not so easy as just pulling new wire through cause they staple it down inside the wall, so you still need to cut out sheetrock a few times and pull new wire through. I wasn't sharing the dryer plug BTW, when we bought the house we ran a gas line for a gas dryer, since that's cheaper to use. The dryer plug and breaker are sitting unused. However, when we run the new wire, we are just putting in a new plug in addition to the dryer one because why not. An electrician I called wanted $450 to do this. My uncle who is a contractor is doing it for much less. I just gotta wait a few weeks and trickle charge in the meantime.
 
Hey everyone. Thought that you might like to know that my charger is finally legit! Ran new 8AWG wire on a 2-Pole 40AMP circuit. Charger is plugged in and wired to an 8AWG Nema 14-50 cord. So we are good to go. Just noticed that the Bosch charger that plugs into the car is actually 10AWG? WTF? So code requires 8AWG everywhere else, but the Bosch can use a 10AWG? How does that work?
 
tkdbrusco said:
Hey everyone. Thought that you might like to know that my charger is finally legit! Ran new 8AWG wire on a 2-Pole 40AMP circuit. Charger is plugged in and wired to an 8AWG Nema 14-50 cord. So we are good to go. Just noticed that the Bosch charger that plugs into the car is actually 10AWG? WTF? So code requires 8AWG everywhere else, but the Bosch can use a 10AWG? How does that work?

The NEC only covers the wiring inside the wall. Outside #10 in bundles is easily good for 32A.

If you have a 14-40 with a 40A breaker, that is allowed but you should label it 40A.

Tony Williams feels that every 14-50 should be wired for 50A. I feel this is un-necessary. When at 40A it is protected by the 40A breaker. In my case I can not allow a 50A circuit since that would be half of my 100A service. We are not all rich with at least 200A service.
 
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