Hey there, wondering about the charging at home. But doing some watching and reading and my overall thought is that the lower amperage that you can have for charging is better for the battery. For example, I can have a 50 amp breaker on my level two but I decided to go with a 20 amp breaker. My rationale is simply for a slower charge being easier on the battery. I’m even contemplating using a 120 for a 24 hour charge. I’m at home and can simply plan when I have to drive and need a quicker charge. I’m also in eastern Canada and get cold winters so my rationale is that if I can keep it concert charge on the battery it’ll keep it warm, since we know the leaf has no battery heating. What do you think? Am I out to lunch on this? Cheers.
Amperage to charge for Level 2
- Thread starter Rudynfld
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Talk to your electrician, find out what is possible. A 50 amp outlet will be the most versatile thing you can install, now and for the future. Most of the Leafs on the road now can take up to 27.5 amps at 240. Most of the plug in EVSE's even the adjustable ones, come with a 14-50 or 6-50 plug.
Unless your electrician says you only can run less, then I would go with the 50 amp.
The C/B and the circuit only set the max amps the plug can see. The EVSE (wall unit/charging cord) can be fixed rate or adjustable. The onboard charger looks to the wall unit and determines how much current it is allowed to draw. The charger on the car is limited to 27.5 amp max, but will function on much lower also.
A 50 amp plug and circuit, with an adjustable EVSE, you can play with charge time and current input to limit overall recharge.
If for some reason you are limited to 30 amp or 20 amps of 240, there are chargers that can be set for those circuits limits, 16 amp for a 20 amp max circuit and 24 amps for a 30 amp max circuit.
Unless your electrician says you only can run less, then I would go with the 50 amp.
The C/B and the circuit only set the max amps the plug can see. The EVSE (wall unit/charging cord) can be fixed rate or adjustable. The onboard charger looks to the wall unit and determines how much current it is allowed to draw. The charger on the car is limited to 27.5 amp max, but will function on much lower also.
A 50 amp plug and circuit, with an adjustable EVSE, you can play with charge time and current input to limit overall recharge.
If for some reason you are limited to 30 amp or 20 amps of 240, there are chargers that can be set for those circuits limits, 16 amp for a 20 amp max circuit and 24 amps for a 30 amp max circuit.
When I use the unit that came with my 2021 Leaf, it uses up to 32 amps at 240 volts or 12 amps at 120 volts. If I were to plug it into a 20 amp 240 volt circuit, it would still draw up to 32 amps until the breaker trips.
I use a 40 amp circuit. A 50 amp circuit would work the same, but I might want the extra capacity in the future. The chargers that can handle 40 amps and higher currents can usually be configured to limit the current to work on lower capacity circuits.
I use a 40 amp circuit. A 50 amp circuit would work the same, but I might want the extra capacity in the future. The chargers that can handle 40 amps and higher currents can usually be configured to limit the current to work on lower capacity circuits.
How are you determining your current draw? The Leaf charger can not draw 32 amps, the most that has been documented it 30 amps on a 208 volt circuit. This was from a test done at the Idaho Labs by the DOE.
I have a EVSE that is limited to 32 amps, but the draw on the line is 27-28 amps on the display. This is in line with the 6Kw onboard charger.
A 50 amp breaker circuit can sustain a 40 amp load (something that will never happen with a Leaf) and can be used to charge at lower rates also. Any charger that is a "plug in" type and is over 24 amps but less than 40, needs a 50 amp plug, between 16 and 24 amps need a 30 amp circuit and 16 amps and lower a 20 amp circuit.
Just because the EVSE is capable of a 32 amp draw, doesn't mean it will, that is determined by the onboard charger on the car. It chooses the lower of the two limits.
henrydehoja
Well-known member
I would go with a 50 A circuit (breaker) for future-proofing purposes. That gives you more options when it comes to choosing other EVSE models in the future.
The Leaf on-board (Level 2) charger is rated for 6.6 kW, which is 27.5 A on a 240 V circuit, as mentioned above.
rsbrax
Active member
Agree with all responses. The purpose of the breaker is safety. It does not allow for "adjusting" the amps.
So using a 20 amp breaker does not appear to meet the goal of what you want to accomplish.
Also, I think it helps to remember the basic formula below:
Watts = volts x amps (ex. 6600 watts = 240 volts x 27.5 amps)
Volts = watts / amps ( 240 = 6600 / 27.5 )
Amps = watts / volts ( 27.5 = 6600 / 240 )
So using a 20 amp breaker does not appear to meet the goal of what you want to accomplish.
Also, I think it helps to remember the basic formula below:
Watts = volts x amps (ex. 6600 watts = 240 volts x 27.5 amps)
Volts = watts / amps ( 240 = 6600 / 27.5 )
Amps = watts / volts ( 27.5 = 6600 / 240 )
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Kenny
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The factory Nissan EVSE on a NEMA 14-50R receptacle draws 32 amps. If you’re asking if you can install a 20 amp breaker instead of a 50 amp breaker to limit charging amps then no, that is not possible. An EVSE draws what it is designed to draw and it has no way of knowing what breaker or what size wire you have installed. What you can do to give yourself the most options is to install the NEMA 14-50R (commonly referred to as a stove plug) with a 50 amp breaker then purchase adapters to use whatever aftermarket EVSE you wish. Myself I have an adapter to use use the factory EVSE at 120V and I also purchased a 14-50R to NEMA 6-20R adapter to use with a 3.6 kWh EVSE. This gives me the flexibility to charge at either 1.4, 3.6 or 6.6 kWh from a single 14-50R receptacle. This comes in very handy for changing my rate of charge depending on time of year. I predominantly charge at the lowest amps to keep the non-liquid cooled Leaf battery cooler in the summer months, then switch to a higher amp charge rate to help keep the battery warmer in the winter.
nfettinger
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There is a lot of bad information in this post so let me clarify a few things.
The max amperage your electrician installs is what you are going to be limited to in the future. It is based on your wiring and panel size. This is as high as you can ever go and should determine your breaker size.
The wall charger that plugs into your vehicle is responsible for telling the vehicle the maximum amperage the vehicle can pull safely. It is the responsibility of the installer to program it accordingly. If it is programmed to allow more amperage than the breaker can accept, it was programmed incorrectly and should be fixed immediately! The wall unit is a little more than a embedded computer, a relay, and some safety controls.
You can program the the wall charger to an artificially low value of desired, to slow down the charging. This is how the PV divert function on the openEVSE chargers work. In this case, the max it allows the vehicle is based upon what your solar is currently producing.
Your vehicle is what actually carries the charging unit, its size determines the max rate the vehicle can actually charge at (6.6kw for current vehicles). It talks to the wall into to determine how much it can pull from the plug, does some self checking, and then asks the wall unit to close the relay and provide power. Your vehicle then draws up to the max depending on many factors including the batter SoC.
The max amperage your electrician installs is what you are going to be limited to in the future. It is based on your wiring and panel size. This is as high as you can ever go and should determine your breaker size.
The wall charger that plugs into your vehicle is responsible for telling the vehicle the maximum amperage the vehicle can pull safely. It is the responsibility of the installer to program it accordingly. If it is programmed to allow more amperage than the breaker can accept, it was programmed incorrectly and should be fixed immediately! The wall unit is a little more than a embedded computer, a relay, and some safety controls.
You can program the the wall charger to an artificially low value of desired, to slow down the charging. This is how the PV divert function on the openEVSE chargers work. In this case, the max it allows the vehicle is based upon what your solar is currently producing.
Your vehicle is what actually carries the charging unit, its size determines the max rate the vehicle can actually charge at (6.6kw for current vehicles). It talks to the wall into to determine how much it can pull from the plug, does some self checking, and then asks the wall unit to close the relay and provide power. Your vehicle then draws up to the max depending on many factors including the batter SoC.
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I found very little bad info, most is all saying the same thing that you are. What "bad info" are you referring too?
nfettinger
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It seems some of the posts I was originally reading have been deleted. It looks much better now.
Kenny
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To who’s post are you referring to and what info is wrong?
TronJockey
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The breaker simply determines the amperage trip point. Beyond that it does not regulate current. Installing a lower amperage breaker simply lowers the trip point leading to the breaker tripping far more often - not good for AC breakers. Beyond the safety issues, replacing a 50 amp breaker with a 20 amp breaker will render most 240Vac appliances inoperable (they'll trip the breaker immediately). Even the Leaf's Level 2 on-board 6.6kW charger, which pulls roughly 28 amps, will trip a 20 amp breaker the moment you plug it into its associated 240V outlet.
Depending upon year and model a Leaf has a few "hardwired" AC charging options as determined by the on-board charging circuity. Level 1 charging (120Vac) produces roughly 1.4kW of charging, pulling less than 15 amps from the wall. This allows charging via a standard 120Vac outlet which typically employ 15-20 amp breakers. This provides the least stressful charging profile for the Leaf especially if the temperature is below 32F. The Leaf's Level 2 on-board charger is either 3.3kW (early model Leaf) or 6.6kW (after 2013 I believe). Level 2 charging is via 240Vac and pulls less than 30 amps so can be operated from a typical 240Vac @ 30 amp service. Neither Level 1 nor Level 2 charging is capable of stressing the battery under most conditions. So, unless it's EXTREMELY cold or EXTREMELY hot (think Arizona's 115F daytime highs), there's little to worry about with either Level 1 or Level 2 charging. Besides, even in scenarios where it does reach extreme temperatures the BMS should protect the battery pack by sensing the temperature and automatically making adjustments to the charging current. Trying to regulate charging current externally (in front of your EVSE equipment) could risk damaging the Leaf's internal (on-board) charging circuitry.
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thew
Well-known member
You need to size that Service Breaker to what your evse dock requires. Most will want a 30 amp breaker for a Level 2 EVSE. Look at the Tag on the EVSE dock and provided that Breaker size. anything else will be a fire hazard and your Insurance on your home will not cover a fire etc if you under or over size that breaker.
Jnovoseljr
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A lot depends on how many miles you tend to drive in a day. I never bothered to installed a Level 2 charger. I just use a regular 110-volt outlet, and when I need to I charge from 11:00 PM to 7:00 AM. That adds about 40 miles of range, which is more than I usually need, and I try to keep the pack up around 80 percent charged so if I need to make a longer trip I can.
Why spend the money on a updated circuit if you don't really need it?
fotajoye
Well-known member
And, this is what I recommend for the latest generation Leaf, 2018-2024.
A professionally designed and installed circuit protected by a 50 amp circuit breaker, using #6 wire and terminated in a nema 14-50 connector.
I use the supplied portable EVSE and the 14-50 adapter out of the car as the interface; just hang it on the wall with string and plug it in. You want to hang it so it can easily be removed if you ever want to carry it with you as a backup.
Just wondering re "over 24 amps but less than 40, needs a 50 amp plug", etc. Is this "best practice" or is there some other reason? I have been using the supplied charger on a regular 30A dryer outlet for over a year now. I measure a 27A draw.
NEC ("code") requires derating to 80% when the load is considered "continuous". So therefore the statement. I bet the wires are getting a bit "warm" at that rate.
