Anyone charging 2 EV's using 100amps mains?

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dvu

Active member
Joined
Nov 20, 2016
Messages
35
Location
SF Bay Area
When we purchased the Leaf, it was a place holder for a model 3 but the Leaf has served its purposed pretty well so we're going to keep in. However, having the Tesla we'll need to add a 2nd 40amp 240 to the house. Our mains is only 100amp.

Will I need to upgrade my service panel to a 200 amps?

Our stove is electric and so is our dryer, I can't imagine having all that running at the same time along with charging 2 EV a good thing on our old house service panel of 100 amps.
 
It seems very likely that a load calculation for a house with (2) 240V 40A EVSE circuits would exceed 100A, in which case you would need to upgrade your electrical service. An alternative would be to use two EVSEs designed to share a single 40A circuit, such as these:

https://store.clippercreek.com/Share2-HCS-40-Bundle

There may be other brands available.

Cheers, Wayne
 
We have an AV 30 amp EVSE that was installed within two weeks of getting the Leaf. We almost always have the Leaf set to charge to 80% so we plug it in as soon as we get home. In less than one hour it i ready to go again. Once every week or so we charge it to 100% so the battery pack gets to balance.

For the Tesla Model S 75D we leave it set for 90% while on trips, then set it for 50% while at home. However we only plug it into the same EVSE when the charge gets very low. This is done overnight after the Leaf is already at 80%. So far now conflict.

However, we do have a 50 amp breaker unused on our 200 amp panel, left over from a hot tub that was removed when we built a patio room where the hot tub was located. I purchased a 14-50 outlet, a wall box, and 7 feet of 6AWG just in case we ever did need to charge both at the same time. I expect it will only be used a couple of times each year, if that. However, it was worth the cost and my labor to have it available for those rare occasions when it will be needed. While I was at it, I also added a 20 amp 120 volt GFI outlet tied to one side of the 14-50 so at least we would have 120 volts available on that side of the garage. And we know to not use the 120 volt outlet if we plug in the Tesla.

Not knowing your situation I would still think that a 200 amp service would be call for. You can get away without it, just make sure you only charge one EV at a time, and not while cooking with more than one burner and running the electric close dryer at the same time.
 
dvu said:
When we purchased the Leaf, it was a place holder for a model 3 but the Leaf has served its purposed pretty well so we're going to keep in. However, having the Tesla we'll need to add a 2nd 40amp 240 to the house. Our mains is only 100amp.

Will I need to upgrade my service panel to a 200 amps?

Our stove is electric and so is our dryer, I can't imagine having all that running at the same time along with charging 2 EV a good thing on our old house service panel of 100 amps.

If you are willing to accept the EV charge rate varying, there is a modern version of the so called load minder available and meets code, it affectively is upstream and shared off of your panels available load, meaning if you are charging and turn on your oven one of your EVs will cycle between charging and not charging while it's in use <or> the more advanced solution reduces its rate to what's left over.

There was a thread with a Canadian guy who could not upgrade his home electric that had a link to one.

Depending on how expensive a panel is it might be cheaper to just use what you have with a modern load minder.

My guess is your oven doesn't run 8 hours a day nor does your dryer so you are likely safe to let your ev(s) charge a little slower the short time you are running both.

A link to such a device was posted in another thread
 
Thanks guys, great options out there. It'll set us back between $3k to $5k for the service upgrade, With out Leaf, we haven't had the need to ever go below 20% of it's charge. I'd imagine it'll be the same with the Tesla. It'll also be very seldom that both will need to be charged from emptied together since I work at home and the leaf's is the wife's commuter of about 30 miles RT and charging is available at her work.

I like the shared EVSE idea for its simplicity since we already have a plug in place.

Just tried to search for the load minder but came up short. I'm a day one reserver, but probably won't see the M3 till the end of the year if I'm lucky, so I still have some time to decide.
 
rmay635703 said:
dvu said:
Our mains is only 100amp.

Will I need to upgrade my service panel to a 200 amps?

Our stove is electric and so is our dryer, I can't imagine having all that running at the same time along with charging 2 EV a good thing on our old house service panel of 100 amps.

If you are willing to accept the EV charge rate varying, there is a modern version of the so called load minder available and meets code, it affectively is upstream and shared off of your panels available load, meaning if you are charging and turn on your oven one of your EVs will cycle between charging and not charging while it's in use <or> the more advanced solution reduces its rate to what's left over.

There was a thread with a Canadian guy who could not upgrade his home electric that had a link to one.

I'm not sure if this is the thread rmay635703 was thinking of: http://www.mynissanleaf.com/viewtopic.php?f=27&t=23698&start=30, and he was in Alaska not Canada, but quoting from ermackey "New solution idea: Using a Samsung Smartthings Hub and a few Z-wave relays, I can put my Hot Water and two car chargers, on Z-wave "smart" switches. One of the new app features is the "Max Energy" app that turns off specific devices as KW consumption is reached. I could "tier" my appliances to operate on a priority tier ranking. AEON makes a energy monitor that works with Smartthings to utilize this feature." In that same thread, gshepherd's suggested the extremely energy efficient "condensing" dryer, and freed up a 240V breaker.

I was wondering too about converting the stove and/or the dryer to gas. I live in Florida, and everything here is electric too, but gas is so much nicer for cooking, and using electricity to turn into heat for a dryer seems almost criminal when the electricity could do so much more.

Another idea might be PV with or without a battery backup. That would be a way to get more out of sunny days, although with just a 100 amp panel it might require a line-side tap, which is less than optimum and power companies frown upon. But even if it was a small enough system and just use a 20 amp backfed breaker, it would help.

And, instead of a simple load calculation, it is possible to gather 30 days of real-world usage and use that for the calculations and still be code compliant. But you'll have to consult a very sharp electrician for that who really knows code.

Call me "thrifty," but I'd explore a lot of options before I'd pay $3K - $5K to upgrade the panel, even if the panel is considered low for modern homes.

Of course, you could do it the real simple way and just charge the LEAF at 120V when the Tesla needs topping off. It is a dilemma I'd love to have. :D
 
sub3marathonman said:
rmay635703 said:
dvu said:
Our mains is only 100amp.

Will I need to upgrade my service panel to a 200 amps?

Our stove is electric and so is our dryer, I can't imagine having all that running at the same time along with charging 2 EV a good thing on our old house service panel of 100 amps.

If you are willing to accept the EV charge rate varying, there is a modern version of the so called load minder available and meets code, it affectively is upstream and shared off of your panels available load, meaning if you are charging and turn on your oven one of your EVs will cycle between charging and not charging while it's in use <or> the more advanced solution reduces its rate to what's left over.

There was a thread with a Canadian guy who could not upgrade his home electric that had a link to one.

I'm not sure if this is the thread rmay635703 was thinking of: http://www.mynissanleaf.com/viewtopic.php?f=27&t=23698&start=30, and he was in Alaska not Canada, but quoting from ermackey "New solution idea: Using a Samsung Smartthings Hub and a few Z-wave relays, I can put my Hot Water and two car chargers, on Z-wave "smart" switches. One of the new app features is the "Max Energy" app that turns off specific devices as KW consumption is reached. I could "tier" my appliances to operate on a priority tier ranking. AEON makes a energy monitor that works with Smartthings to utilize this feature." In that same thread, gshepherd's suggested the extremely energy efficient "condensing" dryer, and freed up a 240V breaker.

I was wondering too about converting the stove and/or the dryer to gas. I live in Florida, and everything here is electric too, but gas is so much nicer for cooking, and using electricity to turn into heat for a dryer seems almost criminal when the electricity could do so much more.

Another idea might be PV with or without a battery backup. That would be a way to get more out of sunny days, although with just a 100 amp panel it might require a line-side tap, which is less than optimum and power companies frown upon. But even if it was a small enough system and just use a 20 amp backfed breaker, it would help.

And, instead of a simple load calculation, it is possible to gather 30 days of real-world usage and use that for the calculations and still be code compliant. But you'll have to consult a very sharp electrician for that who really knows code.

Of course, you could do it the real simple way and just charge the LEAF at 120V when the Tesla needs topping off. It is a dilemma I'd love to have. :D

It's funny that the idea was to use a Zwave relay as I was just thinking the same thing. I don't use Smart Things but Vera, I already have energy monitoring of my "whole house" and already have a log of what my house uses on standby and how much it draws when A/C is running or when the stove is running. Great idea, I think a dry contact relay would do the trick just fine.

I know my house draws about 1kw at any given time due to all the servers and electronics I have running. My A/C typically add another 2000w to it and if I recall correctly, with 1 stove running, it'll spike up another 2000w.

I can easily add a dry contact relay to the EV charging circuit to shut it completely off when the house is drawing anything more than 2kw which is mostly midday in the summer when it's hotter than usual and during dinner time. But it'll still be charging through the night. If I take the stove out of the equation, it'll be easier since my HVAC is also tied to the home automation.

Since the A/C shuts on/off I'm just concern of the the reliability of the charger being on/off.

in case someone else is reading.... this should fit the bill nicely

https://www.amazon.com/Aeon-Labs-White-V3-26-AL001/dp/B00MBIRF5W
 
dvu said:
It'll also be very seldom that both will need to be charged from emptied together
Alternately, why complicate things? Just install 1 EVSE such that you can only plug in one of the EVs at any time. This avoid all the extra costs and complexity for a "very seldom" condition.
 
jlv said:
dvu said:
It'll also be very seldom that both will need to be charged from emptied together
Alternately, why complicate things? Just install 1 EVSE such that you can only plug in one of the EVs at any time. This avoid all the extra costs and complexity for a "very seldom" condition.
Yep and he could still plug the leaf into L1 in the mean time
 
$3000 to $5000 to upgrade a service panel that costs $150 is ridiculous. Several years ago I needed to upgrade the service panel in my home, I got quotes around $1100. that was a rip off too, would up hirinig friend electrician did it for $150.
 
dvu said:
Will I need to upgrade my service panel to a 200 amps?

Our stove is electric and so is our dryer, I can't imagine having all that running at the same time along with charging 2 EV a good thing on our old house service panel of 100 amps.
I agree that you COULD do all of the energy-spreading things mentioned in the several replies above, but do you really want to be the house controller manipulating usage manually, and with all the usage restrictions that will go along with that? On the face of it, you have a 100-amp main and are adding 80 more potential amps of consumption (two 30-amp capacity loads wired to 40-amp circuits presumably). I would be concerned cutting usage this close given the rest of the house would be protected by only 20-amps of cushion, the equivalent of only one room's lighting and outlet circuit. Obviously, my recommendation would be to upgrade source power and forget the multiple controls. Plus, you then have a far better safety factor built in, let alone the additional power should you add more juice consumers in the future. But, you are not me. Also, a power upgrade can be far beyond just changing out the load center, or it may not. To try to be helpful, here are some other factors to consider from when I upgraded our home's power:

1- Will you need to upgrade the power lines coming from the provider's pole (your expense, typically)?
2- Will the provider need to upgrade the transformer you're connected to (their expense, typically)?
3- Is a new meter (their expense) as well as the new load center (your expense) needed?
4- With the Tesla, will you EVER want to upgrade to the 72-amp charging station?
5- Have you inventoried all of your high-current-draw items? I'm guessing it is more than just the stove and dryer. Everything with a compressor can be high-draw, especially at start-up, including any central HVAC or window A/C units, refrigerator(s), dehumidifiers, freezers. Also, like the stove which you can easily control, what about the hot water heater, which is pretty easy to forget to control but draws a lot of juice, more so if you have a tankless unit.
6- Do you know the likely current loads from your other devices like outdoor landscape lighting, floods, can lights, and any lighting you have not already migrated to LEDs? It can be surprising how quickly incandescents and halogens add up just in normal use.
7- How about other items with motors: pool pumps, irrigation pumps, sump pumps, water features, HVAC blowers, bathroom fans, ceiling fans, vacuums.
8- If you were to get a whole house standby generator, how big would that have to be? Just having a competent installer compute this for you could be very telling in whether 100-amp service is adequate and safe, or risky.
9- And consider high-wattage heating devices: toasters, toaster ovens, coffee makers (the ubiquitous Keurig draws about 1350-watts or so, or about 12+ amps at 110v while heating), bread makers, heating blankets, hot pads, radiant flooring, portable room heaters, and so on.
10- If home sale or gifting is ever at issue, and it certainly will be someday, having the upgraded capacity will be an buyer expectation, and without it a detraction to sale.

My point is to really evaluate all of your power consumers against your lifestyle today and in the future before dismissing a power upgrade out of hand because of cost (although I do think 5k is a tad excessive unless you have special circumstances like being located in the middle of a lion preserve for example). It could be a reasonable investment for safety, peace of mind, to eliminate the unending power balancing act, and enhance your home's sale ability.

Good luck with your decision and implementation!
 
SalisburySam said:
I agree that you COULD do all of the energy-spreading things mentioned in the several replies above, but do you really want to be the house controller manipulating usage manually, and with all the usage restrictions that will go along with that? On the face of it, you have a 100-amp main and are adding 80 more potential amps of consumption (two 30-amp capacity loads wired to 40-amp circuits presumably).
Good luck with your decision and implementation!

Doing an energy audit of your house is fairly easy and worthwhile

That said the most advanced load share systems would be a full 100 amp breaker upstream of your main box,

The most advanced systems would throttle the EVSEs output based on the home loads, the full 100 amps would be available to home + EVSE loads and throttle the EVSEs down as home loads go up.

Key is cost, sometimes these systems are quite cheap and he can always upgrade his service anytime , any loadshare systems would still work if he upgrades his panel.

So agreed
Old addage measure twice cut once applies
 
Excluding other loads a 100A panel is good for 80A EVSE loads. When you consider other loads two 30A eves's are doable. All J1772 cars respect the current offered so a model 3 will happily charge at 30A,

I upgraded my service to 200A because by FPE panel caught on fire one morning. The 200A panel is required by local code but the only thing it gets me is more slots, In a non- electric home 100A is fine. The biggies are an electric stove and water heater. All my appliances are natural gas.
 
40A is the "over rating" for a 30A aka 7Kw. 3.6Kw chargers are 15A. If both cars have 6.6Kw chargers then you would need to stagger charging times. Only Teslas can actually use 40A or even up to 80A with a proper Tesla HPWC, but those are mainly intended for commercial locations.
 
While it's unknown what the Tesla Model 3 will come with, it's likely going to have the same portable EVSE they are using today. It pulls up to 40A (on a 50A circuit) and can add 29 miles/hour on a Model S. (it will pull less depending upon the circuit you plug it into, or you can drop the current manually). I don't think the OP needs to worry about buying a dual charger on the 3 (even if they offer it, which again is unclear).

Back to the OP: I think you still want to just have a single EVSE and not spend thousands to upgrade your service.
 
aluminumwelder said:
$3000 to $5000 to upgrade a service panel that costs $150 is ridiculous. Several years ago I needed to upgrade the service panel in my home, I got quotes around $1100. that was a rip off too, would up hirinig friend electrician did it for $150.
i just had my main service panel upgraded from 100amps to 200amps. It cost less than $2000, in fact I think it was closer to $1700 in the end.

I had mine upgraded, just last week, because I'm in the process of installing solar. They were looking for some breakers to bring everything into the main panel and we were short. I also saw a day when I would be putting more load on my system anyway.. as I moved all services from gas to electric so I went with it. the install was not done "as well as doing the solar" it was a day on it's own. They will be coming back another day to complete my wiring for the solar side of things.

I'm glad I did the upgrade.

Shop around. $3000 is a lot more than I was charged. For my last house a electrician came out, back in 2014, to to look at our panel and wanted $5000 to upgrade it and I quickly showed him the shortest way to leave our subdivision. there is a lot of price gouging going on right now because there is a an abundance of work for them. You'll find a team that will do it for a proper price.. keep shopping.

Had I got a friend who could have installed it for me at a much reduced price.. like above, I'd have done that too. I live in Utah and you are allowed to do all the work yourself but if I did the inspector would have spent more time going over it and he might have insisted that I did hire a proper electrician to do it anyway.
 
My upgrade cost $2500 in Southern California. Prices will vary per region but I think the city got more than their share. I demanded that the upgrade had a permit and it was inspected. Good thing since I and my electrician did not know that Anaheim does not allow splices in the service wires. They ended up at their cost moving the panel down 6 inches so the existing wires would reach.

It was that or pay thousands to run new wires in conduit instead of the 1976 direct burial wires. The city would love to see conduits but they allow grandfathered wires. I was just lucky the wires were big enough for 200A service.
 
Check with your utility if they can split the service into a second meter for EV charging only, a fairly simple affair for overhead feeds which often doesn't require feeder wire upgrade, as a bonus depending on utility you may get a better EV rates on that meter.
 
I plan to eventually upgrade my panel to 200A (already have a panel, just need to get the electrician and the cash to pay him)
But I'd be doing it more for other reasons (want a hot tub)

My short term plan is Chevy starts charging at 7PM when the rates go down, LEAF starts charging at 10:30PM when we usually are heading to bed and the Volt is likely just about done charging anyway.

This avoids the likelyhood of having 2 EVSEs, AC, and Oven/Dryer all running together.

We've had 1 L2 going for 3 years without any issues at all. Timing them so that they are not runnning at the same time is easy, both cars have charging timers built in.

Aside from that, I bought the SL with the DC Quick charge port for a reason. There's an L3 station with free power on my way to and from work. :) It's at the utility company's office. They wanted a nice display of a solar panel charging cars out front, so they give free L2 and L3 charges.
 
I'm surprised that no one has mentioned that the new Tesla Wall Connectors can share a circuit. You could buy one from Tesla for your Model 3, and a J1772 converted one from Tony and have them share a single 50a circuit.

http://shop.quickchargepower.com/J-Wall-40-the-premium-40-amp-wall-mounted-J1772-charge-station-JWALL40.htm
http://shop.quickchargepower.com/J-Wall-80-Premium-80A-Wall-Mounted-J1772-Charging-Station-JWALL80A.htm

If both cars need to charge they each get 20a, if only one needs to charge (or only one is plugged in) it gets the whole 40a. That way you can just plug both cars in whenever it's convenient and have a fair degree of confidence they will both be charged in the morning. Expensive, but a lot cheaper than a panel upgrade. If you later move, or decide to do the upgrade, you can have them both share a bigger circuit.
 
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