Chargers that share available power
 

Which, if any, of the available quick chargers talk between themselves to share the available power?

Let me back up a bit. Much to my surprise, my workplace is looking to Green up their image by (among other things) installing some EV charging in our parking lot.

The general idea appears to be one lighting transformer to be shared by several chargers along one line of the parking lot. There are .. maybe 30? .. parking stalls in this line. I don't expect that the budget will allow for 30 quick chargers. But the stalls that don't have quick chargers should at least get a dedicated 20A 208V weather-resistant receptacle ... which is better than the existing 15A not-weather-resistant receptacles we use for our block heaters in the winter :)

The largest reasonable size transformer (fits into a parking stall, so we lose just one of them) appears to be about 250 KVA, if we are stepping down to 208V three phase ... but are we? Our input is 575VAC (Canada) three phase. Since some of the quick chargers are up to 800V (last I read) I'm not sure if we can actually step down the voltage. Perhaps I need to drop to 460V instead, or perhaps the chargers boost from 208V three phase? If the charger can be fed directly from 575 VAC three phase, we can use more power (the feeder is 600A) ... then the limiting factor would likely be the size of the cable we are willing to bury.

Having the feeder breaker trip or the transformer overheat is not reasonable. I expect that vendors have figured out a way to share the available power ... but I don't remember reading about that. I think I remember reading that the Tesla chargers measure voltage drop and reduce output based on that.

I'm confident that many people have investigated this and come up with good solutions. I'm not looking for a cutting-edge solution. But it would be nice if it was as future-proof as I can manage.

Thanks in advance!

200 ish volt for charging seems universal, not fast but not week long slow so whatever you use up there for dryers should work for stock chargers. The quick charge people go exotic voltages. You might want to look at the appropriate specs because you dont need to go full blown tesla.

Block heater taps would even work. So what if you only half charge dring the work sift, it's free. Charging on 120 for 8 hours would still get me home and back.

J1772 don't talk to each other or share the circuit as a as I'm aware.
Only tesla does that and I think they work in pairs.
Then you have 3 or 4 different DC fast chargers at the moment.

They are not going to pay to install DC fast chargers unless it's to do for profit charging. I occasionally see them used and they still run $8,000 to $10,000 each.
I don't know how much they are new.

Just put in some J1772 like everyone else.
Our nation electric code has guidelines for installing evse circuits.
In the US large numbers of public charging stations grouped together normally use 208v.
Then the chargers can be limited to anything from 6 amps all the way to 24 amps for a normal affordable j1772 charge setup.

I'm interesting in the 'Then the chargers can be limited to anything ...' part. Is that a manual setting on each charger, or can I install a supervisory controller that talks to these units ... or perhaps there is some other way?

There is presently one model X, a couple of chevy Volts, one Mitsubishi outlander ... I think that about does it for the parking lot survey.

I'd like to think that things will be getting better in the near future. One or two stalls that can give you enough juice to get home if you are only at work for a couple of hours (over-time call-out) would be nice. For the rest of them, I agree for now.

If 'this is important, for some reason, right now' and I have the budget to 'do it better', or have a plan to make it better later but I need to bury a bigger cable ... or whatever boundary condition will limit options ... Well, I'll go as far as I can with the budget I'm given.

Sounds like fast chargers are kinda non-standard. I'll contact the vendors directly and see what they say. I like to have SOME info before I go there ;)

J1772 is a simple, cheap, dumb charging protocol it doesn't have instrumentation and controls.
The J1772 sends a signal to the car telling the car how big it is, say a 24 amp capacity, then a car like my old leaf will accept up to 16 amps because that's all it can handle.
Newer cars will take all 24 amps.
The J1772 units don't talk to each other. If they did it would be some proprietary control and evse system. To me that's a waste of money.

The cheapest thing would be to run 4 wire wye 240/480v on 4 gauge wire. That way it can handle 70 or 80 amps.
Let's say 70.
So if you ran 30 charging spots and ran 1 line to 10 spots that would allow for 6 or 7 amp charging on each spot.
What I would do is run 9 spots, 1 line to 3 spots and limit the charging current to 20 to 22 amps or less.

Unless this is for profit charging?

The EV charging industry is way less inviting than I was hoping :(

- J1772 chargers appear to be 230V input
- ChaDemo .. or some variant ... also appear to be 230V but can be 208V 3 phase

Anything higher than 'Level II' is apparently a secret ... and you need to be a dealer ... or have an NDA ... or some other strange silliness ... in order to get information.

No one appears to be taking 'green-washing of dirty industrial sites' as an opportunity to sell/install some product.

If anyone has info on a set of chargers that will co-operate between themselves to 'share' a 600 amp feed at 575VAC 3 phase ... please get me some contact information.

I have 30 parking spots. Not all need to charge all of the time ... for example, 1 charger with an appropriately long charge cable could service 2 or 3 parking spots. But each parking spot not covered by a 'quick charger' would at least get a dedicated 20A 208V weather-resistant receptacle.

Are there any vendors out there that will share some information?

This is an industrial site, that is not selling charging services, but that would like to provide charging for employees and contractors in exchange for looking like a progressive, eco-friendly company. I'm sure that the project will get pasted onto some corporate literature ... so there may be additional sales as other sites seek to implement a solution that has already had the details worked out.

I got an email saying that the thread had been updated, but could not find this post :(

If you have vendor info, please pass it along!

I have $30K to gather specs, costs, etc this year in preparation for an install in July 2020.

If it costs $500K, it likely won't get approved. But if I can get something reasonable for $200K it might. Or it might get trimmed to $150K. The $500K install ... which eventually will get done .. since electric vehicles are where we are headed .. may need 2 runs of 350 mcm 3 phase cable buried. The install of the buried cable costs way more than the copper cable. So I'll find the money somewhere to get the right cable buried instead of the minimum cable size for the cheaper option.

I'm *NOT* ripping up the parking lot twice!

Most if not all of the public chademo units are 480v 3 phase powered in the US. 3 phase 240 and 208 are probably available for convenience. If you have 480 or whatever is common in Canada maybe 380v? Use that for rapid chargers.

What's providing the power?
Probably start there. Mainly what's the voltage?
Then if it's not a big enough transformer, service feeder, or enough remaining capacity to tie into there may be no point in running an mcm size wire.

I have learned more about the j1772 protocol. It appears that it can change on the fly in 1 or 2 amp steps from 6 to 70 amps. The pilot signal can chang and direct the car to draw less power. But I do not know of any j1772 setups that talk to each other like that to limit the amps on the feeder, but it appears possible and as if that were the intent of the design.

575 VAC is the 'normal' industrial voltage in Canada

The feed is coming from a 1250 KVa transformer, through a load center. The load center breaker is rated for 600A continuous.

The cable is over-sized for voltage drop, nominally 3%. 2 runs of 350 MCM is easier to bend around the corners and route into the electrical equipment than a single run of ... 500 MCM maybe?

Depending on which area of the parking lot is dug up and whether they put the cable along a fence or some other area that does not see vehicles parked on top ... 600 - 800 feet from the load center to the common point of the chargers. Sorry for the wishy-washy numbers ... I'm on vacation ... I don't have my design notes handy.

In a best-case future, where electric cars are purchased as quickly as people replace cars ... it is STILL *VERY* unlikely that we would ever see 600A used for charging electric cars and trip the load center breaker, at least for a long time to come. But due diligence dictates that it be looked into. If there are some vendors investigating how to do it ... that's one more column on my technical evaluation spreadsheet.:thumbup:

That's such a long run it may be better to have the power company run a service lateral and use a standard residential 37kw pad transformer. But they may have a maximum limit to the length of the underground wire.
If you have 575 volt then you already need a transformer. A residential over head high voltage to single phase is probably cheaper than an industrial 575 to 240v transformer.
To run 37kw on 4,160v they would only need to run about a 12 gauge feeder wire. So the trench, conduit ect would be small, so less parking lot to fix.

I don't think the underground part is limited in length ... but they do have line length limits from the 15KV distribution transformer to the residential pad. I think

We have several transformers - we do our own distribution within the plant site. I don't want to pay for ANOTHER transformer.

I don't think it would be reasonable to get another SaskPower (utility) feed.

Our local utility distributes residential at 14,400V (they still call it 15KV) and the transformer that they install if you don't ask for anything extra is a 200 amp service at 240 VAC. That's less than one 50 KW fast charger, isn't it?

37 kw at 4160V is still less than one fast charger. I guess I'm a bit confused?

Industrial distribution in Saskatchewan starts at 72 KV, but you are encouraged to install at least 138 KV, and we were encouraged to install 230 KV when we did our last expansion in 2012.

Our site is fed with 230KV and the site covers about 2 miles by a mile. We step the 230KV down to 15KV, and use a separate 15KV building to house our 15KV feeders that distribute to the various buildings. The 575V transformers range from 1000 KVa to 4000 KVa. We also have a few 4160V transformers that range from 2500 KVa to 6000 KVa. But I don't have a 4160V feed closer than a quarter mile. It's just not practical.

It's also a matter of economics and space. We have an existing 15KV distribution building with limited room. Our electrical group is rather protective of the 1 or 2 breakers that we have spare. If we used one, the 15KV distribution breaker, buss, metering, protection, etc are quite expensive. North of $50K per cell. And the 15KV building is a long way from the parking lot - maybe 1200 - 1500 feet.

One of our standard 15KV to 575V transformers (1250 KVA) takes some room, as well as a 15KV disconnect, a distribution panel, etc that would need to be outdoor rated and would end up taking at least 2 of the parking spots. We'd have to put fencing around the 15KV gear as well. So less parking spots, and less money for buying EV chargers. I would have 1250 KVa instead of 350 KVa ... I think that's a lose-lose scenario. Or am I missing something?

My apologies for not posting all of the relevant information for the design up front .. but my issue is that the suppliers, or the charger vendors ... won't tell me how or if their chargers talk to each other to share the available power. Can they accept 575V three phase directly? Do I need a breaker and a disconnect for each of their chargers? Somebody has this info ... somewhere .. :D

I didn't think you were installing fast chargers.

DC fast chargers can probably take 575 volt power, but j1772 can't.

From a purchasing view: if they won't talk about being interconnected, then they dont interconnect.

Pick a common local universal standard. Whatever the local places use.

Except for the Tesla and oilpan, nobody NEEDS super quick charging, and everyone I know has a box of adapter plugs. I don't believe someone will show up at work bone dry and then have to drive a hundred klicks by lunch. If they do, it shouldn't be your problem to fix.

I was happy my work allowed me to plug into the 117v school bus prewarmer circuit or the pipe warmer circuit when I was running FLA.

Good point!

J1772 seems to be what is used most. It's just sort of the minimum.

Maybe not this year or next. But in 10 years that could be considered 'normal' ... who is to know?:eek:

This is Saskatchewan, Canada. It gets cold here. Like 40 below F, -40C. So we have 10A at 120V available at each parking spot to run the block heaters and interior car warmers that everyone has in their ICE vehicles. That's the good news.

But 10A * 120V .. 1200W gets you about 10 KW-h in an 8 hour shift. Minus whatever power is required to heat up the batteries so that they can take the charge (Lithium packs don't really charge when they are below 0C, so the liquid cooling/warming system needs power to warm up the batteries before/during the charge). That's the bad news. There's power ... enough maybe in spring, summer and fall. Not enough in winter.

Since someone at head office decided that our sites should be greener, and EV charging is becoming a thing ... we got some money to engineer/investigate how to put in charging infrastructure.

Taa-Daa!

I still need information, if anyone has some!

I thought this forum would be a good place to start. I'll be sending out formal info requests to ABB, Eaton, Siemens, and whoever else I can find contact information for when I get back from vacation.;)

I like having *SOME* information before I send out the info requests. It helps when I know what I'm asking for.:D

I would go with 30a 220 outlets for employees, and something bigger for the visitor spots, the people above you wanting to say they are going green don't care about how much power each employee can get, they are counting spots.

What he said.

The bus warmer example was for illustrating that I was happy at 1KW.

I've been to Grand Forks AFB, NoDak, I know cold.

As far as I can tell the big industrial suppliers don't mess with car charging stuff.
My home chademo peaks at about 8kw, but averages about 7kw, which is almost no improvement over standard 6.6kw charging found on 2013 and up electric vehicles.
But I do have a 100 amp 240v circuit going out to my garage, it's for my welder. But I could breaker it at 80 amps for continuous use, some kind of 70 amp j1772, but no one makes a 70 amp j1772 charging car yet.