Charging at public level 2 charger - actual wiring question

[Jon]

This topic has been discussed at length in a theoretical sense, but has glossed over some details.

Out here in Colorado, there are number of EV chargers near good trail riding, and even more near good supermoto riding. I think it would be great to drive the truck and bike out to a riding spot, park next to an EV charger, and just circle back when I need to recharge. The rapid charger and other wiring can stay in the truck, and I can charge with peace and quite. See bad whiteboard drawing below for detail.


However, in looking into making a J1772r to L14-30r converter, I've run into the old 4-prong vs 3 prong issues. A few other post have addressed how to tackle this issue for a 120v adapter, but I'm a little lost about how to deal with it when using both hot lines. The J1772 standard has 2 hots and a ground, while the rapid charger is looking for both hots, neutral and ground. I know just enough about electricity to be dangerous, so I'm a little concerned about the safety of going in this direction. Here are my thoughts/options

Option 1
Connect the hots and the grounds and leave the neutral unused. It's my understanding that this will trip the GFCI, but I don't know. Anyone got any ideas?

Option 2
Connect the hots and hook the bike neutral to the charger ground. Leave the bike neutral unused. I think this means there is no ground fault current path, meaning that if something goes wrong, the current could discharge through me without tripping the breaker. This seems very bad, right?



Option 3
Bridge the neutral and the ground. This seems like the best option to ensure a safe ground fault current path and balanced current for the GFCI. However, I have been told that in the context of home wiring that adding a second neutral-ground bridge outside of the junction box is bad. I don't fully understand why this is bad, but I don't want to forge ahead without understanding the ramifications for this application.



So yeah: is this do-able? I know I've seen other adapters online, but just because someone is selling one online does not mean it is done right.

 

[snydes]

Jon, the Alta chargers don't use the neutral prong of the 240v plug at all. Just pop the plug off and have a look for yourself. Only 3 wires going into the GFCI. That should simplify things for you.

 

[Jon]

Wow... Now I feel pretty dumb for putting so much thought into this.

Thanks

 

[snydes]

Wow... Now I feel pretty dumb for putting so much thought into this.

Thanks

Haha, no worries. One would think the neutral would be used, but alas, not the case.

 

[VINSANITY]

So if we make this adapter then we need to plug it into the fast charger correct.

I believe these are the two connectors we need to make this adapter.

Would appreciate if someone could do a wire schematic even though it is probably very simplistic.

 

[snydes]

Don't forget there is the "handshake box" to deal with the communication aspect that would need to be incorporated into this.

 

[VINSANITY]

Could the fast charger be the handshake box.

 

[bluefxstc]

I have used these in the past for J1772 communication in the past with pretty good luck. I don't know of any way to program an Alta charger to handle the J1772 communication. It may be possible, but is way beyond my programming ability.

 

[VINSANITY]

So do you think that with this control module it would be possible to plug an Alta into a public level 2 charger?

 

[VINSANITY]

It seems you would need this communication adapter and the fast charger to be able to charge at a charge station with a J1772 connector.

 

[Rashid510]

It seems you would need this communication adapter and the fast charger to be able to charge at a charge station with a J1772 connector.

The Hacksmith: Charge a One Wheel at any EV Charge Station

Hacksmith was able to charge his Onewheel off of a L2 charging station with the setup above. Essentially replace the Alta charger with the Onewheel charger and make up the system in the link above (either swap out the 110V connector or put it at 220V). Few people in the YT comments do indicate holy whoa on the charging setup/layout but...if its wired right the box should allow the Alta charger to connect correctly.

(Theoretical schematic is in the link)

 

[VINSANITY]

Man that would be awesome to have a portable charger to use at public level 2 charging stations

 

[bluefxstc]

So do you think that with this control module it would be possible to plug an Alta into a public level 2 charger?

Yes

In addition to the plug, J1772 is basically a communication protocol and a switch. The communication tells the Alta charger how much current the EVSE (Level 1, 2 or 3) equipment can provide and that it is plugged in. We really don't need the current information since even the fast charger only draws about 15 A, but an older Tesla with dual chargers can draw up to 80 A, so it is an issue then. The being plugged in part is just a safety issue so voltage and current is not at the plug when nothing is plugged in. Once a vehicle is plugged in, the EVSE switches on power and the vehicle charger does the rest.

I used the control module I linked in my post above in my 300ZX conversion and never had a problem charging at public EVSE. My charger was an Elcon PFC2500 so basically the same as the standard charger in a different box and without the CAN bus comms the Alta has.

All you are really looking for is something to turn on the public, or private for that matter, EVSE. Once you do that you will have power, either 240 or 120 Vac depending on if it is a level 1 or 2 EVSE. Once you get power the vehicle charger does the rest. If you don't provide the correct signals to the EVSE it will never turn on so no power.

 

[Rashid510]

@bluefxstc do you see any issues with the setup that I posted? I remember you posted about this before and linked the Tucson guy before...I also got this from the link for conversation sake.

 

[bluefxstc]

@bluefxstc do you see any issues with the setup that I posted? I remember you posted about this before and linked the Tucson guy before...I also got this from the link for conversation sake.

View attachment 5301

It has been a long time since I actually looked at the control circuits needed to provide the necessary signals. I think J1772 also has a proximity switch/signal that also needs to be addressed (prox in the diagram below). I looked into building my own J1772 comm board, but in the end I just used the module I linked above. For me it was easier to buy than build. The biggest issue I see for any J1772 communication is power. The module I linked needs 12 v from the vehicle I think and the Alta's are pretty sensitive to loads so not sure where you could get it. Probably could use a small battery to provide the necessary power until you get the EVSE switched on and then use a power supply to charge the battery and provide power.

The thing to remember it that J1772, level 1 & 2, is not a charger, it is a switch that provides power to your charger and tells the vehicle how much power it can provide. Level 3 provides high current DC so it probably could be considered a charger, but the the work necessary to make an Alta level 3 compatible is way out of the scope of this thread and would require a complete rebuild of the battery pack to accomplish it.

I have never used anything from Tucson EV, nor have I heard anything good or bad about them so not recommending them or telling anyone to stay away. They do make J1772 conversion boxes and communication so they may be a good source of information. If it were me, I would probably just buy one of their boxes for $135 which includes the female plug and the control circuits, but before I bought anything, I would talk to them about power and figure that out.

 

[Rashid510]

Yes the Alta (especially the SM) is picky on loads. I think on the off board charger, not as bad. My main concern is the handshake. Once that handshake is confirmed it allows power from the station to then go to the charger. L1 or L2 would be ideal. L3 would be epic.

 

[bluefxstc]

L3 would be epic.

Epic is one way to look at it. I think L3 will provide something like 100kw so if you don't have good cooling and control it could be very epic. On the other hand you are looking at about a 3 minute charge at that level. With the right control infrastructure you could spool that down to whatever speed the bike and cells could handle and it would be very cool. Realistically, I have seen L2 chargers that will do 16.8kw which probably makes L3 unnecessary. 16.8 kw would give you about a 20 minute full charge on an Alta if the bike could handle it.

 

[VINSANITY]

I really would like to build a J1772 adapter that does the handshake to charge at public charge stations (using the Alta fast charger of course)

I don’t understand circuits well enough to build the unit myself but would be very appreciative if the knowledgeable people on the forum can come together on this one to identify the right components and the right circuitry.

Vince