Accessing J1772 (Level 2) EV Chargers to charge Van/RV lithium system

[Ampster]

I believe I have two hots which makes for a true 220 volts

From a safety standpoint it would be wise to know for sure and then make sure that you are using the correct plug/receptacle for the connection from the J1772 receptacle. A 5-15 receptacle is not the correct connection for 240 volts and future readers could be fooled into a dangerous situation.

 

[berksrunner]

Yup...please read the posts above. My choice of NEMA 5-15 was made for me by a commercially available adapter.

 

[berksrunner]

I messaged the manufacturer using the review feature on their website (you'll see it in public under the reviews for the item), and this was our exchange:

VanDreams (verified owner) –2020-10-13
Does anyone know what the true voltage output is? I’m guessing it represents one leg of the 220V that is the output of the EV charger? I’m being thrown off by the warnings regarding 220V — but how could a NEMA 5-15 possibly output 220V?

• 
  
  evseadapters –2020-10-26
  Most EV charging stations output about 208V to 240V. This adapter supplies a NEMA 5-15 connection as a convenience feature for easy connection to chargers that come with the American standard power cord but are capable of operating at the higher input voltage (a lot of ebike chargers are made for international voltage compatibility so can handle 220V easily but for the American market they ship with the NEMA 5-15 plug). Just be careful to only use this adapter for 220V-capable appliances.

 

[Ampster]

Yup...please read the posts above.

I read the posts and your subsequent post that said that you did not know if you had two hots. It was not clear to me and I was hoping you could clarify simply by using a multimeter. Seven Amps may be the full Amperage that your power supply may pull at 120 volts. I would guess that the warnings are about the 220 (240) going into the J1772 receptacle. The important thing that I would want to know and for the benefit of future readers is whether the 5-15 receptacle is wired correctly for 120 volts.

 

[berksrunner]

I read the posts and your subsequent post that said that you did not know if you had two hots. It was not clear to me and I was hoping you could clarify simply by using a multimeter. Seven Amps may be the full Amperage that your power supply may pull at 120 volts. I would guess that the warnings are about the 220 (240) going into the J1772 receptacle. The important thing that I would want to know and for the benefit of future readers is whether the 5-15 receptacle is wired correctly for 120 volts.

I'll read the voltage next time I'm at a charger and report back.

 

[Hedges]

I messaged the manufacturer using the review feature on their website (you'll see it in public under the reviews for the item), and this was our exchange:

VanDreams (verified owner) –2020-10-13
Does anyone know what the true voltage output is? I’m guessing it represents one leg of the 220V that is the output of the EV charger? I’m being thrown off by the warnings regarding 220V — but how could a NEMA 5-15 possibly output 220V?

• 
  
  evseadapters –2020-10-26
  Most EV charging stations output about 208V to 240V. This adapter supplies a NEMA 5-15 connection as a convenience feature for easy connection to chargers that come with the American standard power cord but are capable of operating at the higher input voltage (a lot of ebike chargers are made for international voltage compatibility so can handle 220V easily but for the American market they ship with the NEMA 5-15 plug). Just be careful to only use this adapter for 220V-capable appliances.

I read that as,
"This adapter conveniently takes 240V input from a charging station and presents it at NEMA 5-15 socket. If you have an ebike charger with NEMA 5-15 plug that can also work on 220V as found in Europe, everything is hunky-dory. But, if you plug a 120V only device into our socket, it will likely catch fire."

 

[berksrunner]

I read that as,
"This adapter conveniently takes 240V input from a charging station and presents it at NEMA 5-15 socket. If you have an ebike charger with NEMA 5-15 plug that can also work on 220V as found in Europe, everything is hunky-dory. But, if you plug a 120V only device into our socket, it will likely catch fire."

Yup...that’s how I read it as well. I’m 99% sure that I’m getting 220V out of the NEMA 5-15 — which I’m sure is a big no-no to many, and for good reason.

 

[Hedges]

It ought to be this kind, which clearly says, "Caveat Emptor!"

 

[schmism]

Level 2 protocol is very simple, you don't need much electronic to implement it

Care to be more specific?

As far as I can tell this is what is required to initiate level 2 chargeing.

Power Management
A J1772 compliant EVSE (detailed further in Section 4.1) requires a ±12-V DC power supply, in addition to
the power required for normal system ICs, such as the MCU. To simplify this design to focus on more
application specific functionality, a preexisting design from the TI PowerLabTM reference design library was
chosen. An AC-DC design with ±12-V outputs was chosen for simplicity, with the additional outputs
providing a bonus for the rest of the application. The PMP10299 device fit all of the core requirements.
The device is based around the UCC28910 PSR controller, has ±12- and 5-V outputs, and has been
designed with automotive quality in mind.
The extra 5-V rail can be used to power the MCU and other ICs on the board, as well as potentially drive
relays. Having 12- and 5-V outputs allows for a wide range of relay selection, which Section 4.3 covers in
further detail.
A TPS62063 buck converter is used to bring the 5-V rail down to the 3.3 V required by most of the design.
This converter has an input range of 2.7 V to 6 V, which makes it ideal for bringing down a pre-regulated
5-V rail to a system voltage of 3.3 V.
1.3
Pilot Signal Interface
The pilot signal interface, which Section 3 covers in further detail, requires a 1-kHz, ±12-V PWM signal to
be transmitted down the length of the charger cable to the vehicle. The duty cycle communicates the
power capability of the EVSE to the vehicle. The EV returns its current state by placing a load on the line,
which causes a voltage drop. To facilitate this, the design requires an amplifier with a wide dual-rail
voltage input and sufficient drive strength to facilitate the various line impedances. This design has
selected the OPA171 amplifier based on its input range characteristics (up to ±18 V) and ability to handle
various line impedance changes, even non-resistive changes in the event of cable parasitics.

^^ that doesn't sound "very simple"

Which is why I find it odd that Berksrunner can claim he is managing to negotiate a level2 charging protocol with this

 

[schmism]

In addition his AC/DC converter is auto ranging on the imput (90 ~ 264VAC). So its happy running on both lvl1 110v and lvl2 220v

 

[BiduleOhm]

Care to be more specific?

As far as I can tell this is what is required to initiate level 2 chargeing.



^^ that doesn't sound "very simple"

Which is why I find it odd that Berksrunner can claim he is managing to negotiate a level2 charging protocol with this

It's mainly just switching a few resistors in sequence and interpreting the PWM duty cycle (super easy by using a low-pass filter and a few comparators) to see how much power you can suck (and you're not even obligated to do that if you just want to use the lowest current).

There's no advanced com like RS485 or CAN, no software, etc...

And if you do use some MCU you can fit 10 of them in that plug easily if you wanted.

More info on the protocol: https://en.wikipedia.org/wiki/SAE_J1772#Signaling

 

[berksrunner]

In addition his AC/DC converter is auto ranging on the imput (90 ~ 264VAC). So its happy running on both lvl1 110v and lvl2 220v

Just to provide an update, I did finally check the actual voltage at the power supply when I am connected to a level 2 charger. As I guessed, I am getting a true 240V across the blades of my receptacle.

 

[freds2]

What a great find and at a reasonable price. I looked at doing this about six years ago for my eBike and it was really expensive at that time.

Technically it only takes a resister to get the charger (actually a semi dumb switch) to turn on. They have probably selected a resister that indicates up to 15 amps service.

Most non-tesla chargers are generally two legs of three phase power so around 208V at around 7KW of available power.

 

[berksrunner]

What a great find and at a reasonable price. I looked at doing this about six years ago for my eBike and it was really expensive at that time.

Technically it only takes a resister to get the charger (actually a semi dumb switch) to turn on. They have probably selected a resister that indicates up to 15 amps service.

Most non-tesla chargers are generally two legs of three phase power so around 208V at around 7KW of available power.

My PSU generates around 62A@24V, so with losses, I'm guessing I'm only drawing around 6.5A@240V.

Total cost was under $400, not including the cost of the internal van wiring. Not bad, imo.

 

[HaldorEE]

I wonder why on earth that vendor made the adapter with a Nema 5-20R plug on it?

I would cut the Nema 5-20R plug off and replace it with a proper Nema 6-15R female plug like this one.

Amazon.com

That way you don't have to be concerned about somebody mistakenly plugging in a 120V device. There is a reason why they make different kinds of plugs.

If the device actually supports 20A, then use a NEMA 6-20R plug.

Amazon.com

 

[HaldorEE]

I found this version one with a NEMA 6-50R. That would be a great adapter to use for powering your RV, risk free. You will need to use a 230V charger (or a 230V to 115V transformer) with it.

J1772 to NEMA 6-50 Adapter – EVSE Adapters

www.evseadapters.com

Better still, they make an all-in-one solution with the J117R receptacle plus a 230V and a 115V output (includes a step down transformer).

EV Charger Power Converter – EVSE Adapters

www.evseadapters.com

 

[berksrunner]

I found this version one with a NEMA 6-50R. That would be a great adapter to use for powering your RV, risk free. You will need to use a 230V charger (or a 230V to 115V transformer) with it.

J1772 to NEMA 6-50 Adapter – EVSE Adapters

www.evseadapters.com

Better still, they make an all-in-one solution with the J117R receptacle plus a 230V and a 115V output (includes a step down transformer).

View attachment 29080

EV Charger Power Converter – EVSE Adapters

www.evseadapters.com

Yup. That was the initially the route I considered. A few problems with this approach:

1. These transformers have a poor reputation vs the Mean Well PSU that I purchased.
2. The transformer is substantially larger than the PSU
3. Transformer output current is substantially lower/higher losses versus PSU

The one benefit is that I would be able to run the output through my Multiplus, which would allow me to run in float/passthrough once my battery bank is fully charged.

 

[berksrunner]

I wonder why on earth that vendor made the adapter with a Nema 5-20R plug on it?

I would cut the Nema 5-20R plug off and replace it with a proper Nema 6-15R female plug like this one.

Amazon.com

That way you don't have to be concerned about somebody mistakenly plugging in a 120V device. There is a reason why they make different kinds of plugs.

If the device actually supports 20A, then use a NEMA 6-20R plug.

Amazon.com

The reasoning behind their use of the 5-20R is that the intended use case is to charge an e-bike. E-bike chargers are mostly 5-15's because they are designed to plug into a household wall outlet. At the same time, many of the chargers utilize switching PSU's.

 

[berksrunner]

Yup. That was the initially the route I considered. A few problems with this approach:

1. These transformers have a poor reputation vs the Mean Well PSU that I purchased.
2. The transformer is substantially larger than the PSU
3. Transformer output current is substantially lower/higher losses versus PSU

The one benefit is that I would be able to run the output through my Multiplus, which would allow me to run in float/passthrough once my battery bank is fully charged.

And let me add that I have been extremely impressed by the Mean Well PSU -- high quality construction, very thick copper terminals, runs surprisingly cool, delivers higher than rated current. It gives me a consistent 62A@27V while remaining extremely cool -- very impressive.

 

[HaldorEE]

And let me add that I have been extremely impressed by the Mean Well PSU -- high quality construction, very thick copper terminals, runs surprisingly cool, delivers higher than rated current. It gives me a consistent 62A@27V while remaining extremely cool -- very impressive.

Does the Mean Well PSU have a LiFePO4 multi-stage charge profile? If not, then I would think you are asking for a shortened battery life if you forget to disconnect the charger after the battery reaches full charge.

I think a step-down transformer feeding the Multiplus would be a better solution.