OpenEVSE - Open Source Charging Station

[eHelmholtz]

wow!, you continually impress me with improvements on the OpenEVSE project!

 

[z0ner]

That is killer, Chris. Meant for an LCD touchscreen I assume?

 

[chris1howell]

Currently, the GUI is running on a PC. It should port easily over to an Android phone or an Arduino with touch screen for direct EVSE control.

The data comes wirelessly from the EVSE and LEAF through xbee radios (or bluetooth).

 

[RickS]

Figured so, thanks for the input. I shall encourage here to update.

 

[lincomatic]

The display adds no functionality to the EVSE but its really cool looking.

Maybe for now, but I'm currently testing one-button menu code for changing settings via the LCD, which I will be releasing soon.

While bumbling through the code to me it looks like the watchdog timer is commented out. Am I missing something?

The watchdog code is not well tested. It *should* work OK, but the trick is, all sections of the code need to "pat the dog" within the specified countdown time, or it will automatically reset the board. It was working OK when I implemented it, but a lot of code has been added since then. I don't have time to test it, but if anyone is willing to put some work into it, let me know if it has any problems. One big pain about debugging code when it's enabled is that since we're running the MCU without a bootloader, in certain situations while debugging, it makes it very hard to load in new firmware if the watchdog keeps resetting the board before you can start the download.

 

[coolfilmaker]

I've been thinking about how we can get more free public EVSEs into service. I think when the Model S comes out there will be a lot of people with money who will want charging stations everywhere. I know that if I had a bunch more money I would put them in at any place I go even occasionally. So my thought is that we could put in a large remotely updateable LED sign that would be placed above the EVSE. It would says something like OPEN/RESERVED and could be updated easily over the internet so people would be able to have their own private charging stations everywhere without wasting a lot of resources. Could this be implemented?

 

[KevinSharpe]

Could this be implemented?

Yes... but why not just put the effort into getting lots of low cost Charging Stations installed?

 

[coolfilmaker]

Could this be implemented?

Yes... but why not just put the effort into getting lots of low cost Charging Stations installed?

The idea is that it would be for more expensive 80 amp stations that can service more people per day.

 

[lincomatic]

Could this be implemented?

The hardware and firmware are relatively easy to implement.
The server infrastructure would cost $$ to host.

 

[garygid]

An 80 amp L2 still services roughly the same number of cars as
a 30 amp EVSE, primarily limited by how long people want to PARK
in the spot.

The second (significant) limitation is how much power the
vehicle can "eat" (16 amps for 2011-12 LEAFs).

QC would actually be much more useful, IMO.

 

[TonyWilliams]

An 80 amp L2 still services roughly the same number of cars as
a 30 amp EVSE, primarily limited by how long people want to PARK
in the spot.

The second (significant) limitation is how much power the
vehicle can "eat" (16 amps for 2011-12 LEAFs).

QC would actually be much more useful, IMO.

It's entirely possible to have both.

An EVSE could be at the full 80 amps in combination with a DC charger at the same current draw. That station doesn't pull over 20kW, so no demand fee, and can service ChadeMo cars, or Teslas or LEAFs with J1772, either at their max rate.

Edit: but not a DC charge and an AC charge at the same time.

 

[asharpleaf]

Does this mean that at the 7-11 in San Bernardino the QC and the L2 could be plugged into the leaf at the same time and charge together?

 

[TonyWilliams]

Does this mean that at the 7-11 in San Bernardino the QC and the L2 could be plugged into the leaf at the same time and charge together?

No.

 

[KevinSharpe]

The idea is that it would be for more expensive 80 amp stations that can service more people per day.

except you then have a single point of failure and issues around waiting for a parking spot to become free. You also have to realise that very few cars will support 80A AC.

 

[LEAFfan]

Does this mean that at the 7-11 in San Bernardino the QC and the L2 could be plugged into the leaf at the same time and charge together?

The manual says the car will stop charging if you try to plug in both at the same time.

 

[GlennD]

Lincomatic, I am not willing to test the watchdog timer on my 2 surface mount boards. It seemed to me that the best test setup would be an aurdino shield setup since if it locked up the processor another $5 chip could plugged in.

Thanks for explaining the reason the watchdog was disabled.

 

[lincomatic]

Lincomatic, I am not willing to test the watchdog timer on my 2 surface mount boards. It seemed to me that the best test setup would be an aurdino shield setup since if it locked up the processor another $5 chip could plugged in.

Thanks for explaining the reason the watchdog was disabled.

I had the lockups occur when I was running the code on an Arduino early in the development cycle. Unfortunately, I can't even remember how I got the MCU unstuck.

While we are on the subject of code, I would like some input on source code control. I personally am not very fond of SVN code hosting on google. In fact, I didn't check any code into SVN except for the latest release. I am thinking of moving the source code over to github, where it's easier to collaborate. Anyone can fork the code, and then send pull requests to me for integration in the main branch, and it's easy to submit and reply to bug reports there. I need a place where I can put the bleeding edge code that's not tested enough for official release and get feedback. For instance, I'm working on a fix for a bug involving the Volt with timers enabled and the advanced power supply. Also, I added code for a settings menu via the LCD using a single button connected to A3.
In the process, I did some code restructuring and cleanup.. this code isn't ready for official release, but I would like some testers.

Is github OK with everyone? They just released a new Windows client to make things easier to use, and it's easy to download the whole repository as a single zip file.

 

[lincomatic]

An 80 amp L2 still services roughly the same number of cars as
a 30 amp EVSE, primarily limited by how long people want to PARK
in the spot.

The second (significant) limitation is how much power the
vehicle can "eat" (16 amps for 2011-12 LEAFs).

QC would actually be much more useful, IMO.

Chris and I were discussing a current sharing system a while back for locations with limited power available.
The idea was to link a bunch of the EVSE's together. Say you have 80A available for all the EVSE's.
One could set up a 4-headed EVSE. When one car is plugged in, it can charge up to 80A. When 4 cars are present,
they eatch get 20A. As each car fully charges and its load is removed, the extra available current can be sent to the other cars.
This way, cars that finish charging won't be hogging the entire EVSE.

It would be great if cars actually pay attention to the pilot's PWM duty cycle during charging and to adjust their current draw on the fly, but I have a feeling that this isn't very common. On the other hand, if a car which can't "eat" much current arrives at the EVSE first, it will only take 16A, and the rest can be allocated to the other ports. Not as efficient sharing, but still better than one car at a time.

 

[coolfilmaker]

The idea is that it would be for more expensive 80 amp stations that can service more people per day.

except you then have a single point of failure and issues around waiting for a parking spot to become free. You also have to realise that very few cars will support 80A AC.

On the contrary, I think you have to realize that very few people will buy cars that don't support that level of charging. I also have never heard of a clipper creek charger failing and I can't really see how they could. Problems only arrise when companies like ecotality try to charge you $2 for 30 cents worth of electricity and fail to make a reliable point of sale device.

 

[coolfilmaker]

An 80 amp L2 still services roughly the same number of cars as
a 30 amp EVSE, primarily limited by how long people want to PARK
in the spot.

The second (significant) limitation is how much power the
vehicle can "eat" (16 amps for 2011-12 LEAFs).

QC would actually be much more useful, IMO.

Chris and I were discussing a current sharing system a while back for locations with limited power available.
The idea was to link a bunch of the EVSE's together. Say you have 80A available for all the EVSE's.
One could set up a 4-headed EVSE. When one car is plugged in, it can charge up to 80A. When 4 cars are present,
they eatch get 20A. As each car fully charges and its load is removed, the extra available current can be sent to the other cars.
This way, cars that finish charging won't be hogging the entire EVSE.

It would be great if cars actually pay attention to the pilot's PWM duty cycle during charging and to adjust their current draw on the fly, but I have a feeling that this isn't very common. On the other hand, if a car which can't "eat" much current arrives at the EVSE first, it will only take 16A, and the rest can be allocated to the other ports. Not as efficient sharing, but still better than one car at a time.

This is definitely the ideal solution. It's sad that with all of the companies making EVSEs no one has done this yet. In regards to on the fly current resetting, you can always just disconnect power to the car and then reconnect it. I don't think it would be much of a problem.