OpenEVSE - Open Source Charging Station

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RedEnergy said:
is the current set by the charger installed in the car or by the openEVSE? In the second case: do I need to set the EVSE to run to a lower current?
The openEVSE announces the maximum current that the on-board charger can draw. You need to set the EVSE to match the circuit it's installed on and its own components (use <=80% of the circuit rating) and leave the car to figure out the rest.
 
The charger in the car controls the current. You can set the EVSE to limit how much can be drawn to avoid overloading the circuit capacity.

RedEnergy said:
Thanks for the very quick and clear answer!

Just a very (VERY) stupid question:
is the current set by the charger installed in the car or by the openEVSE? In the second case: do I need to set the EVSE to run to a lower current?
 
The car sets the limit as long as the EVSE offers enough current. Eg an enhanced LEAF Would draw 27.5A frpm a 30A EVSE. On the other hand it would respect the J1772 protocol and only draw 24A from a 24A EVSE even though it could dray its full 27.5A.

Subject to the limits the car draws its max. There is no difference between the EVSE max of 80A and a non existent 28A EVSE. In both cases the car charger takes what it needs and ignores the rest. Buying more than you need only costs you money. It does not speed up your charging.
 
Thanks to all of you for the answers.

Since I don't need the 120v option, I think I'll buy the 50A mainly because with the current offers it is cheaper than the 30A, if I chose the "no solder" option.


Thanks again. Next project will be to try to connect it to wifi. I'd like to build an arduino home energy monitoring. It will not be easy, considering my (little) knowledge...
 
For the last couple of years I have been building OpenEVSE's for others.

I thought I would post the units I use.

This is my main car EVSE. It consists of a Barbouri ver 4.2 main board, A 40A range cable, 20 ft 40A Quick Charge Power J1772 cable, A RGB display with RTC, A neat Chinese multi meter that Craig Kirkpatrick suggested from Ebay, a 90A Cuttler Hammer contactor, 12V PS, MOVs for transient protection, and the GFCI and current coil. This is mounted in a 8X8X4 inch junction box. it is running ver 3.51. I have an upgraded board with 6N139s and firmware 3.9.4 for a someday project. The current version works fine.

You can see it charging my Mercedes B Class Electric Drive



I also replaced the Lear L1 charger with an OpenEVSE unit. I can now charge at 15A on a 20A circuit or the default 12A on a 15A circuit. I store it in an old laptop case.

 
Received my "OpenEVSE - Level 2 Deluxe Charge Station Combo (50A max)" on Saturday... installed it on Sunday. Works like a champ!

BTW, the updated kits without soldering are just a pleasure to work with. I ran 6 gauge wire (6-3 plus ground) to it in case I ever need a bigger charger... The contactor/relay connector allowed for 6 guage, no problem!
 
#6 allows for 40A, 80% of 50A. The EVSE and contactor will support that. For a Tesla based 40A charging car you just need to replace the J1772 cable. I use a Quick Charge Power 40A cable to charge my Mercedes B Class ( Tesla Based ) car. I went for overkill and used a 90A contactor, the wall shakes when it pulls in.

With the proper contactor and cable the OpenEVSE board will support the spec 80A max. That said, many vendors had problems with overheating contacts so most cables max out at 50A. No car draws over 40A and most are at 30A or less. Regardless of the available current the car only takes what it needs up to the max. A first generation Leaf would take its 16A and ignore the rest.

As I understand it, the original spec was for 30A max but Tesla insisted on a higher limit. 80A would be the level for a Tesla dual charger car.
 
Updated Open EVSE DIY 4.23 board populated and ready for testing this weekend.
23498834626_2661f30b1d_b.jpg
 
Barbouri said:
Updated Open EVSE DIY 4.23 board populated and ready for testing this weekend.
23498834626_2661f30b1d_b.jpg

It looks good! If you connect pins 1 & 2 of the Mid400 sockets you can use the much cheaper 6N139s and reduce the loading by using 220K dropping resistors. Pin 1 us used by the 6N139s but it is ignored by the MID400s. The 6N139s are about 10% of the MID400s cost.

They now use a half wave detection scheme so an AC device is not required. You do have to use high voltage series diode or 1N4148 shunt diodes so the device sees DC.

I have your ver 4.21 unit using them with 220K resistors and 1N4004s in the fuse positions. Since the 6N139s are CMOS compatible they require a very small input LED current.
 
Question for Chris or Glenn or anyone who's an OpenEVSE expert:

I had a chance to get a calibrated amperage reading of my vehicle draw the other day and it showed 15 amps dead even, while my current meter connected to my OpenEVSE showed 16.2 amps. Where can I change the calibration settings for the current transformer?

Been very very happy with my OpenEVSE. The charge timer works great and never fails to charge my car! :)
 
If you are using the internal current metering then modify the calibration factor. the default is usually good but it is easy to modify and reprogram. Try a value of 240 first. Go up or down from there.

It is easy to mod but you must reprogram each time. I think Lincomatic has a utility to set the value but I have not used it.
 
I decided that I will need a portable EVSE. I ordered some parts from OpenEVSE (board, display, CT and J1772 cable). I have two Crydom D2450 50A solid state relays and I will first try to use them, if they get too warm I will switch to a contactor. I have some questions about how the board will come set up: for one contactor or for two relays. I will do some reading about that later.
My main question right now is if I need to use 240V fuses or not. My goal is to keep everything safe and as small and light as possible. 40A fuses and fuse block will take some space. I was thinking of finding fuses that will bolt one end directly to the relays, eliminating the block and some wiring. I will still need to support the fuses properly. The 50A OpenEVSE does not seem to have fuses included in the kit. The 30A does. What is the rationale behind the decision? How important are those fuses?

Thank you.
 
camasleaf said:
The 50A OpenEVSE does not seem to have fuses included in the kit. The 30A does. What is the rationale behind the decision?
Not an expert on OpenEVSE just an owner, but the 50 amp kit has a 50 amp contactor/relay which then leads directly to the 50 amp J1772 cable so all the components that are ever connected to the 50 amps can handle the load. The 30 amp kit has only 30 amp relays. if you are traveling with an EVSE (like I do) to campgrounds where you might plug into a NEMA 14-50 outlet but only have 30 amp capable relays, you can see why that might be less than safe without the fuses.

I wanted my OpenEVSE setup to be able to be used at both 120 and 240 volts (unlike their 50 amp kit) so I got the board (and display) but used a 120 volt 50 amp contactor to avoid the problem. The solid state relays you mention are only good for 25 amps (I think) which at about 28 amps continuous load (assuming a car with a 6.6 kW charger) would be overloaded by a good bit. Of course you could set the charging amp limit lower. However, you might still want to fuse protect that setup if you plan to use 14-50 type outlets.
 
camasleaf said:
I decided that I will need a portable EVSE. I ordered some parts from OpenEVSE (board, display, CT and J1772 cable). I have two Crydom D2450 50A solid state relays and I will first try to use them, if they get too warm I will switch to a contactor. I have some questions about how the board will come set up: for one contactor or for two relays. I will do some reading about that later.
My main question right now is if I need to use 240V fuses or not. My goal is to keep everything safe and as small and light as possible. 40A fuses and fuse block will take some space. I was thinking of finding fuses that will bolt one end directly to the relays, eliminating the block and some wiring. I will still need to support the fuses properly. The 50A OpenEVSE does not seem to have fuses included in the kit. The 30A does. What is the rationale behind the decision? How important are those fuses?

Thank you.

The 30A kit is rated for 24A continuous and has the max fuse size available at 30A in that form factor. 80% of 30A is 24A. The 50A (40A continuous) relies on a 50A external circuit breaker sense 50A fuses are generally very large.

Solid state switches may be used but they are dangerous sense the failure mode is shorted. I also doubt you will find room for the large required heat sinks. The OpenEVSE checks for shorted contacts and for that matter a shorted switch. It will give you a failure but there will still be voltage at the plug. If you exercise some common sense and unplug the unit upon a failure display you will be all right. The standard assumes you have no common sense and it try's to protect you from yourself.
 
Thank you both for explanations. I does make sense. The EVSE would not need fuses if only used within the right circuit. But with all the variations of plug adapters a 30A rated EVSE could easily end up on a 50A circuit.

I will still think about using the SSRs and heat sinks since I have them already. I also like the flexibility of having the 120V option. Still need to figure out how to put the heat sinks outside a waterproof enclosure and still transfer the heat.

One could take a contactor unwound the coil, split it in half wounded back and have a switch to parallel the two the coils to work on 120V when needed. Are there any 50A electro-mechanical relays that will work with the limited current supplied by OpenEVSE board? I would sell my SSRs and buy those.
 
There some Chinese made relays that are supposedly rated for 80A with a 12V coil so they work with OpenEVSE. The wires don't look anywhere beafy enough to use at 80A but appears to work fine at 40A. They appear to be the same relays that are used in EMW's Juicebox. Here's an ebay listing for one.
http://www.ebay.com/itm/1PCS-12VDC-80A-DPDT-Power-Relay-Motor-Control-Screw-Mounting-/171577654018?hash=item27f2d33b02:g:LfwAAOxyNThTdwIM
 
I have a 40A Eaton contactor that I just took apart, the contacts overheated because of a bad wire connection. Came from a Blink that was charging at 25A.

After looking at those relays on eBay, my idea with rewinding the coil on a contactor does not seem that crazy anymore :lol: . I am not sure I trust those relays even at 40A for very long. Any idea how big they are?

Thank you for the link. It is an option to consider.
 
eHelmholtz said:
There some Chinese made relays that are supposedly rated for 80A with a 12V coil so they work with OpenEVSE. The wires don't look anywhere beafy enough to use at 80A but appears to work fine at 40A. They appear to be the same relays that are used in EMW's Juicebox. Here's an ebay listing for one.
http://www.ebay.com/itm/1PCS-12VDC-80A-DPDT-Power-Relay-Motor-Control-Screw-Mounting-/171577654018?hash=item27f2d33b02:g:LfwAAOxyNThTdwIM


I have used the Chinese relays that the JuiceBox uses. The 80A rating is a poor Chinese joke unless you also need a room heater but they work fine at half that or 40A. They are quite large. I doubt that they would fit in any of Chris's enclosures.

Chris's best option for portable use is the 30A (24A) unit. The two relays he uses are small and the unit is fuse protected for portable use.
Remember it does not really matter what circuit you are plugged into since the EVSE limits the current via the pilot duty cycle. Also the car charger only takes what it needs. An enhanced Leaf will draw 27.5A and not use any greater current. It also follows the J1772 protocol and if it is connected to a 24A EVSE that that is all it will draw even though the car charger could draw 27.5A.

A stock OpenEVSE unit will supply at L1 120V twelve amps. At L2 240V the default is sixteen amps but it can be set in 2A steps to match the available current source.

Remember the car sets the charging current as long as there is enough. A 30A EVSE is the same as the 80A spec max. The car only takes it max current. Thea is why first generation Leaf's were able to use Solid State Relays. Even at 240V they maxed out at 16A.

Currently the only cars that can charge at 40A are Tesla's and Tesla power train cars like my Mercedes B Class or the discontinued Toyota RAV4 EV. Everything else is 30A or less. As I said, An enhanced Leaf charges at 27.5A at 240V.
 
Thank you Glenn. I will likely go with a 40A contactor and sell my SSRs and my 40A semiconductor fuses (they are big). I know that the car dictates the current, but if I spend the money and put the effort into building an EVSE I want to have the full 40A continuous capability. I am not sure how I will make it work at 120V, I am still brainstorming about that.
 
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