OpenEVSE Basic Kit

[AlanSqB]

Seems like this version would work nicely with a Bluetooth module and a smartphone. Display and control from the phone while maintaining a "plain" look to deter theft.

 

[dsinned]

It's unbalanced because in the situation described above, you could potentially have 50 or more amps flowing through components that are designed for a max of 30 amps.

If you are using 50A contactor, 50A rated cable and all other in-line components are rated for 50A, you don't need the fuses on the 50A circuit. That box, as sold, contains components only rated for 30A (relays) so it needs the fuses.

Okay, now I understand. The word, "balanced" was throwing me off, as might be used when referencing different phases in a 2 or 3 phase AC power distribution system, which could also be present to some extent even in a "split phase" 240V power circuit, correct? Is this possibly another reason why "two" fuses are needed instead of only one?

 

[AlanSqB]

Yes, because either of the two phases could potentially short to ground independent of the other.

 

[dsinned]

Got it! Thanks!

 

[chris1howell]

100 kits ready to package up...

 

[kubel]

The kit includes 4 locking washers. What are these to be used with?

 

[chris1howell]

The kit includes 4 locking washers. What are these to be used with?

They are not used for this kit, the parts bag is common with the deluxe kit so there is a few washers and extra screws that are not needed on the basic.

 

[jimbo69ny]

Id really like this for a portable dual voltage unit but it would have to have a display so I could adjust the amperage appropriatly.

Do you have any plans to make this unit with a window for a lcd?

 

[dsinned]

This issue keeps coming up with respect to these so-called "basic" kits. Current limiting seems to be sort of a "moving target" especially for "portable" units.

Personally, I don't care for Tesla's solution with resistor mods to a couple of common AC adapters. These cost $50 each. WAY overpriced imho! Not to mention, an adapter for 32A was completely omitted. These are quite commonly required, although there is no standard for "40A" outlets. Thus, many EVSE users are violating code with 50A outlets on less amperage circuits. I'm guilty of that as well!

I became concerned about this, so I did a "controlled" experiment last weekend. I intentionally increased the current limiter on my EVSE from 32A to 40A, which is easy to do with a JuiceBox with key fob and LCD options. I was charging my RAV4 EV with its OBC that allows a maximum of 10kW (or 250V at 40A). I measured ~225V AC line voltage at the EVSE at this load, so I was really only drawing about 9kW from the wall. As it turns out this presented a false sense of security!

On a moderately warm day, it took a little over 60 minutes for a 40A rated circuit breaker to trip in my Main Power Distribution Panel on the outside of my house. I purchased that breaker from Home Depot earlier this year, so I know it was essentially new and good condition. From the 50A outlet to the output cable of the EVSE, surface temperatures were all warm to the touch but not of any real concern. My Juicebox's I/O cables are rated for 50A/40A respectively, and the AC outlet rated for 50A it was plugged in to.

By the time the CB tripped in the main distribution panel, it became VERY HOT; almost enough to burn my finger. Thankfully, it did its job, but I have no idea how hot the internal stranded copper wiring got from the breaker to the AC outlet, which is routed through the crawl space under the house and through a wall into my garage where that outlet is installed. I'd bet hot enough to be worrisome as I believe the dedicated wiring conductors are probably of insufficient gauge for a 40A continuous load. I wish I knew what the gauge size is for certain, but as I recall it is certainly not as large as 6AWG, which is recommended for a 50A outlet.

This points out the inherent danger of using an L2 EVSE without an output current monitor display. These basic DIY kits are all well and good for the lowest cost, bare bones EVSE, but I highly recommend adding an output current monitor display for safety sake. Plus, make certain your circuit breaker protection is appropriate for the household wiring and J1772 output cable you are using, especially if you are using a 50A AC outlet to plug in your EVSE. Which ever has the lowest amperage rating, should match the rating of the circuit breaker. This is something that NO EVSE can determine for you, or warn you when it becomes overloaded, so you have to physically check it yourself. When in doubt, hire a qualified Electrician!

 

[wwhitney]

By the time the CB tripped in the main distribution panel, it became VERY HOT; almost enough to burn my finger. Thankfully, it did its job, but I have no idea how hot the internal stranded copper wiring got from the breaker to the AC outlet, which is routed through the crawl space under the house and through a wall into my garage where that outlet is installed. I'd bet hot enough to be worrisome as I believe the dedicated wiring conductors are probably of insufficient gauge for a 40A continuous load. I wish I knew what the gauge size is for certain, but as I recall it is certainly not as large as 6AWG, which is recommended for a 50A outlet.

As long as the conductors were sized correctly for a 40A breaker (i.e. #8 Cu conductors) and all connections were properly made up, the conductors were fine. The conductor ampacity is a continuous rating; it is the breaker that is not rated for the continuous load. So for a continuous load you have to upsize the breaker, but that of course requires upsizing the conductors, since the conductors need to be protected at or below their ampacity.

Cheers, Wayne

 

[dsinned]

Thanks Wayne.

Originally, the same wiring was used to provide 240V AC power to a Hot Tub in my backyard. The circuit breaker had the same rating (40A) but looked quite old, so I replaced it. (I think the Electrician who installed the Hot Tub wiring used an old 40A breaker he just happened to have in his parts bin.) Several years ago, I had the Hot Tub removed, so this wiring was "freed up" for a different 240V load. Two years ago is when I hired another Electrician to re-routed it to a new 50A outlet in my garage. I can't make out any markings on the insulation from the circuit breaker end, but based on my best guess from the diameter of each stranded copper conductor, I would guess #10 gauge wire; perhaps #8, but I'm just not sure. The length of the wiring is ~35' from the breaker to the EVSE's 50A outlet, so I think I could be on the hairy edge using it to charge my RAV4 EV at 32A. I'm going to check the surface temperature of the insulation where the wires are visible in the breaker box while charging at 32A. I'll do this for an hour or so, and if only ever warm to the touch, I think it will be okay.

 

[AlanSqB]

50A outlet on 40A circuit is allowed by code. As long as the breaker is correctly sized for the wire being used you are within code. Keeping in mind however that the code is just a minimum standard and not best practice.

Stock OpenEVSE is set to a fairly low amperage, 20A I think, out of the box. If built "as-is" with no button or display, it won't go over that. It also includes the fuses as a backup.

I am personally considering building one of these and putting in a Bluetooth FTDI in the box so I can change the settings from my phone. This will give me control/feedback while still maintaining the integrity of the case and keeping it from attracting as many interested thieves as a device with a display.

 

[chris1howell]

This issue keeps coming up with respect to these so-called "basic" kits. Current limiting seems to be sort of a "moving target" especially for "portable" units.

Personally, I don't care for Tesla's solution with resistor mods to a couple of common AC adapters. These cost $50 each. WAY overpriced imho! Not to mention, an adapter for 32A was completely omitted. These are quite commonly required, although there is no standard for "40A" outlets. Thus, many EVSE users are violating code with 50A outlets on less amperage circuits. I'm guilty of that as well!

I became concerned about this, so I did a "controlled" experiment last weekend. I intentionally increased the current limiter on my EVSE from 32A to 40A, which is easy to do with a JuiceBox with key fob and LCD options. I was charging my RAV4 EV with its OBC that allows a maximum of 10kW (or 250V at 40A). I measured ~225V AC line voltage at the EVSE at this load, so I was really only drawing about 9kW from the wall. As it turns out this presented a false sense of security!

On a moderately warm day, it took a little over 60 minutes for a 40A rated circuit breaker to trip in my Main Power Distribution Panel on the outside of my house. I purchased that breaker from Home Depot earlier this year, so I know it was essentially new and good condition. From the 50A outlet to the output cable of the EVSE, surface temperatures were all warm to the touch but not of any real concern. My Juicebox's I/O cables are rated for 50A/40A respectively, and the AC outlet rated for 50A it was plugged in to.

By the time the CB tripped in the main distribution panel, it became VERY HOT; almost enough to burn my finger. Thankfully, it did its job, but I have no idea how hot the internal stranded copper wiring got from the breaker to the AC outlet, which is routed through the crawl space under the house and through a wall into my garage where that outlet is installed. I'd bet hot enough to be worrisome as I believe the dedicated wiring conductors are probably of insufficient gauge for a 40A continuous load. I wish I knew what the gauge size is for certain, but as I recall it is certainly not as large as 6AWG, which is recommended for a 50A outlet.

This points out the inherent danger of using an L2 EVSE without an output current monitor display. These basic DIY kits are all well and good for the lowest cost, bare bones EVSE, but I highly recommend adding an output current monitor display for safety sake. Plus, make certain your circuit breaker protection is appropriate for the household wiring and J1772 output cable you are using, especially if you are using a 50A AC outlet to plug in your EVSE. Which ever has the lowest amperage rating, should match the rating of the circuit breaker. This is something that NO EVSE can determine for you, or warn you when it becomes overloaded, so you have to physically check it yourself. When in doubt, hire a qualified Electrician!

The OpenEVSE Basic kit has protections for exactly these scenarios.

Most importantly this kit has FUSES... This kit is designed for a 30A J1772 cable and power cord (NEMA L6-30P). If installed on a > 30A circuit and the pilot was changed to a value that exceeded the cable/relay ratings by the user the fuses would blow... It is potentiality very dangerous to have various parts with different possibilities and no protection at the lowest value... 50A cord - 60A relay - 32A J1772 with no fuses is asking for trouble...

If the OpenEVSE Basic installed on a smaller circuit and the pilot is not modified from the default value of 24A L2 and 12A L1 then the breaker would trip...

OpenEVSE does not have analog pots, the current setting must be set digitally. With an analog pot and no display it is not possible to know the pilot setting without a special tool or EV Simulator.

OpenEVSE also has firmware protections there is a setting for MAX_CURRENT_L1 and MAX_CURENT_L2. No matter the method of changing the Pilot current (Remote API, CLI, push button, etc) if a value exceeds the MAX_CURRENT the change is ignored...

OpenEVSE is also not sold as an to the general public as an assembled kit, it is for DIY only. The builders have to be involved in the construction and usually are much better informed than the average EV owner.

 

[kubel]

I got mine assembled today, plugged it in (120V) to test, and nothing. No LED, no relay checks clicking. I'm reading 120V across AC(L)and AC(N) on the power supply, so I'm assuming I didn't frak up at least to that point. How should I go about troubleshooting from there?

I also plugged in my old known working Open EVSE board and it fired right up, so I'm pretty sure it's all good up to the power supply. I'm just not sure how to test from there.

 

[wwhitney]

I would guess #10 gauge wire; perhaps #8, but I'm just not sure.

This is worth figuring out because #10 on a 40A breaker is not OK, while #8 is fine. If you can't read the insulation, go get a sample of #8 and of #10 and compare to the wiring in the breaker panel.

The length of the wiring is ~35' from the breaker to the EVSE's 50A outlet, so I think I could be on the hairy edge using it to charge my RAV4 EV at 32A.

In terms of voltage drop, 35' is fine for a 32A load on #8 copper.

I'm going to check the surface temperature of the insulation where the wires are visible in the breaker box while charging at 32A. I'll do this for an hour or so, and if only ever warm to the touch, I think it will be okay.

By design, the conductor near the breaker acts as a heat sink for the breaker, so it will be hotter than the rest of the conductor. Therefore you may find it hot to the touch, but that doesn't mean there is problem.

Cheers, Wayne

 

[dsinned]

Thanks (again) Wayne for your advice. You sound like a very knowledgeable person on such matters. Are you a EE?

I used to be an Electrician's Mate in the Navy for 26 years, so I have a commensurate level of knowledge about electrical safety. Long story short, about 40 years ago, during a freak accident while doing routine maintenance on high power (3 phase AC 480V switchgear), I was badly burned and almost electrocuted, aboard a nuclear power aircraft carrier. As a result, I have a VERY HEALTHY respect for electricity . . . aka "the silent killer". That accident taught me to NEVER take anything for granted when it comes to high voltage/current electrical equipment.

I will follow your good suggestion to determine the wire size fed by the 40A breaker. I suspect it is actually 10AWG, so TWO different "licensed" Electricians involved with that wiring installation must have been cutting corners, knowing what was at either end of the circuit. I suspect the hot tub was less than a 30A load, but the EVSE was known to be 32A. If the wiring is actually 10AWG, would you recommend replacing the breaker with one rated for 30A? I don't believe there is a CB standard rating between 30 and 40A, say one for 32A. I have been using this same 240V AC circuit for nearly two years, weekly to charge my RAV4 EV. A typical 32A charging session last for about 3 to 4 hours after midnight. Dropping the charging rate to 24A would be a fairly significant hit on the duration, but still well within the confines of an overnight (lowest off peak rate) charging session.

According to this wiring chart I found on the Internet, I probably need to consider upgrading my 50A 240V AC outlet wiring circuit to #6 gauge to be conservative.

 

[kubel]

I got mine assembled today, plugged it in (120V) to test, and nothing. No LED, no relay checks clicking. I'm reading 120V across AC(L)and AC(N) on the power supply, so I'm assuming I didn't frak up at least to that point. How should I go about troubleshooting from there?

I also plugged in my old known working Open EVSE board and it fired right up, so I'm pretty sure it's all good up to the power supply. I'm just not sure how to test from there.

Bump. :arrow:

 

[AlanSqB]

Did you check the ground? It may require a longer contact time with the iron to get a good connection.

 

[eHelmholtz]

I got mine assembled today, plugged it in (120V) to test, and nothing. No LED, no relay checks clicking. I'm reading 120V across AC(L)and AC(N) on the power supply, so I'm assuming I didn't frak up at least to that point. How should I go about troubleshooting from there?

I also plugged in my old known working Open EVSE board and it fired right up, so I'm pretty sure it's all good up to the power supply. I'm just not sure how to test from there.

This sounds like the firmware on the new board needs to be reloaded; this happened to me once.

 

[eHelmholtz]

This issue keeps coming up with respect to these so-called "basic" kits. Current limiting seems to be sort of a "moving target" especially for "portable" units.

Personally, I don't care for Tesla's solution with resistor mods to a couple of common AC adapters. These cost $50 each. WAY overpriced imho! Not to mention, an adapter for 32A was completely omitted. These are quite commonly required, although there is no standard for "40A" outlets. Thus, many EVSE users are violating code with 50A outlets on less amperage circuits. I'm guilty of that as well!

I became concerned about this, so I did a "controlled" experiment last weekend. I intentionally increased the current limiter on my EVSE from 32A to 40A, which is easy to do with a JuiceBox with key fob and LCD options. I was charging my RAV4 EV with its OBC that allows a maximum of 10kW (or 250V at 40A). I measured ~225V AC line voltage at the EVSE at this load, so I was really only drawing about 9kW from the wall. As it turns out this presented a false sense of security!

On a moderately warm day, it took a little over 60 minutes for a 40A rated circuit breaker to trip in my Main Power Distribution Panel on the outside of my house. I purchased that breaker from Home Depot earlier this year, so I know it was essentially new and good condition. From the 50A outlet to the output cable of the EVSE, surface temperatures were all warm to the touch but not of any real concern. My Juicebox's I/O cables are rated for 50A/40A respectively, and the AC outlet rated for 50A it was plugged in to.

By the time the CB tripped in the main distribution panel, it became VERY HOT; almost enough to burn my finger. Thankfully, it did its job, but I have no idea how hot the internal stranded copper wiring got from the breaker to the AC outlet, which is routed through the crawl space under the house and through a wall into my garage where that outlet is installed. I'd bet hot enough to be worrisome as I believe the dedicated wiring conductors are probably of insufficient gauge for a 40A continuous load. I wish I knew what the gauge size is for certain, but as I recall it is certainly not as large as 6AWG, which is recommended for a 50A outlet.

This points out the inherent danger of using an L2 EVSE without an output current monitor display. These basic DIY kits are all well and good for the lowest cost, bare bones EVSE, but I highly recommend adding an output current monitor display for safety sake. Plus, make certain your circuit breaker protection is appropriate for the household wiring and J1772 output cable you are using, especially if you are using a 50A AC outlet to plug in your EVSE. Which ever has the lowest amperage rating, should match the rating of the circuit breaker. This is something that NO EVSE can determine for you, or warn you when it becomes overloaded, so you have to physically check it yourself. When in doubt, hire a qualified Electrician!

There are a number of issues with the comments made here. Firstly, code does allow for a 40A circuit on a 50A outlet. Of course, the device being used needs to comply with a 40A circuit. Secondly, your "controlled" experiment last week does not meet code. You have a 40A breaker which means you ought to limit current draw to 32A by code; you pulled 40A. Incidentally, I've used several of the Chinese relays in your EVSE in my OpenEVSE builds and while the relay claims to be 80A and EMW claims 60A, I find that these relays typically work well without overheating only up to 40-50A at best; the real problem is that these relays are variable and it's hard to predict which particular one will not get hot at 40A. Thirdly, there is no inherent danger of using a properly made L2 EVSE without current monitor display; there are plenty of commercial examples. In DIY openEVSE builds, the current should be firmware limited for hardware and outlet to be used. In this, this basic kit the fuses and relays are rated for 30A and so it should normally be set to a maximum of 24A (some have pushed it to 28-30A). If it is thus limited, it can be used safely in any circuit that will support 24A or more. There is, therefore, no added safety to having an LCD or adjustable button. Of course, I prefer to be able to change current even in a basic unit and think it would be very useful if Chris and others would implement an easy way to adjust current up to the max of the EVSE using a simple LED flash system like Phil does with the EVSEupgrade.