# OpenEVSE DIY Tethered 3-phase **URL:** \ **Category:** OpenEVSE\ **Tags:** 3-phase, openevse\ **Created:** [5 March 2018 18:16 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731 "2018-03-05T18:16:21Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [20 March 2020 10:29 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/22 "2020-03-20T10:29:52Z")
Hi Glyn Finally I found the problem. I need a resistor between Ground and PP wire, car side. PP is not connected to the main board. In my case the cable is 6mm2 = 32 A and my type 2 plug is also 32A. The resistor to work with this intensity must be 220 Ohms. I put a 240 Ohms because I had it at home. It charge !!! 🙂 Now the problem is the firmware energy calculation in kWh. Look at the print screen. The charging current was between 16 and 17 Amps all the time in 3 phase. Voltage was around 400V. Thats about 11kW for 1h41 min. The energy must be around 18,7 kWh and no 2,62 kWh as represented. Can you arrange that calculation please? Kind regards Jordi . ![Captura de Pantalla 2020-03-19 a les 22.02.05](https://community.openenergymonitor.org/uploads/default/original/2X/2/2c2645ff1471cbd819f9bd55f11292016151ac1f.png) ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [20 March 2020 11:33 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/23 "2020-03-20T11:33:02Z")
Ah, that’s good to hear. Most EV connectors come with the resistor pre-installed. This is the first time I’ve heard of a connector being supplied without a resistor. Did you make up your own cable? For anyone else following this thread here is some more info on resistors in charging cables: [https://canze.fisch.lu/resistors-is-charging-cables/](https://canze.fisch.lu/resistors-is-charging-cables/) This only applies to Type-2 cables, Type-1 cables don’t have a resistor at the car end, at least not connected as standard between PP and GND. A resistor is connected via the switch on the connector which signals the EV to stop drawing current when the switch is pressed : [![](https://farm6.staticflickr.com/5331/9018719465_9df5c4392e_b.jpg) ](https://farm6.staticflickr.com/5331/9018719465_9df5c4392e_b.jpg) \*\* > [@jo\_llo](#): > > Now the problem is the firmware energy calculation in kWh. > Look at the print screen. The charging current was between 16 and 17 Amps all the time in 3 phase. Voltage was around 400V. Thats about 11kW for 1h41 min. The energy must be around 18,7 kWh and no 2,62 kWh as represented. Enabling `#define THREEPHASE` in `open_evse.h` should enable three-phase energy calculation. This should be enabled as standard if you are running three-phase FW. Could you show me a screenshot of the openevse UI showing the controller FW? It should end in `.3P` if it is indeed running 3ph firmware. ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [20 March 2020 13:44 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/24 "2020-03-20T13:44:57Z")
Hi Glyn Yes I did my own cable and installed a type 2 plug. how I do that?: Enabling `#define THREEPHASE` in `open_evse.h` should enable three-phase energy calculation. This should be enabled as standard if you are running three-phase FW. Could you show me a screenshot of the openevse UI showing the controller FW? It should end in `.3P` if it is indeed running 3ph firmware. ![IMG_4454.PNG](https://community.openenergymonitor.org/uploads/default/original/2X/4/4b687e03d4cbfca56797a841ac44e63295e22ce5.jpeg) ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [20 March 2020 14:24 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/25 "2020-03-20T14:24:53Z")
the FW you send me to install is openevse-3ph.hex in may 2019 ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [20 March 2020 23:40 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/26 "2020-03-20T23:40:51Z")
Apologies, I must have made a mistake. I’ve just recompiled a special OpenEVSE FW with `THREEPHASE` enabled. The firmware version is `5.1.0.EU.3P`. See attached: [firmware.hex](https://community.openenergymonitor.org/uploads/short-url/2M3Cxryp9hWkZIr5P2YnGGbiVew.hex) (85.8 KB) ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [22 March 2020 17:49 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/27 "2020-03-22T17:49:20Z")
Sorry Glyn I just uploaded the new firmware and the calculations are again for monophasic, not triphasic (see pictures attached). Power 3p = 400V x AMPS x SQRT(3) ![IMG_1708](https://community.openenergymonitor.org/uploads/default/original/2X/c/c8965681f571d7960206ae0aece17a97feadb3ab.jpeg) ![IMG_7812](https://community.openenergymonitor.org/uploads/default/original/2X/d/d30c7ad8e7c67d26d1525959ef57b77b4cc20adf.jpeg) ![Captura de Pantalla 2020-03-22 a les 18.34.22](https://community.openenergymonitor.org/uploads/default/original/2X/8/8843f91ce8fbe7d7a57d21547200ec7fd17946f9.png) ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [22 March 2020 19:44 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/28 "2020-03-22T19:44:20Z")
> [@jo\_llo](#): > > Power 3p = 400V x AMPS x SQRT(3) Are you saying that is what the calculation is, or what it should be? If your line-line voltage is 400 V, hence the line-neutral voltage is 231 V (400 ÷ √3), the total power is 3 x VLN × IL = 3 x VLL × IL ÷ √3 = VLL × IL × √3 ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [23 March 2020 19:34 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/29 "2020-03-23T19:34:18Z")
As you can see on the screen shots the calculated power is 230V (V line-neutral) × I = power in monophasic system and I’ve a triphasic. In the calculation formula it’s missing cos(FI). Do you know the cos (FI) value for this charger ? Can you please implemented the following formula to the 3 phasic system FW ? Power = 400V x I x sqrt(3) x cos (FI) ![Captura de Pantalla 2020-03-22 a les 18.34.22](https://community.openenergymonitor.org/uploads/default/original/2X/8/8843f91ce8fbe7d7a57d21547200ec7fd17946f9.png) ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [24 March 2020 00:00 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/30 "2020-03-24T00:00:31Z")
This is how threephase energy is calculated: > ```auto - P(3ph) = V(LN) * I * 3 - V(VL) = 230V (line to neutral voltage) - V(LL) = V(LN) * √3 = 230 * 1.75 = 400V ``` > > > \- Added option to calculate 3-phase energy ~~(multiple current by the square roo…t of 3).~~. > \- Disabled by default > > My notes on three-phase calculation: > \`\`\` > \- P(3ph) = V(LN) \* I \* 3 > \- V(VL) = 230V (line to neutral voltage) > \- V(LL) = V(LN) \* √3 = 230 \* 1.75 = 400V > \`\`\` ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [24 March 2020 08:13 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/31 "2020-03-24T08:13:47Z")
Hi Glyn Thanks for your patience. Please take a look of my screen shot Intensity = 12.76 A and Power = 2935 W That means Voltage = 2935 / 12,76 = 230 V, and not 230V x 3 Then your software to calculate the energy is correct but there is a bug: THREEPHASE is not active in the firmware and it continue to calculate as a Monophasic system. Kind regards Jordi ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [24 March 2020 08:15 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/32 "2020-03-24T08:15:39Z")
Glyn I have a second question: In the formula we miss COS (FI) Power = Voltage LN x Intensity x 3 x COS (FI) do you know the value of COS (FI) in this charger? ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [24 March 2020 08:34 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/33 "2020-03-24T08:34:01Z")
probably TREEPHASE it’s not defined at **open\_evse.h** KR ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [24 March 2020 14:50 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/34 "2020-03-24T14:50:07Z")
Please try again with the FW attached, I have explicitly defined THREEPHASE [openevse-3ph.hex](https://community.openenergymonitor.org/uploads/short-url/7b3SuqU1lhZebuhsCntgqN2Ud31.hex) (85.8 KB) If this doesn’t work you could try building the FW yourself. Three-phase calculation works for the EmonEVSE. ---
**Author:** ![jo\_llo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/jo_llo/32/11291_2.png) [@jo\_llo](https://community.openenergymonitor.org/u/jo_llo)\ **Post date:** [4 April 2020 17:13 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/35 "2020-04-04T17:13:45Z")
Hi Glyn Thanks for your patience Now it works Thanks a lot Jordi ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [7 April 2020 12:21 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/36 "2020-04-07T12:21:45Z")
Fantastic! Very sorry, for all the hassle. The mistake must have been at my end. ---
**Author:** ![Maciej\_Blaz](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/maciej_blaz/32/16324_2.png) [@Maciej\_Blaz](https://community.openenergymonitor.org/u/Maciej_Blaz)\ **Post date:** [28 December 2020 07:10 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/37 "2020-12-28T07:10:52Z")
Hi, I know that this is an old thread, but have a question about 3-phase installation and setting the THREEPHASE constant. Is it possible to change it on the fly? For example have some toggle in the web ui to be able to switch it to either 1-phase or 3-phase? Basically I have 2 cars (one has single phase charger and the other has 3 phase charger) and I would like to be able to switch the param on and off based on which car is currently charging. Ideal solution would be to add one more current meter (on L2 or L3) so that the software knows automatically if I’m charging 1 or 3 phase car. Thanks in advance. ---
**Author:** ![gadgetbazza](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/gadgetbazza/32/8167_2.png) [@gadgetbazza](https://community.openenergymonitor.org/u/gadgetbazza)\ **Post date:** [12 July 2021 13:43 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/38 "2021-07-12T13:43:11Z")
I’ve just had a 3 phase EmonEVSE installed and despite the firmware being reported as 7.1.3.3P, I too see only single phase energy calculations both in the UI and the MQTT feed to my EmonCMS. I’m also unsure therefore if the PV divert is going to be observed correctly on the grounds that the value I’m returning about grid import/export is for all three phases, not just one. I see the reference in this thread to the constant THREEPHASE being defined, but no detail on how to set this? I would also expect that to have been set correctly in this firmware? ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [22 July 2021 23:46 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/39 "2021-07-22T23:46:17Z")
The OpenEVSE UI displays real-time charging current, which is the same for both single and three-phase e.g 32A 1P = 7kW / 32A 3P = 22kW. However, the kWh/wh reported on the OpenEVSE UI and Emoncms will show the correct energy calculation for 3P. Solar PV divert is based on current, therefore should work the same for both single and three-phase. ---
**Author:** ![gadgetbazza](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/gadgetbazza/32/8167_2.png) [@gadgetbazza](https://community.openenergymonitor.org/u/gadgetbazza)\ **Post date:** [23 July 2021 00:00 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/40 "2021-07-23T00:00:26Z")
Hi Glyn, thanks for replying. I get the 32A bit. But on the emonCMS, there is only one energy calculation and it only shows the power for a single phase on my 3 phase unit. Please see attached screenshot showing the consumption at circa 3.7kW, the unit is actually charging at 11kW. This is the reasoning for my query. I’ve had to add the energy feed to each of my 3 phase monitors to get my total usage correct. ![Screenshot 2021-07-23 at 00.55.25](https://community.openenergymonitor.org/uploads/default/original/3X/1/5/15cbb55978e29b6735ddb328993982f44d8ecc73.png) ---
**Author:** ![glyn.hudson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/glyn.hudson/32/35003_2.png) [@glyn.hudson](https://community.openenergymonitor.org/u/glyn.hudson)\ **Post date:** [23 July 2021 14:41 UTC](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731/41 "2021-07-23T14:41:13Z")
> [@gadgetbazza](#): > > But on the emonCMS, there is only one energy calculation and it only shows the power for a single phase on my 3 phase unit. Please see attached screenshot showing the consumption at circa 3.7kW, the unit is actually charging at 11kW. This is the reasoning for my query. Thanks for the screenshot, I can see the issue. The charging power shown on Emoncms is calculated in Emoncms input processing, the `amp` current Input is multiplied by 230V to display the power, this should be multipled by 3x for three-phase. To change this, open up Emoncms Inputs and click the spanner icon next to openevse ‘amp’ feed: ![Emoncms-input-view](https://community.openenergymonitor.org/uploads/default/original/3X/3/7/371d44623fa9601f04943e59638f3807ec1ac0ce.png) Then change 230 to 230V x 3 = **690** ![Emoncms-input-view (1)](https://community.openenergymonitor.org/uploads/default/original/3X/2/5/25b00677ebe9722fd0cc76a86394bcd283803a7d.png) The power will now be displayed correctly. Alternatively, for more accurate power reading, you could multiple by emonPi VRMS feed x3 The `ev_energy` Feed should be correct for three-phase since this energy is calculated on the openevse. To make this easier for new users, I’ve added a three-phase device template which will do this automatically, but since you already have your Feeds setup it’s probably easier to adjust manually. Thanks for reporting this issue. ![3-evse-sw](https://community.openenergymonitor.org/uploads/default/original/3X/8/1/81ec170af54b745d22428cf5259a50b0a1418747.png) [Previous page](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731.md?page=1) [Next page](https://community.openenergymonitor.org/t/openevse-diy-tethered-3-phase/6731.md?page=3)