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Low Amperage Charging - is it possible?

 Hi All, please be kind this is my first post.

I am a proud owner of a Mitsubishi PHEV and have just come home from a trip around Europe with a caravan. Most times in the UK I can use the camping site power supply to charge the car (10A over 5 hrs) Problems arise in Europe when the campsite power trips at 6A, sometimes 4A. Often I am unable to use the electric kettle.

I would therefore like to know if an EVSE has ever been created to only use a low current, say 4A. I would be happy to use it in the above circumstances by charging overnight for 8 hrs or more.


@ Gene Preston


OpenEVSE Advanced support this out of the box. All you need to do is send your solar output from your system in watts to a MQTT server then have OpenEVSE subscribe. Turn on ECO mode and OpenEVSE will follow the solar output.


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Afaik, the J1772 std allows 120V operation. e.g. as in USA. So there's nothing I can see in principle to stop someone using a 230->115V step-down transformer, and running  a 6A EVSE off that. Power draw would then be about 3 kW. Presumably if all EVs obey the standard, they shouldn't mind only being offered 115V or thereabouts?

Hi Gene, your project sounds very ambitious. If successful, you would be a trailblazer in the Pi community. I'm sure that your project would attract heaps of forum support. I've used Pi's for years at home, mainly for audio visual applications. Recently I've added a Pi 4 to the collection and used Pi Os as the base software. There are a few flavours of Linux available, most notably Ubuntu, that can now be used on the Pi 4. I would suggest that you stick to the 32bit as the 64bit is still new and probably not needed on the Pi 4. If you don't want a desktop then there are other headless OS's that would work. I've used PiCore for years and found it very stable and trouble free. Try this site for a review https://www.makeuseof.com/tag/lightweight-operating-systems-raspberry-pi/

Hope this helps.

@Gene


The OpenEnergyMonitor EmonPi combined with OpenEVSE would be all you need.

https://guide.openenergymonitor.org/technical/emonpi/


https://youtu.be/WJtNEPrSSvg 



Here is a guide for solar diversion integrating OpenEVSE and OpenEnergyMonitor.


https://guide.openenergymonitor.org/applications/solar-pv/


Thanks Clive.  I'll load the Raspberry Pi Os with 32 bits assuming its available at startup time.  I have an old windows PC I put windows 8.1 32 bit on and it runs legacy software and the 64 bit system does not.  I need to fire up that Rp Os now that its all sitting on my desk....Gene

Should I load the Raspbian operating system on my new raspberry pi computer?

The CCS simple protocol (AC charging) specifies the the EVSE can signal the car of charging currents from 6 to 80 amps.  So you can't send a number below 6 to the car. 

Whoops, miscalculation by me above, and I can't see how to edit my own append! Running a charger at 115V AC and 6A (the minimum the spec allows) would be drawing 690 Watts, and if powered from a 230->115V transformer, this would mean 700W at the 230V side (assuming 98.5% efficiency for nice round figures!). That's 3.04A at the 230V side, which might be doable for a campsite maybe?

Thanks for the interest Andy. This solution sounds as if it will work, I shall try it on my next foray into Europe.

There are many options for operating systems on Raspberry Pi, the best OS will depend on your needs. 

I was wondering if openevse is best set up using raspberry pi OS?  The default OS?  Im going to assume this is the case and start there.  The reply isn't useful because it contains no info on which op systems would be useful to use openevse.

Hi I have a related question. If the power is coming from solar? 1000w of solar DC produces ~ 18v through solar controllers that come on backside of panels --> 1500w pure sine inverter --> a 12A J1772 120v adapter plugged into the inverter and the J1772 end directly into a plug-in Prius designated at flow rate of 8A, if it gets 'cloudy' and amps fall below 8A, any harm to the Prius batteries? Thanks for any help:) 

Is it possible to build a system that charges a Tesla Model 3 using 120 volts L1 charging that is variable from 6 to 16 amps?  What I want to do is to have the Tesla charge rate track the suns output.  My panels can put out 1800 watts see https://egpreston.com/AMnoonPM.jpg however when clouds come over I would like to have the solar inverter supply less power to the Tesla when less sunlight is available.  This allows the use of a smaller 24 volt battery on the MPP LV2424 inverter since the load would throttle with the solar power.  Right now in the winter time I can get on average about 120 miles range per week off this system from sunlight.  I would like to make it more automatic using the J1772 in these articles.  Is this possible?  my web page is https://egpreston.com 

No worries, We are a kind group around here...


The lowest the charging standards allow is 6A. It is not possible to go any lower.



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