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Discussion Starter #1
I'm curious to find out just what happens when a Zappi or other solar-aware charger decides there's not enough free/cheap electricity available, so it's time to suspend charging for a bit.

Do they completely stop the charge, in which case I'd expect to hear a contactor of some kind go clunk maybe?
In this case, the car would think the charger has disappeared, and completely stop the charge. And then when the sun comes out again, the car would see a completely new charging session starting up, and so so whatever it normally does at the start of a new charge.

Or do they somehow simply pause the charge, by somehow reducing the current to zero in a way that the car thinks the connection to the charger is still there and alive, just no providing any amps right now? A kind of sleep-mode if you like? In this mode the contactors would stay energised, and charging would resume the instant the charger decides there's enough electricity available. Less contactor-clunking, less wear and tear, and faster. Car would think the original charge was continuing as usual.

Reason I ask is, I'm testing a Mainpine ECU inside my Rolec, fitted with a variable resistor which lets me alter the current smoothly from 6A upwards. That part works fine. I can set it to zero resistance, which shuts down the Mainpine and opens the contactors with a clunk.

Problem arises when the charge starts up again! My Ampera gives 2 toots on the horn!! :mad: This will drive me, my wife, & neighbours nuts, if the car honks every time a cloud passes by!

One i3 owner with Mainpine says he's happy, as i3 doesn't beep. What's happening with the rest of you?

I've fired off qns to the OpenEVSE crowd, and some on here who have tweaked these things, as the J1772 spec I have (Aug 2001) isn't as crystal clear on some details as I'd like. I rather think that this "Sleep-Mode" I'd like hasn't been thought of or considered in this spec. I would like to be proved wrong, and shown how to achieve it!
 

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In a nutshell a Zappi has 3 charging modes - Fast (like any other CP), Eco and Eco+. Eco uses as much solar as is available but if the amount drops below 1.4kW (the charging standard) it will use up to 1.4kW from the grid to keep the charge going. Eco+ will pause the charge below 1.4kW, but the behaviour on restarting is then entirely down to the car (though most apparently cope with it pretty well).
 

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Discussion Starter #3
Thx for that! The Eco+ behaviour, in detail, is what I'm trying to understand - the "pause" you mention. I assume that the contactors drop out, and the charge is in effect completely stopped. Rather the same effect as if someone switches off the 13A mains supply while granny EVSE is still plugged in.
 

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We've been doing a lot of development in this area recently.

In short, not all cars support 'pause' but most modern EVs are fine with it.

Sent from my SM-N950F using Tapatalk
 

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In a nutshell a Zappi has 3 charging modes - Fast (like any other CP), Eco and Eco+. Eco uses as much solar as is available but if the amount drops below 1.4kW (the charging standard) it will use up to 1.4kW from the grid to keep the charge going. Eco+ will pause the charge below 1.4kW, but the behaviour on restarting is then entirely down to the car (though most apparently cope with it pretty well).
Just a quick note to add that with Zappi2 at least in Eco+ mode you can set the level of grid power you are prepared to accept so that in reality you only charge when you have over 1.4kW off grid available. Only just installed the new Zappi2. As the installer noted - I think many don't know about the min 1.4kW threshold, however.

My only issue so far is wifi connectivity between my Hub and the Zappi but that's mostly for monitoring only and I can fix!
 

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My e-Niro will charge below 1.4 on Zappi 1 if I put it into one of the lower charge modes.
Interesting...you mean if you put your vehicle or the Zappi into lower charge mode? I was given impression this is not possible on Zappi2 at least (which I hadn't been expecting).
 

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Thx for that! The Eco+ behaviour, in detail, is what I'm trying to understand - the "pause" you mention. I assume that the contactors drop out, and the charge is in effect completely stopped. Rather the same effect as if someone switches off the 13A mains supply while granny EVSE is still plugged in.
It pauses the charge, the contactors don't click in and out every time a cloud goes over, but if its paused for a longer period of time they probably do so the charge as there is a click at times. I haven't watched it to really see what happens with longer pauses but the Zappi doesn't fully end the session until the car is unplugged.

It does depend on the car as well. The Golf responds differently to the Leaf or Niro and causes more issues.
The Leaf and Niro just follow the Zappi.
 

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Interesting...you mean if you put your vehicle or the Zappi into lower charge mode? I was given impression this is not possible on Zappi2 at least (which I hadn't been expecting).
The e-Niro has options to take a lower charge rate as does the Kona. There is a YouTube video of a Kona with a Zappi 1 charging at 0.6 Here
 

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Discussion Starter #11
Ampera doesn't sound the horn when the charge stops, it sounds when it starts! It's just a couple of light beeps, but enough to be a nuisance if it happens every time a cloud goes by. Yo can't disable this feature sadly. Maybe it's meant to be a gentle acknowledgement that your charge is up & running ok, and so saves you having to squint closely through the windscreen to see if the faint green lamp on the dash is lit permanently, can be hard to see on a sunny day.
 

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So this is an Ampera specific problem, nothing to do with Zappi.

You have several options:

Apologise to your neighbours
Use a different Zappi setting so the charge doesn't stop
Recode your Ampera to get rid of this feature
Rewire your car so that the horn only is triggered by the horn button and nothing else (security system?)
Stuff a pillow into you horn when charging
ETC

Let us know what you do
 

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Have you looked ajt the control pilot signal (own) and observed what Zappi does with this when their is no solar power available for charging, at least to meet minimum threshold value.
 

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Discussion Starter #17
I don't have a Zappi, so can't monitopr it myself, hence the qns. I do have a Mainpine ECU which will do variable current charging, but it doesn't have the pause feature. So I'm now planning to intercept the CP signal coming out of that, monitor the solar electricity available, and modify the CP signal in-flight as it were, suppressing the oscillation bit when clouds come over. EVs are required by J1772 to respond within 5 secs (I think) to a change in the CP signal, so if the cloud comes over suddenly, I'd ramp the frequency to reduce the current to 6A, wait 5 secs, then suppress the oscillator. Then I'd wait at least 10 secs before re-enabling the oscillator at 6A then ramping up to whatever's the max of solar-available and EVSE-allowed current. Am hoping I can do all this with an Arduino, but might have to code up a Microchip cpu to do the dedicated oscillator bit, maybe.
 

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Discussion Starter #18
Today had a play with the Viridian Mainpine fitted into my Rolec 32A charger. I'm able to use an AD8400 digital pot to set the allowable current anywhere from 6 to 32A in steps of about 0.2A. (FWIW, CPU I'm using is a NodeMcu ESP8266 board with built-in wifi, and I also have a current sensor input which I intend to use to measure actual current being drawn by the car - this will be useful info if I ever want to have 2 cheapo chargers each nominally 32A, working together to charge 2 EVs but the house can only supply max 32A between them. So lots of scope to prioritise/share etc without spending a fortune on fancy new chargers).

The mainpine doesn't have, as far as I can see, a "pause charging" mode, so I've intercepted the CP line and using a DPDT relay can redirect the car end, and the ECU end when I want to pause charging. For the car end, I feed the car with a 12V through a 1k Ohm resistor, just as if it was the ECU connected but not yet supplying a pwm signal to indicate the amps allowed. For the ECU end, I connect the CP to a diode + 2740 Ohm resistor,simulating an EV that's plugged in, but hasn't yet signalled that it wants some current please.

My Ampera charges at about 14A. If I apply my "pauser" circuit while at 14A, the car abruptly stops charging, and lights up the "Unable to charge" message & gives me an EML engine warning light! So this is obviously rather a brutal thing to do, and should be avoided!

If instead I set the Mainpine to charge at about 6A (I used a 200 Ohm control resistor), and then apply the "pauser", it works much better! The Mainpine doesn't open the contactors in the Rolec, which are noisy clunky items, so that part stays nice & quiet & well-behaved. But the Ampera obviously doesn't expect the charger to pause the supply of current, so thinks the entire charge session has come to an end, and it stops the charge at its end. I'm pretty sure the contactors in the Ampera end do open, as there's a bit of just-audible clicking under the bonnet somewhere. Then when I stop my pauser circuit & switch the CP to go straight back from Mainpine to the car to resume the charge, the car sees this as a new charge session, starts charging, and beeps the horn to tell me it's just started charging!

This is a bt of a bummer. I was hoping the car wouldn't open its contactors & stop completely, as it's the restart wih the accompanying horn-beeps that will drive me up the wall! So I'll now have to investigate how to isolate the horn. I think someone's done this for the Ampera, somewhere in these threads; will be a hunt to find it again.

But the good news is that in principle it's possible to add a simple circuit + logic to the CP line of a charger, at least one that you can control the output current of (e.g. Mainpine), as you want to ramp the current down from wherever to 6A before doing the pause-charge stuff.

As noted above by others, there seem to be EVs which behave better/wose with a paused-charge state being imposed. Clearly the Ampera is less happy than others! At least the Mainpinbe doesn't have to clatter the Rolec contactors noisily, as it would if I were to completely end the charge every time a cloud goes by.
 
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