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Hello from North Norfolk! My first post….

I have just bought a 2012 Ampera - GREAT! - and have started to investigate the possibility of automated variable rate charging.
I need to integrate car charging into our home / business system which is a non feed-in tariff based solar and wind setup.
I am not sure if this subject has been dealt with before but here is my experience.

I should say at the outset - do not attempt electrical work unless you have the necessary knowledge to do so safely.

On the internet I found the 16amp Viridian (Mainpipe) tethered EPC charge controller £55+VAT (Google it) which arrived promptly.
Using a 16amp single ended type 1 cable I was quickly able to set up a test rig.
Power to the whole setup needs to be via a GFCI.
You can download the manual for the controller but here is some helpful empirical info.

Only low amperage cable is needed for connections to the controller which has a DIN rail mounting.
The actual switching of mains voltage to the car is done by a contactor external to the controller which you also need to buy. This is energised by an isolated single pole relay inside the charge controller ( a Hong Fa HF49FD). The contacts appear on the charge controller as P1 and P2.

The car cable labelled CP connects to the CP terminal of the controller (the car cable I bought did not have a PP core).

The resistor which controls the current connects between the IC and 0(earth) terminals.
This resistor gives continuous current control from 6amps (191ohms) to 14.5amps (>330ohms).

Dropping the resistor to 40ohms ( the manual says 100ohms) cuts off charge.

In operation the control resistor sees DC from 0.2v (40ohm) to 1.2v (330ohm) and so a low wattage type is fine.

Usually, after a cut-off (40ohm), charge is re-enabled when you re-connect a 191-330ohm resistor but not always. Sometimes you need at least an 8amp rate resistor (220ohms) to re-start charge.
Sometimes charge will not re-start at all.

A message shows on the dash - 'Not able to charge'. Charge can then only be restored by unplugging and re-plugging the car plug.

I hope this info proves useful to somebody out there!

All I have to do now is hook it up to my system to charge when there is spare solar/wind power coming in!
 

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Hello from North Norfolk! My first post….

I have just bought a 2012 Ampera - GREAT! - and have started to investigate the possibility of automated variable rate charging.
I need to integrate car charging into our home / business system which is a non feed-in tariff based solar and wind setup.
I am not sure if this subject has been dealt with before but here is my experience.

I should say at the outset - do not attempt electrical work unless you have the necessary knowledge to do so safely.

On the internet I found the 16amp Viridian (Mainpipe) tethered EPC charge controller £55+VAT (Google it) which arrived promptly.
Using a 16amp single ended type 1 cable I was quickly able to set up a test rig.
Power to the whole setup needs to be via a GFCI.
You can download the manual for the controller but here is some helpful empirical info.

Only low amperage cable is needed for connections to the controller which has a DIN rail mounting.
The actual switching of mains voltage to the car is done by a contactor external to the controller which you also need to buy. This is energised by an isolated single pole relay inside the charge controller ( a Hong Fa HF49FD). The contacts appear on the charge controller as P1 and P2.

The car cable labelled CP connects to the CP terminal of the controller (the car cable I bought did not have a PP core).

The resistor which controls the current connects between the IC and 0(earth) terminals.
This resistor gives continuous current control from 6amps (191ohms) to 14.5amps (>330ohms).

Dropping the resistor to 40ohms ( the manual says 100ohms) cuts off charge.

In operation the control resistor sees DC from 0.2v (40ohm) to 1.2v (330ohm) and so a low wattage type is fine.

Usually, after a cut-off (40ohm), charge is re-enabled when you re-connect a 191-330ohm resistor but not always. Sometimes you need at least an 8amp rate resistor (220ohms) to re-start charge.
Sometimes charge will not re-start at all.

A message shows on the dash - 'Not able to charge'. Charge can then only be restored by unplugging and re-plugging the car plug.

I hope this info proves useful to somebody out there!

All I have to do now is hook it up to my system to charge when there is spare solar/wind power coming in!
Welcome to the fold, sounds like you have gotten stuck well in there !
Is it feasible to stick a capacitor/battery in there to smooth out the power drops ?
 

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Discussion Starter #3
Welcome to the fold, sounds like you have gotten stuck well in there !
Is it feasible to stick a capacitor/battery in there to smooth out the power drops ?
In my test I used a linear pot when adjusting the current. The charge turn off by turning down to a 40ohm resistance was intentional to find out how it behaves.
In reality you dont have to do that. As you vary the pot in the 191-330ohm range the car stays connected. There are a few 'blue' flashes on the controller but the car has always remained locked into charging.
Because of the unpredictability of taking the car out of charge by dropping to a 40ohm resistance I will be just turning off the AC to achieve zero charge.
In my tests so far that has had predictable results when re-connecting the AC.
 

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Ampy, thanks for your appends - they've spurred me into actually getting down to my version of a variable-charge method.
https://speakev.com/posts/286659/ has details of how I'm modifying my type2->type1 cable. I didn't know the Ampera charging can be tuned to individual 1 Amp levels - I've only ever seen 6/10/16 amps mentioned.

As I understand it, your tweaks are in effect telling the EVSE internal chippery how much current's it's allowed to output, and that's nothing to do with the capacity of whatever connector cable you use. But as I have a Rolec I can't modify, I think all I can do is the cable-tweak which will achieve much the same result in the end, even if I won't be able to match it to my solar panel output quite as well as I might doing it your way. Have I understood this correctly?
 

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Hi Andy
For some reason I'm not allowed to look at your cable mod so can't comment.
I haven't checked with a scope yet but I'm pretty sure that what the Veridian controller is doing is altering the mark/space ratio of the 1khz signal on the CP line which tells the car how much current is available. The car then takes that charge rate unless it is fully charged.
If you download the Veridian manual you can appreciate what is happening better. In the manual are also details of the controller which can drive L1, L2 and L3 contactors.
My Ampera refused to take more than 14.5 amps even though I advertised that more was available.
I hope this helps.
I have a system with 46 solar panels and a 6Kw turbine. They charge a 48volt battery. It is interesting working out what to do with the power!
 

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On the internet I found the 16amp Viridian (Mainpipe) tethered EPC charge controller £55+VAT (Google it) which arrived promptly.
I know it well. :)

Dropping the resistor to 40ohms ( the manual says 100ohms) cuts off charge.
All of the settings are "sticky" to avoid the situation where a borderline resistance/voltage will result in bouncing between one setting and another. So, if you're using a potentiometer that the settings change at different places when going up than when coming down. That is intentional.

The 6A setting is the most-sticky, and yes, you will have to drop quite a bit lower than 100-ohms to get it to stop PWM and then open the contactor.

Usually, after a cut-off (40ohm), charge is re-enabled when you re-connect a 191-330ohm resistor but not always. Sometimes you need at least an 8amp rate resistor (220ohms) to re-start charge.
Sometimes charge will not re-start at all.

A message shows on the dash - 'Not able to charge'. Charge can then only be restored by unplugging and re-plugging the car plug
I've seen these quirks with the Volt, as well. And then you also get to deal with a "service engine light" for a full day or so. They are Voltec behaviors, though, and other than avoiding the situation entirely, they're not really avoidable. Unfortunately, that makes solar charging rather complicated if it won't let you stop the charging and then re-start the charging without such dilemmas.
 

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Discussion Starter #7
Thanks - that makes sense - a bit of hysteresis.
I have already concluded that cutting off / re-connecting the AC is the most predictable way to stop/start, with suitably long time intervals in place so I don't over-use the car relays.
I have a 4.5 kw inverter running our shop and DC heaters to soak up the solar power - but summer is here and I will now be doing air con / car charging via a new inverter. Great fun!
 

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As a solution - although not a very convenient one - to the problem of my 2012 Ampera going into 'Not able to charge' mode it is possible to reset the car by pressing or simulating pressing the release catch on the car plug.
The 150ohm resistor normally sitting between the PP pin and earth switches to 480ohms when the release button is pressed.
The car then charges normally.
 

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I've now modified my Type 2->1 cable for 32A Rolec -> Ampera use. It has a 4-position rotary switch externally, which operates 3 reed-switches + resistor-networks internally. So I have 4 current-capacity settings now, 32A, 20A, 13A, 6A acc to J1772 specs, which means Ampera should use 16/16/10/6 Amps respectively. I think the 16/10 settings are working, as the estimated completion-time goes up when selecting 10 rather than 16, but I'm not sure what it's doing on the 6A setting! The car recognises it's plugged in on this setting, but I didn't hear the Rolec contactor go "clunk" ! Anyway, I'll do a bit more testing and see how it all behaves. It's my first step at trying to match the charging to my panels a bit better! :)
 

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I've now modified my Type 2->1 cable for 32A Rolec -> Ampera use. It has a 4-position rotary switch externally, which operates 3 reed-switches + resistor-networks internally. So I have 4 current-capacity settings now, 32A, 20A, 13A, 6A acc to J1772 specs, which means Ampera should use 16/16/10/6 Amps respectively. I think the 16/10 settings are working, as the estimated completion-time goes up when selecting 10 rather than 16, but I'm not sure what it's doing on the 6A setting! The car recognises it's plugged in on this setting, but I didn't hear the Rolec contactor go "clunk" ! Anyway, I'll do a bit more testing and see how it all behaves. It's my first step at trying to match the charging to my panels a bit better! :)
Interesting...
I have found that with the Viridian/Mainpipe, starting charging at 6amps is hit or miss. I think the car must take the blame. Best to start higher. You can then drop to 6amps ok. As previously mentioned, pressing the type 1 release button wakes the Ampera up from 'Not able to charge' - even from a 6amp start-up failure.
If you can get an AC clamp meter round a live or neutral conductor you can see what is happening.
I have now had a look at the CP waveform. I have the 16amp controller and it is that which is restricting the charge rate between 6-14amps it seems (16amp cable).
My crude solar control watches for AC export to happen (the blinking meter light comes on continuosly) and proceeds to add various loads till export stops, at which point loads start to turn off. A sort of equilibrium is found maximising the spare power. The car charging will be a variable load.
My inverter is set to maintain a constant battery voltage of 52volts. I don't have a separate charge controller I just charge with pairs of panels, series connected. Blocks of panels disconnect if the battery voltage gets high.
I can go off-grid.
I should apply for the feed-in tarrif but I just like to tinker!
 

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I have been experimenting with a similar mod on my tethered CM 30A CP I can get 13A with 1500 ohm and 6A with a 10K ohm , I can't access Andy's link but I would like to know what value resistor you were using to get 10A ?
 

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I have been experimenting with a similar mod on my tethered CM 30A CP I can get 13A with 1500 ohm and 6A with a 10K ohm , I can't access Andy's link but I would like to know what value resistor you were using to get 10A ?
My cable has 32, 20, 13, 6A resistors as that's all the standard has (6A seems to be non-std addition). I was expecting to see 10A draw using 13A setting as that's a v commonly mentioned value e.g. with granny charger.
I rather thought car had 3 values it liked, 16,10,6.
I was wrong. Seems car always asks for 16 and PWM restricts it to anything ≤ that. After buying clamp Meter I see 12.4A when using 13A setting.
So I've got slight control but not what I want.
 
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