Can't afford a Zappi? Turn your granny charger into a solar charger.

Gadget Geek

Gadget Geek

Prominent Member
Joined
Jan 6, 2022
Messages
2,583
Reaction score
3,292
Points
970
Location
Somerset
Driving
MG ZS EV
Hi everyone,

As the title suggests, I already have a home charger, a Pod-Point which came free with my first EV. I have solar panels on the roof and a variable current granny charger which I use to syphon off any excess generation. For this, I have to keep an eye on the weather and use the iSmart app to start and stop the charge.

So, I decided to see if I could connect a light sensitive switch into the Communication Pilot (CP) line to automatically control the charging. I was fortunate that the variable current charger has all the wires labelled and the CP lead was bolted to the circuit board with a crimp lug.

If you didn't want to open up your granny charger, an alternative would be to purchase type 2 male and female plugs with a short length of cable and tap into the CP line on that instead. I've supplied a PDF of the project, but please be aware it is only an example of how I did it. If you decide to have a go, I take no resonsibility for any problems you may encounter.
 

Attachments

  • Granny Charger Solar Switch.pdf
    1.6 MB · Views: 174
Last edited:
I have used a current monitor which the measures the pwer coming of the solar panels and when 2.2 kw are generated it switches a DIN rail contactor with an adjustable off time delay set to 1 minute (to allow for small clouds as I have found that continuous rapid switching on and off confuses the cars charging protocol ) in the fuse board connected to an external socket into which the MG granny charger is plugged. All for around £30, happy days .

​

Parts available from Ebay

GEYA Din Rail OFF Delay Timer Relay 230V Time Delay Relay 1SPDT​

Adjustable AC Current Sensing Switch Rail 35mmDIN Self-Powered Sensing Switch 1x​

 
Alex1985 said:
I have used a current monitor which the measures the pwer coming of the solar panels and when 2.2 kw are generated it switches a DIN rail contactor with an adjustable off time delay set to 1 minute (to allow for small clouds as I have found that continuous rapid switching on and off confuses the cars charging protocol ) in the fuse board connected to an external socket into which the MG granny charger is plugged. All for around £30, happy days .

​

Parts available from Ebay

GEYA Din Rail OFF Delay Timer Relay 230V Time Delay Relay 1SPDT​

Adjustable AC Current Sensing Switch Rail 35mmDIN Self-Powered Sensing Switch 1x​

Click to expand...
Are you saying you switch the granny charger on and off with this?

Not a good idea as contactor spikes could damage the charger. That's why I tapped into the CP lead, it's a safe way to get the car's on board charger to switch itself on and off.
 
Gadget Geek said:
Are you saying you switch the granny charger on and off with this?

Not a good idea as contactor spikes could damage the charger. That's why I tapped into the CP lead, it's a safe way to get the car's on board charger to switch itself on and off.
Click to expand...
But is it any better? Is the cars charger designed to be on off on off on off ?
 
smokie said:
Their website?
Click to expand...
Mmm not much technical info on there ? Unless you know better?

"charge power is continuously adjusted in response to changes in generation or power consumption elsewhere in the home. Your electric car charging will pause if there is too much-imported power, continuing only when there is surplus free power available."

Sounds like the murketing dept to me
 
AK OK said:
Your electric car charging will pause if there is too much-imported power, continuing only when there is surplus free power available."
Click to expand...
There's your answer. The Communication Pilot signal is a 12 volt square wave signal which the car looks for. If it's present, the charging starts, if it's absent, the charging pauses.
 
Gadget Geek said:
There's your answer. The Communication Pilot signal is a 12 volt square wave signal which the car looks for. If it's present, the charging starts, if it's absent, the charging pauses.
Click to expand...
That's not the answer to whether the car is designed for mucho charge stop charge stop cycles in response to home made charger adaptations is it?
 
AK OK said:
That's not the answer to whether the car is designed for mucho charge stop charge stop cycles in response to home made charger adaptations is it?
Click to expand...
No, you're right.

You can always sit in a deckchair in the garden watching the clouds drift by, using the app to start and stop the charge as and when the sun shines. :)
 
Gadget Geek said:
No, you're right.

You can always sit in a deckchair in the garden watching the clouds drift by, using the app to start and stop the charge as and when the sun shines. :)
Click to expand...
Hehe how we laughed!

But would that spare the contactors in the cars charger the extra stress that you wibbled about earlier? Or are you really not that bothered now that someone has asked the direct question? 🤷🏻‍♂️
 
I remember reading ages ago that it wasn't expected to be an issue, so long as it was carried out gracefully rather than just pulling the plug, but that was from a (knowledgeable) bloke on a (technical) forum rather than an completely dependable source.
 
smokie said:
I remember reading ages ago that it wasn't expected to be an issue, so long as it was carried out gracefully rather than just pulling the plug, but that was from a (knowledgeable) bloke on a (technical) forum rather than an completely dependable source.
Click to expand...
I fully expect these items are designed & "sized" for a given number of operations & given what we know they are unlikely (cough) to be generously overspecced... Hence my question...
 
Support us by becoming a Premium Member

Latest MG EVs video

New EVs from MG: MG S9 & MG9 plus hot topics from the forums
Published
Subscribe to our YouTube channel
Back
Top Bottom