WAS-201EC-UK

[wildebus]

Finally got round to finishing this for a Motorhomer Forum Member and thought I would post some info and a few pictures as it came out looking ok Need to tidy up the control wire bit a little but that will be in version 2

I've made this setup before a few times before but this is the first one where the user does not have to do anything inside the box and can just plug in standard power leads without any messing around. The only fiddly bit is the Control Cable and that is just a lead with a 2 pin plug that pushes in so is not a big deal.

The WAS-201EC-UK is a AC Auto Selector box that takes two AC Inputs and automatically routes one of those Inputs to the Outlet socket.
The "UK" part is because it has the UK style 13A 3-pin Socket; The "EC" part means "External Control" - this is an option which makes the unit much more flexible for use with Fridges and Heaters; "201" is "2 Inputs, 1 output"; and "WAS" is "Wildebus Automatic Selector".

Top View - Just as you would think, you plug in the device you want to run

WAS-201EC by David, on Flickr

Side View

WAS-201EC by David, on Flickr
Two inputs, using the IEC style input.
When the Primary Input is live, that is the supply that is passed though to the Outlet Socket
When the Primary is off, the Alternate Input is the supply that is used - IF the External Control is enabled. If the External Control is off or disconnected, the Alternate Input is disconnected internally within the WAS-201.


How/why would you use one of these?
The main purpose would be if you wanted to use spare energy to drive a device like an 3-way Fridge, AC/Gas Water Heater (or even an Induction Hob or other sockets, but generally the multi-power devices are the key items with the EC model).

An example Scenario ...
You have an AES (Auto Energy Selection) Fridge. In auto mode it will use the following sources to power the fridge when available, selecting whichever is available in the following order: 1) DC (12V); 2) AC (240V); 3) Gas (LPG).,
If you are getting some good harvesting from your solar, It might be a good opportunity to use that power to drive your Fridge rather than the LPG and so save on gas (and money!).
In order to avoid drawing down the batteries too much if the sun clouds over or when it gets dark, you can simply connect the External Control to a remote switch to manually enable/disable the Alternate Input when you want, or ideally you would connect the External Control to a relay driven by an SOC Monitor such as a Victron BMV-712. You can then set the relay to turn off if the battery drops to a certain level. Around 80% could be a reasonable number but it really depends on your battery bank and how well the solar is working or if you expect to be fast charging (via driving or on EHU) soon so dropping the battery down a bit further is ok.

The Altenate Input would be from the Inverter and so when the External Control is on, that Inverter power will be used (assuming the Inverter is on, of course).
The Primary Input would be from your EHU, and when that supply is live, this is the one used always regardless of External Control condition. This means that when you plug into external mains, you will automatically have AC power to the Fridge (or whatever is plugged in) without having to mess around with moving plugs around (this is the "Automatic" part in the "Wildebus Automatic Selector" name)

 

[xsilvergs]

Automatic is good, I went down the manual route which is fine but confuses my wife.

 

[wildebus]

Automatic is good, I went down the manual route which is fine but confuses my wife.

I will have the SOC part in my new setup once I fit the Solar Panels, but the Victron EasyPlus provides the fuctionality of the EHU or Inverter switching which is very handy. Without that function, I'd have the full WAS version fitted to provide it

 

[xsilvergs]

I control the inverter with a few restrictions, here is part of my code which is run every X seconds:

var inbound = msg.payload;
var upper = 90.0;
var lower = upper - 3;
if(inbound === true){
var switchState = flow.get("switchState") || 0; //get switch state from this flow, if value is empty insert 0
var MPPTstate = global.get("mpptState", "file");
var StateOfCharge = global.get("stateOfCharge", "file");// get global value for SOC (this comes from ChargerLogger)
var InvState = flow.get("invState", "file"); //get inverter ON or OFF state

if(MPPTstate >= 3 && switchState === "Auto" && StateOfCharge >= upper){ //so long as the MPPT is not OFF or in Fault
flow.set("invState", "ON");// flag so we know what the inverter WAS doing
msg.payload = "ON";
} else if(MPPTstate >= 3 && switchState === "Auto" && StateOfCharge >= lower && InvState === "ON"){// as battery discharges SOC drops but still above my min
flow.set("invState", "ON");
msg.payload = "ON";
}
else if(MPPTstate >= 3 && switchState === "Auto" && StateOfCharge <= lower){// battery now gone below my min so turn inverter off
flow.set("invState", "OFF");
msg.payload = "OFF";
} else if(MPPTstate >= 3 && switchState === "Auto" && InvState === "OFF" && StateOfCharge >= lower){
flow.set("invState", "OFF");
msg.payload = "OFF";
} else {
//msg1 = {payload:"OFF"};
//msg2 = {payload:InvState};
//return[null,msg2];
}

// Manual control of inverter
if(switchState === "On"){
flow.set("invState", "ON");
msg.payload = "ON";
}
if(switchState === "Off"){
flow.set("invState", "OFF");
msg.payload = "OFF";
}

}
return msg;

//End

I only have a single 95 Ah AGM battery, I can't afford to have a low battery state towards the end of the day when in Auto mode so I test that the MPPT is not OFF, AUTO is selected on (obviously) and the battery is 87% SoC or greater. When it gets down to 87% SoC the inverter is switched off and the battery must recover to greater than 90% SoC before the inverter gets enabled again.

Auto switching like your designed would be one thing less to think about.

 

[wildebus]

This is where just using the relay on the BMV-712 is a lot easier

Just go to the settings of the Monitor, choose the on and off thresholds and Bob's your uncle

Just showing this as most people are looking for a simple solution and the thought of having to do any programming would not be good.

 

[xsilvergs]

I like your "simple solution" very much, I guess I've made mine more complicated because i can which isn't always a good thing.

I was already using the BMV's relay to control the Battery Disconnect, am I missing something?

Victron seem to offer many many options to switch a rely but too few relays (in my opinion).

Edit:
I see from your image you can add some hysteresis which I had to add in code.

 

[wildebus]

I like your "simple solution" very much, I guess I've made mine more complicated because i can which isn't always a good thing.

I was already using the BMV's relay to control the Battery Disconnect, am I missing something?

Victron seem to offer many many options to switch a rely but too few relays (in my opinion).

Edit:
I see from your image you can add some hysteresis which I had to add in code.

You are spot on with the relay comment.
The BMV-712 has a relay, but I think is the only BMV that has a relay.
In the GX Range, both the Venus and the Cerbo have two relays, but only one is programmable. The way Victron word things, it is possible that the OS might be updated to make the 2nd Relay programmable as well in the future (I don't think it is a hardware limitation, but can't be sure).
I can see a use - and could use myself - a greater number of relays for sure.

With your approach, it looks like you could latch a whole bunch of different signals on a GPIO output and use them to drive a set of relays?
I have a board like this - https://amzn.to/3r1mClh - but not utilized it as yet (bought it a while ago and I think I was going to do something to do with Alexa Voice controls if I recall?)

 

[xsilvergs]

You are spot on with the relay comment.
The BMV-712 has a relay, but I think is the only BMV that has a relay.
In the GX Range, both the Venus and the Cerbo have two relays, but only one is programmable. The way Victron word things, it is possible that the OS might be updated to make the 2nd Relay programmable as well in the future (I don't think it is a hardware limitation, but can't be sure).
I can see a use - and could use myself - a greater number of relays for sure.

With your approach, it looks like you could latch a whole bunch of different signals on a GPIO output and use them to drive a set of relays?
I have a board like this - https://amzn.to/3r1mClh - but not utilized it as yet (bought it a while ago and I think I was going to do something to do with Alexa Voice controls if I recall?)

I bought some relay boards that trigger at 3.5v (gpio output level).

I've little experience with Alexa, ask her "what's my wife's name". There's that and Google something (I'll get there one day ).

 

[Nabsim]

That would be a good way to power immersions heater if I ever get round to wiring it in

 

[wildebus]

That would be a good way to power immersions heater if I ever get round to wiring it in

My plan is to have in the summer time the battery working the Water Heater (800W for around 10 minutes or so to heat the 10L) and to help with the Fridge part time (200W for around 75% of the time it is on).
Having it automated so I don't have to remember to disconnect it and drain down the batteries is essential with my memory!