Can anyone shed some light on my victron readings?

[Danjwilko]

Hi all, been a little while anyway I’ve been running my small setup for most of this year and has been running a treat. It’s a 24v off grid system so no mains tie in etc.

I’ve had to take down my panels due to bad weather so had the solar side disconnected but kept the system powered on to keep tabs on the batteries via the shunt etc and minimal charging for phones etc.

I’ve reconnected the system this morning and everything working fine. However I’ve always had the input wattage and amps tally up with the whats being drawn until today and it’s baffling me as why it’s now different.

Roughly speaking 200w coming in, 200w being drawn has lead to 0.00 amps going into the battery.

Today I’ve got ~ 200w coming in and 285w being drawn yet the shunt is reading +1amp going into the battery so I am assuming the shunt is having a mare?

Any suggestions or anything I’ve missed?
Cheers all.

 

[Supervstech]

I can't help you on the readings, but I'm curious of the idoms you're using.

It's been running a treat makes sense, but I've never heard it before.

Shunt is having a mare?

Can you explain that one?

Also, what part of the world are you in?

Thanks!

 

[SamDeleted]

Very confusing?

First of all that 286w on the inverter is the AC load , not the DC draw , so with efficiency it's more likely to be 300-320w draw DC

Stupid question... but is the shunt the right way round ?



The next step in my mind would be to drain the battery to eg. 50% , and then let the mppt recharge , observe results

 

[SamDeleted]

Also, what part of the world are you in?

Seems like UK, I'd think maybe Scotland , or certainly northern

 

[Supervstech]

Well, the mppt is outputting 7.8A, the load is around 10 so the battery is supplementing 1.1ish amps...

 

[Danjwilko]

I can't help you on the readings, but I'm curious of the idoms you're using.

It's been running a treat makes sense, but I've never heard it before.

Shunt is having a mare?

Can you explain that one?

Also, what part of the world are you in?

Thanks!

Haha no worries, I’m UK based more specifically Lincolnshire for most of my life, however I’ve been all over the UK and worked with people from varying backgrounds so will have more than likely picked up a few things along the way.

Shunt having a mare - short for the word nightmare, so shunt being awkward or not working correctly giving me a headache ? hope that helps.

 

[SamDeleted]

1.1ish amps

So shouldn't the shunt show -1.1amps ?

 

[SamDeleted]

I’m UK based more specifically Lincolnshire

Hello from Grimsby ?

 

[Danjwilko]

Very confusing?

First of all that 286w on the inverter is the AC load , not the DC draw , so with efficiency it's more likely to be 300-320w draw DC

Stupid question... but is the shunt the right way round ?



The next step in my mind would be to drain the battery to eg. 50% , and then let the mppt recharge , observe results

That’s what I thought, I normally only have a fridge/freezer and a few other smaller lids hooked up, I only had the dehumidifier plugged in at that point.

And no the shunt is the correct way round. Always read correct until today so I’ve removed the variable - dehumidifier.
Which unplugging and just running the fridge/freezer we’re back to normal.


Load 94w, input ~100 amps going into battery almost zero.

So seems the dehumidifier draw is a bit off mind you it states VA if I select the inverter however on the quick stats screen displays the draw as watts.

 

[Danjwilko]

Hello from Grimsby ?

Hello from Skegness (actually classed as Thorpe St Peter but nobody knows where that is )?

 

[SamDeleted]

Hello from Skegness (actually classed as Thorpe St Peter but nobody knows where that is )?

Ah skeggy, Blackpool of the east , spent a good bit of time as a kid at jinglebells market

But mostly was up maybo cause it's cheaper ! ?

 

[CoolWill]

Haha no worries, I’m UK based more specifically Lincolnshire for most of my life, however I’ve been all over the UK and worked with people from varying backgrounds so will have more than likely picked up a few things along the way.

Shunt having a mare - short for the word nightmare, so shunt being awkward or not working correctly giving me a headache ? hope that helps.

Ah Lincolnshire, home of Isaac Newton. I'm sure you'll have no problem figuring it out in that case. Do they still grow apples there?

 

[Supervstech]

So shouldn't the shunt show -1.1amps ?

That would imply the battery was drawing amps, in this scenario, the battery is discharging amps.

Wouldn’t it?

I don’t use a shunt much yet… so, I am unfamiliar with how they should display.

 

[Danjwilko]

So think I’ve figured it out, the victron quick stats list the value of w rather than va which is what it should be (don’t know why).

Anyway depending on the load type either inductive or reactive depends on the power factor which we can convert the va to watts usually ~1 for reactive and around 0.8 for inductive.

As the dehumidifier is a compressor it is an inductive load and has the lower power value as mentioned ~0.8 (could be a little less on calculation).

So converting the VA to watts based on the value from the inverter:
280va x 0.8pf gives us 224 watts.

Therefore looks like the shunt is correct, as if an appliance is of the inductive type and 0.8 or lower power factor then the shunt would show more power going into the battery as it’s not indicating watts but VA. Why they switch units w and va with the same value is beyond me.

At least I’ve got to the bottom of it. Hope it helps anyone else with the same question ?.