Strange behavior

[offgridQLD]

Thanks for that picture Bob.

At least I know a little more about what might be happening and how to adjust it if need be. The likelihood of my two shunts both being wrong and by the same amount is slim. So I am reasonably confident . That said I will do some more tests tomorrow  Using a 3rd shunt reader just to be 110% sure before tweaking the pot.

Thanks

Kurt

[Halfcrazy]

The part that confuses me though was the first issue was the Classic was reading to low? I would probably get an eyeball on it over a period of time before tweaking to much.

Ryan

[offgridQLD]

Yes that was just on Friday It was a oddball day when it pumped out only 30w for most of its time on float and its a mystery that one. I wasn't at the house to see things live. Just using the remote app.

What I have always noticed is the classic showing more amps going into the battery than what the inverters shunt 1 reads. It wasn't until today that I took the time to add a 2nd shunt to see which was out.

Kurt

[Vern Faulkner]

If you guys don't get praised for hands-on customer service, you should.

[boB]

If you guys don't get praised for hands-on customer service, you should.

Thank you Vern !

This particular problem isn't all that big of a deal but it could be some family freezing in
the cold on a weekend and we try not to let something like that happen if at all possible.

[Halfcrazy]

I am still a little boggled here. If I am doing the math correctly I am showing the 1300 AH battery is using 1.2 Amps to maintain Float voltage? This seems to low? Where you measuring current flow on the battery positive leaving the classic with that shunt?

Ryan

[offgridQLD]

I am still a little boggled here. If I am doing the math correctly I am showing the 1300 AH battery is using 1.2 Amps to maintain Float voltage? This seems to low? Where you measuring current flow on the battery positive leaving the classic with that shunt?

Ryan

Yes that's what it boils down to when you subtract the loads.

To be honest I'm not sure what to make of my complete system when it comes to making any logical sense from the data.  I haven't made any changes to the trim pot to adjust the live amp reading of the classic to line up with what my inverter and test shunt are showing.

The reason for that being.  I checked the total DC KWh logged by the  inverters shunt 1 for Sunday .The number lined up perfectly with the classics output for the day 11.4kw and wouldn't you know 11.4kw on the inverter So it got me thinking they where both recording the same total DC kwh numbers for the day but just off in how they displayed the amps  live on the screen. (that wouldn't be a issue to me as its the 24hr totals that are important to me)

The only issue is when I checked back on the past week the totals for each day don't line up between the inverter and classic (but Sunday did spot on) So its all a bit of a mess. I wish I could make some sense of it all as it makes establishing reliable patterns difficult.


To recap on why i am trying to  establish what is doing what each day. All stems from me trying to work out  AC KWH consumed each day VS DC KWH needed to cover that load each day .This is when I picked up on a few odd behaviors like one week day where the battery floated at just 30w and the discrepancy between the live Amp reading on the classic and my inverters shunt monitor.

What I can confirm 110% is that weekdays when I'm not there the house consumes 2kwh AC (confirmed on my inverters logs and the homes analog kwh meter) This is a very stable number that hasn't changes in the 60 weeks we have owned the house and doesn't change more than 2 or 3% from one day to the next.

The strange thing is the DC KWH the classic feeds the battery's each day can range from just 4kwh to as high as 7.5kwh DC to cover this load. (we always have more sun then we know what to do with so the fluctuation is not due to weather variation). So Why the variation and why so much more DC kwh in that AC kwh consumed where my initial questions?

After some research I came to the conclusion that because I have 63kwh 1330ah at 48v of battery and my loads are so small weekdays that the battery spends all its time in the 95% - 100 SOC range and this is a very inefficient range to charge in - most likely around 50% efficient or less. Along with 4000w of PV and a ton of sun the battery's spend most of the day on float . Now this would explain the need to pump so much more dc KWh in than I take out in AC.

What it doesn't explain is why I get so much variation each day in what the classic puts in to replenish the battery's even though the loads for 5 days of the week are identical. I should see reasonably consistent recharge pattern Monday to Friday as I have repetitive and consistent loads.

So even if I ignore all my components and just trust what the classic is telling me the classic its showing different KWH charge totals each day(and different by a big margin) yet it has a consistent load each day.

It's this condition that's got me digging around for answers.



Kurt

 

[Halfcrazy]

Kurt
I suspect the variations are just the amount of Float time etc. Maybe it was sunnier the larger days. I would expect a 1330 AH battery to suck down several Amps just to maintian float voltage.

So back to the readings and the shunt. In your video the Classic is it wired to the dc box with 3 wires or 4? Basically is there a common negative running back to the DC box and the PV- is landed in the box?

Also Where was the shunt connected in that video Classics Battery positive?

I am still suspecting the issue is a differential current from Common DC negatives as the numbers start to add up for me when I do that. The PV was at like 77 volts so the differential voltage would be 25 volts and the controller was showing 6 amps on your shunt so half that is 3 for a total of close to 9 amps so maybe it is still just the placement of the 2 external shunts you have?

Ryan

[offgridQLD]

I will go over the wiring this weekend and draw up a little sketch of how all the shunts were connected. To see if there is something I am overlooking in how they are wired.

Regarding last Fridays (strange behavior) I forgot that I actually recorded a small video last Friday when my battery's were on float for several hrs.

As I mentioned earlier in this thread it was very strange as they were only taking around 30w (as displayed on the remote app live view) to hold float voltage (55v) and cover base loads as mentioned before around 60w AC + the power necessary to just run the inverter. It was strange as usually find it takes a good 100 - 130w to cover this and maintain float voltage and 200- 230w when the refrigerator cycles.

Have a look at the video and you can see why on Friday I was thinking something strange is going on as its only taking 30w and it continued to do this for several hrs until the sun went down. It would jump up to 130w for  15 min or so when the refrigerator cycled and then drop straight back to 30w for 1/2hr to 1hr or so until the fridge cycled again . Its just not enough wattage to cover 1330ah - 48v of battery at float + my AC base loads.

video link
http://www.youtube.com/watch?feature=player_detailpage&v=wFiRUEiQQrA

Kurt

[boB]

Kurt, I can't read the display in that video.

What kind of inverter is it that you have again ?

Does that kW-Hour reading from the inverter only cover the
DC amps and volts from its battery shunt ?  It doesn't
include its AC kW-Hour readings ?

boB

[offgridQLD]

Sorry it was a video of my laptop screen yes its hard to see but you can just make out its feeding around 30w to my battery.

My inverter is a 6000w/48v selectronics PS1 inverter /charger. The Kwh AC reading (its a separate reading in the inverters menu) This gives me the KWh AC what the inverter has produced in to the house sub board (confirmed by also reading the homes analog AC kwh meter) Both  showing 2kwh AC each day + - a few % very consistent. So I trust this is my actual AC kwh consumption as sounds corect for the loads I have weekdays and the inverter and analog kwh meter agree,

I have taken this clear video to  show how the inverter DC  shunt 1 reads battery amps, consumed amps and total dc amps into the inverters shunt.

http://www.youtube.com/watch?v=z1MIa05aWD4&feature=player_detailpage

Kurt

[Halfcrazy]

I will go over the wiring this weekend and draw up a little sketch of how all the shunts were connected. To see if there is something I am overlooking in how they are wired.

Regarding last Fridays (strange behavior) I forgot that I actually recorded a small video last Friday when my battery's were on float for several hrs.

As I mentioned earlier in this thread it was very strange as they were only taking around 30w (as displayed on the remote app live view) to hold float voltage (55v) and cover base loads as mentioned before around 60w AC + the power necessary to just run the inverter. It was strange as usually find it takes a good 100 - 130w to cover this and maintain float voltage and 200- 230w when the refrigerator cycles.

Have a look at the video and you can see why on Friday I was thinking something strange is going on as its only taking 30w and it continued to do this for several hrs until the sun went down. It would jump up to 130w for  15 min or so when the refrigerator cycled and then drop straight back to 30w for 1/2hr to 1hr or so until the fridge cycled again . Its just not enough wattage to cover 1330ah - 48v of battery at float + my AC base loads.

video link
http://www.youtube.com/watch?feature=player_detailpage&v=wFiRUEiQQrA

Kurt

Kurt
A wiring diagram would be super. It will help us assure the Shunts are reading what we think they are reading.

Ryan