amp discrepancy ?

arby

Battery bank in float mode, inverter and all loads turned off,
 trimetric shows .4 amps going in, midnite classic 200 showing 1.6 amps going in.
 Out of curiosity I wonder why the difference?
 

Photowhit

Is the breaker off to the inverter?

arby

The inverter is turned off and the main breaker into the cottage is turned off as an extra measure.

littleharbor2

What size and length wire from the controller to the shunt? Are all connections sound, low resistance? Do you have a breaker between the CC and Battery?

westbranch

have you re-torqued all the connections since assembly?  It needs to be done annually...

Photowhit

arby said:

The inverter is turned off and the main breaker into the cottage is turned off as an extra measure.

If it is not disconnected from the battery (breaker off) it might still be using some energy. You are trying to track down a pretty small amount of energy @50 watts, it may still be in some sort of idle mode even off while connected, likely only 8-10 watts, but you aren't hunting for a huge amount.

If you don't have the Whiz Bang Jr attached, some of it might be energy consumed by the charge controller since the shunt the Midnite sees would be internal. I think they use @5 watts... but recall they are higher than other charge controllers.

Estragon

@arby
My trimetrics seem to show some sort of phantom load as well, even with all breakers off. It's on my to-do list to figure out this summer so would be interested if you figure it out first.

arby

"If you don't have the Whiz Bang Jr attached, some of it might be energy consumed by the charge controller since the shunt the Midnite sees would be internal. I think they use @5 watts... but recall they are higher than other charge controllers."

 Yes I was reading the Whiz Bang. I guessed that maybe the CC was using the extra amps.

Estragon

Mine are out by ~1a as well, and controller at <5w wouldn't account for all of it. My guess is it's a setting or calibration thing with the trimetric, but only a guess. A bit of a mystery to solve at some point.

I do have a problem with CC self consumption as my panels have been had snow cover problems over the last two winters, and logged data is consistent with self consumption of 3-4w on controllers. I'm going to address that by adding winter oriented panels on PWM cotrollers and likely turning off Classics.

arby

Well, I was impressed that it was only taking .4 amps to keep the 400 amp hour bank floating at about a temperature adjusted 58 volts. It was very cold and sunny that day and I hadn't turned the system on for two weeks. Stayed at my friend's cottage across the lake. Even at the  whiz bang's 1.6 amps I was impressed.

boB

When you see this happen at low amps like this, try turning the Classic off and back on again or better, go into the MODE menu and turn the mode off and back on.  See if that makes it come back in line with the Trimetric and/or WB Jr. in case drift was a problem

The current sense in the Classic is very good but it's not perfect and has to be adjusted carefully at the factory...  Also, battery current should be a wee more accurate than input PV current.

The  internal shunts look at the positive lines where the Trimetric and WB Jr. measures at the negative line into the battery - terminal.

FYI, the common negative line from the Classic terminal, if only one single wire is used to tie to battery negative/common, will show difference between input and output current of the Classic, so just be aware of that.  That isn't a problem with the common shunt to battery minus though because the everything else is tied at the battery minus bus.

There IS an adjustment pot accessible but I wouldn't touch that one just yet.

boB

arby

Nice, Thanks. Will do that next time I'm up at the cottage.