Author Topic: Amp reading discrepancy on a system with no load  (Read 426 times)

Muskoka

  • Jr. Member
  • **
  • Posts: 61
Re: Amp reading discrepancy on a system with no load
« Reply #15 on: March 19, 2020, 08:54:25 AM »
I've looked everywhere, and can't find my backups. Brain not getting any younger, but I'm pretty sure it was 2096 (?), number sticks in my head. I was trying to think of a way to verify that, and thought I might be able to see what firmware version I was running at a given point in time in mymidnite, seems to only show the current version.

Is there a log in the controller I can read to get that information, firmware version at a point in time?

Thank you.....

Glen
Off grid - 24v System - Deka 6v 370ah L16's - Classic Lite 150 wBjr - 1540w solar - Honda / Firman generators

Vic

  • Hero Member
  • *****
  • Posts: 2227
Re: Amp reading discrepancy on a system with no load
« Reply #16 on: March 19, 2020, 12:12:54 PM »
I've noticed the net amp hour reading from the wbjr is incorrect, on a idle system, and under load.



I
I noticed it when I had a known load on my system, my tv, a light, and internet, and it was showing too high an amp draw, I knew it didn't look right. So I shut the whole system down, and the controller is showing a -3.8(9)amp draw,  when the clamp meters are showing less than 1 amp.

   …   Shouldn't the wbjr and clamp meters amps read the same, or at least close?

This system was recently changed to 24 volts. The system ran for years at 12v, and I know from years of monitoring that my tv, internet, and light draw around 105w, or in around 8ish amps, and is what the wbjr would show, and was verified with a energy meter.

Well now on 24v the same tv, internet, and light show a draw of 145w, impossible. System voltage is currently 25.3v, and amp draw is showing 5.7a. If the system was drawing 105w at 12v, like it has for at least 5 years, it should still be showing 105w at 24v, yet it isn't, it's now 145w.

Here is an additional thought:

The Buck converter is not 100% efficient.   And this efficiency will probably vary,   based on the amount of current that it is supplying to the load,  on it. This will show up as additional current that needs to be supplied by the 24 V battery.


AND,   had mentioned this before:

Just to try to be clear,   Net Ah,  as shown on the MNGP Wb Status page,  it the total Ah accumulated,  plus,  minus,  or zero.  This is not a real-time instantaneous value  --  it is accumulated,  since the last reset to zero (from the last time that the Classic transitioned to Float,  on its own).   You know this,   but  just trying to make sure.  The Graham App calls this something a bit different,   but just make sure that you are looking at the correct display item when looking for present value current to/from the battery.

FWIW,  just trying to be clear,  and not insult you,   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

FNG

  • Administrator
  • Sr. Member
  • *****
  • Posts: 254
Re: Amp reading discrepancy on a system with no load
« Reply #17 on: March 19, 2020, 12:32:32 PM »
I've looked everywhere, and can't find my backups. Brain not getting any younger, but I'm pretty sure it was 2096 (?), number sticks in my head. I was trying to think of a way to verify that, and thought I might be able to see what firmware version I was running at a given point in time in mymidnite, seems to only show the current version.

Is there a log in the controller I can read to get that information, firmware version at a point in time?

Thank you.....

Glen

Here you go:

http://kb1uas.com/Hemlock57/Classic%20Programmer2096.zip

Muskoka

  • Jr. Member
  • **
  • Posts: 61
Re: Amp reading discrepancy on a system with no load
« Reply #18 on: March 19, 2020, 03:20:53 PM »
Thank you.
Off grid - 24v System - Deka 6v 370ah L16's - Classic Lite 150 wBjr - 1540w solar - Honda / Firman generators

Muskoka

  • Jr. Member
  • **
  • Posts: 61
Re: Amp reading discrepancy on a system with no load
« Reply #19 on: March 20, 2020, 11:52:58 AM »
Well, that was an exercise in frustration. ???

The controller flashed no problem, the mngp was another story. There's enough history here about flashing issues over the years, so I won't expand on that. After multiple attempts, trying different things I gave up. Flashed the latest firmware back to the controller, and mngp, without issue.

This morning was not a solar day, so I decided to strip the system down, completely, then add back one item at a time.

It appears the Trimetric is the problem, although I had isolated it before, and really didn't see any change. Now, with just the controller connected to the battery bank, everything else disconnected, not just breakers off, wires/cables removed, the idle system current draw is down to -1.3a with just the controller on.

If I then connect the Trimetric, that shoots up to -3.1a on the Wbjr screen on the controller. The working current draw of the Trimetric is 30ma, so something has gone awry. Voltage is still showing correct. That -1.8a draw is close to exactly the increase I see in wattage since changing the system to 24v. It also accounts for some of the negative net ah increase I see overnight.

The buck converter added -.1a when I connected it, Wbjr display went from -1.3a to -1.4a.

The series connections (3) on the batteries read -0.13a, -0.10a, and -0.16a, with my clamp meter, seems fine to me? The cable from the positive busbar to the bank reads -0.13a, and the cable from the last battery negative to the shunt reads -0.33a, again, looks fine to me?

I've sent Bogart a email to see what can be done.

Thank you everyone for the help, and your input.

Glen
« Last Edit: March 20, 2020, 12:55:39 PM by Muskoka »
Off grid - 24v System - Deka 6v 370ah L16's - Classic Lite 150 wBjr - 1540w solar - Honda / Firman generators

boB

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3163
Re: Amp reading discrepancy on a system with no load
« Reply #20 on: March 20, 2020, 07:07:42 PM »
I may have missed it but did you try measuring the shunt sense terminal screws with a Flue meter or similar good meter ?

K7IQ

Vic

  • Hero Member
  • *****
  • Posts: 2227
Re: Amp reading discrepancy on a system with no load
« Reply #21 on: March 20, 2020, 07:36:35 PM »
Hi Glen,

Thank You for reporting-in.

SO many times,  when a Poster's problems get resolved,   we get NO feedback.

As,  we all are learning,  closing the loop can benefit many.

Many DC Clamp Ammeters are not that accurate or repeatable,   but they still can give a general indication.

Thank YOU   for the report !   Good Luck,   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!