Battery voltage offset issue

[Muskoka]

Using the latest beta 0.3.24 and having an issue with the battery voltage offset setting. My batteries currently measure 14.7v. The status panel says 14.4v. If I raise the offset .3v and write the data to the controller the status panel then says 15.0v. Maybe I'm not understanding how it works, but if my batteries measure 14.7v, the panel says 14.4v, and I raise the offset .3v it should then show my actual battery voltage, not 3/10's higher? I've been watching it all day, it's been repeatable at multiple voltages.

Classic Lite 150 firmware 1370

Glen

[TomW]

Glen;

Not sure if it is relevant but there is a known issue with the readings on either end of the voltage range being on at one end and off on the other.


I use a voltmeter on the batteries to set mine and it seems to track fairly well.

I do it from the Local Application and with a lite that is probably the only option?

Good Luck with it.

Tom

[Muskoka]

Hi Tom,

I'm measuring voltage directly at the batteries. That's what I'm trying to get "co-ordinated". I have a Trimetric and 2 Morningstar controllers that all read the same (within a few 100ths) and I don't have any issues with their "charge stages", ie. going to float. I have set the Classic with the same charge parameters as the Morningstars and the Classic is going to float too early, no wonder if the voltage is off 3/10's. What "voltage/value" is the controller using for the setpoints, so I can get these 3 controllers to play nice together.

Glen

[TomW]

Glen;

This might be a silly question but when you set the offset in the Local App do you click the little blue arrow to save it?

In the beginning that got me a couple times.

Tom

[Muskoka]

Ya, that's how I noticed the strange? behaviour. I measured the batteries, 14.7v, the status panel (software) said 14.4v, I changed the offset so it read 14.7v to match the actual batteries, hit the blue arrow to write to the controller, then immediately noticed the panel now said 15.0v. The other controllers are right there so I can verify the voltage quickly, they still said 14.7v as did the Trimetric.

Glen

[Muskoka]

Here's a screen shot of the issue. Actual battery voltage is 12.7v. The dash board says 12.5. I adjusted the offset by .2v and as you can see to the right it shows the correct voltage, 12.7v. The dash board is not reflecting the offset voltage. Is the system using the offset voltage for charging set points because the controller is reading low?


Glen

[TomW]

Curious.

I was going to ask if the MNGP showed the correct voltage but a Lite does not have one.

Is it just a Local App display issue? In other words does the Classic trigger on the voltage displayed or the offset voltage you set? A simple test would be to set the aux1 to activate at X volts and see if it turns on  at the offset value or the display value?

If that makes sense.

Actually, I just looked and my Classic 150 is the same. The voltage in the offset menu pane is .1 lower than the Local App gage. I have not seen any issues with mine but and it seems to trigger aux1 as expected. Now I guess I am wondering what is up here?

Maybe boB or Ryan will chime in on this. I am just not very experienced in the inner workings of the Classic.

Tom

[boB]

Well, if the Classic is ~almost~ at the point of Absorb or Float stage and the voltage is off some
when the Classic is putting out current, the voltage drop across your charging cable might
go down when you adjust the offset because the Classic goes into voltage regulation
mode....  Maybe that's it but maybe not.

Something interesting (and kind of weird) to see is when the Classic is actually in
voltage regulation mode, (Absorb, Float, EQ) and you adjust the battery voltage
offset in the Classic, you will notice the Classic voltage reading will stay the
same BUT the actual voltage measured with a volt-meter will be different.
That is because the Classic has a preset charge voltage set-point and when
you adjust the offset, it just regulates to the voltage that it THINKS is that
regulation voltage.

This is something you just have to try to see what I am talking about.

It is somewhat weird and counter intuitive until you see it happen.

boB

[Muskoka]

Thanks for the responses guys...

So, from what I think your saying Bob, the Classic uses the "offset" voltage for charging setpoint, not what is displayed on the dashboard / software. I just need to know which value the controller is using so I can get things co-ordinated between the 3 controllers.

In other words the "true" battery voltage for setting "setpoints" is the offset voltage, not what is displayed in Local App? This can  be mis-leading and cause confusion, especially when at times it's 3/10's of a volt difference. Yes, voltage drop could be an issue, but I don't have any measurable. My batteries are 18" from the controllers with 4awg wire. If there was any voltage drop it would be a couple of 100th's at most, not 10's of a volt. I use a "higher end" clamp DVM for all readings.

Glen

Edit: Nice and sunny today. Everything seems to be working fine and all three controllers went to float within 10 minutes of each other, very nice. It's definitely using the "offset" voltage for the setpoints and not what's displayed on the Local App screen. Is there any way to get the Local App to display the "offset" voltage?

[Westbranch]

Glen, tell us more about your 3 CC's (in the sig line) please. I assume they are not Classics in Follow me mode...