Activation/Setup of Temperature Compensation?

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Activation/Setup of Temperature Compensation?

Postby Stringpark on Wed Nov 07, 2018 8:47 am

Hello,

I have a GS4048A with AXS Port and two RTSs (one plugged in to the Radian and one one for the AXS Port). I have verified that I am running the latest firmware on both the Radian and AXS Port, yet I do not see any controls for temperature compensation anywhere within OpticsRE. On the GS4048A Status page, there is a "Temperature Compensated Target Voltage" that always reads exactly the same as the voltage setting for whatever charging mode I happen to be in. If temperature compensation was working, I would expect this field to show a target value a bit higher than the setting of the current charge mode (as the battery temperature is around 40-50°F right now). Incidentally, the GS4048A Status page does show a reading for the Battery Temperature.

Can anyone provide some guidance?

Thanks!
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Re: Activation/Setup of Temperature Compensation?

Postby Kurt Lundquist on Wed Nov 07, 2018 8:53 am

What is the battery temperature?

-Kurt
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Re: Activation/Setup of Temperature Compensation?

Postby Stringpark on Wed Nov 07, 2018 9:51 am

At the moment it is reading 51.8°F.
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Re: Activation/Setup of Temperature Compensation?

Postby Kurt Lundquist on Wed Nov 07, 2018 10:14 am

The inverter does not have temp comp controls to turn on. The presence of the RTS turns on the temp comp charging.

51.8 = 11°C.

25-11 = 14 degrees.

Compensation slope for 48V battery is 0.12V/°C.

14 x .12 = 1.68V. I would expect your charge target voltage to be ~1.68V higher than the programmed target voltage.

Is the inverter plugged into Port 1 of the Hub?

What is your OpticsRE profile?

Pages 34-35 of the Radian Operator's Manual has more details.

-Kurt
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Re: Activation/Setup of Temperature Compensation?

Postby Stringpark on Wed Nov 07, 2018 10:44 am

Kurt,

I don’t have a hub, so the AXS Port is plugged directly into the Remote port on the inverter and the RTS is plugged directly into the battery temp port.

My profile name is Joe Cooper

Thanks!
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Re: Activation/Setup of Temperature Compensation?

Postby Mike Curran on Wed Nov 07, 2018 10:59 am

I've always found that terminology ("temperature compensated target voltage) confusing. This thread: viewtopic.php?f=15&t=12908&hilit=+Target is an earlier post that might help clear it up for you, but I think the best way to understand this particular data point is to totally ignore the word "target" - it's simply the temperature compensated voltage, NOT the actual voltage you would read with a voltmeter, and not some theoretical "target" the inverter and/or charge controllers are shooting for.

In this screenshot you can see my inverter is measuring (actual) battery voltage as 27.4 volts, and TC target voltage as 27.0 volts:
Screenshot_20181107-125051.jpg
Hope this helps...
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Re: Activation/Setup of Temperature Compensation?

Postby Stringpark on Wed Nov 07, 2018 11:42 am

Thanks Mike, that's good to know! So basically, I should be looking for the "Temperature Compensated Target Voltage" field to factor the appropriate offset amount in the opposite direction than what I was originally thinking. Good info for sure!

However, in my case the "TCTV" value exactly mirrors the "Battery Voltage" value (the row just above it on the Status page). Now having said that, I should mention that I didn't describe the behavior the TCTV field very well in my original post, where I said it mirrored the voltage setting of whatever charge mode I was in. That's true once the batteries reach that level, but it's more accurate to say that the TCTV value exactly mirrors the "Battery Voltage" value. So it would seem that no offset is being applied by Temperature Compensation at the moment.
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Re: Activation/Setup of Temperature Compensation?

Postby Kurt Lundquist on Wed Nov 07, 2018 11:46 am

Hi Stringpark,

I agree it appears that your system is not using the temp compensated targets. It shouldn't make a difference but you could try pulling out the RTS from the AXS Port to eliminate that as part of the issue. Other than that you could force a bulk charge from OpticsRE, then disconnect the AXS Port from the inverter. Use a volt-meter to check battery voltage to see if it is at your 56.8V Absorb voltage or hitting a higher target voltage. As a backup system, your battery stays above 50V most of the time so the system may not hold the Absorb voltage for very long. Float is also temperature compensated so if you see a steady 54.4V then you know the inverter isn't charging per the temperature compensated voltage.

I asked the OutBack support team and they have not seen similar behavior in the past but a single inverter/AXS Port system is not very common.

-Kurt
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Re: Activation/Setup of Temperature Compensation?

Postby Stringpark on Wed Nov 07, 2018 12:15 pm

Thanks for the help Kurt! I'll try those steps when I get home and report back with the results.
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Re: Activation/Setup of Temperature Compensation?

Postby Stringpark on Thu Nov 08, 2018 6:31 am

Great call Kurt! I tested both absorb and float charge modes and both times when I disconnected the AXS Port from the Radian, the voltage across the string increased about 1.2V after a short delay of several seconds. Incidentally, disconnecting the RTS from the AXS Port had no effect. So, do you think its safe to say at this point that the issue has been narrowed down to either something within the AXS Port settings, or possibly even a compatibility issue with a single Radian/AXS Port configuration (hopefully not the latter)?
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Re: Activation/Setup of Temperature Compensation?

Postby Kurt Lundquist on Thu Nov 08, 2018 8:40 am

Thanks for the follow-up. I've let the OutBack team know about the issue. In the meantime, I suggest you consider bumping up your Absorb/Float voltage targets a bit if your battery bank is consistently around 50° this time of year. I have a small backup system similar to your setup and I do not have an RTS installed right now. When it is hot out I set the targets lower, when it is cold I set the targets higher.

-Kurt
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Re: Activation/Setup of Temperature Compensation?

Postby Mike Curran on Thu Nov 08, 2018 9:09 am

Kurt Lundquist wrote:When it is hot out I set the targets lower, when it is cold I set the targets higher.

Hey Kurt - Had to comment on this - I do have an RTS but I still have to do what you're doing to insure proper float voltage is maintained, as the seasons change. With my grid-tied system, my sell voltage setting also controls the battery float status, and since sell voltage is not temperature compensated, I have to adjust it as you do. It's usually only a one time adjustment though, as in colder months my battery box is heated, but only to 60°F (15°C). In the warmer months my battery stays at a relatively constant temperature above 60, as it's located in my garage. It's only during the transitions between warm and cold months that I have to mess with it.
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Mike Curran
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Posts: 843
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: Activation/Setup of Temperature Compensation?

Postby Stringpark on Thu Nov 08, 2018 10:01 am

Thank you both! I’ll make the temporary changes and will be eager to hear what the outback team comes back with.

Thx!
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