Classic150 Temp Comp... not?

[LostInTheBog]

Edit: before you bother reading this, I think I may have found the culprit setting.
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I'm a relatively new Classic user, having replaced an Outback MX60 in a system with a VFX3524 inverter.

As far as I can tell, I have temperature compensation set up properly (sidebar: my new Stark batteries came with nothing more than a sell sheet for a manual; no product-specific temp comp guidelines).

Thing is I see no evidence that the Classic is actually adjusting charging voltages in relation to temperature. I can read battery temperature on the Classic and it seems correct, but while charging my bank (which is typically under the default reference 25 deg C in my Canadian winter) the Classic still seems to use the actual battery voltage during bulk charging rather than a suitably increased voltage.

I've been off-grid for going on 25 years now yet this makes me question my understanding of what is, vs. should, be going on.

I can view the VFX's idea of what the temperature-compensated voltage is through the Mate. I can see the WBJr's temp-adjusted capacity. But no apparent voltage adjustment is happening. It's as though despite the settings, compensation is disabled. Am I missing a setting?

I am presently only home on weekends with a long list of chores to complete before I have to bail out again. I am really concerned that I am chronically undercharging a brand-new bank.

When I feel like I fully understand all the temp stuff betwixt the Classic and the WBJr., I am going to put together a mini-manual on the subject. Sorry to say, as a former technical writer, the Classic manual looks like a rough draft IMHO. That said, the folks at "Stark" (whoever they actually are) don't seem to have made it that far yet. 

[ClassicCrazy]

Are you charging lithium or lead acid batteries ?
You don't want any temperature compensation on Lithium batteries.
For lead acid you need to put the -3 or -5 mv ( as per battery manufacturer)  in on the MNGP Charge / Tcomp setting screen .
For lithium it would be 0
Larry

[ClassicCrazy]

I recommend using the Local Status app from Midnite for changing settings ( though it has a few bugs not too many) .
For monitoring on Android I recommend Grahams Classic Monitor available on Playstore or github
https://github.com/ClassicDIY/ClassicMonitor
For remote monitoring Graham has a project that can send the Classic as mqtt to same Classic Monitor app without opening any ports.
https://github.com/ClassicDIY/ClassicMQTT
There are some other remote monitoring options too but involve leaving a  raspberry pi or linux based computer running.
Larry

[ClassicCrazy]

here are some other details on the Classic not in the manual
https://www.midniteftp.com/support/kb/faq.php?cid=1
Larry

[LostInTheBog]

Are you charging lithium or lead acid batteries ?

AGM LA. Thanks for asking.

One of the few useful things I got from my 6V battery "manual" (aka sell sheet) was a target absorb voltage of 7.3 to 7.4. I went up the middle with 7.35 V x 4 = 29.4 V for my 24 V system.

The culprit I finally found was in the Limits setup group of the Charge menu: Min T-comp and Max T-comp. The latter was set to 29.4 V. Insane coincidence that this was (presumably) limiting the voltage to exactly the uncompensated absorb target? Wild if so. Anyone know what the factory default is?

I want to see the next absorb cycle but that's all I will learn for this weekend. No sun tomorrow and I have to head back out. I think this has got to have been my problem (he says in optimistic past tense) since it absolutely fits the symptom.

The manual doesn't mention limits in the Battery Temperature introductory section. I have not been able to find (note I did not say "there isn't") mention of limits anywhere else in the text - only in the menu map. I missed it on the map too since it isn't part of the T-comp group. I only found it by interrogating the interface until it confessed. 

And of course I finally stumbled across this setting 2 minutes after posting out of desperation in this forum.

Appreciate your responses.

[ClassicCrazy]

Most agm batteries have pretty much the same settings from all that I have ever looked at. I would start at the lower end of the range for the new batteries, and then raise it up as they age. Or if you need to because of the cold.
You may also need to do a couple deep cycles on new batteries to get their full capacity . At least that was what they said on some lead crystal gel lead acid batteries I have.
Do you have a whizbang on your system ? If so you could use ending amps along with Absorb Time so that if the current drops first before a longer absorb time it will stop absorb.
What efficiency do you have set for it ? That is mainly going to be reflected in the SOC calculation ( if you have the whizbang) and it won't effect charging.
Look up East Penn Deka for their solar agm recommendations if you can't find any from  your manufacturer.
Usually the charge defaults go to something that is low enough that no one would cook their batteries if they didn't know enough how to set them up properly.
Larry

[LostInTheBog]

Thanks again, all very valuable info. I will check our those resources. Just having a bite here and then back out to push snow.

1. Yes on WBJr.

2. Initially had efficiency at 90 and then read something (in Classic manual?) that suggested 80. That surprised me, but I adopted it. Again, no OEM data, so I figured it would be safer to err on the low side.

3. I want very much to use ending amps, but again, I only have an estimated value from the Classic manual to go on. Is there a test methodology? I've never seen mention of one.

I knew when I decided to go with sealed batteries that I would miss being able to use a hydrometer. And I have two very nice ones...

4. Considering that the Classic's default bulk voltage for a 24 V system is 28.6 V, 29.4 V seems like a plausible default for T-comp Max. I still think it would be pretty funny if the default happened to be my exact target uncompensated voltage.

[ClassicCrazy]

What I did to confirm ending amps is watch the whizbang and when it gets close to 100% then the current should start dropping and sort of hold at a certain point. Of course this depends on the efficiency that you put in on how long it will take to get to absorb .
I think that there is something about ending amps in the knowledge base link.
Larry