In and out of Absorb

[Kameronk]

Running a classic 200 on a 48 volt system. I never get my 3 hours of absorb. Bulk works great to go from 90% SOC when the sun comes up to 100% then starting Absorb but then Kicks between float and absorb about every 3 minutes. I don't believe I am loading it with amps like it should be. SG levels are still a little low.

[boB]

Your batteries... How many amp-hours are your batteries ?     And how many watts (rating) is your solar array ?   Just to make sure you have enough PV for the battery size.

What are the loads on your inverter ?  Could there be appliances turning on and off like a refrigerator or air conditioner  that might be making it come out of Absorb ?

What kind of PV input voltages do you see ?   Open circuit voltage?  Voc ?

Do you have any partial shading ?  That can cause reduced output of course.

How much power or current output do you see when in Bulk-MPPT ?

boB

[Kameronk]

Thanks Bob, 385ah, 5k pv system, no shading. The in and out could relate to a fridge kicking on and off. I see that it goes into absorb when the fridge applys the 4 amp load. It goes back to float assuming when the fridge shuts off and I go back to a 1.2 amp load.

Pv volt in bulk run from 110 to 120v. Adding about/up to 20amps in bulk this time of year.

Home is in hibernation currently so there is minimal power use going on there which is why my loads are so low. Seems like it needs a load to stay in absorb?

[boB]

Well, if it has been working, maybe it's just the weather ?

If conditions were good, you should be getting over 75 amps or so battery side output.

boB

[Kameronk]

It is charging, I was just curious if kicking in and out of absorb like that was typical. From information I had read I was under the impression that I would bulk mppt up until I hit 100SOC and then it would absorb for my 3 hr time limit consistantly and then go to float.

[ClassicCrazy]

It is charging, I was just curious if kicking in and out of absorb like that was typical. From information I had read I was under the impression that I would bulk mppt up until I hit 100SOC and then it would absorb for my 3 hr time limit consistantly and then go to float.

It will be in bulk until it gets to Absorb voltage setting. Then it will go to Float after your Absorb time ( if you don't have ending amp set ) . The SOC does not do any controlling of the charging. If you have everything set correctly ( ah battery capacity, efficiency) , then usually the Absorb and 100% SOC happen about the same time. But once it goes to Float it resets the SOC to 100% even if it isn't at that yet.
Could it be that you have Rebulk setting at something that makes it go back to bulk charge again ?

Larry

[ClassicCrazy]

This explains how to set end amps.
I would verify with specific gravity reading for flooded lead acid batteries.
 https://www.midniteftp.com/support/kb/faq.php?id=113
Larry

[Kameronk]

Here is the screen shot from today's progress. I believe I left the ending amps at the default of
20 amps. I will have to review the rebulk voltage setting. I have it set to rebulk daily due to short sun hours this time of year. Seems to jump in and out of absorb in correlation with additional load from what I can tell. I believe it may be something in the settings though.

Thanks, I have read the end amps link but haven't performed that test.

[boB]

 20 amps ?  That seems awful high.   But it would go to Float.

20/384 would be 0.05 C (C being capacity)

But if it isn't going to float, then that's probably not it.

boB