Classic / Kid Boost mode : Stealing from the XW MPPT 60

[ChrisOlson]

The main advantage I've seen here with three-stage charging (bulk/absorb/finish) is that once the battery reaches gassing voltage (absorb stage), limiting the amps to the battery during the first part of it cuts water use and keeps the battery's temperature down.  It still needs the higher voltage to properly desulfate it, and that's what the finish stage does.  The overall charging time is longer using three-stage.  But it's more efficient.  Our cycle efficiency is in the 92-93% range with three stage charging (according to the TriMetric).  With just regular bulk/absorb charging the cycle efficiency is around 88%.

[zoneblue]

ChrisO, can you say more about why adapting auto EQ didnt work? If the "finish" stage was just timed, i would have thought it would work. I know that manual EQ doest wait for absorb to finish, and i do find that strange aswell.

[boB]

ChrisO, can you say more about why adapting auto EQ didnt work? If the "finish" stage was just timed, i would have thought it would work. I know that manual EQ doest wait for absorb to finish, and i do find that strange aswell.

It's probably because EQ always goes to Float if it ends when the timer expires.  It may have done what he
wanted if instead of going to Float, it would go to Absorb first for its time or ending amps.

That may happen eventually, which might be a decent work-around as long as it can do it every so often instead of havint to happen every single day.  OR, happen below a preset SOC% maybe.

[ChrisOlson]

ChrisO, can you say more about why adapting auto EQ didnt work? If the "finish" stage was just timed, i would have thought it would work. I know that manual EQ doest wait for absorb to finish, and i do find that strange aswell.

boB, what it did for me was that when the auto EQ activated it would not absorb the battery first, but instead it just kept charging at full power until the EQ voltage was reached, totally skipping the absorb stage.  So it wouldn't actually do a two-stage absorb (or absorb/finish) like I wanted it to.  The only way I could get it to work was to sort of monitor it and when absorb was getting close to done, then manually force the EQ.

The result using the auto EQ was that the battery was at way too high of voltage for its SOC so it got hot from taking on too many amps, as it wasn't absorbed yet.

I haven't tried it now for about a year because after we put in the XW system here we got XW controllers to go with our system.  And the Classics only do wind now.  So maybe this was all changed in later firmware?  If the Classic can absorb to 2% C/20, and when it exits absorb have auto EQ kick in with the EQ voltage set to the proper finish voltage recommend for a three-stage charge profile, the Classic is already capable of three-stage (bulk/absorb/finish) charging.  Just set the EQ timer for what the battery needs for finish charge.  That's what I was trying to get to work a year ago.

One of the nice side effects about bulk/absorb/finish charging is that it eliminates periodic equalization charges because the higher voltage finish stage fully desulfates the battery and keeps it healthier.  No need to abuse your battery for long periods at high voltage doing EQ every month because the bulk/absorb/finish charging keeps the SG's (at least in our batteries) within 15-20 points between cells.

I gotta get me one of those Whizbang Jr and try this again.  The firmware updates for the Whizbang probably "fixed" a lot of the problems I had when I was experimenting with it (for one, end amps actually works properly with the Whizbang, which is a key factor).

[Resthome]

Not fixed yet Chris. I happened to try it the other day since I had never used it and was surprised to see it in EQ MPPT at 7am in the morning. So you are correct NO ABSORB stage with Auto Equalize.

[ChrisOlson]

Darn, that's what it did for me too.  I had Follow Me set up with one controller that initiated the auto EQ.  I was not around to watch it when it happened the first time, and caught it when the batteries were taking on 150 amps from two controllers at finish stage voltage.  So I halted the whole process and forced a bulk charge, and the battery was already up to 41C.

The second time I watched it and it totally skipped over the absorb stage again.  That's when I decided it don't work.

[Halfcrazy]

Hm I would think you would want it that way so the battery gets to EQ voltage quicker? You are saying you prefer to complete an absorb cycle and then complete an EQ cycle? In my case there would not be enough sun for a 5hr absorb cycle and a 2-3hr EQ. I can say that going straight to EQ and staying there for 2-3 hrs always gets my specific gravity where it needs to be?

[vtmaps]

You are saying you prefer to complete an absorb cycle and then complete an EQ cycle?

He said earlier that going straight to EQ without stopping at absorb voltage for awhile makes his batteries get too hot. 

fwiw, most battery FAQs I've seen on the internet say to only EQ a fully charged battery... none of them say why.

--vtMaps

[ChrisOlson]

I don't know.  On our system it pushes way too many amps early in what should be the absorb stage if the battery isn't fully absorbed first.  And the batteries get really hot.  Our XW controllers, and inverter, will refuse to do any equalizing until absorb is complete.  You can push the button and the inverter will flash that EQ is pending (and the controllers too).  But they will not start EQ until absorb is done.

I don't know of any battery manufacturers that recommend doing an EQ unless the battery is charged as much as possible beforehand.

[Resthome]

Our XW controllers, and inverter, will refuse to do any equalizing until absorb is complete.  You can push the button and the inverter will flash that EQ is pending (and the controllers too).  But they will not start EQ until absorb is done.

Found that out on a friends XW invertor. I tried to get it to equalize and could not figure out why I could not force an equalize. Dug out the manual and found out it had to complete the time absorb cycle and then it would equalize.   

[ChrisOlson]

Found that out on a friends XW invertor. I tried to get it to equalize and could not figure out why I could not force an equalize. Dug out the manual and found out it had to complete the time absorb cycle and then it would equalize.   

Equalizing without fully charging the battery first is a good way to cause a thermal runaway on a bank that has some sulfated cells.  As the hardened sulfate comes off the negative plates, internal resistance drops and causes amps to actually increase for a time as the cells even out.  You don't want to be doing that kind of stuff when you're pushing > C/10 amps into the battery at EQ voltage.  On a system where the amps is limited by available solar capacity, you can probably get by with it.  But IMO it's still best for the charge controller to make sure the battery is ready for an EQ before attempting it.

[Resthome]

Found that out on a friends XW inverter. I tried to get it to equalize and could not figure out why I could not force an equalize. Dug out the manual and found out it had to complete the time absorb cycle and then it would equalize.   

Equalizing without fully charging the battery first is a good way to cause a thermal runaway on a bank that has some sulfated cells.  As the hardened sulfate comes off the negative plates, internal resistance drops and causes amps to actually increase for a time as the cells even out.  You don't want to be doing that kind of stuff when you're pushing > C/10 amps into the battery at EQ voltage.  On a system where the amps is limited by available solar capacity, you can probably get by with it.  But IMO it's still best for the charge controller to make sure the battery is ready for an EQ before attempting it.

I agree with you Chris. It was over a year ago and I though it had already completed an absorb cycle but had not been set to equalize. Too long ago to get all the fact correct. And I probably remember it wrong. Just remember it had to do an absorb first.

So with your XW inverter, if once you have completed an absorb and no equalize was pending you can go to equalize without going through another absorb?

[ChrisOlson]

So with your XW inverter, if once you have completed an absorb and no equalize was pending you can go to equalize without going through another absorb?

Nope.  If absorb is completed and you press the EQ button the controllers say Equalize Pending on them and the inverter flashes its red light for EQ Pending.  The whole system goes to absorb and verifies that the amps to the battery are less than 2% of what you have entered into the system for the battery amp-hour capacity.  It takes it 60 seconds to verify that, then the whole system goes to EQ.

If there's not enough power to maintain EQ voltage the system aborts it.  It will allow 60 seconds below EQ voltage before it aborts it.  The red light on the SCP starts flashing and there's a warning message on the screen that says it was aborted due to insufficient available power.  All you have to do is acknowledge the warning by pressing the Exit button and the warning message goes away and the red light stops flashing.  But the system saves it and will attempt the EQ again the next day after absorb is complete.

[Resthome]

So with your XW inverter, if once you have completed an absorb and no equalize was pending you can go to equalize without going through another absorb?

Nope.  If absorb is completed and you press the EQ button the controllers say Equalize Pending on them and the inverter flashes its red light for EQ Pending.  The whole system goes to absorb and verifies that the amps to the battery are less than 2% of what you have entered into the system for the battery amp-hour capacity.  It takes it 60 seconds to verify that, then the whole system goes to EQ.

If there's not enough power to maintain EQ voltage the system aborts it.  It will allow 60 seconds below EQ voltage before it aborts it.  The red light on the SCP starts flashing and there's a warning message on the screen that says it was aborted due to insufficient available power.  All you have to do is acknowledge the warning by pressing the Exit button and the warning message goes away and the red light stops flashing.  But the system saves it and will attempt the EQ again the next day after absorb is complete.

Thanks for the explanation Chris.

[boB]

The whole system goes to absorb and verifies that the amps to the battery are less than 2% of what you have entered into the system for the battery amp-hour capacity. 

Does your XW system know what is going into the battery ?

Why don't they just limit the current and thus the rise to EQ voltage by looking at the battery temperature ?
That might work pretty good.

Since you don't do a manual EQ very often, you could just manually do it after you've done an absorb.