A couple basic questions about starting with lifepo4

[rslifkin]

What settings are there for absorb mode other than voltage? Is there a timer or anything else used to determine when it should switch from absorb to float?

[Chotu]

Originally Posted by rslifkin

What settings are there for absorb mode other than voltage? Is there a timer or anything else used to determine when it should switch from absorb to float?

Yes. It goes down to one hour minimum. There’s a one hour absorb that’s set.

It’s a mode that’s not even needed. I wish I could skip it. But there doesn’t seem to be a way to do that.

Every time it gets into that zone and that’s where everything goes haywire.

This is the manual. It’s really just a guide on how to hit the settings. It doesn’t really give you any theory on what to do.

https://www.outbackpower.com/downloa...ner_manual.pdf

So, really it’s the absorption phase that’s causing this issue. I have completely disabled the equalization mode. (Set to 000 for never)

[wholybee]

Originally Posted by Chotu

Yeah. I think I’m going to have to dig a little deeper. I think this has everything to do with the flex 60.

I went through the menus and there wasn’t too much to change. But maybe I have to figure out some more advanced settings like you are talking about.

Today, at 14.3, by 1 PM the inverter was howling again. Overvoltage situation.

I got a chance to watch the battery voltage and it was proper. 14.3. But then it jumped to over 15 for a second. Amps going in were almost nothing.

And when I ran over to the flex 60 to see what it was doing, it’s in absorption mode.

This is exactly what I didn’t want when I changed to this type of battery.

I didn’t want my batteries to become a new hobby and waste of my time. I’ve seen endless threads on this forum discussing all of the problems with these battery systems. It did not inspire confidence.

It’s not like I don’t have millions more hours to spend on building the boat. I like the old Lead system because set it and forget it. Just water it once a month.

Batteries were always full and it worked perfectly.

The fork in the road is behind me though. Now I have to deal with this situation.

If the voltage goes to 15, and amps to nothing, then there is an open circuit. That is probably the BMS cutting off charging. Not for battery overvoltage because you can see it isn't, but because a cell is overvoltage, which you can't see. Your battery cells are not balanced.

You need to drop the voltage to a point that doesn't happen, start at 14V, if it still happens drop to 13.9V. Then charge it, and set it to absorb until current is 1 or 2 amps. Then, slowly increase voltage and repeat. This process will balance the cells in the battery. It might take multiple days to complete.

Another option, since these are new batteries, is to call the manufacture for advice. They might warrant them and send you batteries that are not out of balance. Or, they might give official instructions on how to balance them.

[rslifkin]

Originally Posted by Chotu

Yes. It goes down to one hour minimum. There’s a one hour absorb that’s set.

It’s a mode that’s not even needed. I wish I could skip it. But there doesn’t seem to be a way to do that.

Every time it gets into that zone and that’s where everything goes haywire.

This is the manual. It’s really just a guide on how to hit the settings. It doesn’t really give you any theory on what to do.

https://www.outbackpower.com/downloa...ner_manual.pdf

So, really it’s the absorption phase that’s causing this issue. I have completely disabled the equalization mode. (Set to 000 for never)

I just flipped through the manual and it looks like you should be able to set the absorb time anywhere from 0.0 to 24.0 hours. There's also an absorb end amps setting that can end absorb earlier than the timer, but that's not particularly useful for LFP, mostly for lead-acid batteries.

[wholybee]

Originally Posted by Chotu

Yes. It goes down to one hour minimum. There’s a one hour absorb that’s set.

It’s a mode that’s not even needed. I wish I could skip it. But there doesn’t seem to be a way to do that.

Every time it gets into that zone and that’s where everything goes haywire.

This is the manual. It’s really just a guide on how to hit the settings. It doesn’t really give you any theory on what to do.

https://www.outbackpower.com/downloa...ner_manual.pdf

So, really it’s the absorption phase that’s causing this issue. I have completely disabled the equalization mode. (Set to 000 for never)

If you can't lower absorption time, that isn't terrible. You need some absorption anyway for the battery to balance. There is a relationship between absorption time and absorption voltage. The higher the voltage, the less time needed. The lower the voltage, the more time needed. So, it is 100% ok to lower the voltage (to no lower than 13.8v) to compensate for a longer absorption time. At 14.2V, an absorption time of 20 minutes per 100Ah is reasonable, so you are in the ballpark if you have a larger bank. Lower the voltage a bit below 14.2 if you need.

I don't think that is the issue causing the voltage spikes though. I think your BMS is cutting off due to a cell imbalance.

[Chotu]

Originally Posted by wholybee

If the voltage goes to 15, and amps to nothing, then there is an open circuit. That is probably the BMS cutting off charging. Not for battery overvoltage because you can see it isn't, but because a cell is overvoltage, which you can't see. Your battery cells are not balanced.

You need to drop the voltage to a point that doesn't happen, start at 14V, if it still happens drop to 13.9V. Then charge it, and set it to absorb until current is 1 or 2 amps. Then, slowly increase voltage and repeat. This process will balance the cells in the battery. It might take multiple days to complete.

Another option, since these are new batteries, is to call the manufacture for advice. They might warrant them and send you batteries that are not out of balance. Or, they might give official instructions on how to balance them.

That’s really good insight. Thank you.

There is another clue that I wasn’t considering here.

This behavior started happening after I hooked up the second battery. When I was just running on one of the batteries this did not happen.

That definitely points to an imbalance between the batteries.

Before I do anything else, I will try this approach.

[Chotu]

Originally Posted by rslifkin

I just flipped through the manual and it looks like you should be able to set the absorb time anywhere from 0.0 to 24.0 hours. There's also an absorb end amps setting that can end absorb earlier than the timer, but that's not particularly useful for LFP, mostly for lead-acid batteries.

I will have to review that again because I could have sworn it can only go down to one hour. And I did fiddle around with the ending amps for the absorption stage also. It didn’t really have any effect. I only went up to a few amps with it. Who knows? Maybe if I went higher I could just disable that absorption setting.

Edit: there are two different places to set that absorption time. I found one in the advanced menu with the more granular time units that actually can go to zero. I said it to zero. Is that a good idea? Or do I really need that absorption time for balancing the cells? I do want to take that approach starting low and working up. I’m at 14 V now. Hoping that’s low enough. On second thought, I had better reenable the absorption stage. Because I think that’s the only stage that you could do balancing in.

[sailorboy1]

Originally Posted by Chotu

Yes. It goes down to one hour minimum. There’s a one hour absorb that’s set.

It’s a mode that’s not even needed. I wish I could skip it. But there doesn’t seem to be a way to do that.

Every time it gets into that zone and that’s where everything goes haywire.

This is the manual. It’s really just a guide on how to hit the settings. It doesn’t really give you any theory on what to do.

https://www.outbackpower.com/downloa...ner_manual.pdf

So, really it’s the absorption phase that’s causing this issue. I have completely disabled the equalization mode. (Set to 000 for never)

If you aren't going to go into the advanced programing etc and make the proper settings why keep this thread going. I have the same controller!

[rslifkin]

Originally Posted by Chotu

That’s really good insight. Thank you.

There is another clue that I wasn’t considering here.

This behavior started happening after I hooked up the second battery. When I was just running on one of the batteries this did not happen.

That definitely points to an imbalance between the batteries.

Before I do anything else, I will try this approach.

That definitely makes me think it's an imbalance (or an issue with the second battery), so trying to get them to re-balance is definitely a good next step.

[Chotu]

Originally Posted by sailorboy1

If you aren't going to go into the advanced programing etc and make the proper settings why keep this thread going. I have the same controller!

What are you talking about? What we are discussing is in the advanced settings.

[Chotu]

Originally Posted by rslifkin

That definitely makes me think it's an imbalance (or an issue with the second battery), so trying to get them to re-balance is definitely a good next step.

Definitely. That is the approach I’m taking right now. Starting out at 14.0 with a one hour absorption time (advanced settings, Sailorboy) and seeing if that balances.

I will proceed lower if not. I will bring them up a 10th of a volt each day

[sailorboy1]

did you calibrate the controller to the batteries yet?

I got my 400ah LFP bank to 0ah out yesterday on my battery monitor and decided to do thing balance this and changed my solar to 14.4v and my system never did not do any weird things

[andrzej0nl1ne]

As a recent convert to LFP, I'm following the multiple discussions as well as delving into lots of youtube content. I'm no technical expert, but I'm a willing student. I like Will P, and recently began watching Andy at off-grid garage. I admit I'm having difficulty in making sense from all the varied input, especially as it only spans less than half a volt. I watched one segment where Andy defines all the different settings parameters, and I watched a follow up to that segment. Which is where the light bulb went off for me.

All the discussions so far are aiming to identify the correct numbers to set our chargers, but Andy's summary is that there are no correct numbers, since they all reflect different conditions. The fine differences in cell chemistries dictate a small voltage variation, the amount of time one has to recharge the bank dictate voltage variations, the state of discharge, etc.

What's missing from our conversations is an ordered list of our goals, exactly what is it that we are attempting to accomplish. Yes, we are attempting to keep the batteries in a charged state, but that is too vague. The two lessons Andy highlighted in his videos are that once the individual cells get out of balance, crazy performance occurs; and that time is required at the balancing voltage to force the cells to rebalance.

Our collective trend to focus on keeping the batteries at below 100% charged seems to miss that primary objective. My take away from the YouTube lessons is that the primary goal of our LFP charging discipline should be to hit that cell balancing voltage for a long enough duration to actually achieve balanced cells. That voltage and that duration differs by cell chemistry, BMS settings, and circumstances. However, if we fail to achieve that balancing, unpredictable behavior will occur, the types of events you have been describing.

Thus goal #1 is to hit and maintain that cell balancing voltage for the required time length. The exact voltage is not generic nor is the duration. Thus, any of our attempts to identify the proper numbers is applicable at best to only certain products or circumstances.

The goal #2 appears to me to define the settings that will enable us to reach that cell balancing voltage for sufficient duration, given our circumstances. Again, there is no correct number, but lower & slower is better for longevity, as long as you hit those balancing voltage numbers, but you must hit those balancing numbers.

The internal BMS cell balancing takes place at under 1 volt, thus it takes a long time to rebalance the cells once they get out of balance. Typically this entails multiple full drains and recharge cycles of an individual battery.

Hope this helps refine our quest for that sacred set of numbers. I have to admit that I was getting more lost with every discussion I read until I watched the segments that lit the light bulb.

First, reach the balancing voltage for sufficient duration, and only then calculate the better path to get to that balancing given your particular configuration. I still don't have the exact numbers, but I think I understand the road map to get there. Previously I just had a headache.

[Chotu]

Originally Posted by sailorboy1

did you calibrate the controller to the batteries yet?

I got my 400ah LFP bank to 0ah out yesterday on my battery monitor and decided to do thing balance this and changed my solar to 14.4v and my system never did not do any weird things

The vBattCalibration option?

Sure. I’ll give that a go tomorrow.

There are a lot of things that could be causing this.

[Chotu]

Originally Posted by andrzej0nl1ne

As a recent convert to LFP, I'm following the multiple discussions as well as delving into lots of youtube content. I'm no technical expert, but I'm a willing student. I like Will P, and recently began watching Andy at off-grid garage. I admit I'm having difficulty in making sense from all the varied input, especially as it only spans less than half a volt. I watched one segment where Andy defines all the different settings parameters, and I watched a follow up to that segment. Which is where the light bulb went off for me.

All the discussions so far are aiming to identify the correct numbers to set our chargers, but Andy's summary is that there are no correct numbers, since they all reflect different conditions. The fine differences in cell chemistries dictate a small voltage variation, the amount of time one has to recharge the bank dictate voltage variations, the state of discharge, etc.

What's missing from our conversations is an ordered list of our goals, exactly what is it that we are attempting to accomplish. Yes, we are attempting to keep the batteries in a charged state, but that is too vague. The two lessons Andy highlighted in his videos are that once the individual cells get out of balance, crazy performance occurs; and that time is required at the balancing voltage to force the cells to rebalance.

Our collective trend to focus on keeping the batteries at below 100% charged seems to miss that primary objective. My take away from the YouTube lessons is that the primary goal of our LFP charging discipline should be to hit that cell balancing voltage for a long enough duration to actually achieve balanced cells. That voltage and that duration differs by cell chemistry, BMS settings, and circumstances. However, if we fail to achieve that balancing, unpredictable behavior will occur, the types of events you have been describing.

Thus goal #1 is to hit and maintain that cell balancing voltage for the required time length. The exact voltage is not generic nor is the duration. Thus, any of our attempts to identify the proper numbers is applicable at best to only certain products or circumstances.

The goal #2 appears to me to define the settings that will enable us to reach that cell balancing voltage for sufficient duration, given our circumstances. Again, there is no correct number, but lower & slower is better for longevity, as long as you hit those balancing voltage numbers, but you must hit those balancing numbers.

The internal BMS cell balancing takes place at under 1 volt, thus it takes a long time to rebalance the cells once they get out of balance. Typically this entails multiple full drains and recharge cycles of an individual battery.

Hope this helps refine our quest for that sacred set of numbers. I have to admit that I was getting more lost with every discussion I read until I watched the segments that lit the light bulb.

First, reach the balancing voltage for sufficient duration, and only then calculate the better path to get to that balancing given your particular configuration. I still don't have the exact numbers, but I think I understand the road map to get there. Previously I just had a headache.

That seems reasonable. Almost sounds like an equalization charge is in order for that.

I can do one manually. So maybe I should just hold the batteries at the balancing voltage for some unknown length of time but a sufficient time?

Or maybe hold them at the absorption voltage for a couple of hours? How will I know when they are balanced?

Some of this information I can probably get from the manufacturer as somebody said above. They are very responsive on support.

But to be honest, this is exactly why I didn’t want these batteries to begin with. It’s ridiculous. Every thread I read it’s just a whole series of problems. It’s like it looking at the open CPN threads.

Nothing but struggles.

I didn’t want my batteries to become a hobby or some thing I have to put many hours into. I should’ve just went with the regular lead batteries again. I could have just got those and then forgot about it and moved on to other things.