A couple basic questions about starting with lifepo4

[andrzej0nl1ne]

From my readings so far, again, I'm just a novice trying to learn, it seems that once we understand how to operate these devices, they become easy with many benefits. Our problems are that we may be approaching the task from the wrong perspective.

My suggestion, just an opinion at the moment, is to start by balancing the cells in each battery individually so we start with a level playingfield, and then combining them in parallel, but to always strive to reach that balancing voltage for some duration (for my SOK that's published as 15 minutes). If you do that every so often (don't know the frequency) they'll serve you well with very little maintenance. It just seems that our efforts to optimize their charge routines without having a clear understanding of the goals or consequences got us all tangled up. The classic operator error with 20 20 hindsight. But who knew.



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[Chotu]

Originally Posted by andrzej0nl1ne

From my readings so far, again, I'm just a novice trying to learn, it seems that once we understand how to operate these devices, they become easy with many benefits. Our problems are that we may be approaching the task from the wrong perspective.

My suggestion, just an opinion at the moment, is to start by balancing the cells in each battery individually so we start with a level playingfield, and then combining them in parallel, but to always strive to reach that balancing voltage for some duration (for my SOK that's published as 15 minutes). If you do that every so often (don't know the frequency) they'll serve you well with very little maintenance. It just seems that our efforts to optimize their charge routines without having a clear understanding of the goals or consequences got us all tangled up. The classic operator error with 20 20 hindsight. But who knew.



Sent from my SM-N986U using Cruisers Sailing Forum mobile app

OK. That’s definitely part of the plan. To balance the batteries.

Although I can’t quite do it individually because I’m off grid.

I have to take them up with the solar charge controller.

[newhaul]

Originally Posted by Chotu

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.

Ok take the batteries offline one at a time and test to see if it happens ? When you figure out which one does it well that one needs to go on the shore charger untill full and fully balanced. Yes running the genset is a pain but will solve the issue

[fxykty]

Originally Posted by Chotu

It looks like my outback flex max 60 was trying to initiate an equalization charge. And it kept trying to do that. Every time it was full.

I think that’s what was happening.

To set my controller for LIFEP04, you are supposed to set the equalization charge equal to the absorption charge so you don’t really get a true equalization charge. However, it looks like it starts at some high spike and then comes back down to where you set it. That’s what seems to have been happening on mine.

Also, for some reason, it would not get out of the absorption state. Even when it was doing this voltage spike. It didn’t indicate an equalization. It always said “absorbing” on the status screen. (Never “float”)

What I did was went into the advanced menu and changed the absorption amperage to one or 2 A. Then I also changed my absorption voltage and equalization voltage back to 14.4. Like the manual said for my batteries. But while I was in there I hit “stop” when I was in the manual equalization charge menu. And it changed everything. Instead of being stuck on absorb, the charge controller now says that the batteries are fully charged. And it’s doing nothing. It’s just letting the batteries be at 13.7.V and handling loads I turn on.

This seems to be the correct state of affairs since they are filled right up right now.

I guess I will see how it cycles tomorrow. But it looks like it might be good.

Can you turn off equalisation? With LFP you definitely shouldn’t be doing it and even at lower voltages it’s not good for the battery.

[fxykty]

Originally Posted by Chotu

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.

Start with quality 3.2V cells, put as many of them in series to create a battery with the voltage you want. Then get a decent external BMS. Use Jedi’s system drawings - they’re just about plug and play for anyone - to get the other components for disconnects and relays and whatever is needed by the BMS you select to control your charge sources and your inverter. Put it all together, configure properly and test to make sure it works, then set and forget.

Using LFP drop ins and sub-standard BMS is a source of most problems (not necessarily yours, I’m not pointing fingers). Using chargers and other components that were designed for Lead Acid chemistry can mean that they do not have appropriate settings and ranges for LFP. As you’re finding out, an LFP battery has cells, and those cells govern the battery performance and behaviour. The BMS must manage the cells as well as the battery as whole - this is often where drop-ins and cheap BMS fall down.

Don’t despair - once you work things out the battery does become set and forget. We check our SOC twice a day, mostly to figure out whether we can leave the water heater on overnight in the evening and whether we need to start an engine to charge in the morning. Usually the answers are yes and no respectively. Cell balancing, SOC resynchronisation, charging start and stop, is all done automatically.

[Chotu]

These batteries are brand new I’m definitely not buying new batteries.

So, I will be bouncing these ones out. And I guess I will just use the generator for that. It only takes a couple hours to fill them up anyway. So maybe that is the way to go.

With them already full to begin with, it shouldn’t take very long at all I’m thinking

[rgleason]

Too much power. Heat domestic hot water.

[Chotu]

Originally Posted by rgleason

Too much power. Heat domestic hot water.

The more I have been reading online the more I am thinking my balance is also off because I haven’t taken them down all the way yet.


I was reading that balancing them involves going all the way up but also all the way down.

I’m going to try that as well.

[newhaul]

Originally Posted by Chotu

The more I have been reading online the more I am thinking my balance is also off because I haven’t taken them down all the way yet.


I was reading that balancing them involves going all the way up but also all the way down.

I’m going to try that as well.

Don't know your batteries but for my cells when I built they told me to charge to hvc then discharge to 12.0vdc to do the initial " commissioning " of the bank . Check with the manufacturer of your " drop ins" .

[Chotu]

Originally Posted by newhaul

Don't know your batteries but for my cells when I built they told me to charge to hvc then discharge to 12.0vdc to do the initial " commissioning " of the bank . Check with the manufacturer of your " drop ins" .

Yeah. My manufacturer only talked about topping them both off and then hooking them together for 24 hours and then putting them into use. There was no talk of taking them all the way down.

I did the best I could. I got them both charged all the way up and put them together for a few hours and then started using them.

Both batteries definitely weren’t at the same voltage when I put them together because one had been recently charged and the other had been charged previously.

I’m not exactly operating with perfect conditions out of a dock here. Even if I was, they would still be different voltages when I put them together.

At the same time, today, taking Wholybee’s advice, The problem has gone away.

I put in 14.0 as a starting point to get them up to. The charger apparently reached that because it’s in float right now and I never had any of those problems with the inverter detecting weird things going on and sounding alarms.

The batteries are full and floating at 14.

Edit: Sorry. I didn’t say that the right way. They went up to 14, had an hour at 14.0 in absorption, and now are floating at 13.6. Without any issues.

I’m going to just work my way up each day very slowly. See if I can get all the way back up or if I start running into the problem at a certain voltage.

[newhaul]

Originally Posted by Chotu

Yeah. My manufacturer only talked about topping them both off and then hooking them together for 24 hours and then putting them into use. There was no talk of taking them all the way down.

I did the best I could. I got them both charged all the way up and put them together for a few hours and then started using them.

Both batteries definitely weren’t at the same voltage when I put them together because one had been recently charged and the other had been charged previously.

I’m not exactly operating with perfect conditions out of a dock here. Even if I was, they would still be different voltages when I put them together.

At the same time, today, taking Wholybee’s advice, The problem has gone away.

I put in 14.0 as a starting point to get them up to. The charger apparently reached that because it’s in float right now and I never had any of those problems with the inverter detecting weird things going on and sounding alarms.

The batteries are full and floating at 14.

Edit: Sorry. I didn’t say that the right way. They went up to 14, had an hour at 14.0 in absorption, and now are floating at 13.6. Without any issues.

I’m going to just work my way up each day very slowly. See if I can get all the way back up or if I start running into the problem at a certain voltage.

Ok but not necessary except occasionally to balance most of the time at 14 and float at 13.6 is great for everything . Keep us up on how it goes .

[John29]

Chotu, appreciate if you can update on present state. And if you are happy with LFP or wish you'd stayed with lead. Thanks

[Chotu]

Originally Posted by John29

Chotu, appreciate if you can update on present state. And if you are happy with LFP or wish you'd stayed with lead. Thanks

I went kicking and screaming, but you should make the switch.

I thought lead acid batteries were set it and forget it. They almost were. Except you had to worry about watering them and only discharging them halfway and long charging times.

If you put in the same size bank that you have now and switch battery chemistry , it’s a world of difference.

These things are so easy to deal with that and you don’t even deal with them.

I was getting the boat equivalent of range anxiety needlessly. Because I can use twice as much of my battery capacity now (depth of discharge advantages), I am able to go days in clouds and rain without solar input and I’m still just fine.

Then when it comes time to put all that power back in, they accept charge like you would not believe.

As a matter of fact, I kind of don’t even realize that I have batteries anymore. I don’t look at them for days on end. There’s no need to anymore.

And since every pound counts on my boat, they are a real win in that department as well.

[newhaul]

Originally Posted by John29

Chotu, appreciate if you can update on present state. And if you are happy with LFP or wish you'd stayed with lead. Thanks

I have never seen anyone that switched from LiFePO4 back to lead. To many advantages to LiFePO4.

[John29]

Thanks, if going for 400 Ah LPO am I better with 2x200 or 4x100? I assume same size at least is preferred ie. not 1x300 and 1x100. Space and weight are not an issue and cost appears very similar.