Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?

[gord12]

This is a great help to me many thanks will be referring back to this page

 

[New Felicity User]

Thanks for the helpful information here. I am excited

 

[Padzb]

Anyone care to have a stab in the dark at what the SOC might be for these? 300Ah Catl, 4s 12v. Victron set to 13.85v absorption straight to 13.35v 'float'.


Just under 8a going in when it went to float. Interesting watching the victron smartsolar regulators push up the current slowly when the fridge started at 14:10 then easing it off again when it turned off.


Victron smartshunt says 85% and seems to end up round about there each day but likely has drifted since SOC last reset. Not that bothered tbh, they're getting well charged but not too much every day & if they are happy so am I ?. Feelin good about these settings, seems to be as good as any, lower absorption meant sometimes going to float early if the regulators saw a little peak in the voltage, smartshunt shares the voltage with the solar regulators over bluetooth.
Any comments/suggestions welcome ?

 

[Horsefly]

Anyone care to have a stab in the dark at what the SOC might be for these? 300Ah Catl, 4s 12v. Victron set to 13.85v absorption straight to 13.35v 'float'.
View attachment 158935

Just under 8a going in when it went to float. Interesting watching the victron smartsolar regulators push up the current slowly when the fridge started at 14:10 then easing it off again when it turned off. View attachment 158936


Victron smartshunt says 85% and seems to end up round about there each day but likely has drifted since SOC last reset. Not that bothered tbh, they're getting well charged but not too much every day & if they are happy so am I ?. Feelin good about these settings, seems to be as good as any, lower absorption meant sometimes going to float early if the regulators saw a little peak in the voltage, smartshunt shares the voltage with the solar regulators over bluetooth.
Any comments/suggestions welcome ?

13.85V is a pretty good bulk / absorption voltage, but I would not drop immediately to float, as it sounds like you are doing. If you hold absorption at 13.85V until the current drops down to 0.02C you will know you actually did get to 100% SoC.

I don't have the settings in front of me, but I know the SmartShunt doesn't set SoC to 100% until whatever voltage you set has been met or exceeded for some number of minutes. That also points to holding your absorption voltage for a few minutes will get the shunt to reset to 100%. I actually have my max absorption time set to 60 minutes, but the tail current setting of 0.02C drops it out of absorption before 60 minutes has elapsed.

 

[Padzb]

13.85V is a pretty good bulk / absorption voltage, but I would not drop immediately to float, as it sounds like you are doing. If you hold absorption at 13.85V until the current drops down to 0.02C you will know you actually did get to 100% SoC.

I don't have the settings in front of me, but I know the SmartShunt doesn't set SoC to 100% until whatever voltage you set has been met or exceeded for some number of minutes. That also points to holding your absorption voltage for a few minutes will get the shunt to reset to 100%. I actually have my max absorption time set to 60 minutes, but the tail current setting of 0.02C drops it out of absorption before 60 minutes has elapsed.

I don't need or want to go to 100% though. ? I did hold absorption for an hour before but it just acted like float, mA going in to the battery so stopped doing that, seems no point keeping the voltage high for more than a few minutes for a few % more soc. More interested in what SOC it might actually get to with those data ? Don't need to know, stopping on the way up the knee is fine, just interested ?Thnx

 

[Horsefly]

I don't need or want to go to 100% though. ? I did hold absorption for an hour before but it just acted like float, mA going in to the battery so stopped doing that, seems no point keeping the voltage high for more than a few minutes for a few % more soc. More interested in what SOC it might actually get to with those data ? Don't need to know, stopping on the way up the knee is fine, just interested ?Thnx

Ok. Just so you know, going to 100% if you are only using about 3.45V/cell will never harm the cells.

I'm not sure what you will ever get out of the Victron SmartShunt if it never thinks you get to 100% SoC. Periodically resetting to 100% is kind of fundamental to it's using Coulomb counting to give you an estimate of your SoC as you discharge.

 

[Padzb]

I'm not sure what you will ever get out of the Victron SmartShunt if it never thinks you get to 100% SoC. Periodically resetting to 100% is kind of fundamental to it's using Coulomb counting to give you an estimate of your SoC as you discharge.

Yep, agree. Just interested what the team think it might be. Think I'll reset it to 90% once in a while as it drifts & go with that rather than bother changing the regulators to get to the top of the knee. Really doesn't have to be bang on accurate. Thnx.

 

[Padzb]

update for anyone interested > original question was partly because the data didn't quite make sense and seemed to vary a bit day by day. From logging showing more of a voltage drop under high load turns than there used to be with some investigation one of the connections wasn't great, seems much more logical now. Though I really can't see any benefit of absorption, all it does is keep the voltage high, next to no current goes in to the battery. Here the regs went to float at about 16:47 (then the fridge started) so I altered the regulators to stay at absorption for 1 hour & you can see the current tail off to next to nothing. So couple things learned for me, no point in absorption, also the victron smartsolar regulators don't track the smartshunt moment by moment, they lag behind and seem to sort of average out. I had to cover a panel for 5 minutes after changing settings otherwise they would see a high voltage even though the smartshunt was reading much less even though VE.smart networking was correctly set up. . After a few minutes they seemed to settle down & track much closer
The joy of data ???

 

[12VoltInstalls]

I had to cover a panel for 5 minutes after changing settings otherwise they would see a high voltage even though the smartshunt was reading much less even though VE.smart networking was correctly set up. . After a few minutes they seemed to settle down & track much closer

I’m mostly being sarcastic here, but if you want more ‘instant’ tracking: the cheapo powerMR 60A SCC’s track quickly in variable light; the voltage and watts go wildly hunting and all over the place second by second at higher battery charge states or variable sun. So maybe you just spent too much lol ?

With Victron the “slow” reactions are probably intentional and well thought out in the coding would be my guess.

 

[RCinFLA]

LFP cell cathode material is much more rugged than other Li-Ion battery chemistries. It is due to the iron providing vertical lattice structure support when most of lithium is removed from positive cathode at full state of charge. It is reason why LFP cells have long cycle life. Downside for LFP is lower electrode potential yielding lower energy density.

LFP cycle life is dominantly the degradation of negative graphite anode and electrolyte where most other lithium-ion battery chemistries are life limited by positive cathode material degradation.

For LFP cells, greater cell voltage accelerates electrolyte and negative graphite electrode degradation slightly, but LFP is much more tolerant of being fully charged.

High-rate charge and discharge current is more degrading to LFP when level of current gets into electrode ion starvation region. The thicker the electrode material the lower the current for the onset of electrode ion starvation. Most of the DIY'ers' 'Blue' cells start to have layer ion starvation at about 0.5 C(A) discharge rate.

 

[Padzb]

I’m mostly being sarcastic here, but if you want more ‘instant’ tracking: the cheapo powerMR 60A SCC’s track quickly in variable light; the voltage and watts go wildly hunting and all over the place second by second at higher battery charge states or variable sun. So maybe you just spent too much lol ?

With Victron the “slow” reactions are probably intentional and well thought out in the coding would be my guess.

think all I really want is to find out a bit more of what's actually going on in the hope it might be useful ??
And very happy with Victron, wouldn't go anywhere else now. ? Just was a bit surprising the regs didn't actually follow the shunt voltage better, but that was only for a little while after changing settings so who knows. Doesn`t matter really.
So logging helped lots, amazing what a little raspberry pi zero can do. Tried regs set to 13.85v as end of bulk today straight to float. Seems just fine, reliable to stop at the knee, matters little what the actual SOC is, it works, is up not too far from full & is reliable. Boat is a happy boat. Love lithium, what a game changer from lead acid. ????

 

[Padzb]

LFP cell cathode material is much more rugged than other Li-Ion battery chemistries. It is due to the iron providing vertical lattice structure support when most of lithium is removed from positive cathode at full state of charge. It is reason why LFP cells have long cycle life. Downside for LFP is lower electrode potential yielding lower energy density.

LFP cycle life is dominantly the degradation of negative graphite anode and electrolyte where most other lithium-ion battery chemistries are life limited by positive cathode material degradation.

For LFP cells, greater cell voltage accelerates electrolyte and negative graphite electrode degradation slightly, but LFP is much more tolerant of being fully charged.

High-rate charge and discharge current is more degrading to LFP when level of current gets into electrode ion starvation region. The thicker the electrode material the lower the current for the onset of electrode ion starvation. Most of the DIY'ers' 'Blue' cells start to have layer ion starvation at about 0.5 C(A) discharge rate.

Any links to the research about this would be interesting if you have them. ?

 

[12VoltInstalls]

Any links to the research about this would be interesting if you have them. ?

I’m not sure but his links might be attached to a degree… you can autodidact, too.