Float mode on solar controllers?- why?

[a64pilot]

Realize now its likely you have some parasitic loads that are a part of that 4 or 5 amps you see, fridge or something may be pulling a few amps, so you have to either disconnect your bank and wait a few minutes for the charge to stabilize, or know what your parasitic loads are.
My fridge pulls 5 amps, so even if my bank was accepting no charge at all, my charge current will be 5 amps if the fridge compressor is running. So with the fridge on and running, when I get to 8 amps, I'm fully charged, cause 5 of that 8 is the fridge.

On edit, that last couple of percent seems to take longer than the first 30% or so.
When they get near full, acceptance rate is really low I guess

[Sulaire]

Hi guys,

Thanks for all the advice. I appreciate it.

I think what i will do is alter the float voltage on each charger to be equal to the absorption voltage at 14.4v, and keep an eye on the amps going in at this voltage during the day, as maine sail says, this will be the true indicator of SOC. An i will be aware of any loads such as fridges cycling on and off. We do use the multiplus during the day also to get 120ac at times, so i am quite sure this usage alone will keep me from overcharging.

Hopefully my days of premature - floatulation will be over!😈

C.



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[Stu Jackson]

If you reread MS's first post, IIRC, he's saying deprogram the float voltage, keep it at 14.4 or your absorption voltage, monitor the amps at THAT higher absorption voltage, and be done with it. Good luck. Nice catch.

Isn't being a utility company just so much fun???

[Skuzzlebutt]

Great Info, thanks everyone!
Think I'm finally starting to understand...

[Canuck Sailor]

Well, thank you all. I have been having trouble with this walk down problem and didn't realize I wasn't all alone. My system has been suffering from "Premature Flotulation".

I changed my AGMs to LiFePo4 (along story), still using my BlueSky Energy 3024I and when I asked for help last time the comments were it all works fine. Except my set up didn't and no one could tell me what I was doing wrong, not even BlueSky.

After two weeks of sitting on the anchorage with my 450 watts of PV, I have to run the engine to bring the 500AH battery up to its proper voltage of 13.2V. It will walk down from there.

It has required up to 10 hours of running (~50A x 10hr) time when I leave it too long and it cycles the battery. (battery shuts off on low voltage) Running this long is no problem on long passages but not so great at anchor. Perhaps I should be thinking of a suitcase generator as well. I will also re-evaluate my float voltage settings.

Thanks again.
Walk down, hmmmmm!

[Maine Sail]

Originally Posted by Canuck Sailor

Well, thank you all. I have been having trouble with this walk down problem and didn't realize I wasn't all alone. My system has been suffering from "Premature Flotulation".

I changed my AGMs to LiFePo4 (along story), still using my BlueSky Energy 3024I and when I asked for help last time the comments were it all works fine. Except my set up didn't and no one could tell me what I was doing wrong, not even BlueSky.

After two weeks of sitting on the anchorage with my 450 watts of PV, I have to run the engine to bring the 500AH battery up to its proper voltage of 13.2V. It will walk down from there.

It has required up to 10 hours of running (~50A x 10hr) time when I leave it too long and it cycles the battery. (battery shuts off on low voltage) Running this long is no problem on long passages but not so great at anchor. Perhaps I should be thinking of a suitcase generator as well. I will also re-evaluate my float voltage settings.

Thanks again.
Walk down, hmmmmm!

Walk-down is caused by sulfation in lead acid batteries during PSOC use. LiFePO4 batteries don't sulfate and don't walk down due to sulfation..

However, with any bank not getting back to full each day can still result in walking down in SOC. With LFP it is tough to tell SOC because your voltage profile is so flat.

[SV THIRD DAY]

Originally Posted by Canuck Sailor

Well, thank you all. I have been having trouble with this walk down problem and didn't realize I wasn't all alone. My system has been suffering from "Premature Flotulation".

I changed my AGMs to LiFePo4 (along story), still using my BlueSky Energy 3024I and when I asked for help last time the comments were it all works fine. Except my set up didn't and no one could tell me what I was doing wrong, not even BlueSky.

After two weeks of sitting on the anchorage with my 450 watts of PV, I have to run the engine to bring the 500AH battery up to its proper voltage of 13.2V. It will walk down from there.

It has required up to 10 hours of running (~50A x 10hr) time when I leave it too long and it cycles the battery. (battery shuts off on low voltage) Running this long is no problem on long passages but not so great at anchor. Perhaps I should be thinking of a suitcase generator as well. I will also re-evaluate my float voltage settings.

Thanks again.
Walk down, hmmmmm!

It just sounds to me like your daily power draw is larger than your solar array can keep up with...simple input is less than output so your LiFePO4 battery slowly loses charge. The benefit of LiFePO4 batteries is that they don't have this "walk down" SOC problem.

Do you have an Amp Hour meter to measure your daily power draw compared to your daily power production?

[Canuck Sailor]

Thanks for the information MS & 3rd Day. I do have or did have the SOC on my IPN ProRemote on the 3024I. My last charge session with the engine, it didn't show up. I will have to look into that.
I do have the float presently set at 14.2 and it seems to be making a difference but I won't know for sure until this evening when I run the engine again to further charge the battery. It is now down to 13.1V. I have acceptance set for 14.4V.

To respond to Third Day the solar panels appear to be more than enough wattage for the SOC suggested on the meter of 90% battery and ~-50 to 75 AH used overnight. The SCC changes to float usually between 1100 - 1300 each day unless I have something else happening like the draw on the water maker or cloud cover. At the time of going to float, the meter states 100% battery and -00 AH.
It may do this for days on end but the battery voltage is usually dropping as well. If I leave the boat unattended like I did recently, then it drops down until the PCM shuts down all load and disconnects the battery as it is supposed to do.

I will try to get the SOC working again but can rely on the voltage with this battery as it is a good indicator.

[Captain Bill]

Originally Posted by Canuck Sailor

Thanks for the information MS & 3rd Day. I do have or did have the SOC on my IPN ProRemote on the 3024I. My last charge session with the engine, it didn't show up. I will have to look into that.
I do have the float presently set at 14.2 and it seems to be making a difference but I won't know for sure until this evening when I run the engine again to further charge the battery. It is now down to 13.1V. I have acceptance set for 14.4V.

To respond to Third Day the solar panels appear to be more than enough wattage for the SOC suggested on the meter of 90% battery and ~-50 to 75 AH used overnight. The SCC changes to float usually between 1100 - 1300 each day unless I have something else happening like the draw on the water maker or cloud cover. At the time of going to float, the meter states 100% battery and -00 AH.
It may do this for days on end but the battery voltage is usually dropping as well. If I leave the boat unattended like I did recently, then it drops down until the PCM shuts down all load and disconnects the battery as it is supposed to do.

I will try to get the SOC working again but can rely on the voltage with this battery as it is a good indicator.

I have an IPNPro on my blue sky controller and IMO the SOC algorithm is pure crap. The only time I have ever seen it be accurate is within 1 day of a true 100% charge. That is after I have seen the absorption voltage stay at 14.5 and the amperage decrease down to 2v on my 420 AH bank. After a bit of draw down overnight it never reads correctly again. Sometimes it will tell me I'm at 70% to start and I charge it with the genset to 90 at which time it's only taking 4 amps and climbs to 91% slowly and down to 2 amps at which time it jumps to 100%, Other times it's telling me I have 95% charge and it's still taking 20-25 amps. Other times it's telling me it's at 100% charge but still accepting 7-8 amps. The SOC is pretty much useless. I judge SOC by how many amps the batteries are accepting and the Voltage going into them. The IPNPro is supposed to "learn" your battery charge characteristics and adjust the hysteresis parameter but I see no evidence that mine has done anything to improve the SOC tracking in the 3 years I have had it.

[daletournier]

On the morning star controller, when attached to a pc , I have the option to tick a box that disables float. I wish I had of done this 5 years ago. My 6v batteries often charge around 14.2 v for half the day , haven't seen a problem with this in the last 2 years. I was always frustrated how the charger would flip into float mode prematurely.

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[Stu Jackson]

Originally Posted by Captain Bill

I judge SOC by how many amps the batteries are accepting and the Voltage going into them.

Right. This is exactly what Maine Sail has been telling us for many, many years.

[Canuck Sailor]

Capt Bill. Thanks for the input. I didn't run the engine last night to charge the battery as it was still at a decent 13.1V but I am watching it and did use my normal amount of power overnight.
Thanks all. i didn't really mean to start a new thread here but I do appreciate the back up and I have a high float voltage going in, just the same.

[svlamorocha]

Originally Posted by Maine Sail

Big difference and the .5% net acceptance needs to occur at 14.4V not float......

Amen!


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[Sulaire]

Ok, so i did put my float voltage up to 14.4, the system gets up to 14.3 v and no more, which is ok i think for 7 year old batteries,because lifeline call for 14.3-14.4v.

Now after reaching this voltage i see 1.5 amp going in without any load (615amp bank), will this damage the bank if it goes on for a few hours? Ie 14.3 volts with1.5 amp going in.

C.


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[mitiempo]

Originally Posted by Sulaire

Ok, so i did put my float voltage up to 14.4, the system gets up to 14.3 v and no more, which is ok i think for 7 year old batteries,because lifeline call for 14.3-14.4v.

Now after reaching this voltage i see 1.5 amp going in without any load (615amp bank), will this damage the bank if it goes on for a few hours? Ie 14.3 volts with1.5 amp going in.

No it will not.