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04-06-2023, 13:43
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#46
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Registered User
Join Date: May 2006
Posts: 1,111
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Re: LFP maintaining during low load
Quote:
Originally Posted by sailorboy1
As the OP I wouldn't worry. Only people still posting are reading this by now in order to wage their private battle. This stuff isn't on topic at all.
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Sure you would not worry we know that, but some of us like to try to provide quality information that helps people without causing confusion…it’s a constant battle on here.
We know you don’t care, all threads go off topic, just as well I’m not one of the moderators or things would be very different for you.
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04-06-2023, 14:04
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#47
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,364
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Re: LFP maintaining during low load
I bet correcting the wrong on the internet is hard work
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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05-06-2023, 14:39
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#48
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 2,828
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Re: LFP maintaining during low load
Quote:
Originally Posted by s/v Jedi
The balance leads are not after the main fuse, they are from each individual cell.
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I didn't reply to your balance leads answer...well i condiser it a bad design if you need to remove all balance leads if you wanna be able to disconnect your BMS. Sure you can do.
I replied to FUSS mentioning "I imagine that we do not want to remove 4 , 8 , 16 fuses, times however many batteries we have." He should have 1 main bank fuse that disconnects the main bus or 2 if seperate load and charge bus of his whole bank, consisting of several batteries. Besides convienence to pull one/two fuses and all is disconnected, thats also done quickly in emergency case and can spare you a lot of damage
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05-06-2023, 14:45
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#49
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Registered User
Join Date: Jul 2020
Location: Virginia, USA
Boat: Tayana 37
Posts: 960
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Re: LFP maintaining during low load
Quote:
Originally Posted by CaptainRivet
I didn't reply to your balance leads answer...well i condiser it a bad design if you need to remove all balance leads if you wanna be able to disconnect your BMS. Sure you can do.
I replied to FUSS mentioning "I imagine that we do not want to remove 4 , 8 , 16 fuses, times however many batteries we have." He should have 1 main bank fuse that disconnects the main bus or 2 if seperate load and charge bus of his whole bank, consisting of several batteries. Besides convienence to pull one/two fuses and all is disconnected, thats also done quickly in emergency case and can spare you a lot of damage
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The entire discussion was about shutting down the BMS to produce 0 watt drain in storage. Baring some insane setup pulling main fuse or cutting main breaker is not going to cutoff power to BMS.
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05-06-2023, 14:47
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#50
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,364
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Re: LFP maintaining during low load
Quote:
Originally Posted by Statistical
The entire discussion was about shutting down the BMS to produce 0 watt drain in storage. .
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Wasn't the discussion at at all. That is just what a few drifted it into
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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05-06-2023, 15:23
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#51
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 2,828
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Re: LFP maintaining during low load
Quote:
Originally Posted by sailorboy1
I currently am in a slip with lower house loads so have adjusted my solar to only charge to 13.4V for an hour and then drop to 13.3V float. Been 2.5 weeks like this and the batteries appear to be staying within 70% SOC in morning to 90-95% in afternoon.
Anyone see a problem with this? Should I maybe let it go lower once in a while and then recharge to 100%?
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No problem doing that, in summer thats actually how my bank is running on anchor.
Just don't plug in shorepower (i never do, even in marina, expect if i work on the battery or electrics) and run it like you will be on anchor. Maybe once in 2 weeks plug it in and charge to 100% so the BMS can calibrate, balance and get its reference value.
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05-06-2023, 15:49
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#52
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Registered User
Join Date: Jun 2010
Location: Easton, MD
Boat: 15' Catboat, Bristol 35.5
Posts: 3,510
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Re: LFP maintaining during low load
IMHO and in my own case, the value of LFP is high charge rate and nearly 100% charge efficiency. I'm not concerned with longevity that much. They will last over 5 years without much care. If you make your own bank with prismatic cells they aren't that expensive. (326AHr for $800) Less now.
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21-10-2023, 06:46
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#53
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,364
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Re: LFP maintaining during low load
Quote:
Originally Posted by kmacdonald
From what I've read, it is best to store at 40 or 50% SOC. 100% SOC is not good for them.
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Not aimed at the above poster, just using the quote.
I looked for an actural testing study to support the "better to store at 60% than 100%" thing.
I finally found one (I didn't, someone posted a link) and it is true in absolute sense.
But the study found the difference between loss of capacity of a LFP battery stored at 80-100% SOC and one stored at 40-80% SOC was only a difference of 3%.
Pretty meaningless really for real use on a boat.
So I changed my solar to 14.4V absorption for 30 min or 8A output and then to "float" at 13.5V. Battery cycles a little during the night and fully recharges each day long as enough sun is out next day.
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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21-10-2023, 07:05
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#54
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always in motion is the future
Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 18,866
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Re: LFP maintaining during low load
Quote:
Originally Posted by sailorboy1
Not aimed at the above poster, just using the quote.
I looked for an actural testing study to support the "better to store at 60% than 100%" thing.
I finally found one (I didn't, someone posted a link) and it is true in absolute sense.
But the study found the difference between loss of capacity of a LFP battery stored at 80-100% SOC and one stored at 40-80% SOC was only a difference of 3%.
Pretty meaningless really for real use on a boat.
So I changed my solar to 14.4V absorption for 30 min or 8A output and then to "float" at 13.5V. Battery cycles a little during the night and fully recharges each day long as enough sun is out next day.
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Doesn’t sound like you store your batteries at all, you’re just using them.
__________________
“It’s a trap!” - Admiral Ackbar.
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21-10-2023, 08:08
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#55
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,364
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Re: LFP maintaining during low load
Quote:
Originally Posted by s/v Jedi
Doesn’t sound like you store your batteries at all, you’re just using them.
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No I don't store them as they are always on line and there are loads. They cycle between 80-100% on 95% of days. I bet we really don't know the long term impact of that.
I ran them down to 40% last week by disconnecting solar and later charged back gto 100%. The morning voltage has been higher since. But don't know if it had anything to do with the "cycle" or if it was that I found some loose terminal bolts during that.
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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21-10-2023, 08:18
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#56
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 2,828
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Re: LFP maintaining during low load
Quote:
Originally Posted by sailorboy1
No I don't store them as they are always on line and there are loads. They cycle between 80-100% on 95% of days. I bet we really don't know the long term impact of that.
I ran them down to 40% last week by disconnecting solar and later charged back gto 100%. The morning voltage has been higher since. But don't know if it had anything to do with the "cycle" or if it was that I found some loose terminal bolts during that.
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yes loose terminals create higher resistance and fools charging and discharging. Also going down to 40% and 100% and you have a higher voltage already implicates the BMS reclaibrated and your battery was out of balance and the BMS was able to balance that and higher charge it. you didn't state the end of charge voltage, so we cannot know if its fully top balanced now or only partly.
100% SOC stated doesn't automatically mean its fully charged.
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21-10-2023, 08:25
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#57
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,364
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Re: LFP maintaining during low load
Quote:
Originally Posted by CaptainRivet
Also going down to 40% and 100% and you have a higher voltage already implicates the BMS reclaibrated and your battery was out of balance and the BMS was able to balance that and higher charge it. .
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that is nothing but a WAG, I bet those batteries were "balancing" even with the loose terminals as the current flow at 14.4V was so low there wasn't any resistance drop to make any difference
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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21-10-2023, 08:55
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#58
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 2,828
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Re: LFP maintaining during low load
Quote:
Originally Posted by sailorboy1
that is nothing but a WAG, I bet those batteries were "balancing" even with the loose terminals as the current flow at 14.4V was so low there wasn't any resistance drop to make any difference
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you see 14.4V going in but you don't see the resistance between terminal and BMS that gets fooled by that in a drop in. sure they were balancing but if correct or not you and nobody else don't know as your BMS is not communicating that and you don't have access to the cells.
having total higher voltage afterwards implicates that what i wrote happened. due to imbalnce the battery shut off earlier before and due to balnancing and calibrating new could charge higher=higher voltage.
by the way happened to me too but i have a BMS thats communicating all it does and I have access to the cells so could check what happend...and that was the above.
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21-10-2023, 09:20
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#59
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,364
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Re: LFP maintaining during low load
lot of worry about nothing
maybe the only reason the voltage was higher is that the loads had all been turned off for 30 minutes!!!
it is just spinning a story and certainly not a fact
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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21-10-2023, 11:57
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#60
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 2,828
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Re: LFP maintaining during low load
Quote:
Originally Posted by sailorboy1
lot of worry about nothing
maybe the only reason the voltage was higher is that the loads had all been turned off for 30 minutes!!!
it is just spinning a story and certainly not a fact
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Nothing to worry, you asked why and i answered.
30min at 10A is 5AH, thats only visible in the absolute last 1% from 99 to 100% in the steep end of the curve but below 3,45V maybe 0.01V.
Most likely not the root cause.
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