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 > Lifepo4 float setting?

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jaycocreek

Idaho

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Posted: 05/04/22 08:38am Link  |  Quote  |  Print  |  Notify Moderator

I have not had to deal with a float setting so far with PWM controllers but I have a Victron 75/15 coming tomorrow and reading up on the settings,it is confusing especially the float setting..Some say float will shorten the life of a LFP battery and others say hogwash..

Float at what setting for a 100ah LFP battery that settles at 3.3+..?

Any input welcome...


Lifepo4-380ah/Lithium NMC-140ah/Solar-400 watts/Wagan & Giandel PSW/Engel & Iceco 3-1 compressor fridge freezer/5K Window AC/Honda 2K

2oldman

NM

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Posted: 05/04/22 08:40am Link  |  Quote  |  Print  |  Notify Moderator

Shouldn't the battery maker have that info?

jaycocreek

Idaho

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Posted: 05/04/22 09:00am Link  |  Quote  |  Print  |  Notify Moderator

2oldman wrote:

Shouldn't the battery maker have that info?


For this particular battery,there impossible to communicate with and the reason why I did not buy another one of there batteries when I needed another..The battery I did get instead of there brand says float 13.8 which is higher than recommended everywhere I look..

I don't think some of these cheap batteries have very good customer service,some do,some don't.

2oldman

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Posted: 05/04/22 09:02am Link  |  Quote  |  Print  |  Notify Moderator

Then I wouldn't bother floating it. It's a miniscule amount more charge and Li's don't care if they're fully charged.

Itinerant1

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Posted: 05/04/22 09:09am Link  |  Quote  |  Print  |  Notify Moderator

It's been said a bunch...pick your posion. Are you cycling them daily or storing the trailer for awhile then using it?

It will interesting after a 2-3 years with many new folks getting lfp what the survival rate will be of said batteries. With so much mixed info being regurgitated of how to use (charging, absorb, float) the batteries.

As long as you can get the cells to balance and have your SOC meter sync to the capacity of the battery bank occasionally life should be good.

What voltage is need for "your" batteries to accomplish this?


12v 500ah (5,120Wh usable), 20 cells_ 4s5p (GBS LFMP battery system). 8 CTI 160 watt panels (1,280 watts)2s4p,Panels mounted flat. Magnum PT100 SCC, Magnum 3012 hybrid inverter, ME-ARC 50. Installed 4/2016 been on 24/7/365, daily 35-45% DOD 2,000+ cycles.

BFL13

Victoria, BC

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Posted: 05/04/22 09:23am Link  |  Quote  |  Print  |  Notify Moderator

Don't see what PWM vs MPPT has to do with it. The battery doesn't care--solar is solar. Voltage goes down every night, which sort of counts as floating for any type of battery, depending on the scenario.

The concern over float voltage with LFPs seems to be more with converters left on for long periods. With solar, float voltage settings should also depend on the scenario? Is this just for when camping or for when the RV is sitting at home for long periods?

If the latter, the usual story is run the LFP down to 50% SOC and disconnect. Get your 12v from the converter.

While camping off grid on solar I guess it depends on how many days/weeks in a row and whether you get to full charge or not and even when during the day that is. It still gets dark at night though.


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jaycocreek

Idaho

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Posted: 05/04/22 09:35am Link  |  Quote  |  Print  |  Notify Moderator

Quote:

Don't see what PWM vs MPPT has to do with it.


With both of my Renogy PWM controllers,the float is not adjustable,it is preset to what the boost is which is adjustable..It appears with the Victron,float is adjustable as well as some other parameters the PWM will not let the user change..

I guess I could just leave it at the Victron lithium pre-set but was looking for the best settings for a generic LFP battery..Battleborn has all the recommended setting for there cylindrical cell battery and the Victron controller but I would think there is a difference in cylindrical and prismatic cells as small as it may be..

jaycocreek

Idaho

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Posted: 05/04/22 09:40am Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

It's been said a bunch...pick your posion. Are you cycling them daily or storing the trailer for awhile then using it?

It will interesting after a 2-3 years with many new folks getting lfp what the survival rate will be of said batteries. With so much mixed info being regurgitated of how to use (charging, absorb, float) the batteries.

As long as you can get the cells to balance and have your SOC meter sync to the capacity of the battery bank occasionally life should be good.

What voltage is need for "your" batteries to accomplish this?


I am cycling daily..That battery is getting 24hr useage running the TC and compressor refer..I suppose I would just turn off float if it was possible...But not being possible,I am looking for the best setting if there is such a number..My guess would be for this battery somewhere around 13.3 and 13.5?????

Lwiddis

Owens River area

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Posted: 05/04/22 09:44am Link  |  Quote  |  Print  |  Notify Moderator

I don’t float my Lithium battery nor do I store it at 100%. The gel battery setting may work.


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pianotuna

Regina, SK, Canada

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Posted: 05/04/22 10:02am Link  |  Quote  |  Print  |  Notify Moderator

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

If I had LiFePo4, and wanted MAXIMUM lifespan, I'd charge to 85%, not go lower than 40%, and disable float. If that is not possible, I'd float at 13.2. Unfortunately I can't use LiFePo4


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

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