LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[Maine Sail]

Originally Posted by dlentz

My balance is running from 5mv across the cells while under load to 50mv when nearing 13.8 on the pack. It's not changing, I would suspect I didn't top balance as accurately as you might have. I initially charged each cell to 3.7V and when the acceptance rate drop to +/- 1% (7 amps on my 700A cells) I called it good. While in theory it'd be nice to have all of the cells identical, I'm thinking as long as one cell isn't going too high while charging, there's little to no harm with slight imbalances. (I hope that doesn't cause a big stir.)
Again thanks for your work, it's providing real world House Bank data that doesn't exist.
Dwain

I top balance by wiring the cells in parallel and charging to 3.8V as a parallel pack. It needs to be watched carefully and you need a power supply to do this but it is pretty easy.


Personally I think every boat owner should have a power supply for home charging use..... I don't even use "battery chargers" in my shop at all.....

For parallel top balancing you will want a 30A or larger power supply as the bank gets VERY big.. This is 1600Ah @ 3.4V....... I own 50A, 30A and 5A power supplies and they all get used quite frequently....

[deckofficer]

As per Maine's suggestion over a year ago I also bottom to top balanced using the variable PS he recommended, and it was a good price too. My cell voltages have stayed tight since the balance.

[dlentz]

Originally Posted by deckofficer

As per Maine's suggestion over a year ago I also bottom to top balanced using the variable PS he recommended, and it was a good price too. My cell voltages have stayed tight since the balance.

I also have a V PS. Found one locally, Circuit Specialities, 25A to 15V, under $100. My bank has been in use for about 9 months now and I would call my balance "good".
For discussion sakes, define "tight". And where and why would you (everybody) consider a "rebalancing" necessary. Again just for discussion as I don't believe there is any real use data on this.
Dwain

[deckofficer]

Dwain,

I had to balance because my new cells were 3 years old from the supplier. Tight is 3.32 to 3.34 volts.

[dlentz]

Originally Posted by deckofficer

Dwain,

I had to balance because my new cells were 3 years old from the supplier. Tight is 3.32 to 3.34 volts.

Mine were also "clearance cells". I'm totally convinced an initial balance should be done or a least verified, but when would you think about redoing a balance? So 20mv at what state? charged and sitting? under load? or? Again I'm just curious, I don't believe there is a right or wrong here.
Dwain

[deckofficer]

I have two 12 volt banks, that one has sat for 8 months. From Maine's results to date I don't think a rebalance will be needed for many years.

[steelwrk1]

Hello,

The below is specific info directly related to my LiFePO4 House Battery bank, I have copy pasted from this site on "Solar Power and Battery Monitor Shunt Questions ''

I think it is important to understand, if not fully then enough to begin to study it and apply ...Thanks to Stu Jackson and Maine Sail as well as others

Originally Posted by Stu Jackson

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

Link-series Charging Algorithms -- The "Gotcha" Factor!

DEFAULTS are factory settings that are made to be modified to suit your setup.

Thank you Stu and Maine Sail and others,

This explaines the different 100% charged readings I get from My Victron BMV 600S Battery monitor and the Elite Power BMS read out of my LiFePO4 Batteries house bank.

I noted a difference (the longer I stayed away from a dock connection or ran my genny to fully charge my house bank ) between the Victron mounted in my pilot house and the Elite display mounted right next to the house bank in my master cabin. I had no idea why the difference and a self correcting problem ???? made it more challenging to understand.

I came to rely on the Elite Power BMS ( EPBMS) and recorded as much as a 24 % difference with the Victron showing 30.6 % SOC and the EPBMS showing 55% capacity.

At the opposite end I had the EPBMS displaying a 82%% capacity and the Victron displaying 100% SOC at the worst extream during the cruise.

Not being electrical by experience I was concerned as this was in my first weeks on cruise with my new to me LiFePO4 Batteries.

With 1260 amps of House bank and 1000 amps programed as my usable bank, I was always safe re over and undercharge.

I can trick/force , connect or disconnect a second 80 amp charger to top off my bank manually and did not under stand the correction of the Victron "SOC" to be within a few percentage points of the Elite Power System "Capacity's" display after I had been on shore power for a while or topped off my batteries to full charge ( 3.55 volts each )

My ultimate certification that my house bank is fully charged is my top end bleeding off boards (Elite Power Systems stand-alone cell balancers # BL40 ) that show a red light when individual cell voltage goes over 3.55 volts. and they begin to bleed off charge to allow the slower cells to catch up and all become equal. When I begin to see these come on I monitor the second charger and am sure to shut it off if I had just " fooled it by turning it off and on " and it is putting out too much amperage for the little boards to handle.


I still do not fully understand all of this , but will re read , study and use this knowledge next season to get a better use of my Victron and want to THANK YOU for this important info.

Again TKS Maine Sail and Stu Jackson as well as others who posted this in the other forum....important info for LiFePO4 batteriy monitoring

Best Regards,
Pete

[Singleprop]

Here is a good lithium story from a RV'er.
He is using Victron and Elite Power Solutions.
A Year On Lithium | Technomadia

[campr]

Interesting picture/article from an overcharge of LiFePo cells here:
lithium & solar power LiFePO4, LFP cells will bloat if overcharged The photo...

[T1 Terry]

:lol: it's those new banana cells. Why weren't they strapped as well????
As far as determining when to do a balance, then the charging current is low and the majority of the cells are over 3.45v and you have difference of 150mV between the highest and lowest, then just charge up the lowest till it matches the highest. use a sensible end of charging voltage if you want a long life from your cells, regular trips over 3.6v or even staying at 3.6v for any length of time will result is a shorten cell life.

T1 Terry

[careka]

Originally Posted by Maine Sail

I top balance by wiring the cells in parallel and charging to 3.8V as a parallel pack. It needs to be watched carefully and you need a power supply to do this but it is pretty easy.


Personally I think every boat owner should have a power supply for home charging use..... I don't even use "battery chargers" in my shop at all.....

For parallel top balancing you will want a 30A or larger power supply ..

Afther being reading these 202 pages more then once
it looks like it is not an easy job to have these batts in our boat, looks like a set of Gels gives you a lot less work.
or am i wrong.
----

[Wraith_Mac]

Originally Posted by careka

Afther being reading these 202 pages more then once
it looks like it is not an easy job to have these batts in our boat, looks like a set of Gels gives you a lot less work.
or am i wrong.
----

I think you're wrong but some things I find simple others don't.
MaineSail and a number of others go into quite a lot of [much appreciated] technical detail to document the development of LiFePO4 house banks because they are conducting research not just saying "shove them in and go".
They have a professional duty of care and would need that documentation to support their work, we are fortunate it is shared here.
Even AGMs and FLAs have a methodology to their installation, use and care. A fact that seems to be conveniently overlooked on a recurring basis as are the catastrophic failures that often occur with LAs wherever their used.
Of course there are still those that argue that LA is a safe tech and doesn't have to be protected from under or over charging despite the evidence.
Here's a link to an installation that's simplicity itself:
Lithium Batteries
Research your own costs as those quoted are now outdated, as are those of Frank Taylor whose had them in for over 2 years now, full time cruising with no 'extra special' equipment.
Lithium Ion Batteries for Boating | Tahina Expedition
Cheers,
Mac

[goboatingnow]

Originally Posted by careka

Afther being reading these 202 pages more then once
it looks like it is not an easy job to have these batts in our boat, looks like a set of Gels gives you a lot less work.
or am i wrong.
----

The last thing you want is Gels, tricky finicky cells

Dave

[careka]

Originally Posted by goboatingnow

The last thing you want is Gels, tricky finicky cells

Dave

OK:
i still have my original led/acid onboard, but was hopping these new once will be easy to install, and maintain, But now after reading al this it looks like you have to do a lot with then, check this and that. i want to have something that needs to lowest , or lessest work from my side. and still be dam good. i can pay for it as long as it keeps me happy
Don't want anything that needs to be looked father al the time. i want to sail and have my anchor drink, and enjoy life

[deckofficer]

careka,

Wraith_Mac took all the mystery out of this and for others that don't want to wade through 202 pages, his link, which I agree with the Aussie sales agent, for our size banks forget the BMS. Lithium Batteries