Lifeline Charge Efficiency Setting

[gkerlin]

My lifeline AGM's Manual does not list a charge efficiency.   (95%...  96% etc)

The Classic 150 asks for a value and I've been using 97% but am wondering what others who have more experience with the controller and Lifeline AGM Combo are using.

I have a Magnum Inverter in my RV with the Magnum Control Panel and shunt.   The Magnum was set on "Auto" for charge efficiency where it "learns" how the battery charges.   It seems my local app tells me I'm back at 100% while the magnum says I have another 5% or so to go.

Wondering if I should trust the Magnum or the Classic with the Whizbang.

I've got a 900ah 12v Bank in a Motorhome.  A classic 150 and 1120w of Panels.

[ClassicCrazy]

I would set it lower - like 94% or even lower at 90% .
If you have it set lower than actual efficiency that will just mean that you always have a little bit of reserve compared to what the SOC says.
And as batteries age their efficiency goes down too so you can compensate for that and get used to their decreased capacity ahead of time.

You won't ever be able to really tell where your are batteries are at with AGM. I mean with flooded lead acid you can test the specific gravity of the electrolyte and see how well it corresponds with when whatever meter you are using says they are 100% . But you only can go by voltage with AGM so you just have to trust that. And I can tell you from my experience with smaller AGM that the voltage is not always a good indication of their true capacity when they get older.

Larry

[Westbranch]

I just searched for  " lifeline AGM  capacity test", went here due to the specific reference to a capacity test in the short description :

A load test and/ or capacity test can determine how severe the damage may be ...

http://www.lifelinebatteries.com/marine.php

I scanned to the bottom of the page, and there is a (sort of ) reference to recharging a dead (8V) battery..., because that is what the capacity test will do, take it to the bottom !
then there are a list of links that may be helpful

ADD:  if you want the 2 sensors to match, lower the Classic's but 1%  a time until they match...

[Resthome]

Like Larry said lower it to 94-95%. 97% is way too high.

I matched mine to my Link10 battery monitor which is defaulted to 90% so I set the Classic to 90%.  You typically have to put back in 10% more AH than you took out to really get the batteries to 100% SOC.  At least that has been my experience with my set and they are 3 years old.

[RossW]

I would set it lower - like 94% or even lower at 90% .

Agreed. My old AGMs (500AH/2V cells, 24 in series per bank, two banks in parallel) - seemed to be close to 90% after 5 years.
My 300AH LFPs are showing 97.9% after a little over a year of constant hammering.

[ClassicCrazy]

My lifeline AGM's Manual does not list a charge efficiency.   (95%...  96% etc)



Wondering if I should trust the Magnum or the Classic with the Whizbang.

I've got a 900ah 12v Bank in a Motorhome.  A classic 150 and 1120w of Panels.

Also keep in mind that the Classic  temperature compensates the SOC based on battery temp - a lot of other meters don't do that so they may never read the same for that reason too.

Larry

[gkerlin]

Thanks for the replies thus far.

I understand more amps need to be returned vs removed.   Lifeline says between 102-110amp for a 100 amp draw.  That would be an efficiency between 90 and 98% depending on all the factors that influence that including battery condition.

Why I tend to think my setting might be ok however is this:

Lifeline Technical Manual says to end absorb when current in is .5% of bank capacity.  It also says the battery if fully charged when it will only accept that .5% of rated capacity.   On my 900ah bank that is 4.5amps.   I have the whizbang set to end absorb at that amount.  Lifeline says the battery is fully charged at that point.   My Local app says 100% charge when I go to float like it should.   My magnum says I'm less than that.

[ClassicCrazy]

It is nice that they give you those ending amp specifications.
On a flooded lead acid battery you would check the specific gravity to confirm the ending amps and 100% state of charge.
Of course that is not possible on the AGM .
The more deep cycles you do - the less lifespan your batteries will have. I never like to take more than 50% out of mine before I recharge for maximum battery life.
With a lot of 12v batteries in parallel configuration it is easier for some cells to get unbalanced. It is best to make sure you have them wired up in a configuration so that you try to eliminate that happening as much as possible. There was a good diagram I saw somewhere and if I find it I will post it for you.
Not sure if this is the one I saw before but it has some wiring schematics - look down to the one that says balanced draw.
http://rvroadtrip.us/library/12v_system.php

here is another way - not sure which is best
http://www.trailerlife.com/wp-content/uploads/2010/04/25667d06-f2d7-4c70-9f42-ebb613d74295.jpg

[Resthome]

  My Local app says 100% charge when I go to float like it should.   My magnum says I'm less than that.

You want to look at the Net AH to see if it is positive when it goes to Float. The 100% SOC is programed to go to 100% as soon as it goes from Absorb to Float. SOC on a Classic doesn't take all factors of battery charging into account but it does pretty well considering.

[Westbranch]

Should ask, How old is the bank? 
Have you ever done a conditioning charge?

from the above link, Trouble Shooting section

Checking the open circuit voltage should be step one. A fully charged new 12v Lifeline Battery will have a resting voltage of 12.9v or greater. If the battery won’t return to a full charge through normal charging procedures it may be sulfated and require a conditioning charge. (see technical manual)

hth

[Cniemand]

Ross : As a fellow LFP guy, how are you determining 97.9% Efficiency? I ask because the Classic is in 1% increments.

[zoneblue]

I imagine thats because Ross has extensive data logging going on.

Out of curiousity an sql oneliner for the agms here yeilds:

Code Select Expand


select
    count(*),
    sum(ahdischarge),
    sum(ahcharge),
    sum(ahdischarge)/sum(ahcharge)
from classicdaylogs
where date_created < date(now()) -- today (incomplete) will muddle the math

count(*) sum(ahdischarge) sum(ahcharge) sum(ahdischarge)/sum(ahcharge)
------------------------------------------------------------------------------------------
595 26082.700000000015 26890.30000000001 0.969966865375247


Which is surprisingly high considering this bank spends almost all its life in high states of charge. I was expecting worse. Those recombinant catylysts must actually do something.

[Cniemand]

ZB : If we are taking efficiency simply from what is taken out relative to what needs to be put back in to meet 100% SOC.... (Which makes sense to me mathematically)  I run into a question.

On my local app I show 3161 kWh Total for the entire time of having my system up since June 2013. (Most of its lifetime I used 2-3 kWh/day rather than its potential of 8-10)

I have only owned a WBjr for a couple months now. If you go to the WB page on the MNGP and click the more soft key you get a screen listing aH + and aH - . That screen lists 2839+ and 2801- respectively.

How is it deriving that data? That is : BEFORE WBjr I had a tally of probably 2700 or more and only 400-600 kWh worth on the WBjr.

I cannot see that the Classic itself would have any means (without the WBjr) to figure out what is leaving the battery. Only what it has placed in....

[zoneblue]

Not having a MNGP, bob would be able to say more definatively, but my recollection is that those plus and minus amp hour figures only started when teh WBJr and its matching firmware came along. So that probably explains why they are much less than your overall watt hour production. That being the case you ought to be able to divide those out similarly... maybe. Unless you had the firmware but not the WBJr for some of that?

Its actually an interest of mine, (charge effciency) and ive got all the parts to build an automated battery cycler, an AGM, some LFP, and various other lithium chemistrys waiting to do a comparison. Particularly i want to explore how SOC range effects charge efficeincy in both FLA and AGM.

[Cniemand]

I've had firmware that supported the WBjr for some time. Just never had the WBjr itself but for the last couple months.


Side note: ZB, Do you still believe in a rapid adoption of Solar by 202X -2030? Your "Kurzweil" prediction.