Magnum "Absorb Done' Time vs Amps vs SOC

[Smitty77]

In various posts over the last month or so, I shared that I lost my to me young 5 year old Lifeline X's4 L16's. (Most likely due to multiple years of under charging them. Waiting for some feedback from Lifeline who is looking over my old batteries.).

I've received bits and pieces of input in these threads, as well as some help from a few via PM's and Emails.

Before: I had lived off of SOC. Used the Magnum 'Auto' for charge efficiency. I never altered the size of the AH Bank Size down from when new 800AH's. (I had assumed the combo of Auto and AGM1 logic would account for battery aging.)

I had Absorb Done set to SOC 100%.

Now/Future: It has been suggested that using the Absorb Done SOC may have contributed to an undercharging of the previous bank. So I was going to go with Absorb Done of 3 Hours.

But for my MidNite Classic150 Contoller, I'm using 'Ending Amps' (Which I interpret as being the same as Magnum's 'Absorb Done' of 4 Amps (The proper ending amps for the Lifeline 800AH bank.)

So I'm wondering why I should not use the Magnum Absorb Time, wet to 4 Amps, to reflect fully charged battery bank?

Note: For quite sometime now, I have not had the Solar Controller on at the sometime as the Magnum MS2812. And we have done very little boon docking these last few years, on Shore Power while traveling and or stored next to our garage when not. I mention this, because the Solar was not 'topping off' the bank to full, as it probably had been for the first few years with this bank.

Was thinking that Lifeline Tech Manual shows the bank to be fully charged when it reaches the Ending Amps value of 4A. Would that not trump a set Absorb Done Time of 3 Hour? If it gets to full charge in say 2 hours, great, Float mode. If it was not at 4A at the end of 3 hours, well, then I'd again be undercharging.

Am I thinking this thru correctly? Input appreciated!

Best to all,
Smitty

(800AH X's .5% = 4A)
(MS2812; BMK Meter; SBC; AGS; Temp Sensor. Solar 1200W 48V; MidNite Classic150 Controller; WhzBngJr; Temp Sensor (After going thru a re-review of the Magnum settings. I'll walk thru the Classic's again too.))

Other Charger Settings, as of now:
-Absorb = 14.4V
-Float = 13.4V
-Equalize = 15.4V
-Max Charge = 100%
-Absorb Done = 3Hrs (Time) (Plan to change to Amps = 4A)
-Max Charge Time = 12 Hrs
-Final Charge = Multi
-Charge Efficiency = 92% (For the first few charges of this bank. Once a few cycles of discharge/full recharge are complete - will set to 'Auto')
-SOC Reset (Plan to Reset Quarterly, once I've confirmed Full Charge vs Voltage Readings. This will be rested unloaded, with at the battery multi meter reading)

[CountryFit]

smitty,
i am using the same midnite classic 150, but with a different battery pack.

on the midnite controller, you can and should set both the absorb hours and the ending amps (i set the former 6 hours and the latter at 20 amps). when you don't set hours, in daytime when solar is strong, controller sees a 'floating' voltage higher than float voltage and turns into float mode although you only have 60% soc, for example.

don't worry about too long of absorb hours. when battery is full or near full, the resistance increases, the charging current is diminishing, thus the controller will hit the ending amps and go into float mode safely.

setting absorb hours is under "charge". if you need further info, when i get back i'll look up the path.

[Smitty77]

Thanks CountryFit - May bug you some next week when I review the MidNite Controller settings!

It was the Magnum MS2812 three choice settings for 'Absorb Done' that I'm trying to pin down now. Had used SOC 100% for the majority of the previous battery banks life. Was advised on a few threads to not use SOC to determine when to finish Absorb cycle. I set it to Time at 3 hours. But then I noticed a third choice was Amps. And since Lifeline says my bank would be Fully Charged at 4 Amps, I thought setting Absorb Done to Amps and the value of 4A - would be better then time(?).

(I'll probably cross forum post this, as I'd been getting input from RV.Net Tech section from a few 'seasoned/salty/knowledgeable/colorful' members!)

But wanted to ask here, as know this group has a built up braintrust of knowledge too...

Best to you and all,
Smitty

[CountryFit]

maybe because you are using arc-50 while i am using me-50 remote, i don't see the option of 'ending amps', but only 'absorb hrs'.

i think either 'absorb hrs' or 'ending amps' will work for you, 'ending amps' might be better. it will guarrantee the battery being full before changing into float mode.

[757driver]

Originally Posted by Smitty77

Thanks CountryFit - May bug you some next week when I review the MidNite Controller settings!

It was the Magnum MS2812 three choice settings for 'Absorb Done' that I'm trying to pin down now. Had used SOC 100% for the majority of the previous battery banks life. Was advised on a few threads to not use SOC to determine when to finish Absorb cycle. I set it to Time at 3 hours. But then I noticed a third choice was Amps. And since Lifeline says my bank would be Fully Charged at 4 Amps, I thought setting Absorb Done to Amps and the value of 4A - would be better then time(?).

(I'll probably cross forum post this, as I'd been getting input from RV.Net Tech section from a few 'seasoned/salty/knowledgeable/colorful' members!)

But wanted to ask here, as know this group has a built up braintrust of knowledge too...

Best to you and all,
Smitty

Smitty,

If you have DC loads that come directly from the batteries Magnum does not recommend using ending amps for terminating the charge. In order to use ending amps you would also have to set it up as a CC/CV charger and I think that you might better off with Bulk/Absorb/Float and set the Absorb time to 3.0 hours.

[Smitty77]

The reason I'm looking at the Absorb End of Amps setting vs Time, is because on Saturday during my first charge of the new bank of L16's - Absorb End was set to Time and 3 hours. But, while monitoring every 45 mins, at 2 hrs 15 mins it was already in Float mode? Why 45 mins early shut down of Absorb Time 3 hours? (I did have Battery Efficiency set to 92%, but from reading the Magnum manual, I expected that if anything - to increase the AH's being added back into the Bank(?).) And nowhere could I locate that Absorb End Time value would be overridden by anything else?

So, I went down the Absorb End option of Amps to see where that would take me...

I had already sent a list of questions to Magnum, and this is one of them. The usage of Absorb End Amps vs Time setting...

So will be interested to see their answer too!

Appreciate the input,
Smitty
(And note: Asking lots of questions here, and elsewhere, lately. I do usually use Google Search to see if I can answer these myself before posting. Many times I do, via RV board postings, off grid postings and or boating community postings. But sometimes I don't find answers, or understand them!!)

[Smitty77]

I neglected to comment on the DC load when using Absorb End of Amps.

Having just replaced the old bank with the new bank, I can positively state that the House battery Negative is only going thru the Shunt. So no direct to the battery loads.

I also looked, and have not yet determined what "CC/CV" stands for? (Probably because my eyes are becoming a little fatigued from research and reading!)

And a comment on CountryFits post. As I recall, you as did 757driver, took the leap to Lithium house batteries(?). And as I understand it, one of their benefits is that they are not bothered by no reaching a Full Charge at least every 3-4 days(?). Where as AGM's are probably the most finicky of the battery types on needing a Full Charge to avoid sulfation build up.

Until I hear back from Magnum, I've reset Absorb End to Time = 3.2 hours for the 800AH bank. A bit on the high side of their time chart 3.2, but again I'd rather be on the high side then the low side of Absorb cycle. (And, still puzzled why a 3hr Absorb Time would flip to Float at under 2 hours and 15 mins? Dang if I could find any other setting or write up in the Magnum literature that explains why an Absorb End Time value would be lowered(?).)

Best to all,
Smitty

[CountryFit]

hi smitty
a few comments on your last post -
(1) cc/cv = constant current/constant voltage. it's one of the charge profiles on magnum (and other advanced inverters). the primary audience is lfp, not quite fit for la/agm/gel types. used it on my lfp charging but now i changed to customized bulk/absorb/float for a better result.

(2) too-soon-to-float -
when battery is under charge, there are a few volts in play - charging volt, floating volt, and rest volt. the last one reflects aproximately what your battery real voltage is. floating volt is surface volt; during charging it is always higher than rest volt by a few .1v's. your magnum does not have a tool to distinguish these two. when you set float volt at 13.6v, the floating volt will hit this number sooner than it should, thus magnum prematuarly turns to float mode

to resolve this, i'd suggest reaising your float value to something like 14v.

(3) lfp -
you are correct - lfp does not care about full or fractious charges. i have been using my lfp since 2014, and yet seen a capacity decline (unless analyzed on a lab workbench i guess).

hope this makes sense...

[Smitty77]

Updates:
-I have not heard back from the Magnum Tech I emailed with my questions. So later today I'll just call in and ask for Tech Support and see who the assign me. (Possibly this Tech I've worked with before has left the company, or maybe remembered my questions about SBC from before - and did not want to get involved with me again!) (I could understand that...)
-I have Absorb Done set back to Time pending more info from Magnum. The first two cycles of drain some and recharge starting with Bulk, I set Absorb Done Time to 3.2 hours.
-At the end of a few of those drain and charge until seeing either Full Charge on the Status, or Float and SOC at 99-100% - I set of a Equalize run. I have the Custom setting for Equalize set down to 14.4V.
-I stopped that Equalize charge at a little over 3 1/2 hours, out of the 4 as default. I now considered my new bank of L16's to be Fully Charged. Reset Total AH's to now start my baseline with this battery bank. I have Charge Efficiency set to Auto now.

This was three days ago. And I've left the coach plugged in, and the Charger in Blinking Standby mode. Each day I've gone over and seen the Status of Full Charge, and a battery voltage that supported Lifeline's chart of Full Charge 12.8V, this is a under slight draw voltage, not at rest. So the voltage should be a bit higher then this displayed value. Also, BMK-Meter indicated 12.83V (Rounded down to the 12.8V of the Status screens value.).

But also each day, the SOC value was dropping, until today it indicated 81% SOC, and AH's out match that too.

I'm used to seeing the SOC maybe drop down to 95-96%, and then the Float would kick into maintain the battery level until it was back up to the 100% range.

I'm puzzled as to what setting I need to tweak on the ARC-50 to not have the battery SOC go down so low, before the Charger kicks back in? (Dang if can spot in the various manual, which setting controls when the Charger comes out of Standby?)

And another observation. My Charger Setup for Battery Type is now Custom, due to the slight change of a higher Float rate recommended by Lifeline. (Magnum said I'd have to swap out a Control board to have the AGM1 setting with that slightly higher Float voltage. I have Custom set to 13.4V.). I mention it's not set to AGM1 but on Custom, because the AGM1 battery type setting is the only way that I could see that the unit would know the Full Charge values associated to a Lifeline battery. Lifeline voltage values are different then other AGM or Wet batteries. With Absorb Done now set back to 3 hrs, vs Amp an 4 Amps (For my 800 Amp bank.) - What is it that the unit is looking at to indicate Full Charge status. Voltage? SOC? Combination?

I elected after three days of watching the SOC draw down, to not go any longer. I could have gone out and removed power, and the plugged it back in again, to restart the Charge cycle out Standby mode. I elected to again use the Equalize at 14.4V to get SOC back up to 100% instead.

I have some setting 'Off' on this unit. I've added another question to my list when taking with Magnum Tech Support, on if I need to do any other 'reset's of other components' (AGS, BMK, SBC, MS2812 itself, Etc.) after having all voltage removed during the battery swap out.

And of course, I've not started my review of the Solar Controller settings yet, until I pin down the Magnum. So the Controller remains off, and by the way, it too reflected 81% SOC today.

Best to all,
Smitty

[757driver]

Smitty,

Do you have solar panels and are they active?

What is your final charge set to? If final charge is set to Multi then your charger will go into sleep mode, show full charge on the display and not turn back on until the voltage drops to 12.6v or less. Once the charger comes back on it will only come on in Float mode at a trickle charge and only for 1 hour. With most AGM batteries the 1 hour is not long enough to bring your battery bank back up to full charge because of the higher voltage AGM batteries sit at. If you do not have a significant solar array I would switch final charge to float.

[Smitty77]

Controller is Off until I review the Midnite's settings to.

Final is set to Multi.

So 12.6V is the wake up to come out of Standby. Do you know is this the same on AGM1 setting for Lifeline? Hopefully Magnum would adjust this from the AGM1 being chosen? (Which mine is currently not set to for Battery Type).

Finishing Float when solar is off is a good tip. But wow, from 81% SOC, Float would take along time.

Looks like I'll need to depend on the combo of Magnum and MidNite to maintain this bank. Even when on Shorepower when in storage . And that to me is strange. Or, more regular intervention by me to do a 14.4V Equalize run periodically, if only using the Magnum.

Thanks for the info, again!
Smitty

[hclarkx]

Smitty, I'd be interested in what you experience with the SOC reading. If you charge the battery through a full proper charge cycle you may notice that the SOC reading hits 100% before the charge cycle is complete. If so, that means that the SOC reading has drifted and was reading low before the charge cycle occurs. I there was a recent charge cycle, the drift should be modest, but I've found that charging with solar, when a full charge is not reached for a week or two, my SOC reads low going into the next full charge cycle. I suppose the SOC reading could drift down, but mine seems to drift up causing me to discharge to a lower level than I want to when dry camping in inclement weather.

[Smitty77]

I believe my SOC should be accurate. This is a new replacement bank of X's 4 L16's Lifelines for 800AH's. My initial three battery draw down, and charges, followed by 3 1/2 hours of using MS2812's Equalize set to 14.4V, should have brought the battery bank to Fully Charged. And at that time, I did reset to show 100% SOC. Charge Efficiency of Auto, should also over probably the next 10-15 cycles let it learn more about this bank.

Suppose because the three days after the full charge and reset, was the first time for Charge Efficiency Auto to see things, it could be distorted. But I looked at the 81% SOC and did the math on the AH's Out number compared to 800AH size bank - and it came out at 81%.

The part that confused me, and that 757Driver gave me some info on, is why the Charger on Standby had not kicked in during these three days, well, two full days, it was the AM of the Third day when we reached 81% SOC. But the BMK Meter reading of voltage at basically at idle, was 12.83V. Above the 12.6V indicated by 757Driver before it would have kicked into Float.

I've added questions on my list of now 7 items to review with Magnum, which due to DW's scheduling demands on my time (Which we all know take priority!), I did not get my call off to Magnum on Friday. So on my list of to do on Monday.

I've turned back on the Solar MidNite Classic150 controller until I talk with Magnum. It is set to work off of the WhzBngJr module and use Ending Amps (Set to 4Amps.) to finish charging. And for now, I've kept the Magnum Finishing set to Multi, pending conversation with Magnum.

We're not heading out again until mid June, so OK for me to go slow but steady with this.

Best to all,
Smitty

[C.Martin]

I use the CC/CV with my Flooded Lead Acid batteries...

Constant Current is like bulk charging, Constant Voltage is like absorb charging. The difference is...this is THE method that takes advantage of the ME-BMK. It actually monitors the amperage going to the battery thru the shunt and adjusts the charge to your desired CC amperage. It can compensate for having multiple charge sources. If my Solar happens to bulk the exact same time as my MS2812 (not usually the case)...and let’s say Solar is putting out 30amps...my maximum desired Charge Amperage is set for 95...the MS2812 output will be limited to supplying 65A...so that when combined with Solar it will respect the 95A ceiling.