Magnum MS2812 'Absorb Done' settings

Hi All,

I've my replacement X's 4 Lifeline L16's installed in the coach.

Lifeline has been just top notch to work with during this adventure. And are doing sort of a post mortem on my old bank - expect to find I heavily sulfated them. Regardless, good not have worked with a business that cares more about helping a customer. Helping learn what they can do better the next time around. As well as helping me on the replacement of the slightly out of warranty bank. Salute!!

Recapping on my previous battery bank. I'd lived off of SOC the full time I had the bank. Using the MS2812's Efficiency Setting of 'Auto'. With periodic 'reset' when I knew the battery bank was fully recharged (Well should say 'thought' the bank was fully charged.)

It's been suggested to me in various threads, that using SOC may not be the best way to determine when the battery bank is fully charged. It's one of the tools in the tool box, but should be used/crossed referenced with other measurements too.

--------------=============

My question. The MS2812 Control Panel has 'Absorb Done' settings of SOC, Time or Amps.

I'd changed this setting to Time of 3 Hrs about three weeks ago. But with the new bank, I'm reviewing all settings again.

Since Lifeline's Tech Manual indicates my battery bank will be Fully Charged when Ending Amps reach 4 Amps (800AH's X .05%) - I'm wondering why not setting the 'Absorb Done' to Amps and a value of 4 Amps is not a better way to go then Time?

Would appreciate any opinions or input on this...

Also, as info, below are some of my other related charge settings.

Best to all,
Smitty

(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.) All feeding the care of 800AH House and X's 1 Lifelike 8D Chassis.)

Other Charger Settings, as of now:
-Absorb = 14.4V
-Float = 13.4V
-Equalize = 15.4V
-Max Charge = 100%
-Absorb Done = 3Hrs (Time) (May 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 a rested non load battery reading with my multi meter.)

pianotuna
Nomad III
Apr 01, 2018
I did not worry about amperage. I did reset voltage to the middle of what the surplus acid telecom jars recommend. I do have the temperature compensation probe and two nights ago voltage got to 15.5 due to cold weather.

Occasionally, when the battery bank was "hungry" I've had to limit charge amperage to 108.
full_mosey
Explorer
Apr 01, 2018
Smitty77 wrote:

...

Since Lifeline's Tech Manual indicates my battery bank will be Fully Charged when Ending Amps reach 4 Amps (800AH's X .05%) - I'm wondering why not setting the 'Absorb Done' to Amps and a value of 4 Amps is not a better way to go then Time?

Would appreciate any opinions or input on this...

You need to add the parasitic draw to the 4A. E.g., if you run a satellite receiver that draws 3A while charging, your charge cutoff would be 4+3=7A. I wonder how long that would go on charging.

HTH;
John
BFL13
Explorer II
Apr 01, 2018
Yes, use the amps. With AGMs you leave the charger at Vabs (by battery spec) until amps taper down to near zip, then go to Float. Time to get to there is a variable, doesn't matter how long it takes.

If you set the amps higher to account for loads, then it will be set too high if the loads are not on. If loads will usually screw things up at that point, you could split the bank and finish half properly while the other half does the loads, then swap. Once both halves done, you can go to Float on all. (Maybe have one of those "1,2, Both" switches in the set-up?)
landyacht318
Explorer
Apr 01, 2018
Amazing how in the quest for automatic, function is compromised to the degree it is.

Unless the magnum has its own amperage measuring device, seeing what the battery is accepting, then end amps can never be programmed correctly as any loads on the battery will throw it off.

My manual adjustable voltage charger becomes more and more simple. Watch ammeter, twist dial accordingly.

I also do not see any possible use for a charger, which is completely guessing as to state of charge, allowing the option to stop charging at anythig other than what it tinks is 1005 state of charge.

gee, no, 92% is just fine, stop charging there.

I don't know how you are going to achieve it, but if you want these batteries to get fully charged, hold absorption voltage until amps INTO the 800 AH of batteries, tapers to 4.
pianotuna
Nomad III
Apr 01, 2018
Turned off Magnum charger. 1.6 amps @ 14.2 volts from Blue Sky with float light flashing. Plugged in for 7 days. 556 amp-hours of battery bank.
Smitty77
Explorer
Apr 02, 2018
Well, gee, surprise:)! More input revealing what I did not expect:)!

Magnum is a pretty well known and popular supplier of Inverter/Chargers/And now, Controllers. The Magnum family BMK-Meter module added to the mix, is even more finite of info and options for battery management.

So, as I read the few posts hear indicating that battery load plays, or could play, a roll on the end results of using 'Absorb Done' Amps option - it did surprise me:)!

Seems I need to add a call to Magnum Tech Support and ask some questions:

-If I have a load of say 7 Amps on the battery bank. And I want the Absorb to End at say a 4 Amps value - do I need to set it to 7, or 4 Amps? (Is the BMK sophisticated enough to calculate a draw in the determination of reaching the 4 Amps level.

-And if the answer is yes, use Absorb Done value of 11 Amps in this example. Well that makes the Absorb End by Amps value relatively meaningless for my usage. (No way I can predict when the Fridge will be on, or while living in the coach other draws are on too. It's not like it will be parked with no electric activity in the mix. And, if I do have the Solar Controller on, that too could complicate the actual determination of the achievement of the MS2812 reaching the pushing in of a 'Tapered 4 Amp' level.)

-My expectations, and perhaps wishful thinking, is that the MS2812 along with the BMK are only going to look at the combo of Voltage & Amps being pushed into the battery from the Charge side of the MS2812. My hopes, are that it would ignore say a parasitic draw of 7 Amps, in this example.

-If this is wrong, well then I suppose 'Absorb Done' setting by Time would be the way to go...

More homework ahead, and sorry, another follow-up question on Magnum too:)!

Best to all,
Smitty
full_mosey
Explorer
Apr 02, 2018
Yes, time based charging is best for automatic charging while the bank is being used.

Manually controlled charging will do better because someone is watching the charging as it progresses and can assess the real-time status.

What I do is use the programming capability of my Morningstar SunSaver MPPT 15L solar controller to vary the length of the Absorption stage for the day.

At each sunrise, the controller performs a startup process. One thing it does is note the overnight low Volts(OLV) of the battery.

I use three settings for Abs:
1. OLV < 12.4, Float is cancelled and holds ABS
2. else OLV < 12.6, 4hrs Abs
3. Otherwise, 2hrs Abs.

I can look at a graph to see if I need to take corrective action.

Explained HERE

HTH;
John
MEXICOWANDERER
Explorer
Apr 02, 2018
Hope this posts...

14.40 volts Reach .5% for 10 minutes duration GREAT

14.40 volts Reach .5% for 2 hours duration GREAT

This is NOT sensitive! Just for fun I left a charger set at 14.40 volts OVERNIGHT on a Lifeline

Ambient Temp 67F

Terminal post temp 70.7 F

Delta T 3.7F

Set your gizmo's menu for plenty of time to insure the amperage will sag to one half percent.

Then go have fun.

Or maybe my seven-year-old Lifeline and 2 year old Lifeline cannot understand English. The 7 year old revealed a 103% capacity test in October.
BFL13
Explorer II
Apr 02, 2018
With a monitor like a Trimetric that only shows the amps to the battery, not the other amps, there would be no problem here.

The OP's problem is that his Magnum monitor (or display) seems shows all the amps it makes. Similar to a solar controller's output amps--not all go to the battery. (The Kidd whizbang is supposed to separate those if fitted, but with the shared shunt, it could be getting mixed up --I suspect the installation of all that is "problematic". )
Smitty77
Explorer
Apr 02, 2018
I wanted to thank you all for your input on this question.

I did also get the following feedback from Don (757Driver) on IRV2:

"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."

Which is similar to the feedback here too.

I think what throws me off about all of this. Is my first charge of the new Bank of batteries, installed on Saturday. (I first ran the oven and 1500W heater for about 20 mins to remove enough Amps to lower the batteries down to kick into at least Absorb mode.)

I had the Absorb End set to Time = 3 hours. And after about 10 mins of Shore Power and Charge starting, the Amps seemed to settle at about 92 Amps. I went back every 45 Mins to write down the Amps reflected, and at the end of 90 mins it was down to 18 Amps. 45 mins later, now at 2 hrs 15 mins - the ARC-50 reflected Float mode. So 3 hrs Absorb End Time - 2 hrs 15 mins = 45 Mins early termination of Absorb cycle? (THAT IS WHAT CONFUSED ME. And why I started thinking Absorb End of 4 Amps might be the better way to go...).

Fun, fun...
Smitty

Forum Discussion

Magnum MS2812 'Absorb Done' settings

About Technical Issues

Related Content

Magnum MMS1012 settings

Magnum MSH3012M

Shock Absorbers

Magnum Chassis

Lifepo4 float setting?