AGM Battery Charging THE PRIME DIRECTIVE

[MEXICOWANDERER]

I have gotten several communications about AGM battery maintenance. Using solar voltaic charging.

The big error I read is that the subject of total and complete recharging is not mentioned. And that is the # 1 most important mandatory requirement in AGM management.

If panels cannot do it and your electricity charger cannot do it you are condemning the battery.

The battery must be subjected to enough power to allow resistance to rise so that applying 14.4 volts across the battery...

One group 24 battery allows .4 AMP or less into the battery

Group 27 or 31 .5 amp

GC220 1.1 amp

Multiple batteries? Add each additional battery. Four golf car batteries -- 480 amp hour total = 2.2 amps maximum at 14.4 volts

Forget amo hour counting, slide rules or hocus pocus -- one half amp per hundred ampere hours at 14.4 volts. That's the battery's law not mine.

And this is a CHEMICAL matter, so time spent discharge is critical. Cycled to 50% every day is not as significant as cycling to 50% and then allowing the battery to remain at 50% level for days on end.

The CLOSER you can recover to that 1/2% flow of amperage the longer you can go without actually reaching the half percent at 14.4.

The deeper the discharge the more critical it becomes

It's exactly like radiation dosage. Accumulation is far more important than intensity or time. Only in this case it is depth of discharge and time spent at depth. A battery that is discharged to only 70% total capacity and then spending many weeks at that level is affected every bit as much as a battery that is discharged to 40% state of charge for 10 days.

But no matter what getting the battery at 14.4 volts and one half of one percent amp hour capacity amperage flow is key.

A measly 400 watt megawatt power supply can take over when your converter falls flat on it's face delivering less than 35 amps and the megawatt which is set a 14.4 volts will finish the job.

[pianotuna]

My Magnum plays well with my Blue Sky 3024di solar controller.

[Smitty77]

Well maybe I should try a third call to Magnum specifically on Absorb End - Amps setting, when a BMK-Meter is in the mix. Go with a 2 out of 3 answer:)!

As I do now believe after my 'Burned as I learned:)!' poor management of the previous battery bank - that Absorb End set to Amps, would provide the best Magnum method of assuring the battery bank is getting back to a 'Full Charged' condition.

And yes, the MS2812 is a 4 Stage vs 3 Stage, my comment was more generic as in nature. I should have just said a Multi Stage Charger for my comment about even with Smart Battery Chargers - manual involvement of battery management maybe prudent/required.

Will take another run at Magnum for Absorb End set to Amps:)!

(And again, not knocking the Tech Support. I had a list of 7-8 items I went thru with the Tech I talked with. Mostly trying to understand the IRV2 poster 757Driver's info on how the MS2812 executes once it has reached Full Charge display. (The needing to drop to a value below 12.7V, and then going into Float for only 4 hours.). We spent the bulk of the time talking over this area, maybe 5-7 minutes reviewing my settings and talking about Absorb End - Amps vs SOC vs Time was within this 5-7 minutes. As well as the description on why the BMK-Meter displayed Amp values would at times be simnifically different then would be seen on Line 2 when on the Inverter/Charge menu. I had run about 5 cycles of draining down out about 150-175Amp out of the new battery bank, using a 1500W heater to be the main draw. Over 50-60A differences in what the two displayed. (BMK-Meter displayed Amps are from the Shunt. The Inverter/Charger Line 2 display Amps were from the Inverter.)

Fun stuff this be for sure:)!

Best to all,
Smitty

[brulaz]

WRT the Magnum inverter/charger and BMK+shunt:

Apparently Magnum's MPPT solar charger can be networked in along with the BMK+shunt and ARC (advanced remote control). It can be controlled by the ARC and inverter/charger settings so the BMK's estimate of battery SOC can be used to terminate absorb from solar charging as well as from shorepower charging.

But if instead you use a NON-Magnum, NON-networked solar charger, things might go awry with the Magnum's logic?

Pretty complicated networked system:

[BFL13]

Almot wrote:
BFL13 - what troubleshooting... My UPG are near dead. Self-discharge rate is as high as in some 8 years old Walmart flooded battery. Can barely support low loads that I am running.

....

No idea. Be sure it is not a load you are unaware of, and not a bad battery? Check batt voltage one at a time while disconnected and then with a load, etc. Don't know what you have already done.

Bad luck if they are toast. I know where you can get an ESG 6GFM250 for $250 (Can.), but maybe not so handy to your location! 😞

[Almot]

BFL13 - what troubleshooting... My UPG are near dead. Self-discharge rate is as high as in some 8 years old Walmart flooded battery. Can barely support low loads that I am running.

Mex, - the only problem with rice and beans is too much jet propulsion. 3 hours cooking is cut down to 40 minutes on low propane flame with $20 pressure cooker and overnight soaking. Rice - 8 minutes. But you already know that. Wonderful machine, highly recommend. Mesquite wood and all kind of driftwood is what rural Mexico is living on, to save on propane. And - generators, esposas can't live without daily fix of soap opera.

[jharrell]

Smitty77 wrote:

Another fact I learned over the last few weeks is that the Magnum Charger portion logic has a significant design parameter problem for AGM's maintenance. When in storage for up 2-3 months at a time, we're plugged into a 15A outlet. We leave the MS2812 Inverter On (In case of power outages.), and the Charger On to maintain the batteries. Once the Magnum reached Full Charge via reaching 100% SOC (As displayed on Line 1 of the ARC-50 Remote Display.) - it will not go back into charge mode until after the voltage drops below 12.7V, so basically when it reaches 12.6V the charge will kick back on. But, it then kicks back on in Float Mode only, and only runs for 4 hours. From 12.6V level, Float mode for 4 hours will not bring the batteries back to Full Charge. The conclusion from talking to Magnum Tech Support, is that this contributed to my previous battery bank 'walking down', and sulfate build up.

The Magnum is actually a 4 stage charger by default but this can be changed:

03G Final Charge Stage – This setting determines what charge stage(s) occurs after the
Absorption Charge stage has finished.
Default setting: Multi
Range: Multi, Float, Silent

Multi does what you describe, and I have changed mine to Float to act like a 3 stage charger as I didn't like that behavior either, this is Magnums reasoning for multi:

Why should I use Multi? Multi is the most commonly used charge mode. It is suitable for most
applications and assures a full charge to the batteries, without overcharging. If there is another
alternate charge source charging the batteries (PV, wind or hydro), then Multi mode uses the
inverter/charger to complete a full charge. The inverter/charger transitions to Full Charge mode
and the alternate charge source then maintains the battery voltage. If the alternate source is unable
to maintain the voltage, the charger enters Float mode for another 4-hour period. The Full
Charge feature in the Multi mode also helps reduce water consumption in fl ooded batteries when
they are left in charge mode for extended periods, such as in a backup power application.

The Magnum manuals are very detailed and more completing than any I have seen from other competing product such as Victron. The only issue is the information is split between the inverter manual and the remote manual, most of the information on settings is in the remote manual, where the inverter manual is more about installation.

Smitty77 wrote:

So it seems to me the Absorb End - Amps value is best used, and would work well, for those who have everything turned off in their coach. No inverter or parasitic draws. Now if I was in the coach like when we're using it for months at a time. I could manually monitor the Amps via the BMK-Meter Amps display. But while in storage, I'm not in the coach daily... And as mentioned, the dang values used by Magnum to wake up the Charge cycle once Fully Charged value is reached, as well as the going into Float only, are not supportive of my Lifelines. (With the new bank, in testing, once I knew for certain I was at Fully Charged status on the battery. I monitored the SOC values daily over three days. I was down to 81% SOC, and the Voltage was still above the 12.6V needed to goose the Charger back on. So lots of up/down of battery usage, and then again, the Float for 4 hours would not get the bank back to full charge.....)

Again this is not my understanding, if you set done based on amps and you have a BMK installed it will be monitoring the shunt current not the charger current. This way loads will not effect the calculation. If you do not have a BMK it only knows the amps leaving the charger and cannot account for loads, in that situation they do not recommend using amps for done, also the DC amps leaving the charger are calculated from AC amps and not accurate below 1 amp ac / 10 amps dc, the BMK however is accurate to a tenth amp DC all the way to zero.

[pnichols]

MEXICOWANDERER wrote:
PAIN...is the purchase of a USA manufactured AGM battery

Not necessarily.

My deep cycle Group 31 Fullriver AGM RV batteries cost just slightly less than Group 31 Lifelines. 😉

P.S. I was not price shopping so I could have gone with Lifelines, but I needed deep cycle AGM batteries with a higher float voltage spec.

[pianotuna]

Hi Smitty,

I guess we talked to different techs at Magnum. The remote reads from the "head" amperage if there is no shunt and the tech I spoke to said "that is usually pretty accurate".

But, in fact, I do have a Blue Sky 3024di which displays charging amps from the solar system.

[Smitty77]

Thanks jharrell - Appreciate your taking the time to insert the Magnum manual info.

On SOC - Had the Magnum on Auto for Efficiency. Over a period of time it's supposed to learn and adjust based upon the battery shifting life cycle (Older batteries do lose capacity as they age.). With my Absorb Ending set to SOC 100% for the life of the previous bank, Absorb charge would end at the 100% SOC mark. However it looks like when in storage (With the Solar Controller off, and only the Magnum maintaining the battery bank.), the Absorb cycle never got close to a Tapered Down to 4 Amps, which for the 800AH bank was the Fully Charged magic value. The term used to me by Lifeline, and on a few other threads, is that the battery bank 'walked down' gradually over the years. And without reaching the Ending Amps Fully Charge of 4 Amps - sulfation built up.

In hindsight, I should have periodically manually validated the bank was at true Full Charge, and then reset the SOC values on the Magnum. This would have kept the 'calculated SOC' more accurate.

Another fact I learned over the last few weeks is that the Magnum Charger portion logic has a significant design parameter problem for AGM's maintenance. When in storage for up 2-3 months at a time, we're plugged into a 15A outlet. We leave the MS2812 Inverter On (In case of power outages.), and the Charger On to maintain the batteries. Once the Magnum reached Full Charge via reaching 100% SOC (As displayed on Line 1 of the ARC-50 Remote Display.) - it will not go back into charge mode until after the voltage drops below 12.7V, so basically when it reaches 12.6V the charge will kick back on. But, it then kicks back on in Float Mode only, and only runs for 4 hours. From 12.6V level, Float mode for 4 hours will not bring the batteries back to Full Charge. The conclusion from talking to Magnum Tech Support, is that this contributed to my previous battery bank 'walking down', and sulfate build up.

The logic on maintaining AGM batteries, once the MS2812 has reached Full Charge as seen on Line 1 - are not optimum for AGM's in general, and even a bit worse for Lifeline's which have different voltage needs. When I asked the Tech Support about the AGM 1 Lifeline Setting, and could not the logic behind Full Charge kicking back into Charge mode be altered based upon this setting? Well yes, that would be better to support Lifeline and or in AGM 2 setting, other AGM batteries. But nothing in the works to do so. And if they did this, it would require a replacement Control Board (Which by the way, is their solution for me to use AGM 1 with the revised slightly higher voltage for Float values that Lifeline recommends in their Feb, 2017 Tech Manual. No software flashing update capability...

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On Absorb End on Amps - Well sir I agree that the BMK-Meter is the thing to look at to get the best info of AH values in relation to what is going in/out of the battery bank at any given time. Say vs the Inverter values which are displayed on Line 2 of the ARC-50 Remote. (Line 1 may say Absorb; Line 2 may say DC 13.4V 16A.) However for the Absorb End setting to work well for me, at my banks 4 Amps. It was suggested that I turn off the Inverter (Which I leave on to support the fridge in case of power outages.). And that i turn off all other House battery draws. In my case the Salesman Switch inside the Front door does this. Talking with the Tech, if I did those two things, the Absorb End set to Amps would support me pretty dang well. But, I do leave my Inverter on, and it does have the idle draw. And I frankly leave my Salesman Switch on too, as I have other 12V minor draws on monitoring equipment I have on 7/24. So the best advise from the Tech was for me to 'estimate my at idle/parasitic' AH draws on the house battery, and then add my desired Ending Amps value onto this, and set that Amp Hour value on the Absorb End - Amps setting. (9-12A idle/parasitic House bank draw = 4A to be Fully Charged - would give me a range of between 13-16A to choose from. Too high, and it shuts down Absorb too early. Too low, and Absorb runs too long.

So it seems to me the Absorb End - Amps value is best used, and would work well, for those who have everything turned off in their coach. No inverter or parasitic draws. Now if I was in the coach like when we're using it for months at a time. I could manually monitor the Amps via the BMK-Meter Amps display. But while in storage, I'm not in the coach daily... And as mentioned, the dang values used by Magnum to wake up the Charge cycle once Fully Charged value is reached, as well as the going into Float only, are not supportive of my Lifelines. (With the new bank, in testing, once I knew for certain I was at Fully Charged status on the battery. I monitored the SOC values daily over three days. I was down to 81% SOC, and the Voltage was still above the 12.6V needed to goose the Charger back on. So lots of up/down of battery usage, and then again, the Float for 4 hours would not get the bank back to full charge.....)

So the MS2812 for my way of storage is not too supportive of maintaining the Lifelines.

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And don't get me wrong. I like Magnum, I like the MS2812, especially when I bought about 6 years ago - it seemed to be the best selection at that time for us. Would like to see Magnum make some logic changes, and while I would prefer for those changes to be software update patches, I'd be OK with buying and installing a new Control Board to get them. The Magnum, and all of their related components, play well together with my coach. (MS2812/AGS/SBC/Temp Sensor/ARC-50/Etc.) Timing of my Solar install missed the PT100 Controller by about 6-8 months. I would have liked to have had that, as then I'd have had the full Magnum component set - and they should have played well with each other:)!).

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On the comment about reaching the Lifeline recommended Ending Amp at .5 Amp per 100A capacity, 4A for my 800AH bank - that is what I'm doing (And also validating that I have the settings set properly.). I've turned back on my MidNite Classic 150 controller. I do have the WhzBngJr module, which does support the usage of what MidNite calls 'Ending Amps' value. It's set to 4Amp.

So while in storage here is what I'm doing:
-Magnum Inverter on, charger on Standby
-MidNite Classic 150 Controller on, and Ending Amp used to stop Absorb, with Temp Sensor enabled
-I checked every AM for a about 8 days, and about 6:00AM each day, the BMK-Meter and MidNite Classic Display SOC values indicate 98% SOC. This is the idle/parasitic 12V draw on the house bank
Note: To confirm, ALL In/Out of the House bank is via the BMK-Meter Kits Shunt Valve. Nothing is attached directly to the House Bank.
-My 1200W of panels get good sun from about 7:30AM to 2:00PM (Where it is parked next door at our other house, it has a two story garage/apartment 5' to the West of it. So around 2:00PM or so the panels start shading.
-The four to five times I've had the time to go check during the day, usually by around 10:30AM the MidNite is displaying Float mode.

So getting some draw down on the battery bank from the inverter and parasitic draw, and recovering to full charge per Ending Amp of 4A each day. Then float maintain until it shifts to MidNite's 'Resting' status.

-------

I've said this on other threads, and even other sites. Smart Battery Chargers are not always all that smart:)! For those who do no mind replacing battery banks on a shorter lifecycle due to possible less then ideal battery maintenance - these charges do an adequate job. For owners that have expensive battery banks, and want to optimize the lifecycle - these chargers require manual augmentation of hand's on monitoring, and manual override of 'auto' only control.

So different owner's with different approaches can come at battery management from different perspectives. And that's just fine... The danger is for those owner's that believe Smart Chargers are capable of 100% efficient management of their battery bank under all conditions - from what I can see this not the case.

For me personally I've shifted from letting the Smart Charger handle everything (As I assumed they were doing the job well.), to one where I'll be much more hands on in monitoring and managing the care and feeding of this replacement bank of X's 4 Lifeline L16's.

My next task is to completely review the MidNite Classic 150 settings. (I have done a quick look, to confirm Absorb/Float values as well as the WhzBngJr and Ending Amps value of 4A.) What I have never done, is successful upgrade of the Classic Software (To get the WhzbngJr update added, I had to get help from Starlight Solar's Larry - who had to talk with MidNite, as it did not flow/update for him too. Finally got it done with Larry talking with MidNite tech support:)!). As they have a new software release, I'm going to try to do this one on my own and see how it goes. The Classic 150 has some great download/logging files, that I have never bothered learning how to access. So that is on my To Do tasks list too. This should be my best monitoring tool on the condition of my Battery Bank going forward.

The DW has a large list of 'non RV' items for me to accomplish, and since we will not be head out until late June - the MidNite deeper dive will be over the next few months.

------

Finally (Yep, long winded:)!), I can only go with what I learn as I go along. I ask Lifeline, Magnum and in the future MidNite Tech Support for help and guidance as I work my way thru the knowledge curve. And I have found that sometime's a companies Tech Support technician's can provide different answers, or by accident incorrect info, at times. (Went thru this when talking with Magnum last year on SBC issues. Honest mistakes happen.). And I also admit that at my level of knowledge, at times I may not fully have understood what a Tech was saying to me. I've had many times when I thought I understood, even said it back to a Tech in my own wording and had them confirm I 'got it' - to later find that we were both wrong. Often,it is members on forums such as this that help clarify and or correct things:)!).

Great asset to have here, with everyone helping each other. And the is what all RV'ing is about, like minded enthusiast all helping each other...

Best to you, and all,
Smitty

[pnichols]

BFL13 wrote:
Recharging AGMs once you get home is so easy !!!

Just set the adjustable voltage charger to 14.8 (if that is the "cycle use" spec) and make sure the charger is current- limited to no more than the spec for the battery (27 amps per 100 for my 27 format 100AH ones- so I use a 55 amp charger set to 14.8 on the pair)

Wait till amps fall to under an amp (needs an ammeter--I use the Trimetric) for under 0.5 each and then declare victory. Crank the charger down to 13.8 Floating spec and leave it all till next camping trip.

Well, as you know that's "almost" what I do with our RV's 230 AH deep cycle AGM battery bank when we get home from a trip: Set nothing and just let the stock 45 amp fixed voltage Parallax 13.8 volt converter bring the bank back to full charge per the ammeter ... no matter how many hours it takes ... and then continue leaving the converter turned on and the battery bank switch turned on while in storage. Our AGM batteries are also supposed to be floated at 13.5 - 13.8 volts.

IAW, all our AGM batteries ever see is the engine alternator and the converter (plus sometimes a little 2-10-50 Sears charger in parallel with the converter).

Our RV battery life couldn't be easier ... pretty much zero maintenance all the way around.

[MEXICOWANDERER]

Yep Steve

It's when you *aren't* cool with them, that you need to do something.

Increased depth and frequency of discharge can turn a mild natured Dr Jekyll, battery into Mr Hyde so quick it'd knock you on your butt.

If it ain't broke don't mess with it
Is a common sense truism

It's when things are not all cherry blossoms and sunny sunrises is when these issues need to be dealt with.

Common sense should tell a person when to deviate from a course...

[maillemaker]

All this stuff about adjustable voltage chargers and figuring out how many amps you need per volts or amp hours or whatever, it's no wonder so many of us are "plugger in and walk away".

My house batteries are regular old Walmart deep cycle wet batteries. I never check the water levels. I'm not even sure if you can. I charge on the way to site and home on the alternator, and when I'm on a site with electric my batteries are boiled with a 28-year-old converter/charger. Last set of house batteries lasted about 8 years without me fooling with them. I'm cool with that.

Steve

[jharrell]

Smitty77 wrote:


Curious which Magnum you have that will show you the AH's going into the battery?

MS2812, at least as far as the Magnum Tech explained to me, does not give you the 'Charging Amps' going into the battery. It is the combination of AH's being consumed, and AH's going into the battery bank, that is displayed. (If your Shunt is seeing say 10 Amps of draw from the bank, and the Magnum Inverter/Charging is putting out 6 AMPS, the Magnum Remote display would reflect 16 Amps. It might also display on Line One of the display, that the battery is Absorb mode, where as the Line 2 should display the Voltage (Say 14.4V for this example.) that the Absorb is programmed to. Along with also on the Line 2, the Amps of '16A'.

I must have asked at least three different ways, was their anywhere with the ARC-50 Remote Display and the BMK-Meter option that I could see the actual Charge Amps, as in Taper Down to Amps, specially going into the Batter Bank. The end result was always, nope!!!

Hard to reach the appropriate fully charged Tapered Down Amp, when you have not display of this value:)!

Maybe I am not understanding correctly, the BMK Amps reading is the actual charge amps and is what the Magnum will use to determine done amps, from the manual:

Info: If DC loads are connected directly to the batteries and a Magnum battery monitor
is not installed, the Absorb Done Amps setting should not be used. To charge the
batteries—plus run the DC loads—the charger must increase the current delivered to
the battery bank. This may result in overcharging the batteries since the return amps
reading will be skewed by the DC loads.

Info: It is highly suggested that you install a battery monitor if the Absorb Done Amps
setting is used. If a battery monitor is not installed, the Absorb Done Amps setting
relies on the METER: 01B DC Amps value to determine when to transfer out of the
Absorption charge mode. This is the most accurate DC amperage measurement.

The BMK reading DC Amp BMK under BMK Meters is the value it will use and should be accurate regardless of DC loads so long as the shunt is installed correcty. If the charger is putting out 16A but the BMK says 10A then 12V loads are taking 6A. The main display will say 16A as that what the charger is putting out, but it should end absorb based on BMK reading.

Also absorb end based on SOC should do this for you so I am curious as to what it didn't do right, again from the manual:

The battery’s state of charge—which is the best indicator of the condition of the batteries—is
indicated on the METER: 05B Battery SOC display. This display shows that the batteries are fully
charged (i.e., SOC = 100%) once the following three conditions have been met:
1. The charging voltage has stabilized over a period of time (see Figure 8-1).
2. The charging current has decreased to a low % of the AHr capacity—normally less than 2%.
3. The AH that were removed from the battery are within 1% of fully being returned.

Its not very adjustable but on paper it seems to be doing the right thing, but setting absorb done to amps with a bmk installed should let you do Lifelines exact recommendation of:

A voltage setting of 14.3 volts ± 0.1 volts (7.15 ± 0.05 volt for a 6 volt battery) should be used when the battery temperature is 77°F (25°C). The battery is considered to be fully charged when the current drops below 0.5% of the battery’s rated capacity (0.5A for a 100Ah battery).

[MEXICOWANDERER]

BFL13

PAIN...is the purchase of a USA manufactured AGM battery

RELIEF....is a drawn out process, best enjoyed over many years.

Sorry to hear about your Chinese product...but after all China cannot manufacture a basic airplane jet engine. China reminds me of a cheapo USA Auto Parts store that offers Lifetime Starters and Alternators

Keep smiling and giving replacement garbage until the customer rolls over and cries "Uncle".

I had to live like a Tibetan Monk to afford Lifeline batteries. Rice with undiluted off-brand mushroom soup concentrate. Grilled Sandwiches with melted milk product. French toast with Acme syrup. Tacos were a widely spread out treat.

And to have a chain store reject battery blow an inner cell bar on a Sunday morning at a cheap hotel 300 miles from anywhere (remote Mexico) and then there was the "Money Saving Douglas Tires" from the same nightmare that sold me the battery. Low-price is so tempting except when the price isn't THAT low and it all turns out to be a ripoff.

I greatly hope your vendor stands behind the product.

[BFL13]

"Declare victory? I wish. My AGM have developed a defect through either my mishandling (long storage prior to use), or as a congenital disease, being Chinese UPG. Low current now doesn't mean anything, big solar is the only thing that keeps system afloat. "

Almot, perhaps there is a test method or two you haven't tried that guys here can advise on to trouble-shoot your batteries.