Breaking in new AGM deep cycle batteries

[WalkaboutTed]

I'll start this off by acknowledging that I know that "deep cycle" 12 volt batteries don't really exist, but I have questions about my new batteries. And I wish that we would have purchased 6 volt golf  cart batteries in the first place, but I didn't know better and now I have to live with what I have until I kill these.

This is going to be a very long post. 


We finally finished installing our refrigerator and hooked it up . We're now running it 24/7 to assess our setup to see if our solar/battery/alternator situation is adequate for our future needs. 

I'll start by saying that we want to be able to be off - grid for weeks at a time.  So it's important that we don't have to drive and run the engine or go to an rv park to recharge our batteries more than every two to four weeks. 

We have 280 watts solar on roof and 100 watts portable. We haven't messed with the portable, aside from making sure that it works, because we need to make sure we have enough solar with what we have on  the roof.  The extra 100 watts is for supplement in case of cloud, trees, et cetera. 

We have three 100ah UPG group 27s.  The solar and alternator run through a CTEK d250s and Smartpass with temperature probes and compensation.  

The fridge is a Truckfridge tf130, which is supposed to run at 24watts/hr under  "perfect" conditions (whatever that means).  We haven't put in all the insulation around it yet.  But we have it set at keeping water and beer at 40F.  I haven't put in the fan to blow the exhaust away from the fridge yet, but it's a very wide open area and I've sat inches from the compressor and the temp may be only marginally warmer. I cant really feel a difference. 

So I've been running the fridge, along with the Fantastic Vent exhause fan on low (1 amp an hour) because of the heat. I have the windows half open at night and also have the sliding door open during the day, facing east, where it is shaded by a tree.  It's been 95F the last couple of days. Between the solar and the alternator, I figured that there should be no problem keeping the battery, under the new load up in the area of 12.5 or so, given that it's been running 12.8 or 12.9 after resting all night prior to the fridge and fan.  The batteries were at 12.8v when I got them and I kept them on a charger until they were installed. 

Instead, the voltage has been at about 12.3 in the morning. But that is with the uninsulated fridge going a lot (though I haven't sat out there to watch how often it cycles) with the fan on. 

I charged the batteries all last night with the ctek 25000 that is meant to charge battery banks.  I took the charger off this morning and won't drive (no input from alternator to skew results) until this test is over. I would think that between the starting full charge and the brilliant sunshine that we have had, that the batteries should be able to last at least three days or more before needing current from the alternator or charger. 

My questions:
1) is that a reasonable expectation? 
2) do the batteries need to be "broken in" and how much of a difference would that make? 
3) do I need more solar watts? I'm thinking yes because of laptop /TV use, especially with the numbers I've been seeing.
4)how much a difference is this heat making? We're stuck in the low desert for at least one or two more months, with just a couple of runs up into the mountains. 
4) how to roughly assess AGM batteries state of charge with the constant load and solar input? Now the batteries never get a true rest. I don't have a built in ammeter, but I have a multimeter with a clamp DC ammeter. I don't know what I'm looking for. 
5)am I missing something ?

I'll see tomorrow morning where I'm at voltage wise and will keep running the system until it gets to 12.2v. When they get to that voltage, I'll put them on the charger. As an aside, every time I use the charger, I put it on a different battery to keep them equal. 

 Any ideas on what I should expect? Anything I should be doing or doing differently? 

I'm sorry for such a long post, I wanted to give all of you as many details as I can to reduce the number of questions. 

Thank you all, 
Ted

 

[WalkaboutTed]

Okay, I was looking around and I found a link (pbase)that Sternwake had in a post. With a 5.25 amp load, the state of charge is 65%. My load is a little higher, so I know that it invokes Peukart's law. The physics and math are way beyond me. So I guess the takeaway is that I shouldn't let the voltage go below 12.3v.

But I still don't understand why the batteries are discharging so rapidly. And if the batteries are crap, will more solar overcome that, if only for a while? We don't want a tether to the grid or using extra gasoline if we don't have to.
Ted

 

[SternWake]

I would need to know how many amps your fridge is Pulling and how many minutes it runs per hour to maintain your temperatures, as to whether 12.3v in the morning is a sign you have hard working batteries, or batteries not performing well.


YOu have a clamp on Meter, clamp over one fridge power wire and Measure the amps when the compressor first comes on and ~again 4 to 5 minutes later right before it shuts off.  How long did it run and how long before it cycles back on?  Home many minutes per hour, Over 3 hours  during the hottest parts of the day in the Van?

Get some idea of duty cycle in the temperatures you are asking it to maintain 40F or Below in.

There is no special break in procedure with batteries.  If properly recharged to full after each discharge, they can gain a few AH of capacity in the first 2 or 3 dozen cycles.

Hook your charger up with - on battery #1 and + on parallel battery #3. This is much better than hooking clamps  to battery 1 one day and battery 2 the next and battery 3 the third recharge.

90F internal Van temperatures will have the stand alone upright  fridge sucking 2x the amount of electricity as it would at 80F.

and in 95f will consume twice that as 90F.  Solution, More insulation and Less internal van temperature via IR blockage and ventilation exchanging outside with inside air, And of course having the condenser release its heat to atmosphere with as little resistance as possible. 

If you really suspect your lowest possible  budget AGM batteries are not performing as they should, then I would recommend you ensure you are fully charging them.

When fully charged, and held at 14.7v by the charging source, they should accept well less than 1.5 amps.  Hold them at 14.7v until amps taper to 0.75 or so, then lower voltage and hold them at 13.6v until amps taper to nearly zero.  I'd recommend 45 or more amps initially  applied for 3 of those group 27 UPG AGMs at sunup morning voltage of less than 12.3v, before the too little too slow solar has a chance to begin their low and slow AGM tickling endeavor.

Agms like the occassional high amp recharge from their most depleted state and even more so when the charge is not terminated until they reach 100% ASAP.  A high amp recharge to true full from a deep depletion level, is like the AGM battery reset, to maximum remaining capacity.

If your Fridge is by itself, pulling 300Ah of  fully charged AGM batteries to  a low of 12.3v in the morning.  Then it is an energy whore that needs more insulation or less Ambinet temperatures to fight against.

My 50 liter danfoss powered fridge has consumed 34.2AH in the last 53 hours maintaining 32.5 F interior temps with 60F overnight lows and 75f afternoon highs

Insulate the fridge and Windows, and ventilate the van and the fridge cooling unit, or get more solar and more battery.

 

[John61CT]

I'll start this off by acknowledging that I know that "deep cycle" 12 volt batteries don't really exist

There are a few, Trojan T1275 is true deep cycle 12v.

 

[John61CT]

 
4) how to roughly assess AGM batteries state of charge with the constant load and solar input? Now the batteries never get a true rest. I don't have a built in ammeter, but I have a multimeter with a clamp DC ammeter. I don't know what I'm looking for. 
5)am I missing something ?

I'll see tomorrow morning where I'm at voltage wise and will keep running the system until it gets to 12.2v. When they get to that voltage, I'll put them on the charger.

Sounds like you want to try to get good lifespan from your bank. Without deep cycle, you won't, but investments in gear and learning with this set will pay off when you invest in the real deal, hopefully a full year or two away.

Accurate SoC, voltage just won't cut it.

IMO Smartgauge is the way to go, get State of Health feedback as well as your AH capacity declines (this bank likely pretty quickly).

If you really want to see specific Amperage in and out, and get a rougher SoC idea as well, coulomb counters like Bogart's Trimetric, or one of the Victrons.

Maretron is good too spendy, look at Blue Sea, lots out there.

These, while fine for showing Amps in/out need resetting and calibration every cycle when you get back to known true FULL 100%, in order for their SoC reading to even come close.

Smartgauge much more accurate for SoC and user-friendly, simpler all round. Many use both it and coulomb counters.

Speaking of "known true FULL 100%"

Ideal would be a big-amp source like HO alt, or genny driving a charger that puts out at the recommended max amps for your batteries, should run every morning through CC/CV well into absorption, longer when its cloudy, depends on your panel wattage.

Then use solar to do the long tail low current try to get to known true FULL 100% as often as possible. Without that morning fossil-fuel "head start" you need a LOT of panel watts to get there alone by sundown.

You really should for bank longevity, be shooting to reach this every cycle. Only four times a week will slowly murder even an expensive deep-cycle lead bank, once a week pretty quickly, less than that IMO you're treating those big batts like disposables.

Which many if not most people do, it's up to you to balance up-front costs vs long-term payback, and other limits and priorities of course.

 

[Trebor English]

If you go to Amazon and search for "amp hour meter" one of the results is:
https://www.amazon.com/bayite-6-5-100V-Display-Multimeter-Voltmeter/dp/B013PKYILS
It has an external shunt and can go up to 100 Amps.  $18.75


I have https://www.amazon.com/Digital-Balance-Voltage-Battery-Analyzer/dp/B01N3BACF2
Internal shunt, $11.50.  It says 100 amps but really, with those skinny wires, it's good for 20 Amps.  You can hook that up to your fridge to see what it takes for a day or over night.  You can hook it up between your solar and the batteries and see what you get from the sun.  I usually leave it between the solar controller and the battery.

If I had a fridge I'd get two, one for solar, one for fridge.  For $12 each they let you see what is going on.  It won't tell you State Of Charge but If you see 20 amp hours out and 25 amp hours in with late PM voltage at 14.5 with amps down to .1 you will know that you can repeat the cycle tomorrow.

My plan with the cheap amp hour meter lets me see what is going on and confirms that I have plenty of excess power. 

Flooded 12 volt deep cycle group size 24, 27, or 31 may be unicorns.  AGM are not all in the same mythical unicorn category.  No matter what the battery type is, if you don't treat it well it will die more quickly.

 

[jimindenver]

Do your charge controllers have the ability to do a set equalization?

My Lifelines were 4 years old when I bought them. Two sat at 13.0 and 13.1v, the third was at 12.8v. Before I connected them into a bank I equalized the third several times until it rested with the other two. Had I not been able to bring it up I would not have used it in the bank as it would have pulled the other two down. With multiple solar controllers and a adjustable voltage charger I can break my bank down and check the health of the individual batteries, something I will do when I know I have a month that I am not moving. I can run off just one of the three batteries if I need to although I'm likely to separate just one at a time.

You mention taking the bank down to 12.2V. The only way I would intentionally take a bank down would be a capacity test where I applied a known load for a certain amount of time. That way I can say I used say 10 amps for 12 hours on one of my 8-D's and expect it to rest at a voltage representing 50% after stabilizing over night. It's a crude test and hard on the battery but it will show you if there is a real problem. That would be the voltage dropping too quickly or not responding to being recharged as expected.

You mentioned running the fridge and then later added TV and laptop use. A real count on how many amps hours you are pulling would be a good thing. That's going to be harder since the fridge is a variable and you have to account for a inverter especially if you leave it on all the time. I don't use a lot of power over night but do notice the difference when I leave my inverter on with the various chargers plugged in.

I say all of this knowing it may be useless since I have different batteries, no amp counter and certainly less knowledge than others here. They will tell you if I am completely off base.

 

[IGBT]

Our Lifeline AGM, which are true deep cycle, did have somewhat of a break in period.   Unfortunately I did not measure it exactly at the time, but as Stern mentioned, it probably was something along the lines of 5ah additional capacity for the 125ah batteries but maybe as much as 10ah.  I think Lifeline mentions somewhere about this forming of the batteries takes several dozen cycles. 

As for a scientific reason for it?  I think the batteries are shipped without all of the lead oxide (PbO) paste having been fully converted to lead peroxide (PbO2).  Probably would take too long during manufacturing to get a 100% PbO2 paste.  Maybe it is like 90% PbO2 when shipped.  During the first couple of dozen cycles it gradually rises to around 95% PbO2.   I just made up these percentages because I really have no clue.

 

[John61CT]

From my notes:

​Break AGM batteries in by cycling them more deeply than usual, just a few times and recharging GENTLY to full 100% SOC.

Most AGM batteries will come up to their full Ah capacity in maybe 8 cycles. Flooded batteries a lot more, maybe 50+ cycles.

This is another benefit for AGM's.

 

[WalkaboutTed]

***ANOTHER VERY LONG POST:***

Here's my update and answers to questions.

I checked the voltage at 0300 (I'm a night person) and it was 12.5v. At 0830, 12.4v. Hanging out there with the newspaper, I discovered that one of the two 140 watt panels was getting a tiny bit of shade from the tree adjacent to the van until 1040. So we know that is decreasing that theoretical 280 watt output of solar.

Aside from the front vehicle windows, which are facing due North, the van has up to 3" inches of insulation. The only other windows are two 10mm thick marine ports, 7"x12". I have them open for cross ventilation. Between the sliding door open, the front windows open, the two marine ports open and the constantly running exhaust roof fan, the temperature in the van is not a great deal higher than the ambient air, which topped out at 97F at our house today. The area of the fridge compressor fits me sitting and is openly vented all around. It was pretty comfortable in the van (12% humidity doesn't hurt). The fridge runs as much 40% of the time. This is with no insulation except a sleeping bag hanging over the door. It pulled in 4.3-4.7 amps per my multimeter throughout the ON cycle. The overhead fan draws about 0.6 amps continuously. Nothing else is running. So, all in all, the fridge is consuming less than I would have thought in this heat with little insulation.

Now here is the interesting part. At 1300, about 12 solar amps were coming in to the ctek. But the output into the batteries is only 5.8 amps. I measured the output in multiple locations and kept coming up with the same numbers. I was hoping that I had a blown fuse or a loose connection. Nope. I have a good 4 gauge ground. So, assuming that the fridge and fan are running at ~ 3 amps x 24 hours = gross drain of ~72 amps a day. And at 6 amp input from solar into the batteries, say 5 hours a day, we have a positive input of 30 amps. This means we're using roughly 42 amps more a day than I'm taking in (without the variable of intermittent charging from the alternator)

As an additional bit of data which I can't even begin to understand, is that the voltage coming in from the panels was 19.85v and what was coming out the CTEK into the batteries is 12.37v. I'm not even sure if I'm measuring that right, or if it actually means anything.

There are our missing amps, or at least part of them. When we first put in the solar (more than a month ago), the solar amps in to the CTEK matched the solar amps out to the batteries. But, in retrospect, I don't know if the CTEK had ever been working properly, with the negative symptoms masked by regular charges from both the alternator and ac charger.

**added later**
But then, at about 1645, it became even more curious. I measured the solar amps coming in to the CTEK : 6 amps. The solar amps coming out of the CTEK: 6. 2 amps. I threw up my hands.

At 1800 the voltage, under the load of the refrigerator and fan sagged down to 12.2, 36 hours after finishing a twelve hour charge. Which, if everything was on a roughly linear scale, would mean that I had 1 1/2 days of a net drain of 42 amps, which would take 63 amp hours out of my theoretical 150 available amp hours from the 300ah battery bank. That's as good a number as anything to pull out from behind my ear.

*****later in the day*****
I waited until #4 son came home so he could start the engine while I watched the dc ammeter. When he started the engine, and then let it idle, 51 amps went into the batteries (through the CTEK), tapering to 29 amps after 10 minutes. So we know that the alternator function of the unit is good.

I just now went ahead and hooked up the charger. End of current experiment.

The only conclusion that I can pull from my uneducated brain is that the CTEK unit broke, if only the solar input

Now, my esteemed helpers, what do you think? What am I missing? What am I not measuring or figuring right? Any suggestions?

I bought that charging system on the recommendation of several people, especially since it was supposed to be idiot proof (I have no illusions about my status) and requires only minimal monitoring once installed with fairly conscientious battery hygiene. Maybe I did something wrong hooking it up? Was it working properly initially? Something I did later?

CTEK has been very good about responding to my emails, answering questions and has good customer service. As soon as I get input from the rest of you, I'll send out an email to them.

Phew! All this thinking is making my head hurt! But, I just found a half-liter bottle of Mexican Coke (No, you Silly! Mexican Coca Cola!) in the fridge. That makes me a much happier woman after this confusing day.

Thanks,
Ted

 

[John61CT]

I seem to recall elsewhere comments that these built-in solar controllers, ancillary to devices with other more central functions, were not nearly as effective as decent dedicated solar controllers.

I don't recall if that was specifically based on experience with that CTEK unit, but I reckon likely so.

One think to try is take all the loads off the system while charging, and get some baseline numbers to compare.

 

[John61CT]

http://www.caravanersforum.com/viewtopic.php?t=46898

 

[WalkaboutTed]

John, I will check that tomorrow.

But with that caravan thread... Hmm... I don't have to worry about heat under my bonnet, but it is warm inside that...battery box. Seriously, though, I also thought of that too. Logically, if the temperature sensors strangled the CTEK 's solar output because of excessive heat, it would do the same with amps coming in from the alternator. That was not the case, as upon ignition, the CTEK/Smartpass immediately siezed 50 amps (albeit not the full 50 amps for long-it went down to 29 amps} from the engine and kept it up for 10 minutes of idling until I turned off the engine.

So I had to throw away that potential theory. But even if it was that problem, it would not bode well if we're living in the desert with temps of 40C or more on a regular basis.

Besides, these units are widely used in the hot outback of Australia and other harsh environs. If they were that sensitive to heat, I wouldn't think they would be as widely used as they are.

Unless I'm missing something in that general theory.
Ted

 

[John61CT]

I think the core functionality of the CTEK, intelligent DCDC charging with boost as well as buck conversion, is well executed.

But it is not explicitly designed (by the Dutch) for extreme Aussie conditions, needs ventilation for sure

http://www.caravanersforum.com/viewtopic.php?p=803305#p803305

And they likely compromised on the solar add-on, perhaps intended simply for keeping a Starter topped up while long-term parked away from shore power, rather than as a primary source for deep-cycling usage.

 

[WalkaboutTed]

You have a point there, John. And I'm thinking about this: I'm considering potential plans to increase my solar capacity. Perhaps I am trying to make a silk purse out of a sow's ear; the sow's ear being the solar input part of The CTEK.

I'm feeling a bit power hungry. Cogitating on what I'd ideally like to run (fridge, 2 energy greedy laptops, my 800 watt k-cup coffee maker, multiple fans for a post-menopausal woman, TV, rice cooker, et cetera), maybe I need to be more ambitious solar-wise. So, I'm considering putting up another 165 watt panel. That would bring me up to 445 watts on top and 100 portable. I could be a profligate power pig!

To think that when we started this project that I figured we would be happy with an icebox and 100 watts portable solar tickles my sense of irony. I want more!

I already had an email To CTEK about the limits on the mppt portion. I think it's 20amps. If that is the case, I already am exceeding that when I add my roof top and portable solar together. And we already know that the unit processes the output of my portable panel unit. So If I left my portable input attached to the solar input of the ctek, I could get away with a 30 amp mppt or pwm for the overhead solar.

Just when I believed I had it all set. Now if I decide to go that way, I have a bunch of new decisions to make {mppt vs pwm}. I'm still peeved about what is currently (no pun intended) not working with my system.
Thank you,
Ted

 

[SternWake]

You do not have to use the solar input of the Ctek AFAIK, you could run all solar through an separate solar controller of capable wattage.

Does the Ctek even allow for adjustable absorption voltage or duration or float voltages?

Adjustable Absorption voltage and the time to hold it is extremely important in achieving good to excellent battery longevity, So the Ctek might be a neat all in one solution for a menial system, the power hungry seeking good battery life would be much better served by a solar controller that allows the end user to adjust how high absorption and float voltages go, and how long it holds absorption voltage once it gets there.

Disregarding the damage caused by regularly overdischarging lead acid batteries, the biggest factor in their lifespan in deep cycle duty is achieving the absorption voltage, and holding it for long enough before reverting to float voltage.

Your UPG AGM batteries claim a wide allowable absorption voltage of 14.5 to 14.9v and upto 30 amps per group 27 battery, and you have 3.
A solar controller with battery temperature sensor is also a big +, concerning battery life, especially when temperature extremes are likely to occur.

As to how long to hold absorption voltage on an AGM, one requires an Ammeter. When the 100AH AGM only accepts 0.5 amps to be held at 14.X volts, it can be considered fully charged.

This time required to be held at absorption voltage will always be slightly to greatly different depending on the depth of discharge, the amperage rate at which the bank achieves absorption voltage, how many partial state of charge cycles have occured since last 100% true full recharge, battery temperature, battery health, and the position of Saturn's third moon.

Amperage based float voltage triggering is far superior to time based, and an unadjustable solar controller will almost never get the time right, leading to chronically undercharged, prematurely sulfated batteries.

So bypassing the Ctek's solar input could be a very good thing for your batteries, if the solar controller you then employ allows for adjustablilty, has a battery temperature sensor, and you program it correctly.

 

[WalkaboutTed]

Hey Sternwake,
The ctek charge voltage is 14.4 and the float is a relatively low 13.3. It's a five stage charger with temperature compensation and they say it's relatively intelligent. But for the solar, from the user's side, there is no flexibility in settings at all. It's a generic set and forget product that many customers seem quite happy with. But, ya gotta remember that when I started in on this whole project, I was only going to have that 100 watts. Then when I decided I wanted more, the ctek system seemed so brainless. I liked the simplicity of it. But I knew full well that the d250s and the Smartpass was like a "jack of all trades, but master of none". It's like a tutti-fruit jellybean, okay, but not inspiring. I was fine with that-until you came into my life. Ta-da!

Who wudda thought I'd become another Sternwake acolyte, assiduously tracking and coveting every amp? And to think that before now, the only amp with which I was vaguely familiar was an ampersand. You've put visions of coffee, heating pads, and small appliances floating within my reach!

Talking to the Hub, he's game on installing another panel. But we're out of room on our roof. It should be interesting looking as it will be on a hinged plywood panel in order to be folded and fastened down on the driver side of the vehicle while in motion. It will be propped up for deployment once stationary. I haven't quite figured out the whys or the wherefors yet, but give me a couple of days.

Now, for the charge controller. I've narrowed it down to either a Bogart sc2030 or a Blue Sky 3000i. Our highest power usage will be in the morning, so from what I've read, an mppt controller may be better for us.

But we can save that discussion for another thread. I gotta do a whole lot more reading before I can even ask an educated question or two.

So where it stands is that plans have changed for more solar and new controller, unless CTEK has a valley of hidden wonders in their answers to my questions.

I'll follow up with the answers I get from them. Now, off to my Gmail account (sound of little running feet).
Ted

 

[666JTK666]

These guys may have somthing you will find useful.

http://www.sterling-power-usa.com/sterlingpoweralternatortobatterycharger.aspx

I think it's wize of you to go with a seperate solar controller.

 

[WalkaboutTed]

The alternator to the battery function works great. I'll continue to use that because it's a nice five stage charger. I can crank as much as 100 amps into batteries with that.

The solar part not working is moot at this point, but I'm still irritated that it's not perfect. I paid enough for it. I may want to add more solar and run it through the mppt controller in the CTEK as I'll already have 440 watts of solar going through a Blue Sky 3000i (at least that's the charge controller I'm leaning toward for the moment).

I'll update this thread when I hear from CTEK. Thank you all-you guys are great!
Ted