Best Charger for Lead Acid AGM 12v 100ah battery

[wrcsixeight]

Proper Lead acid recharging can be taken to extremes to maximize battery longevity. I find Automatic smart chargers to be not nearly as smart as their marketing will have one believe.

If one were to dip a Hydrometer on a regularly deeply cycled flooded battery, one will see that the Green light flashes its full charge indicator when specific gravity is still in the weak or fair zone. Far too many people choose to believe that soothing blinking green light.

Knowing when an AGM is indeed fully charged is more problematic. Seeing how many amps it is accepting to hold absorption voltages is a good method, but if sulfated can still be misleading.

Temperature compensation regarding charging voltages are often ignored, but should not be. I can get away without doing so due to a mild climate and awareness of a batteries requirements when outside the mild zone, and the fact that I cycle batteries daily and have the tools and curiosity to monitor batteries as they charge and discharge.

Automatic smart chargers cannot have any load on the batteries when recharging
RV converters can handle charging a loaded battery, but they too will prematurely end absorption voltages to the batteries detriment.

Perfecting the charge algorithm requires more than a clever marketing department, and what is perfect for one battery, is not perfect for the next, so a 'one size fits all charger' is more like a one size fits none.

Achieving a true full 100% recharge on a heavily cycled battery requires more than a blinking green light. it can be required that voltages be held higher than normal for longer, and good luck getting a 'smart' charger to do this.

My flooded battery I will allow 16v held for as long as it takes for the specific gravity to exceed 1.285 on my current flooded battery, and my Northstar AGM only gets cycled when I have at least 40 amps to feed it the next day. I'll set my Meanwell power supply at 14.7v, and stop charging when it requires no more than 0.4a to hold 14.7v at 77F.

If I recharge this AGM with 200 watts of solar( about 13 amps maximum in summertime around noon) it behaves poorly when discharging. It simply requires higher recharge currents. Most AGMs benefit from higher charge currents and do not like the traditional low and slow trickle charge method often touted by Grandpa as always being best for every battery no matter what.

Meeting the battery manufacturer recommendations is a good starting point, but not the final point, if maximum longevity is the goal.

Just slapping any charger on any battery is not a good plan, especially with AGM's

 

[SemiMan]

For sure. Experience goes a looooong way with lead-acid batteries. Book-learnin' just isn't the same.

poloman, if you'd like to chat one-on-one about lead-acid batteries and charging, PM me. It's what I do for work. All day, every day - batteries batteries batteries

What do you do with batteries?

Posted by really crappy Tapatalk app that is questionable wrt respect of personal data.

 

[SemiMan]

WrcSixEight: What works well with limited charge current is bumping up the end voltage a bit ... 0.2v though some experiments with higher show good success with AGM and extending cycle life. I have done fully autonomous long life solar chargers .... With the advantage of load control so could say "enough is enough". Add in automated high voltage conditioning after extended lower state of charge .... Makes for great battery life. That's what I use when I charge batteries at home but fed by a big supply, not a solar panel. Nice knowing exactly how it works and always have the logs to fall back on for data.

Posted by really crappy Tapatalk app that is questionable wrt respect of personal data.

 

[wrcsixeight]

Before acquiring an AGM battery I spoke with a technician at odyssey AGM abouyt feeding their 100Ah group 31 via 198 watts of solar in a deep cycle application and he recommended against their battery for such duties.

He did say that lesser currents could complete the task, but only if very low currents were managed in such a way that the battery would be slowly brought upto 16.5V.

I have found my Flooded group 31 USbattery requires 14.9volts absorption, and then a top charge of 15.3 applied for the rest of the afternoon to get my Specific gravity to the bottom of the green, which is 1.265 on my Hydrometer. Every month it requires the 16V equalization cycle, but this has been required as often as every 2 weeks in the past.

The battery has ~ 425 cycles on it now and I doubt it has another 100 in it, but time will tell.

I use every charging source at my disposal to recharge as quickly and as fully as possible. My alternator can deliver 75+ amps into this depleted flooded battery, My meanwell can do 41 amps, and my Solar can do upto 13 amps. The solar restores most of the capacity used, and these higher than normal voltages are required at these slower rates. When I do use the Meanwell's 40 initial amps to recharge from ~50%, Voltages can be lower to get the SG up in the green. but the lower and slower solar requires higher end voltages to do the same task.

My AGm battery, I don't cycle deeply very often, and do so only when I have high amp sources to Quench it. If my Solar completes the task of a 'full' recharge then voltage held under the same loading is noticably less than if higher amp sources were used initially to get the battery upto absorption voltage.

The OP's Asian AGM batteries are limited to no more than 0.3C, and I think they would benefit from a charger that approaches this figure, rather than a lower and slower smart charger and its pre programmed safe algorithm and lesser initial currents.

I wish there were an affordable programmable charging source that allowed one to set the required variables, but since there is not, my plug in charger is a power supply with a frontal lobe element.

My Solar controller allows me to adjust setpoints. If it could not, my flooded battery would have been recycled long ago.

 

[mellowhead]

The business I work for does battery wholesale: car batteries, deep cycle batteries, motive batteries, UPS batteries... and related charging, power conversion, and power management equipment.
We also design and sell PV systems; primarily for off-grid use.

I don't posit to be the most knowledgeable CPF-er on the subject of lead-acid charging, but I do have more than a few years of first hand experience in batteries and charging

 

[SemiMan]

He did say that lesser currents could complete the task, but only if very low currents were managed in such a way that the battery would be slowly brought upto 16.5V.

This makes no sense .... certainly not to that voltage level. That is crazy high and the only time I have seen that used is in a special charging method developed by NREL for Optima batteries. It did not work quite the same with other battery types. Perhaps they meant 15.6V? ... This is a typical voltage used to recover from the start of sulfation, the currents are low, but not that low, i.e. 3-5Amps and you cannot do it on solar.

You can also charge at this very high voltage with tons of current of course ... for flooded too, within limits of the batteries thermal capacity.

I would not trust what most techs say from these companies. I was able to stump most of their apps engineers let alone field tech. Only when you get to the strong chemistry people can you have a real detailed discussion.

Semiman

 

[wrcsixeight]

I am sure that is what he said. I've a hard time believing that as well.

I'm giving my flooded battery a 16V EQ charge as I type. One weak cell is not responding and is .030 less than the other cells.

Amps started rising so now i am lowering voltage to keep it under 6.5 amps for a 130 AH battery, but I expect i will terminate the EQ next hydrometer dipping and plan to acquire a new battery to cycle heavily daily

 

[SemiMan]

I am sure that is what he said. I've a hard time believing that as well.

I'm giving my flooded battery a 16V EQ charge as I type. One weak cell is not responding and is .030 less than the other cells.

Amps started rising so now i am lowering voltage to keep it under 6.5 amps for a 130 AH battery, but I expect i will terminate the EQ next hydrometer dipping and plan to acquire a new battery to cycle heavily daily

What are you using it for? ... cost critical?


Semiman

 

[wrcsixeight]

What are you using it for? ... cost critical?


Semiman

It is to be deep cycled nightly 30 to 70 AH nightly in an RV application. Flooded is fine, and preferable, for the 198 watts of solar which is the primary recharging source. My Northstar AGM battery is primarily used for engine starting and is still healthy.

I will pay the premium for a true 12v Deep cycle battery vs the cheaper marine versions and will seek out a Trojan this time.

I don't need the capacity of two golf cart batteries, and do not have the extra 2 inches of height required either.

A group 31 is the maximum size I can fit in the intended location. It is an extremely tight fit.

 

[SemiMan]

I am not sure what your availability is, but this is one of the better ones out there:

http://rollsbattery.com/public/specsheets/31M120.pdf

Semiman

 

[wrcsixeight]

I am not sure what your availability is, but this is one of the better ones out there:

http://rollsbattery.com/public/specsheets/31M120.pdf

Semiman

Rolls surrette is a special order item in my location, in the group 31 size.

It claims to weigh 6Lbs less and have 10 less AH than a group 31 Trojan.

I've no doubt about Rolls quality, but me thinks their highest end products are their larger taller 2v and 6v batteries

All seems all 12v Deep cycle batteries stuffed into in a BCI group Jar for automobiles are a compromise in design with not enough electrolyte for the amount of lead they stuff inside.

I'm hoping Trojan got it better than USbattery in this size format. Getting that last 8% into the USbattery required ridiculous voltages for extended periods, and without it SG tanked quickly.

Reports from t-1275 users are not that encouraging in this department, that they also require higher voltages for longer to max out SG.

 

[IonicBond]

SemiMan's got it right. Many agm's are killed by merely tickling them to death with not enough current. Sure, you can use less than recommended, but you just get shorter life and poorer performance faster.

DEKA's own application manual states that for the longest life with their standard agm's, that one should try to get as close to the 0.3C *long term* charging limit. It is just a few sentences and easy to miss, but it's there.

Odyssey has REALLY strict operating paramaters if you want to stay within warrantee in regards to not only current, but very strict controls on voltage. Again, low current charging less than about 0.4C when at 50% DOD takes you out of the warrantee window. So too, floating them at anything less than 13.5-13.6 volts. No higher, no lower. This is due to the pure-lead chemistry that differs from say a Deka, that won't mind 13.2v.

So for us propeller heads, take the time to read not only the small consumer guides, but also the large application guides available by them if you want the best performance.

I ran with an Odyssey for solar with low current, but about once every two weeks or so I would absolutely HAMMER it with an AC charger to try and keep it in the best shape possible. So there are work-arounds if you absolutely need it, but I agree that generally, an Odyssey or Optima shouldn't be tickled to death with low current solar.

One thing NOT mentioned is if the Op is starting out on the right foot - that is, has each battery been INDIVIDUALLY charged to full, and THEN placed into charge-discharge service in series?

Note: Burgerman at wheelchairdriver has a lot of info, much of it 10 years old or more. Don't just read one small section of the site if you are truly interested. He also regularly HAMMERS his agm's (when he used them - now lifepo4 all the way) with high-powered inverter/chargers, taking advantage of opportunity charging along with much more info. Aside from the web pages, he also has a forum one might want to visit.

 

[ACruceSalus]

IonicBond I agree Burgerman's site has lot of old information and it takes some work to find the current information. It's almost like a stream of conscientious and very disorganized in places. It took a long time to sort through it.

At one time he may have advocated <.2C charging as others on this thread have claimed but all his current advice doesn't. In fact he said lead acid batteries (ones that he considers quality) can take all the amps that the charger will give it (10, 20, 50, 100). The battery will soak it all up and as it charges the amps naturally drop off. The most important factor when charging is to keep the volts within a certain tight range. Again this is my understanding and whether he is correct or not I don't know because I have little experience or the means to test his advice. Never the less for my purposes I will probably never charge at more than 40 amps so I wont' be testing some of his advice.

He is very responsive on his forum that you pointed out. When I posted something he answered within a few hours. That is where the most current information is.

I'm learning here and welcome any constructive criticism without the name calling. If someone can point to a specific page or information where Burgerman (or anyone else) is wrong and why he is wrong I'm very interested. Otherwise it's a waste of time. The problem that I have and I suspect most people have is separating the wheat from the chafe. Some information is obviously chafe but other information is not so obviously chafe. In addition to Burgerman the best source of information seems to be Battery University.

 

[mellowhead]

Some parts of this pdf document are a little bit sales-ey, but the rest has excellent information, particularly on charging:
(PDF, 1.2MB) https://dl.dropbox.com/s/v14u692uskrbr52/Battery 101 Guide.pdf?dl=1

In addition, and particularly for some heavier-duty applications such as floor scrubbers or golf carts, a balance/termination phase of charging is extremely beneficial in extending the life of AGM batteries. Two methods are shown in the charts below:

The IUU charge method is the "normal" method of charging. I usually see about 5 years of service in light to medium duty applications with this charge method.
A bulk charge rate of 0.1 x C20 to 0.25 x C20 is acceptable. Any less and you're definitely "tickling it to death".
Not many flat plate lead-acid batteries will go past the 10 year mark, even if well taken care of. You can get 15, possibly up to 20 years with some OPzS or OPzV batteries, particularly if they have a "sliding post" to accommodate vertical plate growth.

 

[IonicBond]

Ah yes, the IUU fast-charge algorithm. Problem is, unless you are commercial, the charger that implements this may be hard to find. The only alternative for most is to get bulk/absorb finished fast enough to get at least 8 hours of float in before the next shift - sometimes impossible.

I know we are getting far beyond the usual candlepower applications at this point, but it is fun to go back in time to when AGM batteries were the craze for early EV's, circa 1998 or so. Enersys / Genesis / Odyssey had some great application manuals describing all this in great detail. Later editions left out the IUU algorithm altogether, and I suppose you only got details from a corporate engineer if you inquired. The 1998 application manuals are fascinating - much of it still applicable. Early Optima application manuals are also interesting.

EVDL has some historical documents of interest:
http://www.evdl.org/lib/index.html

Loads of fun!

 

[poloman]

One thing NOT mentioned is if the Op is starting out on the right foot - that is, has each battery been INDIVIDUALLY charged to full, and THEN placed into charge-discharge service in series?

IonicBond, at the moment they are PERMANENTLY connected in series. And charged by 24v charger(while still in series connection)
Should we charge them separately? In this case we can get 2 Bank charger.
Something like this maybe -> http://www.batterystuff.com/battery-chargers/12-volt/marine-chargers/DPSS2.html

If being in series connection is fine, thinking about ordering this one -> http://www.amazon.com/dp/B004LX14Z2/?tag=cpf0b6-20
26amp, which will make it 0.26c. Does it sound like a good choice?
Not crazy about NOCO Genius brand. but don't see options for CTEK that we can order.

 

[mellowhead]

In commercial applications, charging independently is not commonly done. They are typically charged as one "big battery". There is nothing wrong with charging them independently, but it adds complication (and more points of possible failure) to the wiring system and this is why it is typically shied away from. It is important though, especially with VRLA batteries, that they be in an equal state of charge before being put into service. The easiest way to ensure that is to individually charge them to full beforehand. If the batteries were purchased new and from a trusted vendor, then chances are pretty good that they entered service in an equal charge state.

I've had poor experience with reliability on that particular NOCO model, although the other Genius chargers have been excellent. Other brands/models that I know to be good are:
Xantrex Truecharge2 24V - These have an available temperature sensor for temperature compensated charging
Samlex SEC-series 24V - Good reliability, but no temperature compensation

 

[SemiMan]

Ah yes, the IUU fast-charge algorithm. Problem is, unless you are commercial, the charger that implements this may be hard to find. The only alternative for most is to get bulk/absorb finished fast enough to get at least 8 hours of float in before the next shift - sometimes impossible.

IUU is the standard bulk/absorption/float charge method and is standard in many readily available chargers.

 

[IonicBond]

Oops - typo. Yep, it was the IUI that was hard to find from a consumer level. IUU is the norm.

Personally, I've had no problems with the Noco Genius chargers. I'd have no problem with the G26000 for your application. You could use the 12v charge on each just to run it through it's paces and see if the charger detects any major problems individually. Then in normal use, stick to the 24v setting for your series connected pair. At 24v, the charger is only putting out 13A, not 26. But, since those SigmaTek agm's are somewhat generic ups-backup style agm's, then this will do ok for an overnight charge - those generics are not as stringent about getting close to 0.25 to 0.3C like a quality East-Penn / Deka is for longest life.

What is curious is that the picture of the 26000 shown doesn't even appear on Noco's website. It looks as if the whole lineup now includes Lithium (assuming lifepo4), but I don't see it reflected on the site, unless I'm looking at the wrong thing. I know the older models didn't support lifepo4. That's pretty good news for me actually!

 

[SemiMan]

To get the most life, those cheap AGMs need as much care in charging as any other AGM. It's the construction that dictates the requirement.

East Pen /Deja has some quality to it but its cycle life is rather middling compared to better deep cycle AGMs.