AGM battery quality vs cost. Do your research.

[john61ct]

Let's just say you are living off the grid full time and have a set of AGM's that are rated for 2000 life cycles. Those batteries most likely are going to age out way before the cycles are met. There is a remote possibility that they will continue to function after 5 years or more

That is why it would be silly to use such AGMs for that use case. 5 years is nothing for a stationary application!

Of course in a high-duty choice-limited market like Australia, the cells designed to last 15-20 years (before reaching 70-80% SoH EoL) may not be priced competitively.

In which case LFP usually is, much more so than in North America, where top quality lead choices for cheap, torts liability, lack of government support and prejudices against Asian sources, have caused us to lag far behind the rest of the developed world in that regard.

 

[john61ct]

Startup companies supplying quality deep cycling cells in lead?

If that indeed is what you mean, please supply some links.

 

[john61ct]

Note the Y axis is logarithmic. Same data in a linear scale is **much** more dramatic.

As to "40% would be better" there is no magic number just a question of the use case and owner preference as stated.

But certainly regularly going deeper than 70% DoD IMO would be foolish.

800 cycles would be my absolute minimum expectation to bother with the trouble of installing.

And only a true emergency would motivate me to go below 60% DoD, and that would be in a solar-only context.

90% of the time there would be a Fossil Fueled runtime source on hand to prevent that

but yes they do fail sometimes, and comms like a satellite phone, GPS nav gear, rescue beacon etc can be required to operate for survival.

 

[Peter_n_Margaret]

Most owners think going deeper than 60% is fine, even 80% or dead flat

And it is.

That 50% guideline is just a useful shorthand "opener" to a topic
which is more complex than most are iterested to explore in detail.

Then I suggest that folks cease using it like it is some law of batteries when in fact it is no more a sensible number than 30% or 70% or any other that you can pick out of a hat.
Cheers,
Peter
OKA196 motorhome

 

[john61ct]

Nope, works perfectly fine as it is.

Maybe 2% of owners even have the means to estimate 50% SoC within greater than 20% accuracy as it is.

Thanks for the suggestion though!

 

[vtsoundman]

As a small aside, We used to use conventional flooded LA for cranking. They typically died (often suddenly) in 2 or 3 years. Then we tried a "garden variety" AGM as a crank. 9 years later I was replacing the 400Ah of house batteries so replaced the crank too, with another ordinary 125Ah AGM.
I concluded that the flooded LAs were physically falling apart internally from the vibrations caused by corrugations. The AGMs have their plates supported in a gel, so were physically much more robust. The crank is chassis mounted, not under the bonnet.
ps... the Simpson is a special place.
Cheers,
Peter
OKA196 motorhome

This guy gets it...AGMs are superior in just about every way in applications that MATTER to people on THIS site - mobile APPLICATIONS. Optima, Odyssey, etc all use an AGM style construction. AGMs are tightly packed and the acid held tightly within the mat and are highly resistant to vibration.

That is why it would be silly to use such AGMs for that use case. 5 years is nothing for a stationary application!

Of course in a high-duty choice-limited market like Australia, the cells designed to last 15-20 years (before reaching 70-80% SoH EoL) may not be priced competitively.

In which case LFP usually is, much more so than in North America, where top quality lead choices for cheap, torts liability, lack of government support and prejudices against Asian sources, have caused us to lag far behind the rest of the developed world in that regard.

Now LA lasts 15-20 yrs with 70-80% SoH at EoL...haha...in the other thread it was 10yrs!

Could the people installing some of the largest stationary energy storage using Lithium be wrong?? Even those being installed in Australia??? And even in Asia too? Could I be wrong and the others that work in the storage industry be so wrong?

North America prejudice against Asian sources? What are you talking about? - the MAJORITY of lithium batteries, save a portion of Tesla, are manufactured in Asia!

Give a rest, please.

This site is for mobile travelers...not stationary applications.

AGM is more resistant to vibration, more temperature resilient, can easily out cycle, and is in general, better than FLA in APPLICATIONS THAT MATTER to people on THIS site.

GEL is even better than AGM in many regards (not cold) but is more expensive, but not usually worth it.

The majority of the LA chargers are absolute garbage and cannot reliably charge LA batteries of any flavor...so GELS, AGMs get a bad name.

LA batteries for the rv'er/sailor/Overlander have a set of requirements for 'optimum life' that is opposite for how LA batteries need to be used in real life.

LA batteries must be fully recharged very frequently (otherwise they are prone to accelerated death from PSOC cycles), Suffer dramatic loss is usable life if taken down to 30% SOC, and are crazy heavy...having to 100% recharge so it doesn't die an early death is absurd way to design a solar system! Real life has clouds!

AGMs work great as starting batteries b/c they are topped off almost immediately and can handle all sorts of temps.

Bottom line - if half the above about LA was true (FLA in particular), then the majority of auto manufacturer's and all of those working in the storage industry are wrong....but they are not. The majority of auto mfrs use AGM batteries of various forms...not FLA.

Sent from my Pixel 4a using Tapatalk

 

[john61ct]

LOL longevity has never been a goal of industry, least of all the USian auto industry, actually explicit about planned obsolescence for nearly a century!

The battery industry marketed the hell out of AGM, and of course regular consumers happy with 3-5 years are also happy to sacrifice access to the electrolyte for supposed maintenance free.

Optima is no longer good enough to call a deep cycling battery, maybe get 4-600 cycles at best since JCI bought the line from Enersys.

And of **course** LFP is superior no matter the use case, that is not an issue here. Just stateside you're talking 5-8x more expensive even taking usable amps into account, but not including the extra infrastructure and expertise required.

No one is talking about Starter use case here either.

Yes many USians distrust even hate China, and you're exactly right, that has been one of the factors behind why our LFP distribution network is so grossly immature.

AGM is more resistant to vibration, more temperatures resilient, can easily out cycle, and is in better than FLA in APPLICATIONS THAT MATTER to people on THIS site.

Absolute bollocks.

> GEL is even better than AGM in many regards (not cold) but is more expensive, but not usually worth it.

Not so much that, as the lower voltage charging profile usually requires replacing at least some charge sources, much more finicky to care for than AGM, just as AGM is, compared to FLA.

If you need to install sideways, or need higher CAR, or simply don't mind spending 50-100% more per year for that convenience, feel free, I'm not at all saying AGM are bad

and in many markets they're in effect the only game in town, no choice anymore.

Any decent charge source these days has a set of canned profiles you can switch between for different chemistries.

The LFP ones are usually set way too high.

The best let the user custom adjust, say 13.8V for low current rates, vs 14.0V for fast charging.


> LA batteries must be fully recharged very frequently (otherwise they are prone to accelerated death from PSOC cycles)

The impact on AGM lifespan of PSOC abuse is **much** greater than with FLA!

Yes 10-15 years is easily achieved with top quality FLA, and the easier stationary use case is obviously higher than mobile applications.

 

[JaSAn]

I drive a lot of bad washboard.

I am starting year 7 on my Sam's Club GC2s ($86 each). I draw about 50 of 208AH daily and have about 1200 cycles on them.

My 2012 Ram 2500 came with a sealed FLA battery; I just replaced it with another sealed FLA this January. A friends 2017 Ford F150 came with a sealed FLA battery.

I doubt I could get much more service out of AGMs at 50+% higher cost.

 

[vtsoundman]

I drive a lot of bad washboard.

I am starting year 7 on my Sam's Club GC2s ($86 each). I draw about 50 of 208AH daily and have about 2000 cycles on them.

My 2012 Ram 2500 came with a sealed FLA battery; I just replaced it with another sealed FLA this January. A friends 2017 Ford F150 came with a sealed FLA battery.

I doubt I could get much more service out of AGMs at 50+% higher cost.

50Ah out of 208Ah is about 24% discharge. A very benign application. That will give you quite a great cycle life. And I bet you recharge it everytime too. Any LA will do fine. If all you draw is 50Ah, you won't really notice EOL until hit about 40% residual capacity....a 208Ah LA with such a low DoD will give get great economy - regardless of type. So go for the cheapest - great strategy if you have the space and can handle the possibility of acid spills w/o damage.

FLAs are usually a true wet cell that needs to be vented, otherwise pressure will buildup. Water and electrolyte must be replenished...

SLA vs FLA are different types of LA batteries. A sealed SLA may be similar to an FLA, but many SLA are actually AGMs but not marked as such.

An SLA that is basically an FLA has only one advantage over an FLA - less likely to leak acid. Since you can't replenish acid or water, the charge rate must be kept comparatively low. SLAs that are basically FLA and used in deep cycle apps are usually garbage.

A decent SLA must have fully recombinant charge rates, otherwise it will die early. Charge it rapidly, and it will be much more likely to vent...and lead to an early death.

There are quite a few automotive SLA are actually AGM, just not labeled as such.

The AGMs I've suggested will likely match your life and cycle count and are also at a bargain rate. No maintenance, no acid spills. The AGMs will also handle much higher charge currents too. If you can oversize the battery bank as you've done, and carry the weight, then you will get great bang for your buck. Cheap batteries are great in your application.

Edit: deleted 30% - was a typo.

Sent from my Pixel 4a using Tapatalk

 

[DaveInDenver]

Note the Y axis is logarithmic. Same data in a linear scale is **much** more dramatic.

Reproduced original chart. Since they include the full range of zero to 100% it must be on a log scale.



Same data on a linear scale. Not to harp on it, but keep those batteries topped! That last few percent is critical.



Log scale with 0% and 5% DoD removed. Engineering department likes this one.



Linear scale with 0% and 5% data points removed. Marketing likes this one.



The really useful data. Removed 35% of less DoD on a log scale.



Same on linear scale. Out here it's just a matter of priorities since space, weight, budget and reserve margin are as important as useful battery life. Just pick the X-Y point that meets your goals.

 

[JaSAn]

50Ah out of 208Ah is about 24% discharge. A very benign application. That will give you quite a great cycle life. And I bet you recharge it everytime too.
I deliberately sized my bank to give me an extra day of reserve. Longer life is a bonu$.

FLAs are usually a true wet cell that needs to be vented, otherwise pressure will buildup. Water and electrolyte must be replenished...
I only need to replenish water after equalizing - something most AGM cannot do.
. . .
A decent SLA must have fully recombinant charge rates (don't understand what you mean) . . .

There are quite a few automotive SLA are actually AGM, just not labeled as such.
Mine slosh when shaken; don't know about the Ford.

The AGMs I've suggested will likely match your life and cycle count and are also at a bargain rate.
One pays a premium for the same performance; AGM has some advantages and some disadvantages:
- most AGM cannot be equalized; I think this is important for longevity.
- individual cells cannot be easily tested and imbalance corrected.
. . . The AGMs will also handle much higher charge currents too. A moot point with small solar capacity on most campers and small chargers when solar is insufficient.
If you can oversize the battery bank as you've done, and carry the weight, then you will get great bang for your buck. Cheap batteries are great in your application.
For those of us on a tight budget AGM doesn't give us any real advantage for its additional cost.

 

[john61ct]

Note that the relative clout between the marketing department and engineering within a given company, no matter how stellar their products

varies even more than the way they set up the foundational conditions of their lab tests

which vary **enormously** compared to real life usage out in the wild.

These charts are useful only for understanding the universal principles

and comparing the different model lines within a given company.

They offer zero usefulness comparing the products of different companies

and you can guarantee poorer results outside the lab.

But you can be sure, the products of companies that do not publish such charts and do not make technical staff readily available to discuss them with individual customers

will always be much much shorter-lived, usually not earning the "true deep cycling" label.

Full River may be one exception since they are Chinese, given the different business culture and language barriers.

 

[vtsoundman]

I like your approach - many overspend trying to keep up with the Joneses!

Sent from my Pixel 4a using Tapatalk

 

[DaveInDenver]

Some hastily found data from the web.



Data between zero and 10% not included.

Energy given over specified lifespan. Interesting visualization I thought. It should be made clear that I made no attempt to match markets or types so this is not an apples-to-apples comparison. Just four random tech sources I found quickly. Researching your specifics would obviously be wise.



Deka, published by Matrix Energy in Quebec

http://www.matrixenergy.ca/stand-alone-systems/brochures/Batteries%20-%20East%20Penn%20-%20DEKA%20Solar%20AGM%20Batteries.pdf

Lifeline 6-0101 Feb 2017 Tech Manual

https://centexbatteries.com/techmanual.pdf

Odyssey Sept 2016 Tech Manual

https://www.odysseybatteries.com/docs/us-ody-tm.pdf

U.S. Battery AGM 2224 datasheet (6V AGM used the <200Ah)

https://us.v-cdn.net/5021717/uploads/editor/w8/evpp3cd3y84q.pdf

 

[OllieChristopher]

Very interesting and contrasting opinions to battery choices. Some of us are old school beat the crap out of the battery, get a long life, and cycles, and get them for cheap. I'm in that camp.

Of course in a high-duty choice-limited market like Australia, the cells designed to last 15-20 years

Other opinions are the mindset of all about the charge cycles and getting 10 - 20 years out of a AGM bank. Please show me a set of those batteries. I have yet to see a battery in an off road vehicle or any vehicle last that long.