AGM vs flooded charge time

[OldToolmaker]

You may be willing to wait but I'm pretty sure that I won't be around in a decade.

Has anyone made it clear that flooded cell, gel and AGM are all lead acid batteries? The difference between the three is how the electrolyte is treated. Flooded cell spill when you turn them upside down. Gel don't spill but if you charge them too quickly the electrolyte out-gassing makes bubbles in the gel and you lose that much effective plate area because the gell stays bubbled. If you really need a spill proof battery then AGM is the way to go. AGM are also called starved electrolyte because the glass mats that hold the electrolyte aren't charged with enough electrolyte to allow you to corrode the plates by overcharging. You also don't get that last 5% of capacity either but I feel that if you're counting on that last 5% then you need bigger batteries or more of them.

FWIW, an older friend of mine, while dirt biking in the southern California desert proved that if you overcharge an AGM battery and dry it out you can cut the top open, add water and start your engine one more time to get home.

[wa8yxm]

Old T.. I have stated that many times, many many times,, Still folks persist in saying AGM v/s Lead Acid.

PP&M said it best "When will they ever learn, When will they ever...Learn?"

Been what, 50 years or so since they recorded that and still they have not yet learned.

And folks keep saying GEL,, I know of nobody making GEL batteries in the sizes we use, In fact GEL batteries are all but extinct,, AGM is so much better than GEL.

[twinboat]

I have read that gell will outlast AGM, if treated right. "Victron Energy"

And Trojan sells them!!!

[pasdad1]

Originally Posted by dons2346

"I am still waiting on a comparison of charge times with the following conditions:

Same amount of batteries (Example, both banks 230 or 460 amp hours)
SAME CONVERTER."

Cough up the bux to purchase the inverters and batteries and we can get the show on the road.

Lifeline supplies an equation which will estimate charge time of their AGM batteries.

Assuming temperature between 68 - 86 F

Time to reach full charge = [(DOD/100) x Rated Capacity (Ah) / Rated output of charger (amps)] + 2 hours

As an example:

Charger capable of 100 amps
440 Ah battery bank
50% DOD


(50/100) x 440 / 100

2.2 + 2

Time =4.2 hours

Lifeline states you can charge up to a 5C rate.....(500 amps for a 100 Ah battery)

http://www.lifelinebatteries.com/manual.pdf

[Pigman1]

Originally Posted by Tony Lee

Those assuring us that AGM batteries can be equalised might give us some details.

For instance, do all AGM manufacturers recommend equalising?
Which do and which specifically recommend against it.
Is the equalising sequence - times and voltages - the same as that used for conventional flooded LA batteries?
How does one determine that the batteries are "a little down in capacity" and so should be equalised (if that is the manufacturer's criteria)
What precautions should be followed.
Etc etc etc

Unless the recommendations are universal and fully detailed, some members might get a little annoyed if they follow advice and end up wrecking perfectly good batteries.

Well, I can answer some of this.

Lifeline does specifically recommend equalizing, although they call it "Conditioning". Their GPL-4CT 6 volt cells set up in 12V pairs need 15.58VDC for 8 hours at 70 degrees Fahrenheit for this process. That voltage varies slightly with temperature, but they give you numbers for whatever temp you need. We have a Magnum MS 2812 inverter/charger and a ME-RC50 remote controller. For getting the correct charge profile on these batteries the remote can be set to various bulk, absorb, float, and equalizing profiles. Even though Magnum recommends an AGM-1 setting, when you take the Lifeline recommended charge profiles for the GPL-4CT and compare with those available on the Magnum, the AGM-2 profile is closer. THis holds true for all but the equalizing (conditioning) voltages. To equalize you need to reset the profile to AGM-1 then return it to AGM-2 after the process is completed (after 8 hours)

The only way to set your system is to read the technical data and manuals for your rig, your specific inverter/charger, and your specific batteries as recommended BY THEIR MANUFACTURER. To do otherwise invites a shorter battery life, less battery capacity available to run your RV and overall poorer performance of your DC electrical system. For those NOT willing to do these things, what you get is what you get.

There are NO universal settings that get you everything

[Mr_D]

Was just reading the manual for the 3000W SW inverter in the Magna, it specificaly states NOT to do an equalizing charge on AGM batteries. The Magna has 4-8D AGM house batteries and 4 starting batteries also AGM's and I plan to take care of them!

[Pigman1]

Originally Posted by Mr_D

Was just reading the manual for the 3000W SW inverter in the Magna, it specificaly states NOT to do an equalizing charge on AGM batteries. The Magna has 4-8D AGM house batteries and 4 starting batteries also AGM's and I plan to take care of them!

What does the maker of your batteries specify? They are the authority on their batteries! Magna is the authority for the inverter/charger and cannot and should not give a universal statement about all AGM batteries by the many battery manufacturers out there. They cannot know what your manufacturer or later owners installed for batteries.

[wa8yxm]

Originally Posted by twinboat

I have read that gell will outlast AGM, if treated right. "Victron Energy"

And Trojan sells them!!!

I have used gel, with a proper charger/maintainer
I have used AGM likewise
And I still use Flooded wet cell

You heard wrong.

[twinboat]

I read it, from a charger supplier, and other sources.

I heard what you said

[buckeyemike]

I believe in the lifeline literature they are assuming everything is equal when they say it charges 20% faster.. Meaning if use the same charger on a flooded versus AGM the AGM will charge 20% faster