2nd Gen Non-Engine/Transmission Agm batterys

[seafish]

your welcome...


I thought, but could be wrong, that DEKA made CAT engine start batteries..

You are correct that Deka makes oem CAT batteries. IMO, Deka makes a dam good battery, probably as good as the Diehard Platinums, but I chose to run the Platinums in my truck and they have performed flawlessly for 5 years already (knock wood…lol)

 

[Meteorbs]

Ah, l'll try the Agm battery and have the system tested again and see what happens. I hope that it will work well.

 

[SRath]

BK is definitely right that even Optimas can blow up. I had a yellow top in our old Chevy Class C motorhome that we used for motocross racing. On the way home from a weekend of racing in Missouri I was less than 25 miles from home when I saw my vehicle volt gauge was pegged due to internal regulator failure on the motorhome, which used a battery isolator to charge the camper battery when the engine is running. Being tired and that close to home, I continued on. Three miles from home there was a big explosion in the auxillary battery compartment that immediately filled the motorhome with some nasty acid gas. The Optima couldn't handle the over-voltage. After evacuating the family, I called a friend to pick us up since the voltage spike when the battery blew fried the module in the HEI distributor, too, along with the cruise control module. Twenty minutes of work alongside the interstate with spare parts I had at home (and a new alternator) got the camper running again, but the Optima was toast.

We use 12v gel cell batteries, 24 of them, in each of the 3 EPU's (emergency power units) that power the pitch control units (pcu's) and motors for the 3 giant 155' blades on the college's Clipper Liberty 2.5 million watt utility-class wind turbine. They are constantly spinning around inside the hub the blades attach to and are also subject to all the extremes of weather that being 300' in the air in Iowa year-round can torture them with. I had to change out several of them last winter when our temps here were colder than the coldest place in Alaska for more than a week. The wind turbine needs them as part of the safety loop that pitches the blades to 90 degrees and shuts the turbine down in an EFC (emergency feather condition) shutdown. I was amazed at the dates on the old batteries; they had lasted over 4 years in those conditions and only a handful failed, but it was enough to cause multiple faults and an EFC shutdown. The remaining good batteries still supplied enough power for the big DC motors that pitch the blades to stop catching wind. Very impressive batteries considering their small size, which is about half the physical size of the batteries in our trucks. Very expensive, too. What was even more surprising is that I was able to get the turbine back online using some of the old batteries that had been sitting in storage since being changed out years before!

 

[BK]

I've never been involved on the wind power applications, but knew there were VRLAs in there somewhere.

The biggest cause of catastrophic failure in the series string of 12 VRLA's (AGMs), is when one and than more start to dry out, their terminal voltage starts to run lower than normal, and than the others in the string start seeing a higher than normal float (the applied float voltage doesn't change, but how it's distributed amongst the batteries in series does, since their impedances change, like a resistor ladder), and thermal run away starts, and the melt down and fires occur.
When running 2 six volt batteries in series for an RV, this is a danger there as well.

Internally in a 12v battery, there are six 2v cells in series, when a cell shorts, the other cells see a higher than normal float, and they will start to fail and can burn up as well.
The AGMs / VRLAs can burn up real nice even w/o the float voltage going to high.

I've seen internal connections that series the internal cells together fail and under a high current discharge is when that becomes apparent, and poof, nice fire.

BK is definitely right that even Optimas can blow up. I had a yellow top in our old Chevy Class C motorhome that we used for motocross racing. On the way home from a weekend of racing in Missouri I was less than 25 miles from home when I saw my vehicle volt gauge was pegged due to internal regulator failure on the motorhome, which used a battery isolator to charge the camper battery when the engine is running. Being tired and that close to home, I continued on. Three miles from home there was a big explosion in the auxillary battery compartment that immediately filled the motorhome with some nasty acid gas. The Optima couldn't handle the over-voltage. After evacuating the family, I called a friend to pick us up since the voltage spike when the battery blew fried the module in the HEI distributor, too, along with the cruise control module. Twenty minutes of work alongside the interstate with spare parts I had at home (and a new alternator) got the camper running again, but the Optima was toast.

We use 12v gel cell batteries, 24 of them, in each of the 3 EPU's (emergency power units) that power the pitch control units (pcu's) and motors for the 3 giant 155' blades on the college's Clipper Liberty 2.5 million watt utility-class wind turbine. They are constantly spinning around inside the hub the blades attach to and are also subject to all the extremes of weather that being 300' in the air in Iowa year-round can torture them with. I had to change out several of them last winter when our temps here were colder than the coldest place in Alaska for more than a week. The wind turbine needs them as part of the safety loop that pitches the blades to 90 degrees and shuts the turbine down in an EFC (emergency feather condition) shutdown. I was amazed at the dates on the old batteries; they had lasted over 4 years in those conditions and only a handful failed, but it was enough to cause multiple faults and an EFC shutdown. The remaining good batteries still supplied enough power for the big DC motors that pitch the blades to stop catching wind. Very impressive batteries considering their small size, which is about half the physical size of the batteries in our trucks. Very expensive, too. What was even more surprising is that I was able to get the turbine back online using some of the old batteries that had been sitting in storage since being changed out years before!

 

[kscheffler]

I find it ineteresting that the wind turbines use gel batteries why would they not use AGM batteries. WHat is the benefit of the gell over a AGM battery. Gells were poplular in boats until the AGM's came on the market. I have the sears platinums in my truck and fish boat and they work great.

 

[BK]

I find it ineteresting that the wind turbines use gel batteries why would they not use AGM batteries. WHat is the benefit of the gell over a AGM battery. Gells were poplular in boats until the AGM's came on the market. I have the sears platinums in my truck and fish boat and they work great.

AGMs are sort of generically called, incorrectly, Gel cells.
Both have the same basic traits regarding no free electrolyte to spill, and no orientation limits.
But AGMs are by far the most common of the two.

Gel's are more expensive , don't have the power density, and a different charging profile IIRC.

AGMs are better with higher discharge rates, such as for UPS applications. (life expectancy on a "7 year product" is 3-5 years)
Very dense flooded lead acids are also used for even higher power requirements for UPSs, but very expensive and much more labor for PM to maintain the investment.
(life expectancy on a "20 year product" is 12-17 years)
Each jar has two 2v cells @ ~ 2500 amps.
During a load test, we'll see 2200 amps, and it's a weird feeling in the air, when all that current is flowing in the cables.

A room of flooded lead acid cells...

The switchgear battery applications, to supply dc back up power for control circuits, lower currents for a long period of time (8-10 hours), usually are much lower discharge rates, and gel cells would be fine there. But today from my experience, they use either a wet cell (flooded) of lead acid or a Ni-Cad.
I haven't seen a true gel cell in the field , with our customers, in the 10 years I've been with my company.

 

[kscheffler]

Wow that is quit the battery room what is that for? I think the reason most folks have problems with AGM batteries is improper charging. I have a volatage adjustable battery charger and every two months I charge my AGM's to 14.7 volts seems to make a big difference in the life of the AGM's to increase bulk charge to 14.7 in lieu of the 14.4 from the alternator. It is really important for my boat batteries since I run a trolling motor. One thing I see about AGM's is that they act weird once they get below 12 volts. They will drop from 11.9 to 11.6 very fast but if you let them sit for 15 minutes the voltage will recover to 12.2 and then work again for another hour. So once they get below 12 volts they need to be fully charged again.

 

[Mingoglia]

If I were to guess it looks like those big banks of batteries are in a Data Center. Typically this is what you'll find with giant inverters and PDU's used to power all the equipment for the period of time until the diesel generators kick on and transfer power to them.

 

[BK]

Yup,,UPS, typical for a large data center of all types, they use the UPS to handle the critical loads while the generators are coming online and syncing up when utility pwr is lost.
back in the day, could be a few good 7-10mins before gens were online, now a days it's down to 15 seconds, but they still are sizing the battery for that 2x the need... 30mins.

We are seeing more and more ,instead of the big strings of flooded cells, 4-8 cabinets of AGMs (each cabinet has 40 AGMs in it, in series). They don't have the venting needs of the flooded , and don't have the spill containment requirements, and per square inch, less of a load bearing requirement.

A charge on the AGM's up at 14.7 (really about 14.2 for us) would be considered a temporary "equalizing charge" , that is done right after a fresh install of a new bank of batteries.
To help finish forming the plates... a battery doesn't really fully finish forming for about 6 months, some for as much as a year.

Some use to do it every year or so, we don't recommend that to our customers.
A partial discharge at system load for 10-15 mins is better, and also provides a measure of capacity.
Some don't bother, and just replace the AGMs every 3 years, others try and get every month out of them they can.

When the customer signs on for it, we use special battery monitoring systems that measure the terminal voltage and logs it a few times every day, and measures the "internal impedance" of the each battery in the string and logs those measurements too. When trending those measurements you can see the impedances come down. And none of the batteries are exactly the same.

we tend to float a string of 40 @ 540Vdc , right at about 13.5Vdc, but that is at room temp of ~77DegF.
Higher in temp, the lower the float voltage.
The lower the ambient temp, the higher the float voltage. (most cars computers, and older regulator did jump the float volage up to 14.1 or so in "cold" weather.)


13.5 is typical for a "stand by use" for AGMs.

For cyclical use, AGM float is higher and different, but 14.7 is getting high, depending 13.8 - 14.2 is typically specified depending.
But if your equalizing charge every couple of months is working for you, great, the proof is always in the performance and life of the battery.

The big issue with alternators for chargers, and cheapo chargers is that there is too much ripple, and you never get a full charge that makes the plates happy.
The real good maintainers use an extremely clean DC and well regulated float voltage to squeak in that last 10%.
And if you were to watch the profile of the chargers / maintainers for AGMs, you'll see they do start with a short time of a high float, and than come down to a normal recommended float.


yup, your right, once an AGM hits it's low number, they drop like a rock, and they start to get hotter even quicker, cause their internal impedance goes up dramatically.
Leaving it sit, is letting it cool down, and the internal impedance decreases as it cools down.
Get much below 6 voltages, with a decent load on it, and you better get out of the way.
We consider 10.02 the critical low for an AGM.

 

[kscheffler]

Yes I agree the 14.7 is definitely a equalize charge and I only hold that voltage for 4 hours. Ever time I do this the AGM will come back to a 13.0 volts after a 24 hour period with no load. If I charge to 14.4 the 24 hour voltage only obtains 12.8 so it seems that the equalize will bring it back to full voltage. But maybe I should just cut this back to an annual event. Yes you are right lots of folks ruin AGM's buy only charging with alternators they need to be topped off with a good charge from a battery charger.

What do you mean when you say the battery plates need to fully form? I personally think that keeping batteries with no loads on a float battery charger takes life out of the batteries. I prefer to leave them sit and let the battery discharge to 12.6 or 12.7 then hook up the charger and take tehm to 14.4 then hold float for a few days and then turn off the charger. You have a completely different system if the batteries see periodic draws. I was wonder about that air quality in that lead acid room. Thanks BK for your insight.

For those with AGM batteries go to the odyseey web site they have great information on the proper charging of AGM batteries.

 

[BK]

the plates forming, talks to the substrate fully absorbing the acid, and not just on the surface.

If you left it long enough, it should self discharge down to it's natural open circuit terminal voltage.
12.6 / 12.7 is about it, anything higher is a residual left from the charge.
Or a very minor load, should result in the same voltage.

no, no, we've shown that on and off of charge constitutes a cycle, albeit a very very shallow one, but it does detract from life of the cell.
much better to keep 'em on a very clean charge, @ ~13.5vdc , @ 77degF.

Many of the newer UPSs are reducing the amount of onboard filtering to save cost, and counting more and more on the battery to be a filter, the increased ripple is shorting the life of the batteries.
The newest designs, meant to be "greener" , actually turn off the charger for a month or so, and than turn the charger on for a period of time, and turn the charger back off, again, finding a shorter battery life and Battery OEMs are voiding warranties of this topology is used.

Normally charging of the AGMs in this application, are essentially handled per the recommendations for standby use per the OEM.
Same as sitting the single 12v monoblock on your shelf and looking to have it be a happy battery by the start of the season.

The other use is "starting" use, which is extremely higher , short duration hits, for Generator starting and such.
The floats are generally higher for a starting use. But again, a starting battery does have a different design VS a battery designed for standby use.

Equalizing chargers are hard on the cells, they cause heat , heat = decrease in life.
They are necessary and per manufacturers direction for warranty, we do an equalizing charge after the install of a new sting.
but than after that we don't recommend them, just a capacity test each year.
The capacity (controlled discharge) test is healthy for the string as well a provides the best data to see if a cell / unit / monoblock is not healthy.