Opinions on Concorde AGM 2240

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Right now in my small pop-up camper I'm using 2 Trojan SCS225's (12v parallel), but since they are inside, they need and have vented enclosures.  The enclosures don't seal that well, and the 'explosive gas' detector often goes off when bulk charging, and always during EQ.  I've thought about replacing them (using them for another application) with 2ea. Concorde (like the 2240's 6v in series, using a non-vented enclosure (they are taller, and will require a different box, which is OK with me).

My panels are a 75W Siemens and an 85W Kyocera with close specs.  Any downsides to this plan, other than cost?  I can use a different charging program with the TriStar for these, so that should be no problem.  Do I still have to keep their SOC to at least 50% to assure long life?

Any comments are welcome.  Thanks,

John F
LV, NV

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,522 admin
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    Re: Opinions on Concorde AGM 2040

    Concorde says that you can discharge to 20% SOC (remove 80% of the charge) and still have good life.

    http://www.concordebattery.com/xtenderservice.php (80% capacity is the warranty requirement)

    AGM's are sensitive to overcharging (can't replace electrolyte/water if overcharged).

    Check our host's Battery FAQ here:

    http://www.windsun.com/Batteries/Battery_FAQ.htm

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
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    Re: Opinions on Concorde AGM 2240

    Can I take this as a mild 'discouragement' for (mostly) solar RV use? It should be difficult to overcharge with the TriStar properly programmed, shouldn't it?

    On the other hand, you might have saved me $400 or so, so I should thank you and just disconnect the propane/explosive gas detector...

    John F
  • BB.
    BB. Super Moderators, Administrators Posts: 33,522 admin
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    Re: Opinions on Concorde AGM 2240

    No-no-no... AGM's are pretty close to the "perfect" battery for your use. Just make sure you have a good controller that is able to properly "float" the batteries and has temperature compensation (ideally bolted to one of the battery terminals).

    Many of the simpler controllers don't have a float mode... And you either have to set the voltage too high and over charge the battery for long term storage, set the voltage too low for quick charging, or manually set the voltage back and forth depending on what you are doing.

    You will have check the manual for your charger to ensure that it has a float charging mode and you can set the voltages to the appropriate setpoints for the Concorde AGM batteries (using the controller's Sealed/gel battery settings may not be correct for the Concorde).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
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    Re: Opinions on Concorde AGM 2240

    John,

    Your TriStar, its remote BTS and AGM batteries will all get along fine for your camping application. In fact, if (when?) I get another camper, I doubt that I will consider anything but AGM batteries. To me, their higher cost is easily outweighed by their very low maintenance requirements, their high coulombic efficiency (~98% Ah out / Ah in vs. ~90% for flooded-cell batteries), and their lack of special venting requirements. For example, AGM batteries (and their gel cousins) are regularly charged indoors when used with wheelchairs and UPS systems.

    However, as Bill noted, they are sensitive to excessive charge voltage, so the correct charge algorithm and a remote BTS are essential. The TriStar’s battery selector #3 might be a good place to start. As you know, you can fine tune the TriStar to a custom algorithm.

    There are other AGM battery suppliers to consider. Take a look at MK and Trojan.

    http://www.mkbattery.com/
    http://www.mkbattery.com/images/lagm.pdf
    http://www.trojanbattery.com/Products/RenewableEnergy.aspx

    I urge caution if you’re considering wiring a pair of big 6 V AGM batteries in series. I converted my four battery AGM battery bank from a 12 V configuration (four size 4D’s in parallel) to a 24 V configuration (two series strings of two batteries each, and the two strings wired in parallel) a few months ago. When taking battery readings a few weeks ago, I found that one series string was behaving oddly while being charged. While the total string voltage was correct, the voltage of one battery was too high and the voltage of the other was too low.

    Neither situation is good, and the inability to apply the typical flooded-cell battery equalization solution may be a drawback to AGM batteries. Accordingly, I ordered and installed a set of 12 V Powercheq modules. These gizmo’s are designed to “equalize” the charge voltage to batteries wired in series by diverting a bit of charge current around the higher voltage battery. My batteries are now fine, and if you are so inclined, you can read more about this project here:

    http://www.outbackpower.com/forum/viewtopic.php?t=1750

    So, if you chose the two 6 V batteries in series solution, I recommend you also consider a 6 V Powercheq module. See: http://www.evsource.com/tls_powercheq.php Other than that little matter, this approach should work just fine.

    Alternately, you may want to look into a big (and heavy) size 4D (~200 Ah) or size 8D (~250 Ah) AGM battery

    HTH,
    Jim / cewzer
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Opinions on Concorde AGM 2240

    quoted from bb.
    "Concorde says that you can discharge to 20% SOC (remove 80% of the charge) and still have good life.

    http://www.concordebattery.com/xtenderservice.php (80% capacity is the warranty requirement)"

    this is wrong as they gave that for the test conditions. i have literature that states the best dod for the numbers of charge cycles is between 60 and 70%. cycle life drops fast after 70% and this is on a perfectly good battery. to err on the side of caution i don't recommend over 60% and remember this is applying only for concorde sun-xtender agms.
    barshnik,
    as long as a good 3 stage controller with battery mounted temp sensor is used, the agms are excellent for you to use and as jim pointed out there are many out there to choose from.
  • System2
    System2 Posts: 6,290 admin
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    Re: Opinions on Concorde AGM 2240

    The non-venting design is what really has my interest for this application (if not overcharged) as well as the greatly reduced self-discharge rate over floated cells.

    I have a Morningstar TriStar with dip switch selectable programs for bulk, regulated, and float voltages and is PC programmable if none of the built in programs are suitable. It does have a post-mounted remote temp sensor. I assume with this it would be difficult to overcharge if all is working properly?

    AGM supposedly 'charge faster' - is this really noticable (I am running slightly under recommended PV capacity for the battery AH rating - 160w of panels.)

    Brands:
    Concorde - readily available, a few dollars less than the others (I'd probably buy from NAW&S), supposedly slightly thicker plates than the others?
    Trojan - I've had a bad experience with the local distributer, and won't buy from him/them again.
    MK - no opinion.

    crewzer - I'd think that an AGM's lower internal resistance would make them less suseptable to the kind of charge/discharge variations that need diversion correction, but that is just intuitive thinking with nothing to back it up. The wire run between batteries is about 6 ft, and I could double up the dual 8 guage wire I'm currently using to parallel the 2 12v's I'm using now if I were to get the 'golf cart' sized AGM's (6v) and hook them series. I'll keep that device in mind if I do go this way.

    Thanks,
    John F
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
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    Re: Opinions on Concorde AGM 2240

    John,
    I have a Morningstar TriStar with dip switch selectable programs for bulk, regulated, and float voltages and is PC programmable if none of the built in programs are suitable. It does have a post-mounted remote temp sensor. I assume with this it would be difficult to overcharge if all is working properly?

    Right... you're good to go with this combo.
    AGM supposedly 'charge faster' - is this really noticable (I am running slightly under recommended PV capacity for the battery AH rating - 160w of panels.)

    Everything else being equal, AGM's charge faster due to their higher efficiency... ~ 12% faster. Also, they do not require periodic "high voltage" equalization.

    HTH,
    Jim / crewzer