AGM batteries

Discussion in 'General Discussion' started by Great Lakes, Feb 25, 2021.

  1. Great Lakes

    Great Lakes Well-Known Member GOLD Sponsor

    Oct 11, 2016
    Lake St. Clair - Michigan (MacRay Harbor)
    2005 390 Sundancer
    GHS Platform
    Dual 12” Axiom
    Tracvision | FLIR
    Bow/Stern Thrusters
    496
    I have 7 years on my flooded batteries and I’m looking to go the AGM route this time around. Is there a go to place for me to look or a brand to avoid?
     
  2. dvx216

    dvx216 Well-Known Member SILVER Sponsor

    Feb 1, 2012
    Catawaba Island,Oh.
    2000 310 sundancer 5.7
    optional electronic package






















    n/a
    twin 5.7 300 Hp.
    Don't take this question the wrong way but could you tell the reason to switch to AGM over a regular battery. The reason I ask is that it's not recommended that you discharge a AGM any more then 50%. what are the benefits.
     
    Great Lakes likes this.
  3. OllieC

    OllieC Well-Known Member SILVER Sponsor

    Mar 11, 2013
    MinniSoCold
    Sara Belle
    2005 Weekender 215
    Mercruiser 5.0 mpi, Bravo III
    I picked up some Group 31's at Sams Club last Spring. I believe they have an annual Spring sale. They're Duricells IIRC.
     
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  4. Great Lakes

    Great Lakes Well-Known Member GOLD Sponsor

    Oct 11, 2016
    Lake St. Clair - Michigan (MacRay Harbor)
    2005 390 Sundancer
    GHS Platform
    Dual 12” Axiom
    Tracvision | FLIR
    Bow/Stern Thrusters
    496
    Not offended at all. Simply for the lack of maintenance on them. I've always understood they were the best option.

    Talk to me
     
    dtfeld likes this.
  5. be_prepared

    be_prepared Active Member GOLD Sponsor

    361
    Oct 12, 2015
    Mattapoisett, MA
    2002 Sea Ray Sundancer 340DA
    Twin Mercruiser Horizon 8.1 inboards
    If any of your friends/colleagues has a commercial account with Interstate, they might be able to get you a wholesale deal on their Marine AGM's, I have 4 of the Group 31's in my boat, 2 in parallel for house and one engine, a dedicated one for the 2nd engine, and dedicated one for the genny. 3 years on them, with a fair amount of time on the hook and mooring, handles both fridges and all other general loads with a recharge on the genny for a couple hours in morning when making breakfast and showering and nighttime cooking dinner, and running the blender for sundowners.
    List price is crazy, but nobody pays that:
    Interstate Batteries | 31M-AGM
     
    Great Lakes likes this.
  6. SeasNT

    SeasNT Member

    61
    Jan 30, 2016
    Lake Erie
    44 DB 2006
    QSC 500
    7 years with flooded cells, I think you should get an award! We're lucky to get 4 or 5. I would switch to AGM's and add some flexible solar panels to the bridge if we sat more frequently on the hook. Would also need to update inverter/charger. AGM can be drawn down and recharged many more times than flooded. Lithium chemistry is coming along and really great in some applications but the high energy density still makes me nervous on a boat. I also think we might see some improvements with the old flooded cells. I can't believe the lead manufactures are just going to roll over as different storage technologies emerge.
     
    Great Lakes likes this.
  7. Shoyrtt

    Shoyrtt Active Member SILVER Sponsor

    208
    Jul 16, 2020
    Redlands, CA
    1999 450 Express Bridge
    Caterpillar 3126TA
    If you are looking for zero maintenance and the “best option” you should consider lithium. Much higher cost up front, but they last longer and you get more capacity for less generator use. They are also capable of being fully discharged. Here is where I got my system: https://battlebornbatteries.com/marine-systems/
     
  8. Great Lakes

    Great Lakes Well-Known Member GOLD Sponsor

    Oct 11, 2016
    Lake St. Clair - Michigan (MacRay Harbor)
    2005 390 Sundancer
    GHS Platform
    Dual 12” Axiom
    Tracvision | FLIR
    Bow/Stern Thrusters
    496
    Holy..!!
     
    HawkX66 likes this.
  9. The Bill Collector

    The Bill Collector Well-Known Member GOLD Sponsor

    Jun 2, 2008
    Tacoma, WA
    1998 450 Sundancer, Achilles dinghy w/15hp
    3126 Cat's
    I just replaced my Costco Interstates after 8 years with DieHard maintenance-free from Advanced Auto Parts for under $100 apiece.
     
  10. Shoyrtt

    Shoyrtt Active Member SILVER Sponsor

    208
    Jul 16, 2020
    Redlands, CA
    1999 450 Express Bridge
    Caterpillar 3126TA
    I know. My wife (aka "the Fleet Admiral") hates the generator running. She said get the best, so we went lithium.
    Lith2.jpg
     
    SeasNT, RBB, OllieC and 1 other person like this.
  11. The Bill Collector

    The Bill Collector Well-Known Member GOLD Sponsor

    Jun 2, 2008
    Tacoma, WA
    1998 450 Sundancer, Achilles dinghy w/15hp
    3126 Cat's
    Wow, at a $1,000 apiece...?
     
  12. Great Lakes

    Great Lakes Well-Known Member GOLD Sponsor

    Oct 11, 2016
    Lake St. Clair - Michigan (MacRay Harbor)
    2005 390 Sundancer
    GHS Platform
    Dual 12” Axiom
    Tracvision | FLIR
    Bow/Stern Thrusters
    496
    Nice setup.
    We don't mind the gen running. Besides the water splashing, you can't even hear it.
    Classic sales tactic tho. Show me a really expensive product so the mid line ones are “cheap” now... Lol
     
  13. Shoyrtt

    Shoyrtt Active Member SILVER Sponsor

    208
    Jul 16, 2020
    Redlands, CA
    1999 450 Express Bridge
    Caterpillar 3126TA
    Less than that. Battle Born offers package discounts. I also got a new inverter, solar module and battery monitor. Lith1.jpg
    lith9.jpg
     
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  14. Shoyrtt

    Shoyrtt Active Member SILVER Sponsor

    208
    Jul 16, 2020
    Redlands, CA
    1999 450 Express Bridge
    Caterpillar 3126TA
    I'm glad I could help "seal the deal" on a nice set of AGMs...Lol :)

    If you want a little tech behind all of your options, this is a good article:
    https://www.batteryequivalents.com/battle-born-100-ah-lifepo4-12-volt-deep-cycle-battery.html
     
    Last edited: Feb 25, 2021
    Great Lakes likes this.
  15. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    I upgraded when my Group 27's flooded batteries started to leak 2 years ago with Group 31 AGM.

    So far so good.

    I purchased from batteries plus.

    I needed them..... they had them..... I bought them. :D
     
    Last edited: Feb 25, 2021
    Great Lakes likes this.
  16. techmitch

    techmitch Well-Known Member GOLD Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    Your batteries started to leak?
     
  17. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    I will correct my statement above...... the Group 27's were flooded batteries.
     
  18. Joint Custody

    Joint Custody Well-Known Member GOLD Sponsor

    581
    Sep 20, 2017
    Lake Powell Utah
    2001 460 Sundancer
    Twin Cummins 6CTA8
    We went with these.
    This will be the 3rd season on these. The only issue is when they drop below capacity it does take a while running the gen to bring them back up.I have four of them working inline with the inverter.

    56A4CC66-09A4-4515-855C-D3AE707D33D1.jpeg
     
  19. techmitch

    techmitch Well-Known Member GOLD Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    Kinda figured they were flooded batteries, but what did you mean when you said they started to leak?
     
  20. bfernald0

    bfernald0 Member

    77
    May 18, 2020
    Marina del Rey, California
    340 Sundancer 2001
    8.2L Mercruiser ECT Horizons
    This guy does a great you tube series comparing the cost/benefit of Lead Acid vs. AGM vs. Lithium (). For my 340, I have one maintenance free group 31 for each engine and the generator. I added 2 L16 6V Lead Acids for the house bank. They have did not last very long, but I am to blame for that. I'm switching to 2 L16 FullRiver AGMs. I will update on how they perform going forward.

    Based on everything I've read, Lithium still doesn't come close on the cost per kw/hr. You're better off going with Lead Acid or AGM unless you have money to burn. I ultimately decided to go with AGM this time around because they're less messy and the installation options are greater because they can be installed on their side.
     
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