Thin plate AGM batteries vs. flooded deep cycle batteries

LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
Thin plate AGM batteries have received some good press for being fantastic marine house batteries, but I can't make that jive with what I'm seeing on the market.  Can somebody tell me what I'm missing?

The advertised benefits of TP-AGM batteries are:
* more years of service (more discharge cycles)
* more hours of service at each use (deeper discharge)
* higher cranking amps
* faster recharge rate
* zero maintenance
* lower long-term cost

I compared two 90 A-h Group 27 batteries offered by West Marine: the Northstar thin-plate AGM and the West Marine flooded deep cycle battery.  

http://www.westmarine.com/buy/northstar--thin-plate-pure-lead-agm-battery-group-27--15074834

http://www.westmarine.com/buy/west-marine--deep-cycle-flooded-marine-battery-90-amp-hours-group-27--15020324

I'm looking for house batteries, so my main concerns are the price and the number of discharge cycles, because they determine cost per year.  The TP-AGM only gives 15% more discharge cycles (400 vs 350), but it costs 86% more ($335 vs $180).  

I'm getting 4 years from a pair of flooded batteries, so let's call that $90/year.  If I get 5 years from a pair of TP-AGMs, that would be $134/year ... 50% more expensive.  

Is the Northstar just a crappy example?  It doesn't seem to deliver on the promise of thin plate AGM.
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Comments

  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod
    Not sure I can answer your questions, but I'm definitely interested in the topic.  I've gotten 4 summers out of my cheap flooded batteries (group 29 Everstart - $95ea at the time of purchase).  First sign of weakness, I'll be replacing both.  For me, the benefit I'm looking for out of the thin plate is fast recharge and deeper discharge.  If those are true, it will be worth it.  I enjoy anchoring without running genny as much and not have concern about using batteries more (for radio/fridges).

    Dream 'Inn III -- 2008 400 Express

  • F1100F1100 Lake SimcoePosts: 281Member ✭✭✭
    Yes I am interested as well, I will also have to replace the 2 starting batteries and 2 house batteries next spring as well, and have been looking for options.
    1993 300 FIESTA VEE TWIN 5.7L ALPHA GEN 2
  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    Hmm. On northstarbattery.com, they claim 900 cycles at 50% discharge.  On westmarine.com, it says 400 cycles at 80% discharge.  Maybe westmarine.com got it wrong.

    That would shift the balance big-time.  The long-term cost would be cheaper than flooded deep-cycle, plus I'd get faster charging, reduced maintenance and deeper discharge.

    Which claim should I believe?
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod
    edited December 2015
    I'd believe northstar first because it is their battery.  Although, both of what you stated may be correct since the discharge rates are different.

    OK, I looked it up and found their brochure.  It states 400 cycles at 80% and also states the 900 at 50%....so both are correct.

    Dream 'Inn III -- 2008 400 Express

  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    Good catch DI - so longevity depends on how deeply you typically discharge the batteries.  They will last longer for day-trippers than for habitual overnighters.  

    (Note, TP-AGM is also referred to as Thin Plate Pure Lead, or TPPL.)

    "Reserve minutes" might not be relevant here.  It's measured for a 25-amp load.  The typical hotel load for a small cruiser is more like 5 amps per battery. 
  • Michael TMichael T Posts: 6,664Member ✭✭✭✭✭
    edited December 2015

    From my experience with two boats that both had AGMs - AGMs and TPPL AGMs are not just for convenience but they also reduce re-charging costs. What does it cost to run the generator for a few hours to re-charge less efficient batteries? That adds-up pretty quickly, I would think.

    When I replace my "regular" AGMs it will be with TPPL AGMs. Here's the big feature of TPPL AGMs - their charge acceptance rate (recharge time) is 300% (yes you read that correctly) of their ampere hours. Regular AGMs are 40% of their AHs, Gels and Flooded Cells are 25% of their AHs. That is a huge difference. It means that whether using AGMs "straight" or with an inverter - a very short run with your engines or the generator will re-charge them.

    Yes, while reserve minutes measures how long a battery will hold a 25 amp load at safe operating  voltage and may not appear as a real world indicator - it is an excellent indicator of a battery's strength under discharge and a great way to compare batteries (of the same series) to each other apples-to-apples.

    Another superb feature of the TPPL AGMs is their huge cranking power 1,150 CCA and a whopping 1370 MCA. Cranking power is a must for newer electronic-laden engines and Mercury now specifies 1000 MCA "minimum" for their Axius engines.

    I paid about $280 for series 31 "regular" AGMs.  Series 31 TPPL  AGMs have come way down in cost, even in the last 12 months, and will now cost about $50 more per battery  than "regular" series 31 AGMs.

    I agree 100% with @ LaRea (see his comments in the Battery Jumper thread) in that, in my opinion, the bottom line regarding cost justification is how the boater intends to use their batteries. With my AGMs I often forget that I am on battery power and I like that.

    I have been on the hook with two refrigerators running watching a dvd on our 12v TV with the Admiral and my buddies have to keep running their engines or generators to re-charge their house battery bank or sit in semi darkness listening to the call of the loons on the lake! LOL

  • 06Rinker27006Rinker270 Washington, DCPosts: 1,196Member ✭✭✭
    All so very interesting.  Basic question, how do you know the % of discharge?  I have a basic volt meter plugged into my 12v, will that show?

    When you discharge your batteries 80%, how are you able to start your boat?  Or do you just discharge 80% of house batteries?  Or do you need a generator or inverter to charge them?  Possible emergency start if you dont have a genie?
    Patrick
    06 Rinker 270
  • Michael TMichael T Posts: 6,664Member ✭✭✭✭✭
    My house batteries are on a separate system than my starting batteries, so yes I just discharge the house batteries ( 3 series 31 AGMs) I have vessel view 7 so I can monitor my battery status via that but you can put a meter on your batteries. You can also convert the voltage your analogue gauge shows to amperes to see what state of charge your batteries have and this would indicate the % of discharge when compared to the ampere rating of your batteries.
  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    So, the answer for me is: a couple years from now when I've used up my existing flooded deep cycle house batteries, I'll probably replace them with TPPL and see how they treat me. Thanks for the feedback, everybody.
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod

    OK, I thought this would be a perfect time to bring this one back up.  I bought my current house batteries 5 years ago (they are group 29, I had thought they were 31 :) ).  They were basic Wal-mart batteries and never had an issue.  My starter batteries, well, I haven't touched either one of them and honestly not sure how old they really are (at least 6 years old, but probably older).  So, I know I'm gonna be replacing at least my house batteries and probably my starter ones soon as well.  My starter will probably be cheaper ones with the CCA/MCA that is needed. 

    But, house batteries.  I'll spend a bit more (up to 3 times what I usually spend) on TPPL if I can charge them tremendously faster on my generator.  I bought a really good charger a few years back that will charge any type of battery I put in, so no worries there.

    So, anyone out there bought TPPL?  ( @LaRea )  and if so, where and what did you buy?  I'm looking at group 31.

    Dream 'Inn III -- 2008 400 Express

  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    Not me -- I haven't replaced mine yet.  I'm waiting for you to be the guinea pig ... or is it a canary in a coal mine?
  • craigswardmtbcraigswardmtb Mystic, CTPosts: 1,007Member ✭✭✭
    First I'm seeing this discussion on tpagm. Sounds interesting. I'm due for new starting and house batteries this year. Anyone know if I can mix agm house and flooded start on the factory charger from 2005.  I thought I remember this being an issue. I would normally look this up but all my manuals are at the boat. 
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod
    Well, I'm definitely going for it this year.  I'd just like to buy the best one that will charge the quickest.  My goal is to be able to enjoy running fridge & radio and other 12VDC items and then run genny for minimal amount of time to get battery back up to full charge.  What I'm reading is 4-6 hours to get back to full charge.  That seems ridiculously long.  I think 4 hours is all takes right now.  Maybe I'll get longer discharge time, as it states you can take it down 80%.

    Dream 'Inn III -- 2008 400 Express

  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    Have you considered also installing a smart battery monitor that can show the battery's state of health as percent remaining?  

    For example, I've read good things about the Balmar Smartgauge (around $275).  It installs with only 14-gauge wire, and has been endorsed by panbo.com.  
  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    I asked Balmar whether the SmartGauge supports TPPL batteries.  They replied:  

    "yes it will providing you choose the correct battery type. If the battery
    manufacturer has you bulk charge at 14.7 volts then use battery type 1. If you
    bulk charge at 14.3 then use battery type 3."
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod

    Look interesting LaRea.  I typically have a pretty good idea where my battery is at with my meter on the house battery.  I've checked it several times against a multimeter right on the battery and know of any loss between the two.  I can basically use the voltage to determine the percentage left.  If the monitor was a bit cheaper I may consider it.  It may help knowing exactly where the battery is without thinking about it.  Maybe digital meter would be best, as I've seen a few on here install them.  (although my built-in analog is pretty accurate)

    Now I'm just really after the best battery that will charge quickly so I can minimize my generator usage.

    Dream 'Inn III -- 2008 400 Express

  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod

    Well, I'm looking at the batteries again.  My house batteries definitely are done.  If I can't figure this out, I'm thinking of just getting these tppl agms tomorrow:

    https://www.westmarine.com/buy/northstar--thin-plate-pure-lead-agm-battery-group-31--15074842

    I'm not usually one to buy this kind of stuff at westmarine, so if someone can help me find something better, please help.  These look pretty good and are on sale right now along with basically getting 12% back right now.  But, there has gotta be something better for the price.  Again, I'm going for the tppl, well, because @MichaelT ; said I should :)

    Dream 'Inn III -- 2008 400 Express

  • LaReaLaRea Alexandria VirginiaPosts: 3,519Member ✭✭✭✭✭
    Only $45 more than flooded batteries?  I'd definitely go for it.
  • Handymans342Handymans342 Posts: 7,515Member ✭✭✭✭✭
    Hey Dream, is your boat budget for this year busted yet?  LOL
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod

    Oh man, I bought two of these! I don't even want to think about the boat budget at this point! Been a really sucky week!  I am also buying a car for my 16 year old daughter.  Well, I had an accepted offer last Saturday with getting the vehicle state inspected. Called today, he sold it Monday to someone else!  Ugggh!  What a pain!

    Still haven't gotten word on the boat.  I'm just tired of all this crap!  (sorry all, I'm usually optimistic on things, but the money is just flowing out right now!  Good news is it is almost boating time and also almost vacation time! :)

    Dream 'Inn III -- 2008 400 Express

  • Handymans342Handymans342 Posts: 7,515Member ✭✭✭✭✭
    Make sure it has a manual tranny. Hahahahah
  • craigswardmtbcraigswardmtb Mystic, CTPosts: 1,007Member ✭✭✭
    edited March 2017
    I thought about tppl but cheaped out. I just picked up three of the group 31 Duracell/Deka AGM batteries at Sams Club. 180 each. Not a bad deal.
    Let us know how they work out. 
    Post edited by craigswardmtb on
  • Michael TMichael T Posts: 6,664Member ✭✭✭✭✭
    Decent TPPL: CHARGING ACCEPTANCE RATE 300% of Ah - that's about 8 times faster than the nearest chemical type. 400 discharges to 80% (discharge). Over 1000 MCA  (Series 31s over 1300MCA.....VERY important for MPI/Electronic laden etc and especially for any Axius-type pure power needs. Over 2000 initial (pulsed) starting MCAs. Monthly discharge rate at 1% - at least three times less than other chemistries. When I compared prices last I found the TPPLs were about $50 more/battery than the Series 31 "regular" AGMs. I have had two sets of AGMs in Rinker cruisers and they smoked regular deep cycle batteries. When anchored the other guys were running their gennys all the time. So, I figured, if the "regular" AGMs were that good and for $50 more/battery for TPPLs (way more durable and powerful) I'd put them in my next boat. But that's now up to @Bry1429 to try :-)
  • Michael TMichael T Posts: 6,664Member ✭✭✭✭✭
    Geez Dream I hear your pain!!! I have an 8 year old grand daughter and she has already asked me for a John Woods Special Mini Cooper S if her GPA is high. She's pretty smart so I had better start saving?! **** kids! :-)
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod

    Great to hear from you MT!  Been missing you on here!  I do know what you mean about the car! Ended up next day after writing this (on Sunday) buying my daughter an older Acura MDX!  Getting it thru state inspection today!

    I bought 2 of the tppl 31s and 2 west marine agm starting batteries.  They went in the boat today!  Oh, and the other prop hub went as well!!!!!  Ugghh.  The prop hub thing is really getting old at this point!


    Dream 'Inn III -- 2008 400 Express

  • Michael TMichael T Posts: 6,664Member ✭✭✭✭✭
    DI, lucky daughter an MDX is a nice ride....safe too! That ought to ensure she picks-out a high end retirement home for you some day! :-)
  • ChesapeakeChillerChesapeakeChiller Mayo, MDPosts: 98Member ✭✭

    I have been following along and I think I may go with the same setup as @Dream_Inn 2 TPPL AGM North Stars and 2 Standard AGM's. Would there be any issues mixing thin plate AGM with standard AGM on 1 charger. Mine can be set to handle AGM but does not specify thin plate.


    2004 Cruisers Yachts 320 W/6.2L I/B's

    Boat Name- Anchor Management, Mayo MD

  • Black_DiamondBlack_Diamond Holland, MichiganPosts: 4,630Member ✭✭✭✭✭
    edited March 2017
    The Northstar batteries are on sale at West marine too, 15% off I believe.

    Everyone seems to be talking about the Series 31 batteries.  My 342 has 27M for the house (2) and 24M (2) for starting.  Pondering if it is worth upgrading to the 31M for the house.  350MAG MPI.  Not sure it is worth a bigger battery for the engines.

    2003 342FV "Black Diamond", 350 MAG MPI, 20P 4x4 Props, PC BYC, Holland, MI
  • Dream_InnDream_Inn Annapolis, MDPosts: 5,356Member, Moderator mod

    Yes, 15%off for Northstar and 20% on West Marine, that is what I bought and also got 12% back in points.  Not too shabby!

    @ChesapeakeChiller It will work fine on your charger for AGM.  That is what mine will be on as well.

    @MichaelT Thanks!  I want my high end retirement home to move around on the water :)  & yes, safe is why we bought the vehicle.  Unfortunately, between my wife and I, we know two separate families that had teenagers die in an auto accident and could've lived if they had been in a safer vehicle.  Life is too short, but you know that and know how to live it to the fullest!  Cheers!  & some day I am looking forward to sitting on a boat and having a drink with you! :)

    Dream 'Inn III -- 2008 400 Express

  • Michael TMichael T Posts: 6,664Member ✭✭✭✭✭
    edited March 2017

    BD, I'm not getting any younger so my memory might be a bit shaky but when I bought the 2014 EC 360 I bought 5 new batteries. I think the up-size from Series 27 to 31 was less than $20 per battery. I bought Series 31 AGMs for my 2013 EC 310 too. Before buying any of them I spent a lot of time on the phone with battery makers (Penn Deka etc.) and talking with boaters. Everyone I spoke with said up-size. The weight was about the same. The reserve minutes and AHs were about the same but the CCA and MCA were higher with the Series 31..... besides that everyone said the series 31s were more robust and worth the difference. I do remember that Penn Deka told me that the extra plate area of the 31s was better when on the hook for more duration if multiple power draws were occurring simultaneously. As for your engines the 27s would be fine (IMO) as long as you didn't have Axius  which requires a minimum  of1000MCA as per Mercruiser specifications or power robbing aftermarket engine diagnostics. Of course that is where the incredible TPPLs really shine. BTW @DI Northstar are awesome batteries and are described by the big boat dealers in my area as being ultra high performing. Thanks DI, love to have a drink with you some day and hear those 496s roar - you just can't touch those big blocks! I agree that car crashes involving our children are a constant worry. No parent sleeps at night until the car is back in the driveway. My friend lost his son in an auto accident.

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