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Best Group 24 Deep Cycle Battery

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  • Best Group 24 Deep Cycle Battery

    I have 3 battery banks on my boat, a single Interstate SRM-24 Marine/RV Deep Cycle Battery for each engine (2 banks) and 3 of the Interstate SRM-24 Marine/RV Deep Cycle Batteries connected in parallel for house bank (1 bank), all 3 installed in an 8D battery box. I rotate the batteries from the house bank to a starting battery bank every winter so that the load on the batteries is somewhat the same over a season. I have a 3 bank charger that keeps them all charged (7 amps per bank) when on shore power. My charger will only work if ALL batteries are same type and will not charge an AGM bank and a lead acid bank together correctly. The charger can detect the type of battery and changes the charge rate and voltage automaticly. In the beginning I ran all AGMś and all worked well. Later after the house bank started to loose life I swapped them out for Interstate SRM-24 Marine/RV deep cycle lead acid batteries. The charger destroyed the 3 new house batteries in short order because of charging them on the AGM rates. After changing all 5 batteries to the Interstate SRM-24 Marine/RV Deep Cycle Battery all worked correctly the past 6 years. It is now time to buy new batteries and I am considering using the present onboard 3 bank charger for ONLY the house bank and installing a new two bank charger for the starting batteries. This would permit me to use AGM batteries in the house bank and lead acid in the engine banks. I am concerned how the engine alternators will charge these banks if I have the switches set to charge an engine battery and the house bank together or if I charge only the AGM by itself. In all my thinking I want to increase my house bank capacity to as much as I can using group 24 size batteries as the battery box can accomidate these perfectly. Anyone have suggestions or ideas here? With the upcoming cruise around Vancouver Island I am trying to max out battery life while anchored out and have no battery issues on the trip, especially since I have recently installed an onboard 12v Engel freezer for the trip.



    Last edited by Bill V; 02-06-2020, 06:07 PM.
    "Joint Venture" 1978 midcabin 28', twin 2017 Vortec roller cam "bullet proof" 383/6.3L full roller 350hp engines - You name it, I've either replaced it, restored it, rebuilt it, repainted it or repaired it. That's my job now that I'm retired.

  • #2
    My understanding of internally regulated alternators is that they are very dumb, they'll charge at a given max voltage regardless of the battery and are unlikely to have been set for AGMs. So from the alternator standpoint I think you're fine. Then with separate shore chargers you'd be set.

    I ended up going to 1 starting battery for both engines and a house bank. To keep separate "short circuits"(prevent an alternator/starter from damaging the other engine) I added marine rated buss fuses at each engine and at the batteries. That will limit a hard short or overcurrent event to just the failed component. My engine harnesses also have a factory fusible link from the starter to the alternator as well. The start bank is linked to the house bank with an ACR. Stupid simple and no problems all last year with the fuses(I carry a few spares but haven't needed). If you can give up on 2 start batteries you could gain an "extra" house battery.
    https://www.bluesea.com/products/519...k_-_30_to_300A

    I run 4 ancient Trojan T105's (have the receipt from 2007) and a group 24 marine starting battery. Last summer I used just over 100 amp hours(of an original 440) and according to the trojan voltage chart still had 65% charge. Obviously below original capacity but not too shabby for 12 years old. All 5 batteries fit between the stringers up against the bulkhead in 2 boxes.


    I like Yandina's explanations for electrical stuff and came across this, which may allow you to mix AGM and lead acid if you still want to go that way:
    https://www.yandina.com/mixedbattery.htm

    2 alternators/one battery bank
    https://www.yandina.com/combInfo.htm#Q33

    mixing battery sizes
    https://www.yandina.com/combInfo.htm#Q31

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    • #3
      If you only use one starting battery, does both engines use the same source of 12v for the guages & voltmeters? Each one of my engines have the 12v source from it´s own battery. Each engine has two 12v electric fuel pumps, one to supply carb when engine running and the other to transfer fuel from auxillary fuel tank to main fuel tank if switch is turned on. I like your suggestion and it would simplify my wiring I think. If I understand correctly, one alternator charges your single starting battery and the other alternator charges the house bank?

      Yandina´s has a lot of information to digest but very informative.Ideally I would like to run all AGM batteries both for house and starting. I also think I now know why my first set of 5 AGM´s did not last that long, the engine alternators probably killed them.
      Last edited by Bill V; 02-06-2020, 09:58 PM.
      "Joint Venture" 1978 midcabin 28', twin 2017 Vortec roller cam "bullet proof" 383/6.3L full roller 350hp engines - You name it, I've either replaced it, restored it, rebuilt it, repainted it or repaired it. That's my job now that I'm retired.

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      • #4
        I had it rigged one engine to each bank, but as soon as the ACR sees charge voltage it shuts and you have 1 bank anyway. So I when upgraded wiring I put both alternators on the start bank because the runs were more efficient. I also have 2 voltmeters with separate leads and read differently-but I'm willing to bet it's just gauge error.

        That could probably be fixed with a couple of diodes in the appropriate places if desired.

        Edit: the benefit of internally regulated alternators is that they are easy to combine, but they leave a lot on the table as far as controlling charge with different types of batteries and maximizing charge capability(when batteries approach full one will drop off and let the other take the load).

        Using a manual switch/combiner with one alternator feeding each bank answers at least the load share issue, it just wasnt worth it to me since I tend to run the engines long enough after running the house down that even 1 90A alternator would do the trick.
        Last edited by theremikegoes; 02-07-2020, 07:27 AM.

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        • #5
          Read up on a 160 amp combiner and I think I can use one to save me from constantly using Both on my port battery switch to charge house bank when underway. I have a 120 amp alternator on port engine and a 90 amp on starboard engine. My reasoning is to use port engine for all house bank charging. Wish I could tell you how many times I have forgot to use Both or to put switch back to One. I think I will use the optional external remote control for off, automatic, on, I like the ability to connect in parallel banks for assisted engine starting too. I have to have the ability to run both engines off one alternator should the other alternator fail as I have had in the past.You have been a big help Mike, Thanks.
          Last edited by Bill V; 02-07-2020, 08:20 AM.
          "Joint Venture" 1978 midcabin 28', twin 2017 Vortec roller cam "bullet proof" 383/6.3L full roller 350hp engines - You name it, I've either replaced it, restored it, rebuilt it, repainted it or repaired it. That's my job now that I'm retired.

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          • #6
            Yup, cheers Bill.

            I went the ACR route between house and start because I know I'd forget just like you mention. I have one 100A breaker that kills all house loads, and a OFF/ON/COMBINE switch that connects engines to batteries. Combine is just in case the ACR fails. One thing I'll say about the auto combiner is that depending on how you've got it wired (and when you use the auto function) it may still cause overcharge issues with mixed banks of agm and lead acid.

            I also have only one 50A charger so the ACR handles parallel charging house/start(all lead acid) when on shore power-one less thing to have to remember!

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            • #7
              Seems an ACR and a Combiner accomplish the same thing, correct?
              "Joint Venture" 1978 midcabin 28', twin 2017 Vortec roller cam "bullet proof" 383/6.3L full roller 350hp engines - You name it, I've either replaced it, restored it, rebuilt it, repainted it or repaired it. That's my job now that I'm retired.

              Comment


              • #8
                Short answer, yes...

                Automatic combining relay/acr is just the voltage sensing version of a manual combiner switch in “both”. For a dual circuit combiner “on” means a->b and c->d and combine means all connected. With an acr when a battery is getting charge voltage it parallels the other battery and disconnects it when not being charged. It makes the “both” combiner switch position automatic. Automatically separates your start battery from house loads when batteries are no longer being charged.

                Blue sea diagrams with single and dual circuit combiner and acrs:
                https://www.bluesea.com/resources/17...l_Applications

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                • #9
                  I wanted a single battery system on my Tolman and went with a NorthStar Group 31 AGM. It had the best specs (1150 CCA, 1350 MCA, 220 RC) and reviews in my research. I didn't look at the Group 24's but suspect they are probably at the top of the game for that size as well. They also have a 4 year full replacement warranty.
                  They civilize left, they civilize right, 'til nothing is left and nothing is right. (Ben Rumson)

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                  • #10
                    Originally posted by Arne K View Post
                    I wanted a single battery system on my Tolman and went with a NorthStar Group 31 AGM. It had the best specs (1150 CCA, 1350 MCA, 220 RC) and reviews in my research. I didn't look at the Group 24's but suspect they are probably at the top of the game for that size as well. They also have a 4 year full replacement warranty.
                    I looked at the specs of the marine NorthStar Group 24 AGM and there no comperison to the Interstate SRM-24 Marine/RV Deep Cycle Battery. The Northstar AGM is 35-40% higher capacity and almost 3 times the price. I will have to look at that option. Would go all AGM at about $1500 for a complete change out.
                    "Joint Venture" 1978 midcabin 28', twin 2017 Vortec roller cam "bullet proof" 383/6.3L full roller 350hp engines - You name it, I've either replaced it, restored it, rebuilt it, repainted it or repaired it. That's my job now that I'm retired.

                    Comment


                    • #11
                      Batteries Plus sells NorthStar with a different label but all the same specs and warranty. When I got mine, there was a 10% discount for buying online and picking up in the store.
                      They civilize left, they civilize right, 'til nothing is left and nothing is right. (Ben Rumson)

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                      • #12
                        I've been looking into a pair of these for the house bank...
                        https://www.amazon.com/LiFePO4-Volt-...a-571575372143
                        100ah each, but you can use them down to zero without damage. So you get a usable 200AH taking up half the room and a pair of them is only a little over 60# Of course they're $$ though.

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                        • #13
                          Originally posted by Arne K View Post
                          I wanted a single battery system on my Tolman and went with a NorthStar Group 31 AGM. It had the best specs (1150 CCA, 1350 MCA, 220 RC) and reviews in my research. I didn't look at the Group 24's but suspect they are probably at the top of the game for that size as well. They also have a 4 year full replacement warranty.
                          that 31 what i went with to start the cummins in my boat, and a 24 group for the house
                          1980 2400 Cuddy I/O, 2017 Cummins 4BT coupled to a Volvo DP-SM with F9 Props, and a 2014 Mercury 15HP Pro-Kicker "LOOSE CHANGE"

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