Batteries question on a newbie

Discussion in 'Electrical Stuff' started by acp, Aug 14, 2017.

  1. acp

    acp New Member

    Mar 6, 2017
    Fort Lauderdale
    340 Sundance 2001 Dinghy AB 8HP Johnson
    mercruiser 7.4
    I have just purchase a 2001 340 Sundancer. I have four batteries on the boat as I can tell the port side battery have two in series for the house and port engine the other stand alone battery is for starboard engine and the helm radio/cd electronic and other battery for the generator. I would like to have one battery for port and one starboard two for the house one for generator. That way I can tun off my engine batteries and use house only batteries. Reason why I ran my batteries down I was not able to star the engines. I was not ruining the generator. I had both refrigerator on 12v running. Batteries were done in 3 hours. I replace all three batteries with group 29 840 cca had group 27 800cca. Du I have to run the generator when on anchor. Hate the noise of the generator ruining and the fumes wen swimming in the back of the boat. Any suggestion would be appreciated.
  2. Carpediem44DB

    Carpediem44DB Active Member

    Aug 18, 2015
    Sanfransico Bay area
    2006 44 DB Sedan Bridge Raymarine E120 radar chart plotter GPS autopilot
    cummins QSC 8.3 500 HD
    Battery managment is quite an art form. With a couple of house batteries you should be able to be on the hook with out running the batteries down for a couple of days any way. It takes about as long to fully charge a deep cycle battery as it does to discharge it so running the genny or the engines periodically really doesn't fully charge them.
    You really need to consider converting to Led lighting to cut down on load and raise the temps on the refrigerators to keep them from running continuously. Try to use ice chests instead of the refrigerator if you are away from the dock for an extended period. Depending on the size of the boat, solar can be a partial solution as well to help keep the batteries up while away from shore power too.
    Just a few ideas.
  3. trflgrl

    trflgrl Active Member

    Jun 23, 2014
    Middle Tennessee
    1989 Sundancer 300
    Twin 350 Merc/Alpha 1 Gen 1; Quicksilver 4.0 gen
    Welcome aboard! If you haven't yet, be sure to visit the 340 Sundancer Thread for plenty of detail about your specific boat. (I'm about halfway through it, as I'm eyeing the 340 as my next upgrade!)

    There are a lot of threads discussing batteries and battery management so I recommend you do a detailed search in this same Electrical Stuff forum, but the quick answer for your most immediate need is yes, run your generator while at anchor to minimize risk of losing engine starting capacity, as well as to help maintain the health of your generator (they're made to run, not to sit unused). Choose times when you and your passengers are on/in the boat preparing meals and such to avoid the annoyance factor of running them while swimming.

    The second answer--if you haven't done so already--is to learn exactly how your current setup is designed to work and test each component to ensure it's functioning as intended. Then you can make decisions about how to preserve and maintain what you have, and may find you can run the generator less often or for shorter periods of time. For example: if you didn't run the stereo/CD player for those 3 hours, why would the starboard engine starting battery die? Was it already on its last legs and unable to take a charge from shore power and/or the engine/alternator? Is something from the house system drawing from that battery that you don't realize? So by "learn" I mean map everything precisely: turn off one battery selector switch completely, set the other to position 1, then flip every dash switch, house panel switch, appliance, outlet, light, etc. in both the cockpit and the cabin, pull up every float switch in every bilge area, and document what works and what doesn't. Set the same selector to position 2 and repeat the process. Then turn off that selector completely and repeat with the other battery selector, and finally turn off both switches and run through everything again. You'll do the whole routine 5 times, and may be surprised at some of the results. (Bilge pumps should run when both selector switches are off.)

    Major changes we made were to move the stereo/CD wire to the house bank (though typically First Mate uses rechargeable bluetooth speakers with his smartphone) and to switch to LED bulbs in as many light fixtures as possible. The LED change alone freed up enough battery power to run our cabin fridge for a day or more without using the generator.

    Is your long term plan to have 5 batteries? One for port, one for starboard, one for generator, and two for house? You may not need to do that if you maximize your existing, including potentially changing battery size/type for one or more of them: some members have changed to golf cart batteries for house needs, and many of the same threads include info on such mods.
  4. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Hmmm...two group 29 batteries should run your boat for quite a long time without the generator. As in days, not hours.

    If you're planning extended time on the hook (more than just a long weekend here or there) it might make sense to add that fifth battery. If you're like most of us you'll be more than pleased with the four you already have. I'm imagining your first battery depletion experience was based on having bad batteries and was not a sign that you have insufficient capacity. My two cents only of course.
  5. bracketracer

    bracketracer Member

    Aug 23, 2016
    Wilson, NY
    2001 380DA
    Twin 454 Horizons
    I'll add something here. If you're using the original charger/AC converter, replace it. The new ProNautic units are light years ahead of what your boat came with. They treat the batteries much better, for lack of a better description.
  6. Jimmy Buoy

    Jimmy Buoy Active Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    My Amberjack's setup is similar to yours with the exception that both engines have a pair of batteries (group 27 deep cycle) while the generator has its own dedicated starter battery. Half the house and one engine uses one pair, while the other half and remaining engine uses the other pair.

    I've experienced depleted batteries after a night on the hook with this setup, but at the time I knew the two pairs of batteries were marginal at best and needed to be replaced. Knowing that during the night with the fridge running, the head being used, stereo use and using incandescent lights would probably drag them down, I proactively had a set of jumper cables ready to tie the generator's startup battery to one depleted pair. First, the generator was started to ensure that I'd have a backup plan, then I jumped one main pair to start that engine without issue. The second engine can then be started using the "emergency" (battery combiner) switch.

    As already mentioned, with healthy batteries it shouldn't be a problem overnight with your setup.
  7. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    i have the same boat as you do so I assume you have a 4.5kW Westerbeke genny....if your genny is loud and exhausting unpleasant fumes you may have an issue with the genny.....

    my genny is VERY quiet when running...when we are floating behind the boat we cannot even tell it is running unless we are near the genny on the starboard far as the exhaust fumes go, maybe it is time for a tune-up of the genny.....the exhaust from my genny is noticeable if you are near the genny but not overly offensive.....

    I suggest running the genny as much as possible while on the hook while no one is sleeping in the is good for the genny to run and you won't have to be so concerned about the level of charge on the batteries.....

  8. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    That the main reason I keep repeating get the engine batteries and generator battery to stand alone , never on a house circuit.add an additional house battery or two if necessary.
    That way engine starting batteries never can go dead.
  9. skibum

    skibum Well-Known Member

    Jul 30, 2007
    Perry Hall, MD
    2005 Sundancer 260
    496 Magnum HO
    I only have 2 batteries and I'm not sure how your battery switch(es) is/are set up, but I use a simple rule to keep from ending up killing them both when on the hook. On even number days, I only use battery #2, and on odd number days I only use battery #1. This helps me keep them "in balance" from an aging & use perspective as well.
  10. acp

    acp New Member

    Mar 6, 2017
    Fort Lauderdale
    340 Sundance 2001 Dinghy AB 8HP Johnson
    mercruiser 7.4
    Thank guys for your respond. Like I said I replaced the 3 battery hopefully that was the issue that the battery were on last legs or bad. But still I love to have just one battery for each engine and two for the house that way I don have to worry about battery management. I would have fresh battery to star the engines all the time.
  11. 1greatsteak

    1greatsteak New Member

    Aug 1, 2017
    Sundancer 260
    Single 260hp Alpha1
    Most batterys labled as marine deep cycle actully are not real deep cycle. If you see CCA rateing its not a true deep cycle.
    Most are hybrid starter batterys that can take some extra discharge to 60% probably as much as 50% without dammage.
    A true deep cycle can take 75% discharge and will hold charge unattended a long time with maybe 3% discharge per month. Auto starter batterys are made to provide a big current jolt for starteing and will be discharged 5% then recharged. Deep cycleing them will give a short life.
    The CCA rateing is for how many amps can be delivered to a starter. You want reserve capacty ratetng to know the power that is actually in the battery.
    Deep discharge batterys are made for long discharge times at 10 to 100 amps. Have solid lead plates, very heavy constriction and cost a lot more in the short run. Best place to get them and be sure you get genuine deep discharge is a golf cart supply.
    Trojan, club car, ABC, are good.
    Check out the electric trolling motor guys on the web more recommendations there. Group sizes are the same and you can get them in 12 volt.
  12. Aconn

    Aconn New Member

    Oct 9, 2016
    New Hampshire
    340 Sundancer 2001
    7.4 V-drives
    I recently acquired an '01 340 Sundancer as well. As per the schematics and most posts the Port battery bank handles House and Port engine start. With Starboard bank handling genny and strbd start.

    However (we found this out quick) When on the hook our starboard bank would be depleted after no more than 10 hours. CO2 sensor woke us up to that fact! Starboard engine would not start, typical dead battery response, Even the E-Start would not get the strbd engine going, but the genny fired right up and we charged batteries and were good to go.

    Pulled batteries for winter and strbd bank (both 27 crankers) were dead, while both Port, same 27 crankers were still at about 95%, no trickle charge etc.

    My dilemma is IF house is on Port, why did my strbd bank die over night? This was a reoccurring theme over last summer. I did buy 2 replacements; a 27 cranking and a 31 DC hoping to use for house.

    Oh, and I also have an intermittent non-starting problem with my strbd engine, but hitting the start buttons multiple time and or using the e-start usually gets us going. Never a problem one it gets started, only the starting itself.
  13. wayne0

    wayne0 Member

    May 4, 2014
    Newburyport, Ma.
    2000 340 Sundancer
    Twin 7.4 ltr.V-drives
    How old were the batteries we you bought the boat? Sounds like the port batteries were replaced before you bought the boat and the old ones were moved to starboard. My $.02

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