Charger Question.

Discussion in 'Electronics Q&A' started by Forever Mates, May 13, 2018.

  1. Forever Mates

    Forever Mates Member

    Aug 3, 2014
    Owen Sound Ont. Canada
    1996-Sea Ray 270 Sundancer 7.4l Single Garmin echoMap 50s
    Single 7.4l Mercruiser Bravo 111 Drive
    Hello There. I currently have a 96 Sea Ray Sundancer 7.4lt single engine with a Marine starting battery #1 and a house deep cycle battery #2 it is 800CCA, 185 Reserve, 105 Amp Hrs. My factory charger is a Mariner 20 amp original equipment. According to Mariner this charger constantly charges and never shuts off. Its putting out 3-5 amps according to the needle gauge on the charger. The past 2 years I have always left the charger (DC converter on the breaker panel) on at all times with the battery switch on both batteries when on shore power. We are on the boat for 3-4 days at a time using shore power. When we leave the boat for a few days should I be leaving this charger on, or turn it on when we return for a few days. I have noticed that the electrolyte needs to be topped up in the deep cycle battery periodicaly. This battery also doesn't have enough power to start the engine I always use #1 or switch to both when starting. The batteries are 2 years old ,do you think the house battery is toast, as 3-5 amps never seems to fully charge it even after a few days of charging. My volt meter shows house battery at 13.9 volts with charger on. Any help would be really appreciated. Steve.
  2. bobeast

    bobeast Dance the Tide SILVER Sponsor

    Oct 22, 2017
    Isleton, CA
    2002 310DA
    350 MPI w/V-drives
    The short answer is neither. That is to say, you shouldn't leave a dumb charger hooked up for extended periods of time as it's not good for the batteries. On the other hand, your bilge pump(s) is wired directly to your battery, so you don't want to risk a dead battery.

    I would seriously consider upgrading your charger to a smart charger which properly senses your battery condition and falls back to a float charge when the batteries are topped off. This will extend the life of your batteries and can be left hooked up and left on indefinitely.

    I went with the ProMariner 1240P

    If your current battery never reaches full charge, it may well be toast. Measuring the battery voltage with the charger on doesn't really tell you anything as you'll just be reading the output of the charger. To know for sure, take it to your nearest auto-parts store and have it load tested.
    Jaybeaux likes this.
  3. Jimmy Buoy

    Jimmy Buoy Active Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    Over the last 30+ years of boating, I've left the "converter" ON from the start to the end of boating season without issue. If your electrolyte level is low that often it could be that your charger is "cooking" the battery with too much current and the fluid is boiling off. I usually only have to check/top up batteries once per season. Deep Cycle batteries are not really designed to start engines, which needs some high cranking amps but will survive long low level power draws. You should check each cell's electrolyte with a battery fluid tester after being off the charger for a while and see if there is a bad cell. The other thing you could do is disconnect the batteries and connect a load tester to see if they have any strength left. The charger might be the problem but check the individual batteries first.
  4. Forever Mates

    Forever Mates Member

    Aug 3, 2014
    Owen Sound Ont. Canada
    1996-Sea Ray 270 Sundancer 7.4l Single Garmin echoMap 50s
    Single 7.4l Mercruiser Bravo 111 Drive
    Thanks for the replies. I will look into the 1240p.
  5. NickBOE

    NickBOE New Member

    Apr 26, 2018
    Suzuki DF300AP
    I agree with bobeast. I would switch to a charger that uses multistage technology. Promariner makes a great one.
    Jaybeaux likes this.
  6. tony1b2000

    tony1b2000 Member SILVER Sponsor

    Oct 10, 2007
    Salem MA
    350 Sundancer 2010
    496 Mag Seacore Mercruiser , Bravo III
    I upgraded to the Promariner as others stated and it works great! However, I kept tripping my ac breaker. Reason was going from a 30 to 40 amp charger. Fortunately, the charger can be set to draw less power easily by simply pressing a few buttons. Otherwise, you will have to upgrade the wires to the charger and replace the breaker.
    Last edited: May 14, 2018
  7. BlueYonder

    BlueYonder Member

    Jan 12, 2015
    Chesapeake Bay
    QSC 8.3 600
    A battery charger amp rating is at 12 volts DC (unless you have a 24 volt system). The AC amp draw is roughly 10 percent of the DC output.

    The difference in AC power draw between a 30 amp charger and a 40 amp charger is only around 1 amp at 120 volts AC.
  8. SKybolt

    SKybolt Member SILVER Sponsor

    Nov 11, 2014
    Long Island, NY
    1988 460 EC Sea Ray. w/12.5K Westerbeke Genset.
    Twin 6v92TA Low profile's (475hp) with Alison Gears.
    I also have a ProMariner 1250P, it is a good charger. The features is supports are nice and it conditions the batteries well. I am on my 4th season with it.

    The remote is not so great. If your looking for just the charger and not have a remote display for it, then the ProMariner is a good charger. The remote display was very disappointing as it only display's the total charge and rate etc. It does not display the individual battery status.

    If your looking for remote display of the battery status you might want to find a different charger.
  9. Forever Mates

    Forever Mates Member

    Aug 3, 2014
    Owen Sound Ont. Canada
    1996-Sea Ray 270 Sundancer 7.4l Single Garmin echoMap 50s
    Single 7.4l Mercruiser Bravo 111 Drive
  10. Forever Mates

    Forever Mates Member

    Aug 3, 2014
    Owen Sound Ont. Canada
    1996-Sea Ray 270 Sundancer 7.4l Single Garmin echoMap 50s
    Single 7.4l Mercruiser Bravo 111 Drive
    Why would sea ray knowingly use a charger in 1996 that obviously never shuts off and doesn't go into a float mode. This was a very popular model of boat , You would think that they must of had numerous complaints over the years of fried batteries. Its a 20 amp charger but only showing 3-5 amps when charging is this normal.
  11. Jimmy Buoy

    Jimmy Buoy Active Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    I seriously doubt that your OEM charger is "dumb" charger that doesn't reduce charging input as the batteries become charged. Even the most basic old charger I have at home does this. Also, there are most always some current draw when not using the boat from items such as electronics, fridge, bilge pumps that require constant charging input. I've had old chargers on my last two boats (1987 Wellcraft and 1989 SeaRay) and both of those OEM chargers reduced charging input based on the condition of the batteries which may explain your 3-5 amp charge at rest.

    13.9 volts at rest with the charger on sounds about right (13.5-13.8 volts would indicate "float stage" charging) to maintain your batteries.

    If you're trying to start the boat with the deep cycle battery it is not designed for this - use the #1 starter battery. If it doesn't have enough CCA's to start the engine it may be the problem.

    From what I understand, if two batteries are connected to the charger - one bad and one good, the charger will sense the low battery and put in enough current to charge the lower of the two resulting in overcharging the good one (I suspect your deep cycle).

    Before trashing the OEM charger I'd be testing each battery independently of the other.

    See this article on chargers...
  12. insfnds

    insfnds Member GOLD Sponsor

    Jul 8, 2008
    Canyon Lake, TX
    2011 390 Sundancer
    Twin 496 Mag Axius
    If you leave the boat in the water, you should leave the charger on but...

    I had that same boat...and the same charger issues. As others have said, replace it with a smart charger. It will charge faster and the batteries will last a whole lot longer. I replaced the original with a 20A xantrex...way back in 98 or 99 after I figured out why the batteries were cooking. I had to replaced the original AGM batteries and went with cheap wet batteries, and was putting water in once a month in the summer.

    The original 'converter' is a ferro-resonant unfiltered power is not a charger by today's standards. It puts out a semi-regulated 13.8v rectified AC, i.e. pulsed DC.

    13.8v is kind of low to really charge a battery and way too high for a float charger, float is usually 13.2v to 13.3v for AGM and wet cells.

    20Amp charger is adequate for two Grp 31 batteries. Going with a larger charger will require changing out the charger's output breakers but will recharge the batteries faster.

    My educated opinion on battery types: Go with deep cycle marine or AGM (which are deep cycle by default) as long as the MCA (Marine Cranking Amps) meets or exceeds the engine's requirements. (Also get the biggest that will fit your battery trays, grp 31.) You want your bilge and sump pumps to be able to run for a long time on battery power and starting batteries just don't discharge that deep. A lot of people will tell you you need one starting and one deep cycle but that's just not accurate. The boat's pumps and other constant-on accessories are split between the two batteries so both will benefit from being deep cycle.

    Another good investment would be an ACR - Automatic Charge Relay - which connects the two batteries together while the engine is running and isolates them when the engine is off. Then you only need to select one battery at a time but both will still get charged when underway and you have one isolated battery that (should) be fully charged.

  13. skibum

    skibum Well-Known Member

    Jul 30, 2007
    Perry Hall, MD
    2005 Sundancer 260
    496 Magnum HO
    My boat had an old Guest 20A charger and 2 dual purpose group 27 batteries in it when I got it in 2007. Every spring I had to buy 1 new battery. In 2016, I replaced the Guest charger with a Pronautic 1220P and installed 2 Optima blue top group 31s (the deep cycle / starting ones). This is the beginning of season #3 on the new batteries. The 20A charger has proven to be perfectly sufficient for the needs of my 260. When plugged into shore power, it will power everything on the boat and charge the batteries concurrently.

    I believe that I had the situation that Jimmy Bouy described, one bad battery causing the charger to kill the other.
    Little Ducky likes this.
  14. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    Skibum has it right. The thing that presents a problem for your existing charger/converter is the mix of starting and deep cycle batteries on that single charging system; it is desirable to keep battery banks the same age and the same ratings. To reiterate if you are boiling a single or a couple of cells dry then most likely an issue with that battery if you are boiling a complete battery dry then an issue with the charger or adjacent battery (which would be hot to the touch).
    A charger/converter is designed to be on and operational at all times as it then not only operates the 12V loads on the boat but also maintains the batteries. Group 27 series of lead acid batteries are classified as dual purpose, in that, they serve both house and starting functions; For your situation when changing batteries I would recommend a single group 27 starting and dual group 27 for house with an Automatic Charging Relay between and integrated with a modern multi-phase charger. Group 27 wet cell batteries are very cost effective if budget is a consideration.
    If your system has a battery isolator installed that is original it's really time to remove that and replace with the ACR. The older isolators have a 0.6V differential between the charging source and the battery being charged which really doesn't allow full effectivity of a robust charging system.
    Lastly, don't forget the alternator; these can kill batteries also. With the engine running put a good digital volt meter on the B+ and ground directly on the alternator (not on the batteries) and set the meter to AC volts. If you are seeing greater than 100mv of AC power then your alternator needs to be changed as the diodes are breaking down and allowing AC ripple to the batteries which will also shorten a battery's life.
    Last edited: May 16, 2018
  15. PSNI

    PSNI New Member

    Aug 2, 2017
    2000 380
    Mercruiser 8.1 MAG (2005)
  16. scoflaw

    scoflaw Well-Known Member SILVER Sponsor

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Nothing wrong with mixing batteries, cranking and deep, but you need a multi bank charger to properly support that.
  17. PSNI

    PSNI New Member

    Aug 2, 2017
    2000 380
    Mercruiser 8.1 MAG (2005)
    I leave my original Mariner running all the time. Even the 2000 models were smart chargers (3 stage) although clearly not as smart as the current models.

    Attached is a manual that may match your charger in case you don't have it.

    Attached Files:

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