Battery problems

Discussion in 'OnBoard Electronics & Controls' started by chrisroberts37, Nov 7, 2016.

  1. chrisroberts37
    Joined: Nov 2016
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    Location: Nottingham

    chrisroberts37 New Member

    Hello everyone, im totally new to the world of boating and have just bought my first boat a Viking 23. I have had problems with the batteries and am looking at ways to keep them charged.

    As I understand it (and please tell me if im wrong) there is an isolation switch which turns off all battery power, a '1,2, 1 and 2, off' switch to switch between 2 batteries or use both. there is a small solar panel connected directly to one battery no 1 (it looks as though the no 1 battery is the house battery) and a mains trickle charger connected directly to the same battery for when im connected to mains. I realise that both the the solar and trickle charger are only looking after no 1 battery. What im not sure about is whether the alternator from the Suzuki 9.9hp outboard is charging both batteries or just one , do I need the switch on both to charge both.

    Also, can anyone advise the best option to automate spilt charging from all 3 sources, solar, charger and alternator, bearing in mind when the mains charger is on the isolating switch would be off. Im thinking of adding a second house battery in parallel with the first although the area under the rear seat where the batteries are situated is not large enough to accommodate another battery, there is a second under floor area with enough space but it would mean running battery leads under the floor for about 1.5 meters, does that sound plausible.

    Any advice greatly appreciated
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    How much power requirements do you have to need three batteries? You can have a charge management system for three different power sources, but it is overly complicated and expensive for a small boat. Simply use a switch at each source. Put the battery select switch on "both" and both batteries will charge at the same time.
     
  3. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The function of the battery switch is very simple.
    With the knob in OFF position both batteries are isolated from the alternator and all electric devices in your boat, except for the solar panel that tries to keep one battery fully charged.
    With the engine running the switch should be in BOTH position to charge both batteries. When sailing you switch to Nr 1 of 2 to make sure you do not deplete both.

    A simple and inexpensive way to charge both batteries from either the solar panel or the trickle charger is to use (schottky) diodes.
     
  4. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    If you have 3 batteries get a good quality 3 way battery charger that knows how to charge the battery appropriately based on its type. If you hook up batteries in parallel a bad battery will damage the others. Also, I learned a something over the years that makes no sense but it is true. If the battery sits in the bilge with no isolation, the cold or sitting water seems to drain the battery quicker even if not connected than if it is above the bilge. I use solar panels to trickle charge batteries, but either put a diode or remember to unplug it before you start the engine.
     
  5. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    I like CDK's idea more, with inexpensive Shottky diodes (a few 40Ampere diodes parallel, to each battery, will do the job) instead of an expensive 3 way battery charger. Bert
     
  6. The Q
    Joined: Feb 2014
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    Location: Norfolk, UK

    The Q Senior Member

    Though Schottky Diodes will mean the batteries not being fully charged by up to half a volt....
     
  7. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Yes a lot of people think so, the reality is that the alternator gives 14.4 Volt. minus 0.5 Volt gives you 0.1 volt higher than the gassing voltage of a lead acid battery at 25 degrees Celsius. I have been charging and sold a few hundred SLABS for the showjumping industry and I don't have a sleepless night whether the battery is charged at 99% or 100%.
    Bert
     
  8. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    One should understand the charging process of a Lead Acid battery. Let say the battery is discharged to 12 Volt. When the Alternator start charging, the voltage start slowly creeping up to a higher voltage at a high current. The reason is that the charger or alternator gets loaded. When the battery is nearing the "full" status, the voltage reaches the gassing voltage of 13.8 Volt. That is the point that a good regulator or alternator or charger should switch over to constant voltage of below 13.8 Volt, to avoid a battery being damaged and loosing liquid, which happens if you carry on with 14.4 Volt charging. Thus to have a Shottky diode is not a problem, even a good thing for bad chargers or alternators. Bert
     
  9. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    I notice that you used the word automate, which leads me to believe that you'd like a system that will work with no input from you. This is possible with a device called an ACR or automatic charging relay.

    ACR's are devices that function like battery isolators but do not rely on diodes to function. When your engine is running, battery charger is on or a solar panel is providing charge the relay senses the charging current and combines the batteries so that they all get a charge. When there is no charging current present the ACR senses this also and disconnects the batteries.

    I'll post a couple of links below that will provide you with more detailed information. I've been using ACR's from Blue Sea Systems for many years and have never had a problem. On the Blue Sea Systems home page just click on products and then on the ACR tab, you'll see that they make a variety of these devices.

    Blue Sea Systems in based in the United States but I believe you should be able to purchase their products in the UK or have them shipped. Also, don't be afraid to ask their technical staff for advice. They are very helpful.

    https://www.bluesea.com/

    https://www.bluesea.com/support/articles/58/Battery_Isolators_and_Automatic_Charging_Relays

    Looks like these people might carry ACR's in the UK: http://www.mobilecentre.co.uk/
    There may also be an outfit in South Hampton.

    Good Luck and be safe out there!

    MIA
     
  10. gonzo
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    gonzo Senior Member

    Lead acid batteries are divided into flooded cell and AGM. The chemistry is very different in each and so is the charging process.
     
  11. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    What gonzo said better to have a smart charger, there are many issues involved to promote full charge and bartery life. Good Batteries are not cheap, a good stepped charger is not that Much more money
     
  12. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Get real people! The OP has a trickle charger, a small solar panel and a 9.9HP outboard, none of which poses a threat of overcharging the batteries.
    The solar panel (in Nottingham) probably cannot even enable an ACR. It doesn't need a regulator, just two small 3Amp schottky diodes to each battery. The same goes for the trickle charger.
    The small Suzuki has no real alternator, just a coil, magnet and a rectifier. It needs somewhat larger diodes, probably 8Amp will do. Or it can stay wired through the battery switch.
     
  13. missinginaction
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    missinginaction Senior Member

    Point taken CDK. That said, I was just trying to give the OP an option that he hadn't considered.
    I never realized how small the propulsion gear is on those canal boats they have in the UK. He must go a very long way on a liter of gas. I could never keep my battery banks charged with a kicker like that unless I spent nights at a marina and could plug in every evening.
     
  14. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    CDK: a Suzuki 9.9 will charge 6A. That is enough to overcharge a pair of batteries.
     

  15. BertKu
    Joined: May 2009
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    BertKu Senior Member

    That depend totally whether he is charging 3 batteries, of which one is empty or whether he is using electricity while charging. We should get the facts first from this OP. By the way Gonzo, if any sailor is going to sail with a flooded battery, I will feel sorry for him as soon he get some wind in his sails and sail at 55 degrees. Nobody uses a flooded battery on a sailing yacht. I made the chargers for charging 8 batteries at the same time, current limiting for the initial charge and constant voltage charging at the end. In this way one can leave the batteries for a long period of time on the charger without any damage. I agree with CDK, a few Shottky diodes is the way to go. Bert
     
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