Preview: Boat Wiring, Part 1 – How Lead Acid Batteries Work – Wet Cell, Gel Cell, Absorbed Glass Mat

24 Responses So Far to “Boat Wiring, Part 1 – How Lead Acid Batteries Work – Wet Cell, Gel Cell, Absorbed Glass Mat”

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  Robert Taffet says:

  I’m seeing a lot of people talking about Li-ion batteries these days. Can you comment on their use, reliability and suitability to replace the the three reactive type batteries discussed in the videos.
  Also, do they come in cranking and deep cycle flavors?

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    Don Eley says:

    Another good question Robert.
    Li-ion batteries onboard a vessel need to be considered as a system and NOT as a drop in replacement for lead-acid batteries. Flooded (wet-cell), gel-cell and AGM batteries all work on the same principles of chemistry. Li-ion batteries operate completely differently and therefore require a dedicated battery monitoring system, automatic battery disconnects (known as battery protects, and charging systems specifically designed and programmed for Li-ion batteries.
    Li-ion battery systems are most effectively used in dee-cycle applications and are not intended for diesel engine starting systems. Lead-acid batteries still work best as cranking batteries,
    Unfortunately the discussion of the complexity of a Li-ion battery system requires considerably more than I can put into this comment space. Suffice it to say it can take many hours of design work just to put together a complex Li-ion battery system for a vessel.
    Nigel Calder has addressed the Li-ion battery complexity in several excellent articles he has written for Professional Boatbuilder. https://www.proboat.com/

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  Randolph Purinton says:

  1) What does house battery mean?

  2) What kind of battery should I have to electric start my 25hp Yamaha outboard?

  Thank you.

  Randy

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    Don Eley says:

    Randolph, sorry for the long delay in answering your questions.
    A house battery is a battery designed to handle the “house” loads aboard a vessel, such as lights, pumps, refrigeration, etc. Typically they go though the “deep-cycling” of discharging and recharging. Typically lead-acid batteries designed for “house” loads, of small amperage over long periods of time, will have fewer but thicker lead plates in each cell.
    An engine start battery, on the other hand, is designed with lead plates that are thinner in order to provide high energy over a short period of time – for engine starting. Yamaha will specify the Cold Cranking Amp (CCA) battery capacity required for that motor and you should make sure the battery you select meets or exceeds that capacity.

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  Brad Golding says:

  Hi Don, I bought an older Wellcraft Airslot Fisherman with a GMC 350. The previous owner had set up three batteries all of which were boarderline.

  I just purchased 3 new batteries and there all the same.

  Part of the ad: Centennial RV/Marine batteries have the extra strength to crank up the largest power plants, and the lasting deep cycle capacity to keep your trolling motors, fish finders, RV comforts and accessories running strong with power to spare. Most sizes available maintenance free! They each have 800 CCA and 1000 MCA

  I also have a battery on/off switch for 2 batteries.

  I wonder if I should wire two of them in parallel for the starting and the other one would be the house battery. That way I could turn off all three batteries when not in use.

  I’m also putting a three bank trickle charger onboard.

  See any problems with this setup?

  Brad

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  John Simlett says:

  Perfect for my needs. Clear, concise and no technobabble.

  Very much appreciated, thank you

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  Captain Nemo says:

  Great video, Prof. Eley – I’m learning more than I ever knew abut 12 volt systems. (Now if I can just manage to KEEP what I’m learning in my 58 YO brain! LOL).

  I did have a couple of questions as I watched this first chapter – if I may ask them –
  1) I see that the wet cell battery has significantly more space above the plates then I’d realized. I understand that in the traditional battery this space is filled (or refilled) with DI water as the chemical rxn takes place, but my question is – if the fluid is initially a H20/H2SO4 mixture (probably something around 12 molar, down from the original 18M of pure Sulfuric?) why not simply make the plates go to the top of the case, thereby getting the same 13.2 Volts nominal output in a smaller (but probably the same weight) package? In other words, why does the space above the plates need to be that large?

  2) Regarding a battery’s CCA/MCA capacity – I would surmise that the larger the engine (as in the case of my dive team’s fleet of OB engines of 40 to 150 HP) the greater the CCA rating the battery should (must?) have in order to be effective/optimal, correct? (I’m ashamed to admit that we’ve actually never considered this factor when replacing our batteries!). So – SHOULD we make decisions based on the size of the particular engine when choosing a new battery, or is there perhaps an optimal CCA range that will do for everything from 40 to 20 HP outboards?

  Also – I look forward to finding out if in your series, there is information about setting up the optimum 2-battery system for a small boat. We typically run our boats a couple of times a month for drills, or during occasional all-day/weekend searches for missing persons – and we have both double or single battery installations. I prefer two batteries for extra safety — but I don’t know anything about the best way to set these up, or if we can use the double- battery PERKO switch to charge both batteries at once.

  Sorry for taking so much space, I just have so many questions and I feel like I’ve finally found a place where I can get straight answers.

  Greg Mactye
  Former Captain current Curmudgeon-in-Residence
  Garden State Underwater Recovery Unit
  Milford NJ
  http://www.GSURU.org

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    Captain Nemo says:

    That’s 200 HP OB engines, of course! Sorry)
    GM

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    Ron Molk says:

    Regarding #1, the space above the plates is required because the water evaporates during charging. The space basically allows for time to pass before having to check the level. In other words, because of the extra water, you won’t have to check the electrolyte level as often. Maintenance-free lead acid batteries have plenty of space, thus plenty of water, as calculated by the manufacturer that over x-number of charging cycles the battery will use x-amount of water, and, if all goes well, the battery will live out its life as prescribed and not run low on water. Excessive discharging and charging of a lead acid battery will cause the battery to use more water, and hence, its life may be shortened if the water level is not maintained. Because a maintenance-free battery is sealed, water cannot be added, and it may run out of water if run thru excessive discharging/recharging cycles.
    Regarding #2, The engine manufacturer should be consulted as to the minimum requirements of a particular engine’s battery. The physical size of the battery, of course, must be considered for mounting it in a particular location. Aside from that, as long as the voltage is correct, installing a battery with more CCA or MCA than is recommended is not a problem. I always buy the most CCA/MCA that I can get in a particular case size for the application. The starter on the engine will only draw what it needs to crank the engine, and the other electrical components will only draw what they need. In other words, if the manufacturer calls for 650 CCA battery, installing a 1000CCA battery will not damage a thing. Again, as long as the battery voltage is correct, and the battery physically fits where it is supposed to, the extra CCAs is just there if you need them. Regarding voltage, each cell of the batteries we are discussing produces 2.2 volts each, ideally, although 2.1 is more the norm…that is why a voltage test on a battery may yield a reading as low as 12.6 volts. But, using the ideal numbers…There are six cells. 6 x 2.2v = 13.2volts. Regardless of the physical size of the battery, the battery will only produce that amount of voltage. The video explained that “the physical size of the battery does not necessarily determine the voltage.” “Not necessarily” implies that it does, but it definitely does not. The physical size of a six cell, twelve volt battery has no bearing on the voltage at all. That is why you can have a small motorcycle battery and a huge boat/truck battery both produce 12 volts, because they both have six cells. The difference is the plate sizes in those cells. The smaller the plates, the smaller the battery, the less amps the battery will produce(motorcycle). The larger the plates, the larger the battery, the more amps the battery will produce(car/truck). That is why, typically, the larger the engine, the larger the battery required to start it…same voltage, more amperage with the larger battery. Whew, hope that helps.

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  Glenn Meadows says:

  I have a 23ft sailboat (1978) with a four circuit panel. I plugged in an AC-DC inverter into a DC outlet and my main circuit blew and no longer works while all of the other three remaining circuits continue to work. I would think if the main blows then nothing should work. What could be gong on ?? My guess is the Main is just named Main when in fact all of the four circuits are wired independent of each other. I pulled open the panel and it looks old and it does seem that the circuits are independent so I am thinking of replacing it. I will be sure to first watch the six video series.

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  Yurik Maria says:

  Dear Don, I liked your videos and that’s why I decided to become a member. Is it a must to have a deep cycle battery as a house battery ?

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    Don Eley says:

    Yurik,
    A deep cycle battery really is best for a house battery. A typical engine start battery is designed with thin plates to provide high amperage for a short period of time where a deep cycle battery has thicker plates to provide less amperage over a long period of time. Deep cycling an engine start battery will typically shorten its life and will not give the service of a deep cycle battery. My suggestion is to go with a deep cycle gel-cell or AGM battery for house loads because they require less maintenance and seem to hold up better when left in a partially discharged state.

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      Yurik Maria says:

      Thank you Don ! Another question. I have a switch panel to run nav lights and other things. Can I hook up all nav lights (side lights, mast head and aft light) on that one switch ?

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  Rick Vourganas says:

  I am rewiring my boat completely: 1978 Welcraft Step V 20 with a 470 Merc I/O. I have changed out all gauges, but cannot figure out the engine rewiring as well as the throttle control located on the side. Ignition is originally and still on the panel.

  This there videos or assistance on completing this project. I really want to do this renovation my self.
  thanks,

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  John Campbell says:

  Enjoyed a thorough presentation, but then Mr. Eley lost me when he got to interpreting/explaining the AH rating of the deep cycle battery.

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    Don Eley says:

    A battery’s Amp-Hour rating is based on what is called the 20-hour rate. Technically this is the number of amps a 12 volt battery can supply for 20 hours at 80*F before dropping below 10.5 volts. If a battery can supply 5 amps for 20 hours it would be rated at 100 Amp-Hours (5 amps x 20 hours). A battery rated at 32 Amp-Hours would provide 1.6 amps for 20 hours. I hope this clears up any confusion.

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  Sean Kelly says:

  Confused by his description of capacity of deep cycle battery. Shouldn’t it be that 32 AH @ 20hrs means it’s capable of 640amp?

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    Don Eley says:

    A battery’s Amp-Hour rating is based on what is called the 20-hour rate. Technically this is the number of amps a 12 volt battery can supply for 20 hours at 80*F before dropping below 10.5 volts. If a battery can supply 5 amps for 20 hours it would be rated at 100 Amp-Hours (5 amps x 20 hours). A battery rated at 32 Amp-Hours would provide 1.6 amps for 20 hours. I hope this clears up any confusion.

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  Joseph Randazzo says:

  I just joined . I found this topic very interesting. I myself am in the electrical field, mostly land basted did not know of the third option battery. need more information. Thank you Joe R.

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  leland sandifur says:

  I just watched the two Don Eley battery videos. Wonderful, effective teaching. Many thanks.

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  Milton Thrasher says:

  See my wooden boat models that include Aphrodite that the Brooklyn Boat Yard rebuilt frame by frame on http://www.angelfire.com/fl4/mft

  I favor classic wooden boats like those featured in the https://www.offcenterharbor.com videos.

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  KGyG says:

  Thanks! Keep this series rolling!

  Question: I have an electric motor on a day sailor. No power to recharge onboard and captive of the periodic plug-in at the pier. Alternatively one can haul the batteries (2) on shore for a recharge. Not good. What might Don advise?

  Thanks!!

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    Don Eley says:

    You really only have a few options for charging the batteries. If using shore power is inconvenient then solar panels are a possibility. The size of the solar panels will be a function of the battery capacity (amp-hours), the state of discharge between charge cycles and the amount of sun you get during the charge cycles. Solar panels would be a great topic for a future video.
    Don

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  William McIntyre says:

  Timely