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  1. #1

    24 Volt Lithium House Bank Upgrade- Silent Ship

    Following the removal of the broken #1 Kohler genset, we now have extra floorspace in the genset room and new wall space on the front bulkhead. There is now only the 20Kva Phasor genset which meets all our power needs. So its time to start planning for next project.... the Silent Ship.

    The plan is to:

    - Install a 24 volt 300 or 400amp lithium battery bank in genset room,
    - Install 3000 watt inverter/charger in genset room
    - Install two 24 volt solar panels on flybridge roof
    - Reposition the existing 32 volt solar panel to flybridge roof
    - Remove the old 32 volt Furuno 6' radar array
    - Install compact Furuno Wifi Radar to flybridge roof

    I guess there will be interconnectivity between the 32 volt house bank and the lithium battery house bank through DC converters and DC to DC chargers. But the 24 v lithium battery will mostly operate on its own with shore power, genset and solar charging.

    +++

    The purpose of the exercise is to reduce to a minimum the use of the genset and to provide the big refrigerator with at least 3 days power without sunshine. Also to power the ultrasonic antifoul system 24/7.

    The opportunity exists to take most of the continuous load off the port side lead acid batteries, making them responsible only for bilge pumps and DC LED lighting.

    +++

    I'd love to hear your thoughts about this project which should be well underway by September.
    Last edited by scottinsydney; 03-22-2021 at 01:19 AM.
    +++
    1984 61MY #353 with 9' cockpit extension.
    Sydney, Australia.

  2. #2

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    Assuming the 400A, 80% discharge, 240VAC fridge I get to 32 hours of run time..... guess if it's not too hot and you don't open it much that could work. But nothing else added to that. IOW, I suspect you will be buying more LiFe's..... Like I used to buy expensive Vodka.....

    I am contemplating something similar..... Except I am planning to convert the SB engine to 24V. Large bank and inverter attached to it.
    1978 53' Motor Yacht "LADY KAY V"
    Hull number 524
    Chesapeake Bay

  3. #3

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    Hi Oscar,

    Its a big Fisher & Paykel fridge and have monitored it for the past 5 years. It draws through the inverter a continuous 6 amps per hour during summer at 12 volts, except when its cycling and can go up to 70amps for short periods while it defrosts itself.

    400amps (say 350amps useable) = 350/6 = 58 hours which is 2.5 days. Sorry my original maths was poor. Anyway, its a big improvement on what we have now. And the battery can be charged at about 50-70amps per hour which is a vast improvement over lead acid.

    ++++

    So it comes to lithium battery selection and say for 400ah/24 volts .... Victron make nice multiple batteries that talk with one another. Or I can have made a single 400ah 24 volt battery weighing 60kgs (about 130lbs) with 200ah BMS for US$1800 or so.
    Last edited by scottinsydney; 03-22-2021 at 02:29 AM.
    +++
    1984 61MY #353 with 9' cockpit extension.
    Sydney, Australia.

  4. #4

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    I assume this is for long periods at anchor? As long as you don't need A/C or Heat, then it makes sense. Though, I think you are being overly optimistic regarding two solar panels. But I don't know about your sunshine situation. In my situation, I want to eliminate genset use while cruising (marina to marina) and some anchoring. Solar didn't make sense since while cruising we don't use AC and the alternators would keep the inverter bank charged. And though we would use the genset periodically while anchored, we don't anchor enough to make solar worth it, and we would need AC in the summer.
    Prometheus
    1978 53' MY Hull #529
    Viera, FL

  5. #5

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    I ran across this channel, he's a boater local to us when not in Alaska and I found this episode worth the watch if you want to convert to LifePro batteries and reduce genset run time. Great explanation of the before and after results. Might be useful for you.

    https://www.youtube.com/watch?v=sLq0faThyaU
    Matt
    1976 58' YF, Hull #410
    "Time Out West"

  6. #6

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    You are going to want more the 400ah.

    I would say at least 800ah or more. Im thinking about much more than that. (currently have 480 AGM, so that's more like 240) and I would say that 1/3 of what we want.

    We have (2) 3,800 inverters. Or 3,800 240V.

    Look at the Amps off the solar. 2 panel's you should be fine, but most charge controller and most battery setup don't want more than 80-100amp. With the new 320-400 panel's you can get over 100amp in full sun pretty quick.

    Also check your alternator to make sure you don't over heat that. Scott on this forum as a recommend on a smart fix to that.
    Aperture
    1977 53' MY Hull #492

    Barnegat lighthouse, LBI NJ

  7. #7

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    Quote Originally Posted by metama View Post
    With the new 320-400 panel's you can get over 100amp in full sun pretty quick.
    How would 2 x 400 watt solar panels at 24v get to over 100 amp?
    Prometheus
    1978 53' MY Hull #529
    Viera, FL

  8. #8

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    A very helpful discussion....

    I watched the Sea Venture video and considered the differences in how we all might use our boats.

    - Our boat lives 24/7 on a swing mooring.
    - We go away for weeks at anchor using the boat as a mother ship for the speedboat.
    - We never call into marinas to stay any length of time.

    So I guess we are completely off grid the past 5 years. Like in Sea Venture, there is nothing wrong with our basic system. Its been like that for 35 years. Its just that technology is now so much better with inverters, solar, lithium batteries etc, that its a lifestyle choice.

    Personally I hate running the generator to charge the lead acid batteries a couple of times a day. I dislike always looking over my shoulder at the battery monitor for the port bank of batteries. I do appreciate the contribution the single 32 volt solar panel makes in summer. But the house lead acid battery battery's usable amps is just not big enough. (The Sea Venture video gives a great description of this.)

    So as Oscar and Photolmy have indicated 24v / 400amps lithium battery bank is probably not enough. I thought it might be when this post was started, but its not. Sea Venture has 12v / 800amps, but they are connected to shore power, solar, genset and motors. And they live aboard 24/7.

    Maybe 24v/600 or 24v/800 would work better for us. The larger size allows us to go away for a long weekend knowing we have 3 days of DC power. We could still run the genset for the battery charger, hot water, stove, convection oven, dish washer and aircon. The solar panels would charge the big lithium battery bank the following week.

    So this leads on to the physical size of the battery.... a single 24v/800 amp lithium battery is possible, but is physically big, heavy and difficult to manhandle.
    Last edited by scottinsydney; 03-22-2021 at 09:01 PM.
    +++
    1984 61MY #353 with 9' cockpit extension.
    Sydney, Australia.

  9. #9

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    Consider balancing them out. Make a bank out of two 24 volt groups.
    I have golf cart for my 32 and use the 2 other battery boxes for the 24 bank.

    I am thinking about building a salvage set of Tesla battery's. The still have solid life and I need to re-measure but I think you can build a pretty solid 24V system in those existing boxes.

    Regarding the 100amp solar panel comment. Figure the average (single) solar controller in the 80 range can be maxed out by 4-5 panel's. But that is just the controller. Many battery don't like that many amps. Given I think 400ah is about half of what is needed, it's worth thinking about. Easy to feed too many amps from an alternator and solar or solar and shore power battery charger at the same time. Where you the one who posted the photo of the melted AGM batteries?

    I was just cruising with a friend who ran into that issue with his solar bank. He had to limit the amp going into his lithium bank from his panels durning peak hour. He wasn't getting the AH re-charge he needed because his bank was too small and wanted lower charge. His solar array was able to put out more power for a few hours a day that he couldn't capture. I think he had 5-6 panels on a cat feeding a 400ah battery bank. If I recall he was thinking about going to a 800-1200ah system. He was also trying to never run the generator unless they had AC on.
    Aperture
    1977 53' MY Hull #492

    Barnegat lighthouse, LBI NJ

  10. #10

    Re: 24 Volt Lithium House Bank Upgrade- Silent Ship

    Ok, so you want to be able to leave the boat for extended periods, and have it be self sufficient on solar / battery power.

    First, you said the firdge draws 6 amps @ 12 v, which is 72 watt hours, and during (brief) defrost, 70 amps @ 12v which is 840 watt hours.

    A 400AH lithium battery @ 24v and 80% discharge is 7680 watts.

    2 x 400 watt solar panels, with just 3 hours a day would be 2400 watts a day.

    For 3 days you would have 7680 + 3 * 2400 = 14,880 watts

    Assume the fridge uses 3600 watts a day (150 watts an hour avg), then that would be 10,800 watts for 3 days.

    If the solar cells were not active at all then you would only have 7,680 watts available from the battery, which will fall short of the required 10,800 watts for the fridge.

    You probably need double your 400AH battery to be safe and run your ultrasonic anti fouling system as well.

    The 2 solar panels (with sun) would definitely extend the time quite a bit, but not indefinitely.
    Last edited by Photolomy; 03-22-2021 at 11:49 PM.
    Prometheus
    1978 53' MY Hull #529
    Viera, FL

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