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Thread: Deep cycle battery help

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    Default Deep cycle battery help

    G-day there, I'm wanting to run a 2000w 240v appliance for roughly 7hrs only 1 maybe 2 times a week, would anyone here have a idea on how many batteries I would need, which system would be best 12v system 24v system or 48v system , I know it will be a lot needed but I don't have good Neighbours to use a generator which would be best. Any help would be great thx..



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    You can get some very quiet generators these days... just saying.

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    How do you plan on recovering the energy in the battery?
    I mean, after you have used your 2000Watt appliance for 7 hours?

    What options do you have?
    Last edited by oceanboy; 11-03-19 at 06:05 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    lots of big batteries if it is running at the full 2000w

    Convert to amp hours
    A battery’s capacity is rated in amp hours (Ah). As such, you’ll need to convert your total Wh to Ah. You can do this by dividing the watt hours by the battery voltage. You’ll also want to include your ideal depth of discharge (what percentage you want to drain from the battery before charging it). The formula is then: Wh / battery voltage / DOD.


    2000:Wh / 12V / 0.3 DOD = 555Ah for 1 hour to 1/3 battery discharge

    2000:Wh / 24V / 0.3 DOD = 277Ah for 1 hour to 1/3 battery discharge

    2000:Wh / 48V / 0.3 DOD = 138Ah for 1 hour to 1/3 battery discharge

    You now have an estimate for the battery size you need.

    Last edited by fandtm666; 11-03-19 at 05:29 PM.

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    Are you sure you really need to do this?

    Are you on grid power or off grid?

    The batteries needed to cope with that sort of draw will need to be large as fandtm666 posted above.
    As above a 48v or 24v system will be better suited to that kind of load.
    The inverter will also need to be able to cope with 2000w constant draw, so your getting up there in price for that as well if you want clean sine wave power for your appliance..

    Also as oceanboy stated, what are you going to charge the batteries with??
    Cheers, Tiny
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    I have 1800w of solar on my roof already and have 4 200amp agm batteries running my shed and I'm off grid living, all my usage is the basic 12v from led lighting, fridge, fans, tv, and a small radio, my hobby has grown into needing to use the 2000w appliance once a week but it might get used twice now and then. 50% is the recommended for battery life, I plan on putting the other panels I have ( 1600w ) on the roof and getting some batteries just for the 2000w appliance but when not using it I might tap into it for other things of my 12v. I have a 4.4kva generator but can't use it due to people complaining...

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    Ok, well i'm with Tiny on this one, you really are using a lot of power here
    Solar for recovery, wow, you'd have to go big and allow for cloudy days etc

    I used to do Generator + Battery Remote properties (They didn't even use Solar, still don't)
    We had a generator the size of a small car, but the exhaust was feed into a huge hole outside that was filled with crushed rock
    Could hardly hear it was on

    Also the Honda and Yamaha Gen Sets are very quite

    But as you say you can't use a Genset....
    Then mega storage is going to be your option...
    You sure this new hobby is worth the expense?

    So you are using 14,000 Watts a day, or 14Kwh on the day you run you appliance.

    You may want a 10Kw Solar Array
    And Batteries to match and some very fancy Charging and Monitoring gear

    Getting back to one of your questions, it may be cheaper to make higher voltage system, then use a step down for you 12V gear.
    Last edited by oceanboy; 11-03-19 at 07:14 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    yeah way to big , now you say its a 2000W unit you need to run
    but just because it says 2000W does not mean it is pulling that much.

    what you need to do is firstly spend $20 and grab a power meter
    plug it into the power point then plug the appliance into that
    and check how much it is actually drawing per hour.

    Once you have done that and know the exact number then you
    can look at alternative power supply solutions. I know that the
    new range of Yamaha gensets are super quite

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    Yes just looking into it now with some answers from above it will be needing around 1000 hours of storage wow that is a lot I never thought about that I might have to look into another hobby I think or try and get Grid power to my house

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    Mate, there is a few really good YouTube channels about this very subject
    Many of years of trial and error and refining their set ups

    You could quickly school yourself up and on products needed and how you can expect them to preform.

    Here are a couple:



    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    As you say that you are using it occasionally you do NOT need 10kW of panels.

    4kW will give you 16-24kWh a day depending where you live.
    Cloud cover using modern panels still gives you 25%(unless dark rain/storm cloud) so that is still 4-6kW/h, if you can wait until you have accumulated the required 14kWh but I have never experienced full cloud 4 days in a row. Tasmania could be a problem there.

    48V makes things a lot simpler and less expensive with the wiring/breakers, etc.

    As for batteries I am inclined to claim that using LiFePO4 batteries would be cheaper than AGM because you don't need to worry about DoD and lifespan is considerably longer, as long as you charge them only 90-95% 3.4-3.5V per cell (4 cells in a 12V battery). A suitable charge circuit and battery management is required, NOT your run of the mill solar regulator for Lead Acid.
    For 14kWh discharge a battery capacity of 20kWh is more than enough.
    So at least 16 of these (just for a ballpark figure):

    Not too bad, 2 years ago I didn't see these 12V 100Ah batteries under $1000. They claim to have built in battery management but I have no experience with them but I assume they fully charge 100% which reduces cycle life by 50%.

    LeadAcid/AGM I suggest a minimum of 60kWh is required and I am not sure about losses there. A lead acid battery might claim to have 100Ah but at a higher load you are looking more at 80Ah or less. This is NOT the case with Lithium.

    Edit: have you seen my posts(Images) here:

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    Last edited by nomeat; 13-03-19 at 01:01 PM.
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    when i was working in a large plant bakery we had a Detroit diesel backup generator that could run half the plant with the door to the generator room closed you could not hear a thing,but when you opend the door it would nearly blow your eardrums out,couldn't you put a enclosure around your generator to dampen the noise

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