Advise




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Thread: Advise

  1. #1
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    Default Advise

    Hi gentleman.

    Can someone please help me?

    I have two 105A batteries built into my trailer. With the current loadshedding I am think of installing a Victron 800 w true sinewave inverter so that I can run three computers ( two x 27 inch imacís and one desktop windows pc) during loadshedding.

    My question is:

    1. Is the 800 w inverter big enough? and
    2. How long will I be able to run this three computers on the two batteries?

    Thanks. Your advise will be appreciated.
    I do not exist to impress the world. I exist to live my life in a way that will make me happy!

  2. #2
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    Default Re: Advise

    Hi
    Ek het so n victron 800w inverter in 12v, en ek loop n yskas met gemak met hom. Ek sal gaan vir die 1200w een of grooter. Ek martel hom behoorlik partykeer en hy vat dit met gemak...

  3. #3
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    Default Re: Advise

    1. Is the 800 w inverter big enough?

    It should be. Most iMACs are 90W and the desktop won't be more than around 350W if it isn't running a heavy graphics card.


    2. How long will I be able to run this three computers on the two batteries?

    ​Can't help there. Battery duty cycle, inverter losses, etc, too much for me. Maybe Fluffy can help here.
    2012 Jeep Sahara Unlimited 3.6 V6
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  5. #4
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    Default Re: Advise

    This might not be the most constructive comment here but this highlights the advantages of laptop PCs.
    Laptop manufacturers have done a great job with their batteries that keep these devices running for many hours. Keeping a desktop PC running with an inverter and bank of batteries is way less efficient!

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  7. #5
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    Default Re: Advise

    My Dell quad chip desktop with 2 monitors use 180W. Add the 180W as Jelo indicates=360W This gives 30Ah per hour. Loadshed of 2 hours is 60Ah of available 210Ah(max capacity). If it is start batteries this look like giving them a too hard time and life will suffer. Deep cycle would be fine if they are charged after the 2 hour loadshed provided there is not 2 x loadshed cycles on the same day.

    Losses should be less than 12% at a 360W load on a 800W inverter.
    Last edited by ekkekan; 2018/12/04 at 01:36 AM.

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  9. #6
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    Default Re: Advise

    Quote Originally Posted by ekkekan View Post
    My Dell quad chip desktop with 2 monitors use 180W. Add the 180W as Jelo indicates=360W This gives 30Ah per hour. Loadshed of 2 hours is 60Ah of available 210Ah(max capacity). If it is start batteries this look like giving them a too hard time and life will suffer. Deep cycle would be fine if they are charged after the 2 hour loadshed provided there is not 2 x loadshed cycles on the same day.

    Losses should be less than 12% at a 360W load on a 800W inverter.
    Thanks. I spoke to someone else yesterday who suggests I must allow 300-350 watt per computer. Thus rather buying a 1200 w Victron. Your thoughts?
    I do not exist to impress the world. I exist to live my life in a way that will make me happy!

  10. #7
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    Default Re: Advise

    Quote Originally Posted by jccrafford View Post
    Thanks. I spoke to someone else yesterday who suggests I must allow 300-350 watt per computer. Thus rather buying a 1200 w Victron. Your thoughts?
    No harm in going for a bigger unit but a lot of times advice is based on maximum rating and then in use far less power is used. My desktop has a 400W power supply but only uses 150W. I added 30W above for losses. 3 of my laptops have 90 and 120W adaptors and use 30 to 50W from the 12V.
    The very big plus of a 1000W and up inverter is that it would start a home type fridge while 800W might depending on the overload short time rating and varies from make to make.

  11. #8
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    Default Re: Advise

    Lots of good advice.

    You probably will not draw more than 350 watts power which is about 28 amp/hour at 12.5volts

    Ideally your draw rate should not be more than 10% of the battery reserve, if you want to prolong its life and get the most out of it.
    So 28 amps draw - i would ideally design around 3 batteries, but it is not a perfect world.

    2 hours will deplete your 200 amp reserve by 56 amps ( 30% ) which is acceptable for a battery generally.

    I run a 1000 watt pure sine, which powers two computers (one simple for SWAMBO and one with all the bells for ME ) and the max draw I measured is 275 watts, so it is a bit of overkill

    Is it an inverter/charger? Most of these charge at 8-10 amps which means you need 8 hours solid charging after a two hour stint. (Allowing for efficiency of unit.)
    If we go into stage 3 you might not get enough time between outages to fully recharge.

    BTW - Small UPS's are useless in loadshedding, they recharge too slowly to get the battery fully charged and you end up on a downhill slope
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