Batteries / Inverter

Discussion in 'Tech/Mech General' started by Bart, Sep 8, 2016.

  1. Bart

    Bart Funster

    Joined:
    Jun 4, 2016
    Messages:
    1,378
    Likes Received:
    380
    Location:
    N.Ireland
    using an 800W microwave using my 1500W inverter how long would it take to drain my 3 x 130AH batteries to 50%
     
  2. Al1

    Al1 Read Only Funster

    Joined:
    Jul 20, 2008
    Messages:
    37
    Likes Received:
    10
    195 / (800/12) = approx 2.5 hours. Ish.
     
    • Informative Informative x 1
  3. Techno

    Techno Funster Life Member

    Joined:
    Jul 28, 2010
    Messages:
    13,859
    Likes Received:
    14,512
    Location:
    Leeds the one up North
    800 watt microwave will pull at least 1100 watts
     
    • Like Like x 2
    • Informative Informative x 1
  4. Al1

    Al1 Read Only Funster

    Joined:
    Jul 20, 2008
    Messages:
    37
    Likes Received:
    10
    Is that 1100 constantly?

    195/(1100/12)= 2 hours ish
     
    • Informative Informative x 1
  5. scotjimland

    scotjimland Funster Life Member

    Joined:
    Jul 25, 2007
    Messages:
    28,934
    Likes Received:
    25,574
    Location:
    .
    800 watt is the microwave or cooking power.. not the energy used..

    Power
    of a Microwave Oven.

    "A typical consumer microwave oven consumes 1,100 W AC and produces 700 W of microwave power, an efficiency of 64%. The other 400 W are dissipated as heat, mostly in the magnetron tube


    as calaculated by @Al1 .. 2hr ish

    however.. and it's a big however.. that is a theoretical time.. and does not take into account Peukert's law.. ..

    expresses approximately the change in capacity of rechargeable lead-acid batteries at different rates of discharge. As the rate increases, the battery's available capacity decreases, approximately according to Peukert's law.

    if interested .. https://en.wikipedia.org/wiki/Peukert's_law

    and

    http://all-about-lead-acid-batterie...amentals/peukerts-law-and-exponent-explained/
     
    Last edited: Sep 8, 2016
    • Informative Informative x 2
    • Like Like x 1
  6. Al1

    Al1 Read Only Funster

    Joined:
    Jul 20, 2008
    Messages:
    37
    Likes Received:
    10
    Peukerts law takes it to about 30 minutes if my calculator is correct
     
    • Like Like x 1
    • Useful Useful x 1
  7. funflair

    funflair Funster Life Member

    Joined:
    Dec 11, 2013
    Messages:
    4,485
    Likes Received:
    4,742
    Location:
    Guisborough
    To me a microwave is something that runs for a short period of time as in 5 or 10 minutes any more than that and you should be thinking about hook up.

    Martin
     
    • Like Like x 1
  8. scotjimland

    scotjimland Funster Life Member

    Joined:
    Jul 25, 2007
    Messages:
    28,934
    Likes Received:
    25,574
    Location:
    .
    To me a microwave is something you leave at home..
     
    • Like Like x 3
    • Funny Funny x 1
  9. Bart

    Bart Funster

    Joined:
    Jun 4, 2016
    Messages:
    1,378
    Likes Received:
    380
    Location:
    N.Ireland
    Wow really i'm surprised how long they would keep it going , i used it for like 8 mins as a test and batteries finished out settling down to 91%
    i did
    exactly this,, that is why i asked the question, as i though 5 mins would of near flattened my batteries, but in fact after i did this small test where i used the microwave for like 8 mins the batteries finished out settling down to 91% which amazed me. i'm just trying to learn what power i have to use if needed.
    When i was drawing power from the battery bank in the above test , the percentage that was left in the battery bank dropped to i think as low as 52% while it was drawing the power but as soon as it stopped drawing power the battery percentage slowly went back up again,and this morning was back up to 91% and 12.7 volts
    they have not been recharged at all since doing the above test.
    does that sound about right ?
    I know you are not meant to take more that 50% out of you batteries , but is that 50% when under load or after the have resettled down again ?
     
    • Like Like x 2
  10. Bart

    Bart Funster

    Joined:
    Jun 4, 2016
    Messages:
    1,378
    Likes Received:
    380
    Location:
    N.Ireland
    well its built into the MH Jim ^^
     
    • Funny Funny x 1
  11. Neilfg

    Neilfg Funster

    Joined:
    Apr 9, 2014
    Messages:
    447
    Likes Received:
    457
    Location:
    Bucks
    Would agree with this, microwave short period usage, maybe not always on full power either.

    I have finally decided to stick an inverter in the van for a coffee machine (spec says 1100w) have done all the maths adding 20% etc.., but the draw is dependent upon how the machine is used, so decided to set it up at home with a monitor and a spare battery then measuring the amps drawn to make a coffee or two, can then have a think about the measurements and decide if I need more, seperate or different batteries or not.
     
    • Like Like x 1
  12. scotjimland

    scotjimland Funster Life Member

    Joined:
    Jul 25, 2007
    Messages:
    28,934
    Likes Received:
    25,574
    Location:
    .
    when there is no load..
     
    • Useful Useful x 1
    • Informative Informative x 1
  13. Bart

    Bart Funster

    Joined:
    Jun 4, 2016
    Messages:
    1,378
    Likes Received:
    380
    Location:
    N.Ireland
    Thanks Jim
     
  14. funflair

    funflair Funster Life Member

    Joined:
    Dec 11, 2013
    Messages:
    4,485
    Likes Received:
    4,742
    Location:
    Guisborough
    So now you know what you can take out and what affect it has on the battery capacity you need to know how you are going to put it back in as batteries like to be charged straight back up again. We use all the usual much maligned 240 volt gadgets off the inverter and the batteries are always charged straight back up, the battery charger has been switched off for 6 or 9 months so most of this is down to the solar.

    Martin
     
    • Like Like x 1
  15. autorouter

    autorouter Funster

    Joined:
    Apr 27, 2016
    Messages:
    116
    Likes Received:
    46
    Location:
    Manchester
    The battery percentage as soon as it stopped drawing power was 91%. It stayed at 91% until the morning, when you measured 12.7 volts.

    When people say that the voltage of the battery is not a very good indication of the % state of charge, this is exactly the kind of thing they have in mind. The voltage straight after the test was quite low, I presume, and gradually rose over several hours to a final value.

    If you need a minute-by-minute indication of the remaining capacity, you need a 'battery monitor' device, that has an inbuilt computer to add/subtract the amp-hours as the amps go in and out of the battery. There's also a bit of extra wiring involved compared to just using a voltmeter.
     
    • Like Like x 1
  16. Bart

    Bart Funster

    Joined:
    Jun 4, 2016
    Messages:
    1,378
    Likes Received:
    380
    Location:
    N.Ireland
    I'm sorted in that aspect , as i have a 120Amp sterling Battery to Battery charger.
    Well at least i hope im sorted now the inverter will be added to the system drawing much more power,, that is having said that when it gets used.
     
  17. funflair

    funflair Funster Life Member

    Joined:
    Dec 11, 2013
    Messages:
    4,485
    Likes Received:
    4,742
    Location:
    Guisborough
    If you are not moving every day I would stick some solar on the roof as well.

    Martin
     
Loading...

Share This Page