how long will it take

Discussion in 'Tech/Mech General' started by chatteris, Aug 14, 2016.

  1. chatteris

    chatteris Funster

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    I have a 12 volt, 95 amphour 700amp battery in the back of my work van and a waeco freezer thats uses a maximum of 30watts and is set to turnoff at 10.1 volts. if the battery voltage is 12.7 when i turn engine off, how long will it take to discharge the battery to 10.1 volts and the freezer stop working. can someone give me a ball park time.
    Thanks
     
  2. Boringfrog

    Boringfrog Funster

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    95 ah or 700amp
    Confused.
     
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  3. John Laidler

    John Laidler Funster

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    If you are discharging the battery to 10.1 volts it will soon be goosed. You shouldn't let it drop below around 12.0. However, on the basis it is normally safe to discharge a battery to 50% then you have 47.5 Ah to play with. So 30W at 12 volts is 2.5 Amps so you might expect the freezer to run for 47.5/2.5 = 19 hours. You might get it to run longer because the freezer compressor won't be running all the time and the 95Ah capacity itself is only a guide based on a specific rate of discharge. But around a day sounds about right.
     
    Last edited: Aug 14, 2016
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  4. pappajohn

    pappajohn Funster Life Member

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    700 cold cranking amps......pretty meaningless in this sense.
     
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  5. chatteris

    chatteris Funster

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    Thanks everyone thats better than I thought, would it be worth having a solar panel on the dash plug into the spare power socket to help keep the battery charged,
     
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  6. Boringfrog

    Boringfrog Funster

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    Minimum 100 Watt on the the roof would be a lot better. ;)
     
  7. NickNic

    NickNic Funster Life Member

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    That wouldn't work unless the socket on the dash is live without the ignition on.

    As suggested a proper panel on the roof would be a far better option.
     
  8. chatteris

    chatteris Funster

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    Thanks, could bring a socket from battery in back which would be live, battery will get charged from split charge relay to and from work and take freezer in when home and hook up to mains so battery should be ok,just need some cold stuff for when its really hot.
     
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  9. Robin McHood

    Robin McHood Funster

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    Depends on how long your drive to and from work is!
     
  10. chatteris

    chatteris Funster

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    just an update, tried it today stopped at work at 0605 and left work at 1600 so running on battery for 10 hours drove home about 15 minutes turned of and unplugged freezer then waited for half an hour and checked battery voltage, it was 12.5v. the battery is the old one off the van and is quite old so hopefully will be ok
     
  11. chatteris

    chatteris Funster

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    tested again today,12.4v but was about 20 minutes each way today so hopefully will be ok to weekend when a longer run should get everything fully charged
     
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