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Thread: battery amps

  1. #1

    battery amps

    Howdy
    Just bought a new waeco fridge/freezer and wondering how many amps are in my CCA720 battery before i worry about going flat camping. Is it 720 amps or is this different

  2. #2

    Re: battery amps

    mate a battery with a cca rating is usually a start/cranking battery it is not 'ideal' as a fridge type battery .
    a deep cycle battery has an ampere hours rating this type is more suited to to fridge/camping style discharge.

    Cold cranking amperes (CCA) is the amount of current a battery can provide at 0 F (−18 C). The rating is defined as the current a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). It is a more demanding test than those at higher temperatures. This is the most widely used cranking measurement for comparison purposes.

    Ampere-hours (Ah) is a measure of electrical charge that a battery can deliver. This quantity is one indicator of the total amount of charge that a battery is able to store and deliver at its rated voltage. Its value is the product of the discharge-current (in amperes), multiplied by the duration (in hours) for which this discharge-current can be sustained by the battery. Generally, this value (or rating) varies widely with the duration of the discharge period (see: Peukert's Law), therefore the value is typically only meaningful when the duration is specified. This rating is rarely stated for automotive batteries

  3. #3

    Re: battery amps

    Hi does anyone know how large a solar system would be to run the new Waeco fridges apparently they draw about 1 amp

  4. #4

    Re: battery amps

    Of course "it depends"!!!
    Depends
    - how it is used (if using it as a freezer then multiply requirements by at least 2),
    - climate it is in
    - if the battery is also charged by the alternator and how much driving is done
    etc

    But assuming it does use 1 amp average (24AH per day) then if running on dedicated solar you need a solar panel which provides about that on average. If you want to handle a couple of days of crap weather, or if you can't always guarantee that the panel will be in sun (not shade) then that increases the panel size needed.

    Anyway, I reckon a 120W panel with a quality 100 to 120AH deep cycle battery will run a waeco 50L fridge fine.
    120W panel will provide about 10AH per hour of good sun. So you would need 2.5hrs of good sun to replace the 24AH the fridge used in a day.

  5. #5

    Re: battery amps

    Except batteries are only 50% efficient so you need to put in double what you take out, or so I'm told?

  6. #6

    Re: battery amps

    There are losses and inefficencies at every stage. I tend to struggle running a 40L Engel in freezer mode for any length of time on a 120W system. I have to fall back on the gennie or car as a backup if its more than a few days. I would probably double your amp requirements estimate if the weather is warm
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  7. #7

    Re: battery amps

    Quote Originally Posted by death_ship View Post
    Except batteries are only 50% efficient so you need to put in double what you take out, or so I'm told?
    Not so much that they are 50% efficient just that you shorten their lifespan if you cycle them beyond 50% of their capacity.
    If you are using it all the time that's a big deal but if only occasionally using it then it is probably ok to go deeper than 50%.

    Anyway, a 100AH battery taken down to 50% of capacity is 50AH and that will run the fridge for 2 days without ANY solar panel input.
    This is assuming it really is only using 1 amp on average. If the fridge uses more (eg. you put warm beers in it, or the kids open it a lot) then you should assume at least 1.5 amps or maybe 2 amps, as Horse suggested.

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