Compact Refrigerators

What wattage is required to run a 50l car fridge/freezer?

We have an auxiliary battery in the car and would like to install a solar panel on the roof of the car to charge the battery effectively to run our fridge/freezer. Any ideas? Thank you.

Public Comments

1. multiply the volts times the amps = watts.
2. That rather depends upon the product you choose. They range from tiny coolers at around 30 watts up to units consuming over 150 watts and beyond. More even, if also a freezer. When choosing the product just look at the specification and it will tell you (on these kinds of units, it is usually on the box!) Either way, it is not so much the power demanded as the quality of insulation and whether or not it is a front, or top-loader. And whether the unit has a thermostat. Once chilled, the contents (and, importantly, the air around them) will remain cold given adequate insulation and the work (joules per second - watts) will have been done. If there is a thermostat, the unit will then rest. If there is not a thermostat it will continue to run for as long as it is switched on and there is current for it to draw upon. Cold air is heavier than warm air so in a top-loader, will stay in the unit each time you open it. (Like water in a fish tank). But with a front-loader it will spill out each time you open the door, warm air will replace it, and the heat in that warm air will require more work again to pump the heat out. But, basically, the larger the capacity of the unit, the greater the power required (watts) to run it.
3. As you are not likely to get more than 4 hours a day of even close to full output from a solar panel, you will find that you require a lot more panel than you first think. In practice an Engle or similar brand will require at least 100 watts to run, probably more than that including start-up draw, if it runs at only basic cooling level it will need to run somewhere between 1 minute in 5, up to almost continuously depending on the ambient temperature, but assuming a low average of say 25% on a warmish night you have to assume the minimum average of 25 watts per hour x the number of hours the unit must run without charging. This might be say 10 hours. So you need perhaps 250 watts of storage capacity, which in practice translates to about 20 amp/hours @12V (Amps = Watts/Volts) To provide that capacity indefinitely requires the replacement of that power plus all losses, so applying W=C*V you need 240 watts of charge, plus a margin for losses in whatever time the panel(s) are effective without tracking - you will require perfect weather and an 80 watt panel for the above theoretical situation. But if you need to run the system 24/7, and in adverse conditions such as overcast, really hot etc. you will find you could need a system several times that size just to cope. Practical experience suggests one 80 watt panel will supply about a 3rd of the power generation required for that type of load unless conditions are perfect, you need to build in a lot of redundancy with solar and wind power generation, as there is no constant input possible. Night falls, the wind drops, and you are left with only the existing storage capacity and charge level - or a fuel powered generator or charging plant. And that's your options in the harsh light of practical experience. Do not expect a battery that cannot be fully charged every day, and that you discharge past 50% to last any time at all - unless the battery was specifically built to be fully discharged, nor is a starter battery at all suited to this type of cycling - ever, totally different internal structure.
4. Most of the middle class person opting for cars. Cars has become good medium for transportation but big problem are being faced by metro cities in the form traffic and pollution. Altohugh, in many cities CNG are being used in public vehicle which has contirbuted towards reducing pollution substatially. Due to this auto garages are increasing day by day. http://www.magghu.com