Solar Panel advice for a fisherman

[Quigley]

I have a friend who is a keen fisherman and spends days at a time camped while fishing. He has a 60 litre Waco fridge and a spare large 12v battery. He is considering if it is practical for him to get solar panels to charge the battery to run the fridge.
He would like advice as to what system and equipment he needs, likely budget he will need, what to buy and where.
I would appreciate advice, contacts etc that I could pass on to him.

[Judo]

Assuming at least a few solid hours of good sunlight during the day, you wouldn't need a very large solar panel to keep a waeco going. Lets see.....

From Waeco: Av. Power consumption: 0.83 amps/hr = 20amps/day.
Av. full sunlight: 8 hours.
20amps / 8 hours = 2.5AH = 30W solar panel.

Maybe someone can check my math, because 30W is a TINY solar panel. My maths are certain rough averages and you would want more than that anyway, but to be safe, buy a 60W panel.

You also need a voltage regulator. Rough guess, less than $200 for the setup and the battery will be charged to full every day.

[Vern]

average peak sun hours a day would be around 5.
Where did the average amp/hr usage of the waeco come from??

[Judo]

Waeco website for the CF60 model.

With 5 hours:

From Waeco: Av. Power consumption: 0.83 amps/hr = 20amps/day.
Av. full sunlight: 5 hours.
20amps / 5 hours = 4AH = 48W solar panel.

So a 60W is still a pretty safe bet I reckon.

Keep in mind, the solar panel still works in partial sun / morning / afternoon, just not at full power. So the hours/per day is just an average. In summer you would get more like 14 hours of daylight. 4-6 hours at average power, and 8 at full power. In winter of course it's no where near as good...

[Blknight.aus]

.83w is probably the power consumption on 240v.

[Judo]

.83w is probably the power consumption on 240v.

Nah, definitely 12v. It would be rather annoying/stupid if they listed the 240V power usage for a mobile fridge.... (You're right - some companies probably would, but not in this case...)

"Av. Power consumption: 0.83 amps/hr (@ 12 volts, 5 °C interior, 32 °C ambient temperature)"

From: WAECO mobile solutions

[roverrescue]

at 5 degrees thats warm beer :-)
Unless you have it really well insulated, the danfoss pulls 5amps when running and will run for 20 minutes in the hour at proper fridge temps in good conditions.
Id do the maths on 2 amps per hour or 48 AH per day

Gaurenteed cold beer

S

[DeanoH]

........................................
"Av. Power consumption: 0.83 amps/hr (@ 12 volts, 5 °C interior, 32 °C ambient temperature)"

From: WAECO mobile solutions

Beware of companys that give statistics in 'bull****' units. amps/hour is such a unit. Average 'amps/hour' is even worse. To an electrical/technical person it is meaningless and misleading drivel.

Power is measured in watts.

Watts are calculated by multiplying the applied voltage (in volts) by the current drawn (amps).

My 12 volt Engel MF35 fridge draws 2 1/2 amps when running to give a power consumption of 12 X 2.5 = 30 watts. If it ran for 1 hour it would use 30 watt hours of power.

Fridges don't usually run continuously, they have a duty cycle ie. on for some of the time and off for some of the time. If a fridge was on for a third of the time and off for 2/3 of the time it would have a 33 % duty cycle.

The amount of time the fridge runs depends on many things. The main one being the difference in temperature between the temp. outside the fridge (ambient temp.) and the temp. setting of the fridge thermostat (temp. inside the fridge). The bigger the difference between the two the longer the fridge must run to maintain the set temp. and the more power the fridge uses.

How often the fridge is opened, the initial temp of the fridge contents, is it being 'topped up' as you go, is it in a shaded area and importantly but often overlooked is it in a well ventilated area (so that the extracted heat from the fridge contents can be dissipated).

In the real world, in summer (mid to high 30's) my MF35 Engel averages a 50 % duty cycle over a 24 hour period, so power used is 12 volts X 2.5 amps X 24 hours X 50 % = 360 watt hours of power per day.

Your average common or garden variety 12 volt N70 battery has approx. 100 amp hours of capacity (depending on model).

Remembering from earlier................Watts are calculated by multiplying the applied voltage (in volts) by the current drawn (amps).............. this batterys capacity can also be represented as 12 volts X 100 amps hours = 1200 watt hours.

Therefore an N70 battery can last a long weekend in the middle of summer keeping the beer cold. , so if you're looking at a couple of days away between charges does your mate really need a solar panel ?

Also in practical terms, when travelling my 80 watt solar panel just kept up with demand for my Engel and an 11 watt flouro lamp.

In the end I got rid of the solar panel and got an extra battery. It is a lot less mucking around.

Sorry for the long winded reply, hope it helps as opposed to muddying the waters.

Deano

[Vern]

Any calcs to do with batteries and sizing is measured in A/hrs. Well it is in the Stand alone solar world

[bee utey]

Any calcs to do with batteries and sizing is measured in A/hrs. Well it is in the Stand alone solar world

Of course they are actually Ah or amp-hours, not amps per hour. But you would know that!