Average power consumption

Gus1949 · Senior Member

Average power consumption

Dreamcatcher · Veteran Member

I read in article by an expert that the battery source can be what ever you want say 200amp but if the supply to this source isn't big enough to keep that battery up it up the required drawing of the fridge then the power source will drain and you will run out of power.

im not sure if that helps but I would suggest that input into the batteries should be greater than the draw power of your fridge.

reglynn · Guru

The only answer that i have, is that a piece of string is twice halve of it's length.

SnowT · Guru

hey Gus..

going off the figure of 5.8A's for a supply load..
-- IF the fridge operated like a similiar domestic fridge.. it should only be in operation for 8hr's of load... -
- so 8 x 5.8A actually means a load draw of 48Ahr's from the batteries..

The important thing is to make sure that you have the ability to replenish that load in the worst of DAY's....
-- the thing that people seem to forget is the Worst of days...
Passively if via solar...
Actively is via some mechanical form of recharging...be it a Generator and battery charger or via alternator of the tow vehicle..

Your 220w might not be enough to full recharge the expected load.... and that is only the load of the fridge... and that takes the assumption of 100% efficiency..

Don't fall into the trap that everyone does....

" Oh, my batteries don't have enough power to give me all I want, lets get more batteries.." and completely forget about the need to be able to recharge the Batteries..

So Before you do anything else get your self more Solar....

--- --- --- --- --- --- --- --- --- --- --- ---

Or you could do something like me and have a tropical roof of Solar panels.. [ and yes I did say a Tropical roof of solar Panels.. ]

Juergen

oldtrack123 · Guru

Gus1949 wrote:
Thanks to those who have provided advice on connecting a portable solar panel to my van.
Next issue to deal with is the amount of battery capacity needed as we have a Wacoe RPD215 compressor fridge and we intend to free camp wherever possible, but not for weeks at a time, maybe four or five days maximum.
The average power consumption is given in the manual as 70watts which I understand is a current draw of approx. 5.8 amps. Over a 24 hour period I assume this means it will consume 140amp hrs.(obviously the power consumed will vary depending on ambient temperatures, ventilation, how much beer I consume etc). Are my calculations correct?
I have two 100amp/hr batteries that will be supported by 220 watts of solar panels, will this be adequate. If not, is it better to add more solar or another battery? I know more is always better but none of this stuff comes cheap.
I appreciate I am asking how long is a pice of string but any guidance from personal experience will be gratefully accepted.

HI Gus

140Ahrs is the MAX that the fridge will draw over 24hrs

if just being used as a fridge [not freezer]the draw could be anywhere btween 20Ahrs & around 80Ahrs in normal ambient temps

220W of solar will only put in around 75Ahrs on GOOD days

How you use & the ambient conditions for the fridge will determine IF you have enough solar

More solar would be the first priority

Rmember also that the power you draw from the battery requires replacing by around 20<40% more

During the day the fridge would run mainly on solar with whatever is left over recharging the batterries.

So minimizing power used when solar is not available can make a big difference night

As Snow has pointed out one then has to consider those days with little solar input

That is why I like my 3way fridge as well as the Engel biggrin

PeterQ

Muskat55 · Veteran Member

On our houseboat we have 220Ah of batteries and 160w of panels. We run an EvaKool 55 litre fridge that allegedly uses about 50-60Ah per day (5 amps with compressor running on 50% cycle). We have stayed put, using a cd/radio (on 10h per day), water pumps on 20min/day and 150w inverter for 20min a day and lights( LED) at night sparingly. We have sat for 3 days without using the generator, with the batteries down to about 70% at the end of this time. This was on predominantly sunny days, 30-33C and cool nights.

-- Edited by Muskat55 on Thursday 11th of December 2014 08:24:08 PM

Gus1949 · Senior Member

Thank you everyone for your contributions and advice. More solar looks like the best way forward so I will plonk another 100 on the roof and see how we go. Can always run the tug for a while if things get desperate.
Rowan.

banjo · Senior Member

IMO you can never have too much solar on a caravan or RV, we have the slightly smaller fridge the RPD175, we have 2 120AH batteries and 560W of solar.

We travel full time and free camp and CP as and when we feel the need, never currently in three years ran short of power, but we follow the sun whenever possible, in certain conditions we may not have enough solar, solar is now cheap so will repeat, I don't think you can ever have too much.

I would never put more than two batteries in parallel, but some do and get away with it or replace them every couple of years, mine are still like new and I expect a few more years yet.

Batteries are now very expensive compared to a couple of extra panels and a quality solar controller that looks after your expensive batteries.

Aus-Kiwi · Guru

Off topic a little ?.
I have fitted a plastic cover inside our fridge door to keep the cold air in..
It's held there by Velcro.. I found since fitting , elect consumption is way less .
The top half is accessible to get drinks etc..

oldtrack123 · Guru

Aus-Kiwi wrote:
Off topic a little ?.
I have fitted a plastic cover inside our fridge door to keep the cold air in..
It's held there by Velcro.. I found since fitting , elect consumption is way less .
The top half is accessible to get drinks etc..

HI

Any additional insulation is an advantage ,in fact, the more the better wink

I actualy have one of the Engels[ used as a freezre] packed in a box ,with the Vent end open,but 50mm of styrofoam sheet underneath ,on the sides & at the other end

Plus a 2nd lid of the same foam.

When traveling or batteries fully charged I would turn the thermostat to MAX freeze then at night simply turn the freezer "OFF]

Carried a Honda 15A battery charging generator virtualy unused in 40years!

I did similar with the Dometic in the van top & sides[filled the gaps with as much foam as I could get in]

Basically All our trips where away from mains power & I had limited space for solar [200W & 200Ahrs of battery]

Just make sure not to block any ventilation grills

PeterQ