best value for money battery for camping?

[Cuppa]

I just reread the first post and I believe we have strayed.. really.. us noooooo....

Anyway. Best battery.. I got my 120A/h lead acid battery for free.. was 'stuffed' according to the trucking company.. but they turf them as soon as they look like not performing.. as they can't afford down time of a call out..

Strayed off topic? Not really. All we have talked about is a) why trying to use a 120ah lead acid battery to run what the OP wanted to run for 3 days at a time will ensure the battery's early demise & b) discussed an alternative type of battery - which I accept is not for everyone at this time, but would do what is wanted from a battery of the size to fit where the 120ah one fitted.

As I said in a previous post the best sort of batteries ozzyboy could get would be ones like your ex trucking company one - i.e. cheap. Note however my use of plural. One would still be insufficient.

Your smaller Waeco plus led lighting would use half what an ozzyboy's 80 litre Waeco + led lighting + battery chargers would. Very different scenario.

Cuppa

[ozzyboy]

I should of mentioned in my first post, that I do have a 120w solar panel that I use. The battery still ran completely dry

ozz

[Cuppa]

I should of mentioned in my first post, that I do have a 120w solar panel that I use. The battery still ran completely dry

ozz

Ahhhhh.....<slaps head> ... that does rather change things. Assuming 3 things, then a 120ah battery should be up to running your 80 litre Waeco over a 3 day period.
1. that there is sufficient sun.
2. that you have heavy enough cables with good battery connections connecting the panel to battery (not the skinny cables & feeble crocodile clips that many of the cheap panels are supplied with) to ensur you are not losing your panel's input to voltage drop.
3.That your panel has a blocking diode to ensure that your battery is not discharging through the panel at night (essentially an electrical one way valve - not alays needed when good regulators are used, but if using one of those regulators supplied with the panel - who knows?).

Cuppa

ps. 4. Also depends on what you mean when you say 'battery chargers' - depends what you are charging. e.g.. if charging a laptop this could pull 5 to 7 amps on some, if phones not a lot (but could still add up to significant amounts if left plugged in all the time). For charging, 'timing' can also make a difference. Possibly better to do the charging in the early afternoon once the solar has had a chance to replenish what the fridge has used overnight & the sun is still shining, rather than in the evening, making the most of the available slar input.

[ozzyboy]

don't know much about solar panels. I remember buying it because a) I got a pretty good deal and b) a mate told me it was a good 1, with a mppt?? regulator
it does have thin cable and alligator clips tho

ozz

[Cuppa]

Forgetting the LEDs & battery charging

Waeco needs around 75ah per day

Typical scenario
Arrive at camp after 3 hour drive - 10ah already used (assuming fridge was pre-cooled on mains & not put on battery until just before you left)
Put out solar panel before setting anything else up & catch 3 'sun hours' worth of input before dark - 20ah generated, enough to run fridge & reach evening with battery close to full charge again.
2nd 24 hours 75ah used. 35ah generated (5 sun hours @7 amps) balance in battery = 120ah - 75ah +35ah = 80ah
3rd 24 hours 75ah used 35ah generated - balance in battery = 80ah - 75ah + 35ah = 40ah

40ah = 1/3rd battery capacity. Sustainable for short periods. Ok if you put battery on charge as soon as you get back home. Use like this should see battery last better than than what you have had.

BUT..... you can see it is marginal. Toss in the LEDs & battery charging, & a cloudy day & you would be well into battery killing territory. A second panel would make a huge difference & take the worry out of running out of power or killing the battery.

And it really is worth using heavier cables because it is fair to say that that the skinny cables you have will not be allowing the 35ah per day input from the panel as I have used above, potentially a LOT less.
To calculate cable size, dependent on length, see http://hobohome.com/news/?p=581 at bottom of page. 'Round up' (not down) to nearest size. Note that size relates to the copper core in Sq mm, not to automotive cabling size (which includes insulation)

[nissannewby]

CAT batteries are awesome value for money and have a great warranty ozzy check it out. 4 years all up, 1st 2 years they replace, 2nd 2 years they will go halves.

I know its not what your after but I bought the biggest battery CAT make, 1500 CCA and will run the fridge for a week, weighs 60kg though lol. Only cost $360

[alfonso]

75 ah seems a lot for a fridge in a 24 hour period . 3.125 amps per hour As power is only consumed when compressor is working I thought it would be much less

[Cuppa]

75 ah seems a lot for a fridge in a 24 hour period . 3.125 amps per hour As power is only consumed when compressor is working I thought it would be much less

Hi alfonso,
80 litres is a big fridge. Waeco themselves claim an average of 2.9Ah. Average meaning average hourly use taking into account the compressor cycling on & off. 2.9 x 24 = 69.6. This figure is based on the fridge section being maintained at 5 degrees.C in an ambient temperature of 32 degrees.C. Often folk want to run their fridge cooler than this, & in summer ambient temperatures can often be above 32 deg.c, particularly in the back of a car. Both these factors will increase cycling on times & thus increase average power consumption. Add to this that most fridge manufacturers are , shall we say, optimistic with their claimed figures, I think the possibility of 75 Ah per 24 hours to be realistic, & possibly even a bit low.

Cuppa

[threedogs]

75ah does seem a lot , but battery wise look out for 100ah batteries from "UPS" systems as in bank shutter systems and hi-tech computer places.
you can usually pick them up for less than half price. Pic is of my AUX battery, these same batteries are used out in Port Phillip Bay on
the marker beacons. It's 115ah

those CAT batteries sound like the cats whiskers no pun intended.
some use their coolant too, but a bit aggressive on the modern motors
@ ozzyboy on a good sunny day you should be returning around 6 amps
back into your battery.

[Cuppa]

75ah does seem a lot

Sheesh!


The Waeco 80 litre uses the Danfoss BD50 compressor, which when running uses 70 watts. Watts divided by the system voltage equals amps. 70w divided by 12v = 5.83amps. 5.83 x 12(hours) = 69.6 amp hours.
This equates to a 50% duty cycle which would be about right, AND surprise surprise the figure is identical to that given by Waeco!

In hotter conditions, or with the fridge turned down to what most folks prefer for their beer, a higher than 50% duty cycle would be expected.

Cuppa