best value for money battery for camping?

[threedogs]

I hear you Cuppa but I can only go on what happens in the real world like at camp, I could sit next to my engel 40 all weekend and doubt it would run for 1hr at a time {cycle}
On a very hot weekend my Engel lasts 3 days before I'll need to think about charging the battery, never have yet.
Bear in mind I only use my Engel for Food and a few soft drinks, if used as a beer fridge reckon I'd be lucky to get 1.5-2 days from my battery.
That is why I use an ice box for drinks for 4 blokes [96 cans], and if required I can drive recharging my aux on the way to town to get ice. I think real world scenarios on what works and what
doesn't is best advice on these forums. then what works for me may not suit others, then we modify to suit.

[Cuppa]

In your real world you are comparing apples to oranges TD. Primarily a 40litre fridge simply cannot be compared to an 80 litre fridge in terms of power consumption. Secondly the Engel has a different type of compressor. Thirdly it is possible that your Engel has a different thickness and/or type of insulation. Fourthly by your own admission you choose to use your fridge differently to many people, which reduced power consumption.

Suggest you might do a little research ...... Look up Engel's rated power consumption for your fridge at X degrees.C in an ambient temperature of Y degrees.C & compare the figures to an 80 litre Waeco. When you've done that report back what you find!

Cuppa

[P4trol]

Is it the danfoss (as opposed to what is in the engel) compressors that actually use more current as the battery voltage gets lower?

[threedogs]

rather than listen to waeco marketing hype I'll listen to my fellow club members for "real world" figures not laboratory controlled figures .
wasn't trying to compare my little engel to an 80 ltr waeco, just relaying what works for me so , enough said I reckon,
@ ozzyboy what are the main duties of your waeco, just keeping food cold and some throffies, or just drinks and 6 snags.?
understanding what or the way you use it may help find an answer. anyway going away for a while hope you find your battery

[Cuppa]

Is it the danfoss (as opposed to what is in the engel) compressors that actually use more current as the battery voltage gets lower?

Haven't heard that before.
Danfoss (now called Secop since a company takeover in 2010) are the most widely used low voltage compressors in camping, RV & portable medical fridges worldwide. Commonly used are the BD35 & the larger BD50 compressors.

The Sawafuji swing motor used in Engels is almost as efficient, & the Domus (Chinese I think) used in many of the cheaper fridges, less so I understand.

The better Waeco's use a Danfoss, whilst their cheaper models use yet another Chinese sourced compressor - 'Wanbao', which may or may not be the same as the Domus. Either way the Wanbao & the Domus have a 2 year warranty, whereas the Danfoss/Secop has 5 years.

@ TD ... Why would Waeco's marketing hype suggest that their product was actually less efficient than it's "real world" performance? Wouldn't be 'hype' would it? I'm not sure why you are having trouble accepting the matching figures from both Waeco & Danfoss.

[P4trol]

Gee, I was hoping you had heard of it. I had to do more research!

So there is two types of motors. The the rotary one (that the DANFOSS style uses) and sawafuju. The rotary ones suffer from a large current draw on start up. The sawafuji one doesn't.
When the rotary one gets hot or runs on lower voltage, it is less efficient. The motor goes around slower and creates more heat. This makes it hotter, and less efficient.

Not very well explained, I know. The sawafuji motor is different, in that it will work like a swing. (pause)

If you think of a little kid pushing a swing. Not the coordination, just the tiny pushes they are capable of. Given the right timing, pushing the same as they would be able to push, the swing will soon be at a fair height. The sawafuji operates on this principle, able to start up with small pushes (say from a battery of less than optimum voltage. The following link is some Engel propaganda.

http://www.engelaustralia.com.au/about_SwingMotor.asp

As pointed out, we tend to operate our fridges in less than ideal conditions. This means the manufacturer special aren't real life, although if you had the same testing conditions, I have no doubt you would come up with the same results. I do think the Engel has the edge in the lower voltage conditions.

[Cuppa]

Fords & Holdens, Patrols & Landcruisers, Engels & the others.

I certainly agree that manufacturers specs are not the same as real life, but I wouldn't agree that the real life figures are actually better than the manufacturers specs, which is why I've previously suggested that the manufacturers specs are at best optimistic. (some of the other stuff they tell you is at best very misleading, but it helps to sell fridges - check out Waeco's FAQ page).

What you say about the efficiency of the the two diferent types of motor may well be the case but it leaves me wondering why it is that there are many many more danfoss powered fridges out there than Engels, & also why it is that Engel give only a 3 year warranty, vs Danfoss' 5 year warranty?

Could you share the link with the info about the 'problems' with rotary compressors.

I guess at the end of the day efficiency is about how the whole package works. I can see from what you've reported for example, that an Engel may be better at lower voltage than a rotary, but this will only come into play when the battery capacity is getting low & the voltage dropping off. As per my posts elsewhere about ensuring good battery life this is a situation best avoided, & thus, for those who try to ensure optimum battery life, having a compressor which is more efficient at those lower voltages is of no benefit. If getting the longest use out of a battery charge at the expense of battery life is the aim, then there may be a case for choosing an Engel. As for getting hot causing less efficiency in the rotaries, I have run our fridge in the bus at ambient temperatures up to 47 degrees quite successfully. Whilst at that sort of temperature the fridge cycles on more often & thus uses more power, but I have never observed it to be drawing more current whilst running. It always uses the same whilst running whatever the temperature ........ although I'll qualify that by saying my monitor only reads to one decimal place, so it is possible that there have been minor differences I have not seen.

[P4trol]

My guess is there is a patent on the Engels, which they aren't licensing.

Most of the literature I see on the danfoss compressors is that it is now controlled by an electronic board. One bloke believes that prolonged low voltage kills this board.

The waeco UK Site says it happens to all compressors.

"
Also, if the supply voltage from the battery becomes too low, electronics and motors tend to overheat. This occurs with all electronics and all motors no matter who the manufacturer is. And that is why we do not allow this to happen to WAECO products.
"

From http://www.waeco.co.uk/page.aspx?page=faq&s=4

Also on the same page, some models (or maybe all models?) have a 'my beer isn't cold enough switch' (emergency) which bypasses this elec-trickery controlling/protecting the compressor. You are on you own then. I was unaware of the electronic protection in my earliest post.

I'm unaware of the reason for warranty time differences. You know how we only have so many heartbeats in a lifetime...

[Cuppa]

My guess is there is a patent on the Engels, which they aren't licensing.

Ah but............
Patents haven't stopped designs being copied in overseas countries & then imported to compete with the patented product. It's possible they exist, but to date I haven't seen or heard of an Engel copy.
As it is both types of compressors do a good job & have good reputations, & the issue with low voltage only come into play when a battery is being 'abused', so with battery protection built in to the rotary compressors it's not really an issue.

I'm not really wanting to be argumentative, but rather, hope that this discussion may be helpful to others down the track when they are thinking of buying a fridge, which after all is not a small investment. It is my belief that many fridges are purchased on the basis of their capacity & what will fit into the available space, without necessarily considering what will be required to run it. Such decisions are influenced by misleading statements from Manufacturers like can be read here (check the 'How long will my refrigerator keep running for on my battery? section) & then compare it to here , (How long will it run on a battery for? section).

Returning to the power consumption of the 80 litre Waeco, I note from the UK waeco page link in P4trol's most recent post that they provide a more comprehensive table of power consumption for all of their models than I've seen on our local Waeco site.
http://www.waeco.co.uk/page.aspx?page=powercon&s=4
In this the 80 litre fridge (CF80) specs say 5.5 amps current draw when running, which is what I would expect, and a consumption of 84Ah in 24 hours, suggesting it has a higher than 50% duty cycle, & this is at the slightly lower (than on the Aussie site) ambient temperature of 30deg.C. Not hard to imagine this rising to 100Ah on a 40+deg.C day. No doubt some extra insulation, even just a transit bag, would improve this.

I recall reading somewhere that not only the volume of the fridge, but it's shape (dimensions) also contribute to it's overall efficiency. As I recall the most efficient portables are 40 litres & below & I can't remember what the 'best' shape is. Tall & narrow, or low & wide? I'm guessing the former would be the more efficient, which if correct also doesn't sit in the CF80's favour, it being low & wide. This shape makes it more convenient to use (less rummaging around to find what you want), but at a possible price of higher power consumption.
Arguably the best portables on the market, the Trailblaza's have a combination of extra thick insulation, a tall & deep shape & a Danfoss compressor. However the extra insulation (up to 5" thick) makes for a fridge that is just too bulky for many, & they are priced way above the more commonly available brands too.

Cuppa

[rex]

do agree with u cuppa just fridge size I run my 40 litre engel on 100 ah batt with 80watt solar panel was out for 10 days battery never got below 12.5 volts the whole time could not be happier with the set up