compressor fridge or element fridge ?

In fact I think there is something wrong with mine as I've had el-cheapo Repco 3 way fridges that did a better job than this one in the camper.

All 3 way fridges use a huge amount of energy when on 12V and they are not expected to perform in that mode - its only a maintenance mode at best (while your car's alternator is running) - gas is the mode that is expected to provide good cooling.

My ute blew a 20A fuse in the van battery charging circuit whilst we were travelling. Got into the van 5 hrs later to see that the 184 L three way fridge had drained exactly 120A out of the batteries (on battery monitor). This was exactly as per the Dometic specs 5 x 24 A per hr). Another reason to change over to gas quickly when you are stopped.

Sam h6,
It amazes me why some van manufacturers don't pay attention to the correct installation of fridges re wiring size and insulation/clearances.
We all pay $50000 - $100000 for these vans with only 1 yr warranty (on most) and bugger all quality control.
I agree with you. Unless the compressor fridge has more than enough solar and battery back up, you will be always looking at your battery monitor. Everythings rosy whilst the sun is shining!!

What was the damage with the Lithiums mate? I have been thinking of doing the same.

Thanx

Bonz

Broometime,
Please post a report/review of the new battery in next few months as I am sure there are plenty of people interested in new technology. Hopefully price will come down as well

The technology is not lithium-ion, it is lithium-iron-phosphate - LiFePO4.

Many members of our Kimberley Karavan owners club have swapped out the 320 Ah AGM batteries for 260Ah or less of Lithium. When my AGMs die, I will too.

It is not a cheap exercise to do it properly, $2k to $2.5k depending on whether or not you need a new mains charger and a couple of other things. (In comparison a replacement set of AGMs for our vans is about $1300.)

But EVERYONE who's done it is ecstatic and say they would never go back. With 260Ah of lithium you get about 230Ah of usable power. With 320Ah of AGM, using the 50% rule, you get 160Ah.

There is a 70kg weight saving.

You don't need to faff about with multi stage chargers. Charge flat out until the battery is full and switch off or go to float. A solar charging system can deliver its full output until the battery is charged, whereas a system charging a lead-acid battery delivers full output in the boost phase, then spends a lot of time (ie, hours) throttled back for the absorption phase.

Our Karavans are power-hungry if you use all the facilities available. People with Lithiums typically recover to 100% after overnight use about 4 or 5 hours ahead of people with AGMs and similar useage patterns and charging equipment. So you are less reliant on a whole day of perfect sun.

You don't need temperature compensation, there are no corrosive fumes or chemicals, so no ventilation required. Batteries are robust, vibration and shock resistant.

A supplier here in Sydney runs his car on four cells the size of Red Bull drink cans. He says they will out-crank a standard battery for that car.

Their discharge curve is flat, meaning they hold their voltage at near full-charge levels until nearly flat (about 10%, I believe), so all your 12V stuff gets a full 12V all the time.

They don't sulphate. Unlike lead-acid batteries they can live for long periods at partial SOC and then recover fully when a full charge is available, with little or no affect on calendar life.

High quality industrial lithiums are reported to be still going strong after 7000 (yes, 7 and 3 zeros) cycles. Cheaper domestic ones over 3000.

A set of heavily cycled Lithiums will likely outlast 3 or 4 sets or more of similarly cycled lead-acid batteries, maybe more - the technology hasn't been around in the domestic market long enough for that to be properly established yet.

What they DON'T like is over voltage and under voltage. Over-charge and over-discharge will kill them. The conversion kit that fits our vans includes a VSR that will disconnect in either of those circumstances.

They also need occasional cell balancing which is akin to equalisation in a lead-acid battery. A mains charger with a lithium profile, or a lead-acid charger with suitable switched voltages will do that.

Some mains and dc-dc chargers have settings that are suitable for lithiums, but they are a compromise. In many cases replacement will be required. Some manufacturers offer re-programming of their lead-acid equipment, and switch-selectable lithium profiles are beginning to appear on new recreational 12V products.

Those are about the only caveats I can think of.

Cheers

Bonz,

Details of the 320ah Lithium battery pack purchased from "Drive by Nature" in Qld :
8 x 160ah WBLYP cells $1,629
11 x Copper connectors $ 40
Strapping for the 8 cells $ 90
Packing and freight to Sydney $ 100
GST $ 186
Total $2,046

BMV battery monitor gauge $ 212
Eniquest P/L

Pro Mariner PNP 1250- 50amp charger $ 699
RV Powerstream P/L

All up for parts $2957. The installation has not been finished yet, so I have not included that cost.

agree 100%

Agreed, Bantam. Clearance, ventilation and insulation are almost always considerably compromised.

Given that most compressor fridges use an air cooled condenser there is another improvement you can do if you have the skills or contacts to help and that is to water-cool the condenser. The condenser transfers the heat from the compressed refrigerant to the environment, usually by air. A small volume of water can carry away vastly more heat than a large volume of air.

My hybrid camper/van's 130 litre fridge has a remote compressor located in a confined space. In warm conditions it had about a 60% duty cycle and pulled 5 amps when running.

With some design and installation assistance from two very helpful businesses, my fridge now has a duty cycle of about 40% in the same conditions and I have been able to wind the Danfoss compressor speed down so that it pulls only 3 amps when running, to which must be added the draw by the water circulation pump of 1 amp, total 4 amps when running. When you do the maths, that's nearly 50% reduction in amp-hour consumption.

Water is circulated from one of the on-board drinking water tanks.

An engineer friend of mine has done similar with his 3 way fridge with remarkable performance improvement in hot weather.

Cheers