fridge not working to well

lost Gypsy · Veteran Member

fridge not working to well

bill12 · Guru

You have to have good batterys as they like the voltage to be above 12.5v. I have a 55 ltr waeco, and try to keep the voltage up. Check the state of your batterys and the connections. I have a 150 amp/hr deep cycle, and a120a/hr starting battery with a battery switch between them, and it will freeze for about 5 days, without starting the main motor, set on -2c.Solar definately helps , but buy a good regulator.I hope this helps. Bill

lost Gypsy · Veteran Member

ok thanks Bill.

I'll find out what a regulator is and try that, because 1 of my batteries is brand new.

DeBe · Guru

One posibility is the wiring from the battery to the fridge is too small, creating voltage drop. Which model Waeco is it? Also measure the voltage at the fridge when its running on 12V & the compressor is running. Seen plenty of instilations that Auto lecs have used too small wiring.

bill12 · Guru

Yes, wire size does make a difference. I have 6mm wire directly from the battery to the fridge, and the votage loss has got to be less.I am not using an electronic dual battery setup, just a $30 rotary marine battery switch. They are rated to 300 amps! I will post a pic , if you want.Bill

Duckster · Veteran Member

Big Waeco fridge can use 80A a day.

At 11.5V you have murdered your batteries. Need to keep batteries above 12.2V.

If you have old and new battery together, could be killing new battery.

jimricho · Guru

Duckster wrote:
Big Waeco fridge can use 80A a day.
At 11.5V you have murdered your batteries. Need to keep batteries above 12.2V.
If you have old and new battery together, could be killing new battery.

If you have your batteries wired together in parallel you must have identical batteries and replace both at the same time. The load needs to be split evenly between the two. I would also suggest going the extra yards with the spending and purchasing good quality AGM batteries.

If you're having problems with battery life I'd suggest installing a marine type changeover switch similar to Bill12's installation that he has described above. This gives you the option of running them together in parallel or alternately. Also when you select the switch to the off position (as when in storage) the two batteries are isolated from each other as well as from the load.

I consider the best option for using multiple batteries to achieve the required capacity is to use 6 volt types connected in series if suitable types are available. I won't go into details as it will draw fire from the village pedants who are probably already loading their flame throwers now.

-- Edited by jimricho on Tuesday 22nd of November 2011 06:14:17 PM

jimricho · Guru

DeBe wrote:
One posibility is the wiring from the battery to the fridge is too small, creating voltage drop. Which model Waeco is it? Also measure the voltage at the fridge when its running on 12V & the compressor is running. Seen plenty of instilations that Auto lecs have used too small wiring.

Also there is a momentary surge in current when the compressor starts that can cause excessive voltage drop if the wiring is too light. The duration of this "inrush" current is usually too short to be able to measure the consequent voltage drop but it can prevent the compressor from starting properly.

lost Gypsy · Veteran Member

ok , thank you all very much, the information is very helpful , I will check my wires and if you can Bill post a pic of that switch.
Much appreciated.

jimricho · Guru

lost Gypsy wrote:
ok , thank you all very much, the information is very helpful , I will check my wires and if you can Bill post a pic of that switch.
Much appreciated.

Hope you don't mind me jumping in here Bill but I had this picture handy....

This is the type of switch referred to, a bit remiss of me not to have included it in my earlier post. It is available at most marine accessories shops...

(use of Bias Boating image is acknowledged)

lost Gypsy · Veteran Member

smile Thanks jimi

03_troopy · Guru

Also a point to note is that wire sizes vary depending on who you are talking to. If an electrician says 6mm wire he usually means 6mm CCA or Circular Cross-sectional Area (ISO rated). If an Auto Sparky says 6mm wire he is usually referring to "auto wire" and is talking about the total diameter of wire including insulation. The main problem is the "auto wire" classed as 6mm is that it could be anywhere from 2mm ISO to 4mm ISO depending on the manufacturer (or depending on thickness of insulation).

Major manufacturers generally quote wire sizes in ISO sizes ie 6mm CCA (or AWG for yanks because they just need to be different). So the problem is if you get the auto sparky to install wiring, he is most likely going to use wire from his roll 6mm wire which will leave your wiring too light for the required task.

a good read here http://www.motorhomesaustralia.net/cable.html

-- Edited by 03_troopy on Wednesday 23rd of November 2011 09:59:01 AM

jimricho · Guru

Automotive wire sizes can be confusing even for those with a technical background let alone others, due to a lack of enforceable standards.

I agree with troopy's comments about 6mm being too light unless the run is very short. I would consider 8 gauge to be a safe choice (note that's 8 gauge not 8mm). For the cables interconnecting the batteries to the switch I'd suggest a minimum of 4 gauge (note when talking wire "gauge" the lower the number the heavier the cable).... better still, use short lengths of battery cables that can be purchased already made up from most automotive stores.

Install the batteries close together and use the shortest length possible to interconnect the negative terminals and identical lengths to connect the positive terminals to the switch. This is to ensure the load is shared evenly between the batteries when the switch is selected to both.

Having one of these switches installed also gives you the option of having dissimilar batteries provided you operate them with the switch selected to one or other but not both.

dogbox · Guru

i vote for the new battery being killed by the old one

jimricho · Guru

dogbox wrote:
i vote for the new battery being killed by the old one

I agree, it's one of the downsides of leaving batteries connected in parallel.

Duckster · Veteran Member

03Troopy "problem is the "auto wire" classed as 6mm is that it could be anywhere from 2mm ISO to 4mm"

That is not correct at all. Auto wire has defined sizes and always has had. 6mm auto cable is 4.57mm sq copper cross sectional area.

The link quoted has serious errors of fact and should be disregarded.

-- Edited by Duckster on Wednesday 23rd of November 2011 07:36:06 PM

PeterD · Guru

Duckster wrote:
The link quoted has serious errors of fact and should be disregarded.

Duckster, where are the serious errors in that link?

The only error of note is in what 03Troopy posted. He stated that the range of sizes quoted by Collyn were for 6 mm wire. They were actually samples of 4 mm cable that he had seen or had in hand. There is also a date when the samples were taken, March 2003.

There is usually the size in square mm in fine print on the reel as well as the "auto cable" size. In times gone by I have held cables from two different manufacturers in my hands (picked up from different sections of the same shelf) showing different cross sections of copper for the same nominal size in several auto accessory stores. There is no Australian standard for auto cables that I have seen. If you know of one please give me a link to it. As far as I am aware Standards Australia only uses ISO sizes.

In critisizing Collyns article in the way you did, I don't think you are aware of his background. Amongst his experiences he has worked as a research engineer with General Motors (UK,) he was the owner and publisher of an electronics magazine which sold in several countries and he currently publishes books on caravan electrics and solar power, two of which are currently used as course materials in TAFE colleges. His article "On the Ball" that appears in the current issue of Caravan World was checked and passed by several authorities including the staff automotive engineering facaulty of a major tertiory institution. I suggest you consider the facts in any of his papers very carefully before critisizing them.

-- Edited by PeterD on Thursday 24th of November 2011 01:00:32 AM

03_troopy · Guru

OK, firstly I only used 6mm as an example from when I have tried to purchase 6mm marine grade wire from auto eleccos around the Newcastle Maitland area. Maybe the range of discrepancies was slightly exaggerated and probably should have read "approximately 3mm to 4mm cca." Like I said, that is from personal experience of trying to buy the stuff and what I was offered (none of which was marine grade anyway). As for quoting Colin, that is not the case. I added the link as an article worth reading and I had no intention of quoting his figures as I haven't done the research to back them up 100%. The fact remains, many auto electricians have a very different idea as to what 6mm wire is, and it isn't even close to what ISO 6mmsq is.

-- Edited by 03_troopy on Thursday 24th of November 2011 10:21:24 AM

oldtrack123 · Guru

Hi All

I'll 2nd both PeterD's & 03troopy's comments

ALWAYS specify cable by cross sectional area OF CONDUCTOR

Peter

-- Edited by oldtrack123 on Thursday 24th of November 2011 11:42:17 AM

PeterD · Guru

03_troopy - your small mistake was of no consequence to me. The bit "The link quoted has serious errors of fact and should be disregarded." posted in reply to your little boo-boo was though. Sorry if it looked like I was having a big gripe at you.

03_troopy · Guru

PeterD wrote:
03_troopy - your small mistake was of no consequence to me. The bit "The link quoted has serious errors of fact and should be disregarded." posted in reply to your little boo-boo was though. Sorry if it looked like I was having a big gripe at you.

No worries mate