[Jamesb94]

Hi there,

Very much out of my depth with this question so apologies in advance for any faux pas etc.

I purchased a 1994 VW Transporter fully kitted out and since purchasing and having trips out have noticed that the Waeco fridge keeps cutting out and then starting back up again. The more trips we took the more apparent this became, and last weekend when we were hooked up to 230v I got the multimetre out, took the fridge out and ran some tests...

The voltage reading to the fridge kept dropping every 30 seconds or so causing the fridge to cut out and effectively reboot. The zig unit battery condition would go from green to red every time this happened (only momentarily) if the lights are on at the same time this caused them to flicker (again, only momentarily). The fridge would then power for 50 seconds and the same would happen again on repeat.

When the Waeco fridge cuts out the led above the power button inside the fridge goes from blue to orange with a red flashing light above the orange LED (a Google search told me this means there is a voltage drop). We tested the wires running to the fridge behind the unit and there was infact a voltage drop to the fridge (I cant remember the exact readings).

I coudnt solve the problem on site so we continued without use of fridge and drove home on the Sunday (45min trip).

The next morning I checked the leisure battery (12v AH (20h): 75 amps) with the multimetre in idle and got a reading of 13.4v (presumably the engine charged the LB when we travelling back the previous day). I then went to the Zig unit, flicked 12v on, and the touring/on site rocker switch to 'on site' I then turned on all the lights, the fridge on full power and the fridge power LED was displaying blue. I checked the LB voltage and got a reading of 12.4V. I should mention at this point im on the drive and not plugged into mains hook up, this is all on 12V. Everything ran perfectly. I then switched the zig unit from 'on site to 'touring' this (for me) kicks my solar panel into gear and the solar control unit lights up indicating sun is available but my battery is near empty (red)... personally I wouldn't say 12.4v is near empty... Anyway, I did this to see if the solar panel would provide power to my leisure battery to manage the pull from the 6 LEDs and the Waeco fridge (otherwise it would overtime just run my LB flat). Everything worked perfectly for 1st hour and 2nd hour. On checking the 3rd hour, this is what I opened the door to...

The Waeco fridge kicks in (blue), LED lights flicker and takes LB down to 11.7V - solar panel displays red flashing (voltage drop) and zig unit battery condition goes from green to red. This lasts 36 seconds. Then fridge stops and LB goes to 12V - solar panel displays yellow (low). This lasts 50 seconds and then the process repeats.

If anyone can shed any light on this I'd be massively grateful, like I said I'm way out of my depth hear so go easy on me.

UPDATE: After running the above tests my LB was reading 12.3 with everything turned off. I kept the zig unit on 12v and flicked to touring to keep the solar panel running. (The solar panel displayed the battery as green steady which means normal). I rang some people and wrote this discussion and just went to check my LB reading again - im getting 12.6V now so hopefully that means the solar panel is working how it should and charging the LB.

I think it's something to do with this Zig CF8 unit but what do I know!

 

[Or_GazM]

Zig units were designed for caravans.....total garbage in my opinion!
IF charging, teh battery should read around 14.2-14.4 volts.
Zig units only "maintain" a battery (to prevent gassing in a caravan), so are pretty useless.

If the leisure battery has been below 12 volts on load for sometime...it's time to buy a new one.....12.2 is about as low as they like to go (unless AGM type).
Also, check the wiring to the fridge....if someone installed a Zig, they probably also used thin wires for the Waeco....should be 6mm at least, 10mm if the battery is more than 3 metres (total wiring length) away.
The fridge takes around 3.5 amps RUNNING....but requires 10x that to get the compressor up to speed....lower voltage means longer time to start....which eventually burns out the controller due to high currents for a long time.
Problem is...people see 3.5 amps, and use 1.5mm cable!!

 

[Jamesb94]

Thanks for the quick reply Or_GazM!

I'm not keen on the Zig units either, but it seems to be doing everything it should. It's providing a 12v supply to the lights, fridge etc and seems to be charging the LB when hooked up. (Prior to hooking up on the drive LB was reading 13V, when hooked up it is now reading 13.3V).

I must admit, when you said 6mm cable for the fridge I thought that was overkill but your bang on the money, a quick Google search backs you up completely (not that I ever doubted you!) I think you've solved the problem that explains why there is a voltage drop and the fridge cuts out!

I'll buy some 6mm cable and get it fitted this weekend, I don't suppose you know what is best practice- should I hook the Waeco fridge up directly to leisure battery? Directly to Zig Unit or, as some wiring diagrams suggest, directly to the car battery?? (Not sure why you'd do that as as soon as the engine is off the fridge would cut out 🤔

If you could let me know that would be great - thanks for all your help so far, you've been really helpful!

 

[Jamesb94]

UPDATE: I've just unplugged the hookup and the LB has gone down from 13.3V to 13V again - is that normal?

 

[Or_GazM]

1st thing, there's an on/off switch on the fridge....use that rather than go via the Zig.
So straight to the leisure battery via a 10 amp fuse.
Keep both leads as short as possible, and make sure you have a good connection to the chassis for the "earth".

Battery voltage should sit at 12.7 volts with no load on it....
14.2-14.4 volts is CHARGING, the 13.8 that a Zig gives out is MAINTENANCE (simply stops it discharging, but will never charge it).

 

[Jamesb94]

Thanks mate! I'm going to rewire the fridge on Saturday with 6mm cooker cable - I'll let you know how I get on and if it solves the issue 👍

Just trying to locate a 10amp fuse with a housing that will except 6mm cable 🤔 Thanks for all your help so far, and I'll update you in a couple of days.

 

[ubrain]

When you say you got a reading of 13.4v, there must have been some kind of charging happening at the time.
The most you will see as a stable state is a shade over 12.7v. It may show higher just after charging has stopped, but not for more than a few minutes.
Keeping an eye on battery state can be a bit tricky as it will always show less under load (and more under charge). For example, you may have a fully charged, healthy battery ie 12.7v with no load, but spark up the Nespresso machine and it's measuring 11.6v instantly... unless of course the solar panels are at full tilt in which case we may stay >12v.
As I've always got something drawing power, whether fridge or wifi etc. 12v tends to be my tipping point ie. 12.something and I'm quite relaxed while 11.anything and I'm thinking about saving power.

 

[Jamesb94]

Thanks Ubrain! When I got a reading of 13.3v I was plugged into 240v Hook up with the zig unit running. When I unplugged it went back down to 13v. I checked the LB today and with nothing running and the solar panel on i was getting a reading of 13.2v. I'll let you know the LB reading once I've rewired the fridge - as long as the LB is sitting at 12. something with fridge, lights and Zig unit running all should be good?

 

[ubrain]

Yeah the solar panel would have been pushing the voltage up.
To get a check on where your LB is really at, disconnect all load and charging and wait 10-15 mins for the battery to settle down (or in respect of the solar, just look at night 😀 )

I've got a Victron Solar charge controller that logs the max and min voltages each day - really good for spotting when something has gone wrong and is draining charge or something.
Victron isn't cheap kit but it's been both slick and absolutely reliable.

 

[Jamesb94]

UPDATE: I've rewired the fridge directly to the LB using 6mm cable (Waeco fridge didn't have an earth so we left that out). The fridge ran fine for 3 hours (fridge temp came down to 9degrees) then after that the same problem occurred again - fridge cutting out every 30 secs with orange led above power button and red flashing light indicating voltage drop. LB reading came down from 12.3v to 8.something volts when the fridge cut out. This then kept repeating every 50 seconds....

Any thoughts? Pulling my hair out with this one.

 

[Indian]

When you measure your battery, make sure nothing is running off it and disconnect the solar panel. Very strange way of looking for faults.

 

[MadFrankie]

Waeco fridge must have an earth, i can’t believe it only had a positive lead coming from it...

 

[ubrain]

Our Waeco fridge got a bit dodgy (not the same symptoms) and proved to need a new control unit - apparently they go quite regularly.
Got a replacement off FleaBay for in the region of £100 and fitted it myself. Clearly a better option than ~£500 for a new fridge and fridge is totally dependable now.
Not saying that I think this is where you're at but just that it's a possibility that could apply.