12S burnout mods...

[rogerthechorister]

Yes, I worked that out too. I could go for 30 amp twin and earth, but the solid cores are surely susceptible to vibration fractures. I think the stuff to use is the 50 amp cable for powering sub amps - but the problem is how to route it tidily. Still cogitating that one.

[DC850]

Originally Posted by rogerthechorister

Using a different voltmeter (they read slightly differently)

9.96V at the fridge
10.83V at the fusebox
11.38V at the van end of the extension lead
11.97 at the car end of the extension lead
12.73 at the car fusebox (so THAT must be where the autoelectrician took the 25A feed for the trailer box)
13.13 at battery.

I think I'll try a different car now!

Where the reference point i.e. Earth/0V at the same point for all these measurements. As I am trying to figure out the relationship between the measurements. Because moving the reference can hide the true positon of the fault.
If you have jump leads for the car connect one end to the Battery Neg and the end of that lead to the Neg side of the meter then take the reading relating to the Battery terminal. As there is no current through the meter the length of the cables to the meter will not be noticed.

As for Soild wire that would cause more issues, you need multistrand.

Just a thought have you tried just connecting the car using the 12S extenion cable directly to the Fridge input terminals, removing all of the caravan connections and seeing if the fridge works. There could be a fault on the 12V side of the fridge causing high current (but not enough to blow the fuse) causing the increased voltage drop in the cables.

[rogerthechorister]

Using jump leads from the battery is a good idea. I have a heavy duty pair and if I link them together they should be long enough - at least for most of the way.

Yes, I follow that there should be zero current through the meter.

The fridge works - in the sense that it is drawing a current and it can only do that if the 12V element is continuous. I'd like to measure the current draw, but the obvious place to do that is at the van's fusebox which is a little perisher to get at under a seat at the very front of the van!

I might also see if I can actually access the 12V element - the fridge is partly out at the moment - to check that it IS getting hot and heating the right bit of pipework.

But it's not going to be today - I have pleadings to get into court (day job)!

[DC850]

Originally Posted by rogerthechorister

Using jump leads from the battery is a good idea. I have a heavy duty pair and if I link them together they should be long enough - at least for most of the way.

Yes, I follow that there should be zero current through the meter.

The fridge works - in the sense that it is drawing a current and it can only do that if the 12V element is continuous. I'd like to measure the current draw, but the obvious place to do that is at the van's fusebox which is a little perisher to get at under a seat at the very front of the van!

I might also see if I can actually access the 12V element - the fridge is partly out at the moment - to check that it IS getting hot and heating the right bit of pipework.

But it's not going to be today - I have pleadings to get into court (day job)!

If you measure the current directly please be aware the most DMM have a max current of 10amps. this could blow the meters internal fuse or even damage the meter. The currently you will be looking at will be in the order of 20 amps.
As for the Heater working as its drawing current, you could have an internal short, which could reduce the element electrical length hence drawing to much current and no or little heat.

If you what to measure the current through circuit replace the fuse with a low value resistor say about 0.1 ohms and measue across the resistor using voltage. Then calculate the current using A= V/R

Can you measure the resistance across pin 6 and pin 7 of the with fridge set to 12V and then again but with the fridge set to something other than 12V

[rogerthechorister]

I'm expecting the current to be well under 20 amps! The circuit is fused at 15 amps and the specified wattage is 95 watts (both 12V and 240V) so the gossiped figure I had heard of 8 amps looks about right.

On the RM 4206 there are rocker switches for each electrical element - on- off.

Off I read open circuit

On I read 1.6 Ohms.

If I had 12 volts there, that would be 144/1.6 Watts = 90 watts

And current would be 12/1.6 = 7.5 amps.

So as soon as my 30 amp black and red multistrand gets here I'm going to see if I can get up to nearly 11 volts at the fridge by going through the extension lead - and I could be a smart horse and put a 12S on that and run it straight to the car and see what that gave me - which should be a first approximation to what I'll have at the fridge when the van is hooked up directly to the car.

I wonder how much I'm likely to be losing in the spade terminals and the fuse, in the caravan. I could get anal and solder the spade terminals to the wiring and try as an experiment a new fuseholder.

[rogerthechorister]

Soddez cela pour une allouette. Inserted 30 amp cable in vardo - no change in volts to fridge. Changed fuseholder in vardo - no change in volts to fridge. I give up. Early in the morning I will restore as was and although the 12v side of the fridge is doing SOMETHING I'll just load it up with ice blocks to last round trip from North Kent to Croydon to Whistabubble.