I'm not convinced that the manufacturers put that much thought in My non self diagnosis Truma is on the same circuit as other ignitors and I think the wire size is a carry over from when it serviced a convector heater rather than the 6kw blown air 'boiler' fitted to my van. I did have significant voltage drop when in 'top gear' which was much improved by adding a parallel feed and a direct to chassis earth. Previously I did sometimes get hesitation when it tried to put the blower on high speed - this may of course have been partly due to battery voltage but I've had no issues since.Half of the problem is silly specifications. If Truma specifies 2.5mm when the maximum current is around 6.5A for a short time, average around 1.4A, that really is a bit daft. The makers will have tried different thicknesses and decided what is good enough to work reliably. seems like they reached different conclusions.
2mm would give less than 5% drop over 10 metres at 6.5A so going to 2.5mm would be a safe choice.
0.5mm would drop a little over 2v at 6.5A. However, if a little over 10v is enough to power the Truma (error 44 is only triggered when the voltage falls below 10v), is this a problem?
Quite agree with point 1 - having solar will probably mean that hab battery gets much closer to being fully charged than relying on alternator.It probably made up for deficiencies of using an SCR for charging the batteries.
Remember that the SCR effectively powers the fridge from the habitation bank at the same time as topping those batteries up. If they are fairly full before you drive, any losses in the connections or wiring will have less impact.
Ah, yes. 10v is the Combi voltage limit. The 6002 gets upset if the voltage drops much below 11 and a bit.I've read that the Truma 6002 is a bit sensitive to voltage and whilst it wasn't 2V down it was pretty significant.
It won't be running down, but it won't be charging very fast either.Split Charge Relay opens up when alternator is running and is at c14.2V which is almost certainly more than hab battery voltage so I don't see why it would run down.
Really not a good idea. Stick to the original wiring thickness. It was like that for a reason.Right - I have a pretty decent cable to the LB (10mm² direct and 4mm² via original system) so it'll get a decent charge early on if discharged before we drive.