Additional solar system & B2B for compressor fridge

At the risk of being seen as argumentative 😀 with an overall diameter of 1.5mm I can't see this being bigger than 0.5mm² as standard insulation is 2.3mm od at that size (according to the tables I found on the web).
Either way its well small but I won't be doing anything for a while as it works 😀
 
Markd said:
At the risk of being seen as argumentative 😀 with an overall diameter of 1.5mm I can't see this being bigger than 0.5mm² as standard insulation is 2.3mm od at that size (according to the tables I found on the web).
Either way its well small but I won't be doing anything for a while as it works 😀
Click to expand...
argumentative? no, sorry, that role is taken :p
If I can find my calipers, I will do some measuring of various cables I have here out of curiosity.
As an aside, I remember I sold some cable (1mm2) to some guy and he complained to me that it wasn't 1mm2 cable as it was too thick. He thought that "1mm cable" meant it was 1mm in diameter and my cable is thicker. Demanded a refund despite explaining to him how it works.
Hey - maybe he was the guy who installed your heater? :ROFLMAO:
 
I think that in the auto business they used diameter rather than area because of passing through holes and grommets.
 
That new Hymer Charlie had, the truma heating had a problem, hadn't been installed properly. Can't remember what it was but dont think it was wire size. That was a 2017 model as well.

I used to have 3 x 90ah Bosch PowerFrame battery's in my van, it had original split charge system through the EBL, twin mains chargers to allow for the extra ah's, 2 x 150W solar panels with Votronic MPPT controller. I have a 110ltr Waeco compressor fridge and Eberspacher diesel heater which are my biggest power users. The battery just about lasted me 12 months before capacity was too low to cope. For maybe half that time I was using the van 4 days out of every 7 and the rest full time so had a lot more use than most folks will do probably. That convinced me the Votronic B2B was what I needed, costs kept me to a 30amp model and I changed the batteries to 2 x 100ah lifepo4.

My fridge uses 48 amps in 24 hours, dont watch much tv but charging laptops, phones, headphones, lights (led) and my Echo dot and wifi router take the total to around 65 amps per day. I dont switch my fridge off except briefly when it need defrosting. Before I was full time I was unable to fully charge the batteries before each trip and I could see a big difference outside the main summer (sunny) months when setting off without charging, even if a run from Derbyshire to Scotland. The batteries never really got fully charged unless I went on site for a few days which wasn't often. That combined with the fairly high (compared to most) and constant demand caused the early demise of the Bosch battery's.

I dont think there is a right or wrong way (so long as things are fitted correctly) with van electrics, its completely down to what you want to do in the van. I know a lot of guys who go to the scrap yard and pay £10 to $20 for a scrap lorry battery and run happily on that for ages, when it packs up they get another. They mainly run one or two less and charge a phone though. It can be expensive along the way finding the right solution though ha ha
 
I think I've worked out the reason for the wire sizing to my Truma.
Originally this was an ignition circuit for hob, fridge and fire so not much capacity needed and 0.5mm2 sufficient.
They of course they upgraded heating to fan convector heater and again to combi boiler without bothering to uprate the wire! Unbelievable or more likely to be expected 😀
Now they've got a steady 5A load on 0.5mm2 and a hefty voltage drop.
This circuit has 10A fuse which is probably too much for 0.5mm² wire.

Both Truma wires disappear into a 20 wire bundle so if I do feel they need to upgrade it will be a complete parallel job.
 
I don't know if it's a local thing or not, but when I emigrated to Yorkshire I had the install the wiring for our machinery in the new building. Visiting a local electrical factor, I was assured they only sold round wire and none of theirs was Square!!!
 
Well as I've had the solar out of action for a few days and have run down the hab battery quite a bit testing the uprated Truma wiring etc I thought it would be interesting to charge it up using the alternator.
I'm pleased to report that nothing blew up and there was no thermal runaway! So DIY B2B works nicely as expected😀
 
Markd said:
Well as I've had the solar out of action for a few days and have run down the hab battery quite a bit testing the uprated Truma wiring etc I thought it would be interesting to charge it up using the alternator.
I'm pleased to report that nothing blew up and there was no thermal runaway! So DIY B2B works nicely as expected😀
Click to expand...
Nice one.👍
 
Today I replaced the wiring to my Truma fromthe psu with 2mm² cable.
I can confirm that the original was only 0.5mm² !!
I'm actually a bit disappointed to be honest as the voltage drop at full tilt is still 0.5v.
Anyway it's done now!
 
0.5V sounds ok actually (not great but about right for the load and cable gauge)
 
Yes - it's worst case with fan full speed.
It's just that it's not a lot better than with lightweight wire.
It'll have to do!

I'm still amazed that this circuit had a 10A fuse.

Edit - I was concerned about the drop and checked it again a bit more thoroughly.
The first time I only measured the battery before running the heater and it must have been picking up a tiny bit of solar voltage and giving an unrealistic figure.
This time I went back to the battery when at full load it was 0.25v above the Truma.
So I'm much happier that my efforts were worthwhile.
 
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