Compressor fridge wiring

[lummy]

Just a bit of history , taking out 3 way fridge and replacing with small compressor fridge , old setup was 6mm2 cable from starter to 3 way fridge that was controlled with a ignition live cable so only ran fridge when ignition on and a 10mm2 to dc-dc for lithium battery.
Now I am on a compressor fridge will be wiring it to the leisure battery.
So question is the 6mm2 cable that used to go to 3way fridge can I connect it to the dc-dc with the 10mm2 cable give it a bit more juice from starter or is it a bad idea.

Don't like leaving the 6mm2 not doing anything.

Thanks in advance Shaun.

 

[lummy]

Have been looking at this and would a "5-pin SPDT (Single Pole Double Throw) Changeover Relay" work so with a ignition live wire live would switch to starter and then back to leisure when ignition off.?

 

[t0mb0]

There’s nothing really to be gained in switching over to the starter when driving, I’d just wire it into the leisure battery like normal - your DC-DC should power it anyway when driving.

 

[lummy]

There’s nothing really to be gained in switching over to the starter when driving, I’d just wire it into the leisure battery like normal - your DC-DC should power it anyway

anyway when driving.

Hi. Would there be any thing wrong adding 6mm2 to 10mm2 on the supply to the dc-dc charger, or should I just give up on the 6mm2 cable

 

[t0mb0]

Hi. Would there be any thing wrong adding 6mm2 to 10mm2 on the supply to the dc-dc charger, or should I just give up on the 6mm2 cable

I’m not sure I understand what you mean? Are you talking about wiring the fridge into the input of the DC-DC (i.e. the starter battery) or the output (i.e. the leisure battery)? You should be wiring it into the leisure battery through an appropriate fuse - you can happily reuse the existing 6mm cable for that if you want.

 

[Stay Frosty]

The 10mm2 will potentially give you 40A from the starter to the B2B charger which realistically is plenty, fuse it accordingly.
The 6.00mm2 could be used for a conventional accessory load, say an amplifier for the van HU or anything else you might want from the starter rather than the leisure battery.
Putting two different CSA cables in parallel is normally a non starter as you would have to fuse to the smaller cables carrying capacity when dividing the potential load in half.

 

[t0mb0]

Ah, sorry, I misread the original post - I thought you were talking about using the 6mm to wire the fridge into still but you’re actually just asking about using it in parallel with the 10mm between the starter and the DC-DC? As @Stay Frosty says then, I’m not sure that would gain you very much.

 

[lummy]

not to overly confuse the enquiry in my setup i have two "sterling power bb1225" dc-dc chargers both feeding from the 10mm2 cable so what about feed one from the 10mm2 and the other from the 6mm2 cable .

 

[Stay Frosty]

Why two?

 

[t0mb0]

not to overly confuse the enquiry in my setup i have two "sterling power bb1225" dc-dc chargers both feeding from the 10mm2 cable so what about feed one from the 10mm2 and the other from the 6mm2 cable .

Assuming 2m runs of cable, and assuming both DC-DC wired in parallel and delivering the full 25A charge (have you got a really big battery??) then I reckon you're losing 1.5% to losses on a single 10mm cable and losses of about 1% if you wire a 10mm to one and a 6mm to the other. Therefore your gains are really quite marginal and that's only at full power, those gains will diminish as the current drops.

 

[lummy]

Why two?

planed to have only one at first but last year on a three months trip to europe and only driving about 1 hour between stops and not using electric hookup was not enough , and two 25amp dc-dc chargers was the most i would dare to goo without swooping out the 10mm2 cable and all the work that would involve . the sterling power bb1225 is a neat unit self cooling no need for a fan revers charges starter and has a emergency function to boost starter . sterling also said no problem with two together and at £150 each was best upgrade route i could think of . and dont have any solar .

 

[t0mb0]

planed to have only one at first but last year on a three months trip to europe and only driving about 1 hour between stops and not using electric hookup was not enough , and two 25amp dc-dc chargers was the most i would dare to goo without swooping out the 10mm2 cable and all the work that would involve . the sterling power bb1225 is a neat unit self cooling no need for a fan revers charges starter and has a emergency function to boost starter . sterling also said no problem with two together and at £150 each was best upgrade route i could think of . and dont have any solar .

That unit does look like great value, especially with the reverse trickle charging built in.

 

[Stay Frosty]

Solar... cough, we did a month in France June/July last year, only six sites and minimal driving apart from the 200 to 300kms between sites but two 175 watt Flexi panels on the poptop and the 230Ah Roamer seat base battery meant no hookup and not a single squeaky bum fridge range anxiety moment but we did have gas as well as the 2kW inverter and it was sunny!

 

[lummy]

Solar... cough, we did a month in France June/July last year, only six sites and minimal driving apart from the 200 to 300kms between sites but two 175 watt Flexi panels on the poptop and the 230Ah Roamer seat base battery meant no hookup and not a single squeaky bum fridge range anxiety moment but we did have gas as well as the 2kW inverter and it was sunny!

Sounds like a good setup, 230ah battery Wow we are on 100ah lithium no solar on top, I can only dream, we are in a sw base LeisureDrive and on the three months last year used 6 R907 cylinders and that was nothing only the fridge, this year we are fitting a compressor fridge so as to get Away from the gas. Have thought about solar but with the shape of the LeisureDrive roof 100w flexi would be my guess at max and they don't give back much after September.

 

[Stay Frosty]

Poor Waeco compressor fridge ran pretty well non stop for a month with most days well up into the 30s C and did actually manage to freeze and split open a can of lemonade right at the back.
I'll be honest I did park the van orientated to catch the most sunshine at each pitch rather than enjoy some shade so there is a trade off with roof mounted panels, logically portable panels in the sun and van under a shady canopy makes more sense.

That's us right down the end on the right in the Chestnut brown T6 at Lourdes which was probably the shadiest pitch but still had a solid 2 hour window of sunshine from noon bunging in up to 19A so all good.

 

[Bigsidavies]

Put solar on. I've got a 100Ah lifepo and only 100W solar, but in summer in mainland Europe with compressor fridge running and other bits of phone charging and stuff I can stay off grid for days. I lose a net 10Ah per day usually, so an easy 8 days without having to need the dc-dc.

 

[lummy]

Assuming 2m runs of cable, and assuming both DC-DC wired in parallel and delivering the full 25A charge (have you got a really big battery??) then I reckon you're losing 1.5% to losses on a single 10mm cable and losses of about 1% if you wire a 10mm to one and a 6mm to the other. Therefore your gains are really quite marginal and that's only at full power, those gains will di

Put solar on. I've got a 100Ah lifepo and only 100W solar, but in summer in mainland Europe with compressor fridge running and other bits of phone charging and stuff I can stay off grid for days. I lose a net 10Ah per day usually, so an easy 8 days without having to need the dc-dc.

trying if i can to stay clear from solar as the only one possible is a flexi type that have a bad reputation for reliability and when its hot (37c last year ) you are forced to stay in the shade and portable panels when doing a bit of free camping dont realy fit in but may be the only option to extend the stops .

 

[Stay Frosty]

The two Flexi Renogy 175W panels on our camper are over four years old and still working if that helps the solar cause.
As for using six 907 bottles worth of gas over three months that expense would knock a big hole in the cost of beefing up your off grid electrics.

 

[lummy]

The two Flexi Renogy 175W panels on our camper are over four years old and still working if that helps the solar cause.
As for using six 907 bottles worth of gas over three months that expense would knock a big hole in the cost of beefing up your off grid electrics.

The 3way fridge leisure drive fitted was ginormous, tetford n4080, a real gas gusilar at one R907 for 1.5 weeks. Just putting in a dometic nrx60e at the moment so hopefully will work out OK as off to Europe at end of this month for the 90days.

 

[t0mb0]

You can always use a portable suitcase style panel when you’re camping if you don’t want a permanent one?

When we did a five week trip through France in summer our 250w panel meant even our 75Ah AGM was sufficient to leave the EHU lead at home.

Flexi panels definitely do fail but the decent ones have a 5-10 year warranty. For what it’s worth ours has been happily going for about nine years now.