3000watt inverter cable size?

[martynvella]

A quick rule of thumb for working out input on 12 volts is output watts/10=input amps. not 100% accurate but will get you into the ballpark for working out cable runs.

For something that big I wouldn't bother running a fuse but go overboard with the cable insulation, a 3kw inverter would have a 5 to 6 kw surge rating, your talking more power than the starter motor, several times more and is there a fuse in the starter cable......no there isn't.

Also running your engine while you use it, you will stress the bcdc running it at max output but theoretically it should cope, but it will amount to a spit in a bucket as far as the draw required and if you bypass the bcdc while it is running you will need to keep the engine revs well up so the cooling fans inside the alternator will move enough air to try to cool itself, alternators can not run at max output for very long.

[Hollando23]

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[Hollando23]

I'm running a 1225 Bcdc mppt and have a ul-110 ULTIMATE AGM battery. I always have the luxy on and have wired a volt meter up to my aux battery. I use it everyday with a 850watt blender to smash up ice and frozen fruit. The volt meter reads 13.3v while the car is running and charging off the cranking battery. It drops to around 12.6/7 while the blender is on. I have also run a 150watt juicer for around half an hour. I found that a load that small I didn't need to have the rig on. I have just wired up a 120watt solar which is keeping the fridge running 24/7, lights at night and still having 100% charge at night.

[martynvella]

Any of those loads you wont need the engine running, your 850 watt blender doesn't draw 850 from the get go, just when it is loaded up to the point it is struggling. Now if you ever plug in a caddie welder then you will have supply issues. If you are worried about your battery being able to handle the load put in another battery to share the load, but a decent agm will handle a surprising discharge for a reasonable duration. Also an amp meter in the supply line will be more beneficial and scary. But what you are using it for you are way over geared for the load so wont, or shouldn't be a problem.

[Roofes]

Is it possible to mount your inverter next to your battery then to run the 240v power supply to where you need it?
At 240v 2.5mm cable will be ample for those loads.
Also its not gonna pull 3000w all the time, you can also use higher quality cables that can run at a higher temperature I use high temp fire rated cable with silver coated copper inside, this will allow for high amps for a small cable.

[Hollando23]

I have a 25A bcdc.
after 6 months of running this set up with a varying amounts of loads from charging shavers and laptops to running 150W juicers for half and hour and using 800W blender i've not had a single problem. I do run the luxy while the blender is on but while stuff is charging the solar is enough to not only keep it running but charge the batteries to float while still running the fridge/freezer....say if the volt meter is reading 12.6 just turning the inverter on with nothing plugged in will drop it by .1v to .2v so it is thirsty.
in retrospect if I do it again it will only be a 1000W or 1500W inverter 3000W is well over kill no matter how cheap it was to by.

[martynvella]

Thanks for the update and great to hear the system is working well for you and for your tip on inverter size.