Fuses size - Min and Max Current

[Javim]

Hi everyone

I am building a 12v system for my Van. I know the basics of voltage, current and cable/fuse sizing but I still have a questions with the peaks.

Lets say my DC-AC Alternator has an output of

• Max Continuous load 1000w -> It will drag more or less 85A from the battery
• Max Peak load 2000w -> I will drag more or less 166A from the battery

Which Fuse and cable should use? One that covers the maximum of continuous load or one that covers the maximum peak of load? It makes a difference when one has to run cables with 3% lost.

Same applies to the input of the battery. It can be charged...

• Max continuous current 50A
• Max peak current 100A

Should I use a cabled sized for 50A or 100A?

Thank you in advance.

Regards,
Javier

 

[jasonhc73]

I always overbuild for wiring and circuit breakers. The last thing you want to do is have your wire be the circuit breaker.

I think what I am seeing is a financial issue, not a technical issue. Bigger wires to minimize voltage drop cost more and weigh more.

If you are going to draw 166A +/-, it sounds like a 200amp 12V circuit breaker to me.
If you know you are going to have a peak of 100A and 50A continuous sounds like a 150amp 12 circuit breaker.

 

[Javim]

Thanks for the quick answer.

There is no financial issue. I have enough money. But big cables are no so easy to find and not easy to route.

According to this table. If I am going to cover the max peak load of the Inverter, it will take at least a 2|0 AWG cable! That is huge. I do not know where to find those cables in Europe. While the 100A option leave it to much easier wire of 4AWG.

Regards,
Javier

 

[jasonhc73]

Thanks for the quick answer.

There is no financial issue. I have enough money. But big cables are no so easy to find and not easy to route.

According to this table. If I am going to cover the max peak load of the Inverter, it will take at least a 2|0 AWG cable! That is huge. I do not know where to find those cables in Europe. While the 100A option leave it to much easier wire of 4AWG.

Regards,
Javier

Big cables are only eBay clicks away.
10,319 results for 2awg in USA
181 results for 2awg cable in UK

I feel your pain now! 2/0

2 ought, or double zero
Give Farnell a try.

https://uk.farnell.com/