confirming breaker between 3000k AOI and 48v battery

[vallesj]

I am still unsure with the size of breaker to place between my AOI 3000w and the 48V 50ah battery.
Since the battery is supporting the max 3000W from the AOI, that means that the breaker must be (3000/48) *1.25=78 .. I think rounded to 80amps?

 

[OffGridForGood]

If you run a steady 3kW on the inverter at "48v" (anything from 44 to 56 volts depending) then the Amperage from the battery is:
3000/48 = 62.5A
But this isn't really the correct question, the real question is what size cables do you have, so we can pick the correct breaker/fuse to protect the wire from overheating and causing a fire.

An online DC cable size calculator, using 62.5A, 75-degrees C, 2 meter (6 feet) one way length and 48volt DC spits out 6AWG cable size, For battery cables this is a bit small and I would use at least 4AWG cables.
With 4AWG battery cables, a fuse (or DC breaker) of 60 Amps
If you want to go to 80 Amps you would need 2AWG battery cables.

 

[vallesj]

If you run a steady 3kW on the inverter at "48v" (anything from 44 to 56 volts depending) then the Amperage from the battery is:
3000/48 = 62.5A
But this isn't really the correct question, the real question is what size cables do you have, so we can pick the correct breaker/fuse to protect the wire from overheating and causing a fire.

An online DC cable size calculator, using 62.5A, 75-degrees C, 2 meter (6 feet) one way length and 48volt DC spits out 6AWG cable size, For battery cables this is a bit small and I would use at least 4AWG cables.
With 4AWG battery cables, a fuse (or DC breaker) of 60 Amps
If you want to go to 80 Amps you would need 2AWG battery cables.

Thanks! I thought 4awg, which is what growatt inverter recommended, supports higher currents, like 95 amps or more.

 

[OffGridForGood]

Thanks! I thought 4awg, which is what growatt inverter recommended, supports higher currents, like 95 amps or more.

it may, depends on the temperature rating of the cable and the cable length you are planning. In my example I picked some typical values, but you can plug in the correct values for your actual situation. Hope this helps.

 

[vallesj]

never mind... I have not received the battery yet, but looking into its specs, it only receives and supply 50A max... so 50A the breaker will be.

 

[OffGridForGood]

For 50 Amp you could use #6 AWG Although check the temperature rating.
I like to go up at least one size from whatever a DC cable calculator spits out - ie #4 for your case, since the cable is short it doesn't change the total cost much.

 

[vallesj]

For 50 Am you could use #6 AWG Although check the temperature rating.
I like to go up at least one size from whatever a DC cable calculator spits out - ie #4 for your case, since the cable is short it doesn't change the total cost much.

yes, I got 4awg, that may help if I want to add more batteries in the future

 

[OffGridForGood]

And it seems that auto parts stores sell some handy ready-made battery cable sets, typically 4AWG and 1AWG seem common for a decent price if you don't own a crimping tool this can save needing to buy a tool for just a few crimps. (if you 'catch the bug' and go big with solar, you may want to buy a proper hydraulic crimper later).

 

[robbob2112]

And it seems that auto parts stores sell some handy ready-made battery cable sets, typically 4AWG and 1AWG seem common for a decent price if you don't own a crimping tool this can save needing to buy a tool for just a few crimps. (if you 'catch the bug' and go big with solar, you may want to buy a proper hydraulic crimper later).

NOTE - proper hydraulic crimper means something like the Temco or PowerRX style and quality. Many crimpers on amazon, I am talking about AMZCNC, are harbor freight quality and the jaws are really metric but marked in AWG. That leads to wings on some crimps and to loose on others without putting in spacers.

AMZCNC has nothing to do with amazon - it is just a cheap brand sold world-wide and is basically junk that is relabeled into the $40 crimper that is ok for occasional use if you realize its shortcomings.

And for Lugs - proper branded lugs verse the brands that are like scrabble letters pulled from a hat.