Need Help with Wire Guage size

[BILL12831]

Hello all, I'm new and I want to build a basic solar setup for a shed or just backup power in house. I purchased two 12v 100ah Powerqueen batteries, a 2000 watt 12v BougeRV inverter and a 40amp MPPT Bouge RV solar controllar,, I have 2-100watt panels.

I bought a 200amp breaker for the inverter and a 50amp breaker for the solar controller.. I need help with the wire gauges between the rest and I don't understand it all.. Powerqueen shows in the manual to parallel connect to use 6awg wire,, that seems small isn't it? I have seen on ampacity charts people show on youtube that 6awg is not enough for a a 200ah battery setup? Am I wrong in thinking this -- Do I need 2 gauge wire to connect the batteries?

I would appreciate any help in all the connections in between all the equipment I mentioned above in what gauge wires to use. I also may expand to 2 more panels and possibly a 3rd battery in parallel if all works well. If anyone could explain the gauge size and the why behind it. I see mixed builds on youtube with similar setups,, some using 6 awg wire for everything and some using 1/0 awg for batteries.. I'm confused.

 

[sunshine_eggo]

2000W/12V/.85 = 196A - your breaker should be a 250A (1.25X peak current)

You need wire that can handle 200A or more and have acceptable voltage drop.

On a pair of powerqueens, the interconnects can be sized to handle as little as 100A, but you might as well just use the same cable as the 200A connection to the inverter.

Your 50A breaker is properly sized for the output of the 40A controller.

You need wire that can handle 40A or more and have acceptable voltage drop.

American wire gauge - Wikipedia

en.wikipedia.org

Lists wire gage ampacity for 60, 75 and 90°C rated insulation. Marine grade (105°C) and higher are not on this chart, but you should be able to find lots of references.

 

[Tomthumb62]

Powerqueen shows in the manual to parallel connect to use 6awg wire,, that seems small isn't it? I have seen on ampacity charts people show on youtube that 6awg is not enough for a a 200ah battery setup?

I just ran the math. 6AWG is sufficient for 120A for 60 minutes, with 1’ cables each positive and negative, using cable rated for temperature 105C with less than 3% voltage drop. But you can go overkill if you wish as @sunshine_eggo suggests.

 

[BILL12831]

Thank you both for your responses... I wish I understood this stuff better. So is 2/0 gauge wire better? I'm not sure why the manual shows using 6awg to connect in parralel if it isn't capable of handling 200 amps,... I tried reading the chart on wikipedia and I just don't know what I am looking at its foreign to me. I found another chart online that showed to use 2/0 AG for 200 amps.. I've watched several videos 1 guy says to use 1/0 on the batteries, the manual says to use 6awg,, Another video a guy is using 8awg. And I'm curious how did you the information that 6AWG can run 120A for 60 minutes? I am not sure which charts to look at. I've seen several different charts.

 

[sunshine_eggo]

Thank you both for your responses... I wish I understood this stuff better. So is 2/0 gauge wire better? I'm not sure why the manual shows using 6awg to connect in parralel if it isn't capable of handling 200 amps,... I tried reading the chart on wikipedia and I just don't know what I am looking at its foreign to me. I found another chart online that showed to use 2/0 AG for 200 amps.. I've watched several videos 1 guy says to use 1/0 on the batteries, the manual says to use 6awg,, Another video a guy is using 8awg. And I'm curious how did you the information that 6AWG can run 120A for 60 minutes? I am not sure which charts to look at. I've seen several different charts.

Example (counting 195A as 200 for illustration purposes):


2/0 with 90°C insulation can handle 195A
3/0 with 75°C insulation can handle 200A
4/0 with 60°C insulation can handle 195A

Basically this says that the insulation around the copper can handle those temperatures without catching fire.

 

[Tomthumb62]

I'm not sure why the manual shows using 6awg to connect in parralel if it isn't capable of handling 200 amps

It doesn’t need to handle 200A, only 100A each battery can only output 100A continuous (the BMS limits this). So one battery could theoretically release 100A into the other (if a load requires it).

But the two wires coming from say battery A positive and battery B negative to the bus bar or load, THOSE need to be able to handle 200A, because at that point the current will be a theoretically possible maximum of 100A+100A, the total of each battery.

 

[BILL12831]

Thank you that helps clarify somewhat my questions.. I run into articles such as this: https://wattalot.com/what-size-wire-inverter. and he is advising a 2awg wire for a 2000 watt inverter, now this is just confusing to me because a 2awg wire cannot handle 200 amps, according to this chart https://www.bluesea.com/resources/1437 I'm assuming the input draw on the inverter b/c it is dc 12 volt will need more amps than the output at 120v.

 

[sunshine_eggo]

Thank you that helps clarify somewhat my questions.. I run into articles such as this: https://wattalot.com/what-size-wire-inverter. and he is advising a 2awg wire for a 2000 watt inverter, now this is just confusing to me because a 2awg wire cannot handle 200 amps, according to this chart https://www.bluesea.com/resources/1437 I'm assuming the input draw on the inverter b/c it is dc 12 volt will need more amps than the output at 120v.

Some wire may be able to handle that.

2 AWG 1C SRML High Temperature Motor Lead Wire 600V 200C

Specification: Conductor : Flexible Stranded tinned copper, Insulation : SRML is insulated with silicone rubber. Jacket : SRML's jacket is made of fiberglass braid with a high-temperature finish. Standards : UL Style 3231, 3127, 3069, 3070, 8 AWG and 6 AWG are 150°C UL (200°C Non-UL), 4 AWG and...

nassaunationalcable.com

This wire is 200°C rated 2awg and claims both UL certification and 240A rating. It may not yield an acceptable voltage drop depending on length.

Here's a marine grade:

00 Gauge (2/0 AWG) Marine Grade Tinned Copper Battery Cable UL 1426 Flexible with ends

www.batterycablesusa.com

Get wire rated for 200A of continuous use. Use it for your both the interconnects and the main cables for simplicity. The bigger your interconnects, the better balanced the batteries will be in terms of sharing the current.