Controller to Battery wiring?

There is no magic about MC4 wire except it has connectors that will not be used here at either end. But if you have some extra wire then by all means just use it. When you expand to 300+ watts it will be time to revisit the connecting wires.

jmccen58 wrote:

mena661 wrote:
MC4 is typically #10. #4 is WAY overkill for 100W and still overkill even if you maxed out the controller at 30 amps output. It's only 3 feet, #8 is under 1% voltage drop for that distance and can handle almost 70 amps. No need for #4. If you're keeping this at 100W or 200W you don't even need #8.

Could I use MC4 to go from controller to battery then? (without to much of a drop in efficiency)

Any thoughts on this question?

westend wrote:
I used something similar to these to terminate #4 onto the controller lugs. IIRC, the controller lugs were #8 maximum wire size.

Thanks for the Link.....saved me Alot of time !!!

mena661 wrote:
MC4 is typically #10. #4 is WAY overkill for 100W and still overkill even if you maxed out the controller at 30 amps output. It's only 3 feet, #8 is under 1% voltage drop for that distance and can handle almost 70 amps. No need for #4. If you're keeping this at 100W or 200W you don't even need #8.

Could I use MC4 to go from controller to battery then? (without to much of a drop in efficiency)

MC4 is typically #10. #4 is WAY overkill for 100W and still overkill even if you maxed out the controller at 30 amps output. It's only 3 feet, #8 is under 1% voltage drop for that distance and can handle almost 70 amps. No need for #4. If you're keeping this at 100W or 200W you don't even need #8.

Almot wrote:
1) What controller?
2) What is expected output current?
3) Is it 3ft total Pos and Neg or just a distance to battery?
4) Are you asking about wire gauge or exactly about "connectors"? (most controllers accept bare wire end, no connectors required)

PS: Some controllers indeed have inadequately small output terminals, like #8, with 30A output. Midnite "Kid" is one of them, but I'm not sure if there are any others, among known brands. Most controllers have terminals sized adequately.

I haveThis.
It's 3ft to battery.
The MC4 cable supplied doesn't look as large as a #4 AGW cable? why will it work for panel to controller run but not from controller to battery? Thanks for everyones help.

I used something similar to these to terminate #4 onto the controller lugs. IIRC, the controller lugs were #8 maximum wire size.

1) What controller?
2) What is expected output current?
3) Is it 3ft total Pos and Neg or just a distance to battery?
4) Are you asking about wire gauge or exactly about "connectors"? (most controllers accept bare wire end, no connectors required)

PS: Some controllers indeed have inadequately small output terminals, like #8, with 30A output. Midnite "Kid" is one of them, but I'm not sure if there are any others, among known brands. Most controllers have terminals sized adequately.

smkettner wrote:
For 3' do not try to cram larger wire than the connectors are designed for. Then crimp a closed end lug on the wire and seal with shrink tubing for a permanent connection. Usually it is a 5/16" hole you need in the lug for the battery stud.

X2, for 3 feet you don't need monster wire unless you have multiple 100's of watts in parallel. If you already have the wire just trim some strands to make it fit. Nothing wrong with that.

For 3' do not try to cram larger wire than the connectors are designed for. Then crimp a closed end lug on the wire and seal with shrink tubing for a permanent connection. Usually it is a 5/16" hole you need in the lug for the battery stud.