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Controller to Battery wiring?

jmccen58
Explorer
Explorer
what type of connectors should be used for the run from controller to battery? I will need to run about 3 feet. I'm planning on using #4 wire but the terminals on the controller look awfully small to except that size wire....
11 REPLIES 11

time2roll
Nomad
Nomad
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
Explorer
Explorer
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?

jmccen58
Explorer
Explorer
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 !!!

jmccen58
Explorer
Explorer
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)

mena661
Explorer
Explorer
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.

jmccen58
Explorer
Explorer
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.

westend
Explorer
Explorer
I used something similar to these to terminate #4 onto the controller lugs. IIRC, the controller lugs were #8 maximum wire size.
'03 F-250 4x4 CC
'71 Starcraft Wanderstar -- The Cowboy/Hilton

Almot
Explorer III
Explorer III
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.

mena661
Explorer
Explorer
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.

time2roll
Nomad
Nomad
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.

2oldman
Explorer II
Explorer II
You controller owner's manual should say what wire size it will accept. Isn't it just a screw terminal that accepts bare wire?
"If I'm wearing long pants, I'm too far north" - 2oldman