A Forum run by Enthusiasts of MidNite Solar

Charge Controllers and Clippers => The "Classic" charge controller => Topic started by: Solar trucker on February 21, 2016, 12:40:10 AM

Title: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: Solar trucker on February 21, 2016, 12:40:10 AM
I just installed a Classic 150 in my RV and would like to
Use at least 1(00) or even 2(00) cable to connect the
Classic 150 to the battery bank. I'm presently using 4-ga
Cable which seems to be the largest wire the Classic will
Accept...When the controller is rocking and rolling around
70 amps and up... The 4-ga cable gets slightly warm but
Nowhere near HOT...
My question is... If I can run the 7ft or so to the batteries
With larger ga cable...would that cure the
Heat issue?
Title: Re: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: mike90045 on February 21, 2016, 01:47:56 AM
Does the wire get warm along it's whole length or just near the terminals ?  4 ga should be good for 85A, 2ga good for 115A

Is this solid or stranded wire ?

To use larger, you have to use a short 4ga stub to the terminals, and then a split bolt splice to a larger ga wire
Title: Re: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: zoneblue on February 21, 2016, 03:17:40 AM
The industry standard practice is to run 4 awg to the disconnect, which is only 8 inchs  or so to one side. Then higher gauge from the main bus to the battery as needed.
Title: Re: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: australsolarier on February 23, 2016, 11:54:08 PM
yes the midnite classic has very small terminals, i think max diameter is for 25mm2 wire. i used 50mm2 cable between the midnite and busbar. i had to crimp a reducing wire with an elbow to the 50mm2 wire.
i can tell that positive  50mm2 wire gets quite warm, even hot, when running at 96amps. i measured up to 52degrees celsius. so i leave the fuse box open to help cool down that cable. to the battery and the inverter wires i do not feel any warmth, however the current is split up between them.

yes and i wished they would either larger terminals or terminals for lugs.
i am aware the 12volt battery system is not optimal for several reasons.
Title: Re: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: dmclain on February 24, 2016, 01:11:37 PM
I agree with Zoneblue you should have 4 AWG from the classic to your fused disconnect or circuit break located near the classic then you can come off the disconnect/circuit breaker with larger gauge wire to mitigate voltage loss in long runs.
Title: Re: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: Solar trucker on February 24, 2016, 04:03:34 PM
Thank you all for your input on the output side of the Classic to the Battery Bank...
I took your suggestions and only ran about one foot of #4-AWG to distribution Hubs
where I connected with 2/(00)...The load calculator now says I'm less than .05% for
7ft run...I had 82 amps running through it today...The #4 Ga cable got only Very slightly
warm to the Hub, and the 2/(00) cable which is over 6ft long stayed quite cool to the touch
I'm pleased with the result now!

Thanks!
Title: Re: How can I use Larger gauge cable on my Classic 150 to the Batteries?
Post by: CDN-VT on February 25, 2016, 12:55:03 AM
Solar Trucker
Recheck all your torques after a day or so. I find they can be tightened back up to the  torque  , If not they will be next to have a hot spot.

If this is a Truck , do it again in a month since vibration is a pain.


VT