Cable Size to run "before" the MPPT Solar Reg mounted inside front of Vehicle

rob_macca67

Well-Known Member
Guys... for those Electrical gurus...

I currently have an MPPT solar regulator mounted under the centre Console & a 160w Solar panel mounted on the roof. This car doesn't get driven too often and is parked under a Carport making the roof solar useless.
To solve this, I'm thinking of buying a separate Solar Panel to leave out in the sun to charge the batteries in the car during the day. To do this I was thinking of installing an Anderson plug at the rear of the car where the cable would also run up into the Solar inputs of MPPT Solar Reg under the Centre Console and plug the Solar panel into the Anderson Plug to keep the batteries charged.

Now, my question is what size cable should I run from a 160w Panel up to the MPPT Solar Reg mounted under the centre Console?

I'm assuming as long as the cable is rated to carry the current of the panel it should be sufficient? Voltage drop shouldn't really be an issue due to the high volts output of the Solar Panel - Would this be correct?


Thoughts??
 
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discomatt

Moderator
The longer the cable the more drop but I wouldn't worry to much about a bit of loss because if its sitting there long enough the battery needs a top up it will be there long enough to get a charge even with a small loss of voltage but I am no auto elec...
 

CTL

Well-Known Member
The 160 watt panel should only be outputting around 6 to 7.5 amps so use cable rated for 10amps and you will be fine. As you stated, no concerns with voltage drop at 21 odd volts
 

Petunia

Well-Known Member
Chop 1 meter off this and you will have a 5 meter cable commonly supplied with a solar panel of this size.

Buntings Speaker Wire

Note it is 14awg, don't buy the 18awg, if you feeling generous, it comes in 30 meter lengths too, but only cut 5 meters out of it.:cool:
 

CTL

Well-Known Member
@rob_macca67 just another thought. If you already have the 160W panel then obviously it makes sense to use that but if you are buying a panel, and the vehicle battery has no load on it whilst parked for extended periods, then a cheap 20W panel will keep the batteries maintained.
 

rob_macca67

Well-Known Member
@rob_macca67 just another thought. If you already have the 160W panel then obviously it makes sense to use that but if you are buying a panel, and the vehicle battery has no load on it whilst parked for extended periods, then a cheap 20W panel will keep the batteries maintained.
Yeah thought about that but I tried that before with a 10w panel and that turned out poorly. Buying a larger panel I will have greater use for it in regards camping, etc
 

Bru9

Active Member
I'm assuming as long as the cable is rated to carry the current of the panel it should be sufficient? Voltage drop shouldn't really be an issue due to the high volts output of the Solar Panel - Would this be correct?


Thoughts??
Yes and no.
It's possible in extreme heat the panel voltage could drop add in cable drop, mppt eats maybe .2v and your mppt cant raise the batteries voltage. Really mppt was not designed for "12v" aka 18volts max power panels, they are really for pwm, that extra 4volts is for the above losses. Mppt is best suited for 24v/36v max power panels. The cable between the panel and mppt should not exceed 3% voltage drop to be safe, use the volt drop calcs.
 
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