Splice solar cables for minimum voltage drop and maximum safety¿

[WalkaboutTed]

Once again, I have a question for which I can not find a set answer.

Here it is:

I'm wiring up the new 30 amp charge controller. I'll be using the entire 30 amps at full solar output (ideally).  I'll be having the solar power coming in from two different wires from the two different panels as i'm adding the new 165 watt panel on to the pre-existing system. I'm taking each panel's wire (10gauge) and  connecting together, going into one of those big marine on/off switches.  

It's  6 feet from my charge controller to the batteries.  From what I've read, 10 gauge wire for the system will do.  I would like a smaller gauge wire for safety (paramount) and minimum voltage drop (not as important).  I want at least 8 gauge wire.  But, the tap into the charge controller is tiny and I can't find an 8 gauge ring terminal to fit inside and connect.  

So, please help me with the questions:
1) will 10 gauge work and be safe? That would be the best, but I'm ambivalent.

2) if above won't work, where can I get teeny ring terminals for 8 gauge wire?

3) as an alternate, could i splice together two 10 gauge wires going into and out of  the charge controller, so I have a nice fat wire, effectively making it 7 gauge (per this site: 
https://www.wirebarn.com/combined-wire-gauge-calculator_ep_42.html. )

4) if I splice the wires together, if it's a good idea, will t-tap splice connector work?  I don't have a  the tools to solder  wires, nor do I want to go out and buy them for 4 connections (for the same reason I don't want to buy the expensive crimpers for Anderson Power poles-we're running out of money).

If I'm missing part of the equation, please fill me in.  Thank you once again,
Ted

 

[WalkaboutTed]

I forgot to add that the connections will be inside the vehicle connected to AGM batteries. So I'm not worried about corrosion from salt air or hydrogen sulfide.

 

[John61CT]

10 is fine.

Don't solder wiring connections. Proper crimps with proper tools are important, either make the investment or pay a pro, buck or two per crimp.

Better to wait do without until the next paycheck than accept substandard wiring IMO.

Alan at BayMarineSupply is reasonable for quality termination fittings, buck apiece or so.

​genuinedealz.com for custom made cables, excellent service

 

[Spaceman Spiff]

1) You will have a 3% voltage drop in the 6 feet from charge controller to battery with AWG 10 wire, so you will have to up the voltage from the controller to meet maximum charging specs for your batteries. 6 feet of AWG 10 can carry 60 amps safely.  http://circuitwizard.bluesea.com/#

2) Smallest AWG 8 ring terminal I have seen is 1/4".  You can also cut a few strands off the end of the 8 ga wire to cram it into a 10 ga terminal.  I suppose one could file down a spade terminal and drill to work.  None of these kind of kluges is ideal.

3,4) I do not like t-taps.  It is a very mechanically and electrically shaky connection.  Hand wire splicing can be done w/o soldering.  Just make sure you have a good solid connection (pull on it hard).  http://www.knowyourparts.com/technical-resources/electrical/hand-wire-splicing-technique/   Same procedure with 3 or more wires.

If you are running close to max charge controller capacity, make sure your charge controller has over-current protection.  Panels can produce more than their rated amps under the right conditions.

 -- Spiff

 

[John61CT]

If you are running close to max charge controller capacity, make sure your charge controller has over-current protection.  Panels can produce more than their rated amps under the right conditions.

I thought using panels' Short Circuit Current (Isc) rather than Rated Current (Imp)

combined with the fact that decent controllers were able to accept input amperage much higher than max output, plus conservative rating standards

ensured that overcurrent won't be a problem?

 

[highdesertranger]

they make step up/down butt connectors. you could run 8 gauge and the last few inches go with 10. here's an example, http://www.connectorsupply.com/cata....html?osCsid=f5f2426b49072ca07885daa5c6130ad0 . I just used this as an example. they make these for almost all gauges also insulated or non insulated. just wanted to give you another option. highdesertranger