Crimp and solder

[Steve Hansen]

Inspected my electrical system last weekend. Removed electricians tape from lugs only to find poorly crimped and loose connections, and corrosion. Decided to go over entire system and replace as necessary, fuse where needed, and crimp and solder. I've reviewed many of the posts and projects on subject but still have a few questions. I'm convinced of the merits of "solder and crimp" and the question is:

1.) after removing insulation on wire and exposing bare wire, is the wire soldered first then inserted into lug and then crimped, or crimp the lug onto the wire, then solder so tin wicks up under lug (similar to soldering a copper pipe to a fitting). Then use adhesive shrink wrap.

2.) is 150 amp fuse sufficient for protecting the 4 gauge wire used for the starting circuit. (M25XP)
3.) Also going to run a dedicated line directly to starter with on/off selector switch. Start battery is located in forward compartment in dinette. Using 2 gauge which about 10 feet is supplied already, is 150 amp fuse sufficient?

Thank You for any input- Steve

[Ron Hill]

Steve : You are answering your own questions with the answers I would give you:
1.  I like to tin the wire, insert it into the connector, crimp the connector and then solder the connection.  If it's older non tinned wire I like to take a sharp knife and scrap the wire strands till I see the shinny copper color as it makes tinning easier.  With marine grade tinned wire that later step in not necessary.
2.  I use a 150 amp fuse on each of my duel output #4 wires from the alternator.  As I recall that fuse should be within 6 " of the battery or the item that the fuse is protecting (closer the better). 

[Stu Jackson]

Steve

Recommended fuse/breaker sizes are shown in Jim Moe's excellent electrical article in Projects:  http://www.c34.org/projects/projects-electrical-system-upgrade-2.html

[Steve Hansen]

Thanks Ron and Stew for the confirmation and info. I find it amazing how the surveyor could have missed the lousy connections and then an electrician could then have missed them. I guess it pays to become an "expert" of your own boat. With this web site and all of your inputs, it has made the learning curve easier and actually enjoyable. Thanks again- Steve

[Craig Illman]

Steve -

I have a 150A breaker at my start battery in the same location as yours. It's worked fine since it was installed last fall.

- Craig

[reedbr]

Regarding the question:
2.) is 150 amp fuse sufficient for protecting the 4 gauge wire used for the starting circuit. (M25XP)

I'll double-check on this, but every car I've worked on and the marine electronics class I took and taught indicate not to fuse the starter.  Specifically, the large cable running to the starter are not fused.  The starter switch is fused, but it's a relay circuit and doesn't take the full current.  Some cars have fused links that is basically a huge fuse for the whole car electrical system....except for that meaty cable running from battery-starting solenoid and solenoid-starter.  I think the reasoning is the current draw of a starter motor, especially at initial startup and under load, peaks VERY high.  The fuse required would also need to be very high to prevent blowing in a normal start situation.  However, fuses at that high of a current draw can cause voltage drop.  Since volts x amps = watts, and the starter still wants full wattage, if the volts go down, the amps go up.  This can cause a vicious cycle of voltage drops and current increases until the system is in balance, but not necessarily performing optimally.  Additionally, I think once you've got a sufficiently large fuse to avoid this cycle, it is mostly useless for overload protection.  It can make you feel better though.

Again, I'll double-check on this.  I'm open to other opinions, always willing to learn, but that has been my experience so far.

[Ron Hill]

Steve : Brian is correct and I didn't read your question close enough. 
I believe that your starting circuit should, and is only protected by a 30amp fuse to the starter solenoid - NOT the starter.