Battery or starter problem

[dorado42]

I have a 2860 Catamaran with twin F225 (2002). The problem I am experiencing is that sometimes the boat starts right up and sometimes it labors to try to start. I have taken the batteries to two different places and they have tested GOOD. I always make sure they are fully charged before heading offshore. I am thinking the problem is bad cables. It seems to be the worst after i run the boat and let it sit and then go to restart. I have checked that the batteries are reading 14.3-14.5 when the motors are running, so I am guessing the alternator is charging. What is the best way to test the cables to make sure they are ok.... I have taken them all off their connection point (battery, battery switch, motor) and cleaned them with wire wheel. I have replaced the battery switches (just because they looked very old) and due to problem being most prevalent after the boat runs, I thought maybe the cables. Does this sound right??

[rodbolt17]

do a forum search on "voltage drop test".
what your looking for is the actual voltage drop of each cable run.

[throrope]

Cables are cheap, especially compared to anything else on a boat, if you suspect them, I suggest replace. Takes the same time as testing. Worth eliminating the problem and any contribution to another.

When you say labor, do you mean the starter turns the motor slowly? If so, that requires immediate attention. Running a starter on low voltage can cost you one. That's exactly what a bad connection or cable will create.

Also check all fuses and connections. Just before shipping a brand new GPS/sonar back, I checked the fuse and found it corroded, but not blown. The GPS worked for 10 minutes until the corrosion heated up and lost contact. Then it came back when cooled and went out again.

I also suggest that spray on battery terminal stuff when done. It puts a protective coating that's much less mess than grease. I bought a can for maybe two bucks ten years ago and still have enough for another shot.

[boscoe99]

Cables from Yamaha being cheap are subject to debate. I don't see $347 as being cheap.

69J-82105-00-00 YAMAHA WIRE HARNESS $347.81

Do the voltage drop test, do the test, do the test. There are numerous connection points between a battery and the starter motor. Any one of which, or together collectively, can cause low voltage at the starter motor when the starter is engaged.

Or, just disconnect each connection point, clean it and replace it.

[dorado42]

Ok found the voltage drop test info....thank you rodbolt17....i found a battery cable that was only 8.8-9.2 volts....question is how do i "crimp" new ends on cables.....i cut the old ends off and wire looks good about three inches back....i am not wanting fish cables out of boat just to take somewhere and have new ends crimped on. Can i just fill the new terminal ends with soder, heat the soder to liquid form and push cable on it (and not actually crimp it) and then cover with heat shrink...or do i need to "crimp" even after soldering? Thanks again

[rodbolt17]

US coat guard regs say it must be crimped or mechanically secured.

"Only 8.8v" your cables are either trash or you did not do the test correctly.

[dorado42]

Ok found the problem....yamaha cables were corroded. The ground side was the worst. The good news is that i had enough extra cable (after i cut three foot of bad cable off) that i did not have to buy new cables. Motors do not hesitate and turn over with good speed. Thanks AGAIN rodbolt17 for your expertise!! The voltage drop test helped alot!!