Replacing battery cables

[crieders]

I want to install larger cables, to enable the engine to turn over better
I know some people have done this from a prior post
What is the proper size of the new cables, what is the length  to the switch and then to the engine?
What is the best way to fish them through

[Craig Illman]

As an initial step, you might just put new terminals on the existing cables, if you have enough length. See if that makes enough difference first. My original ground connection at the engine was very poor when I re-wired things.

[Ron Hill]

Cliff : Follow Greg's advice.  
I'm sure that you have the length necessary to cut off the old terminal, clean the wire (till shiny) then crimp on the new terminal and I recommend soldering for the best electrical connection.  
Don't forget to use some heat shrink and a boot over the exposed terminal ends.
As always, remember the NEGATIVE as well as the positive connectors.

[Clay Greene]

I would also consider installing the glow plug solenoid before replacing the cables.  Your difficulty in getting the engine to turn over may be the result of inadequate pre-heating and the solenoid will improve that significantly.  I may be wrong but I don't remember reading that any other owners have said that increasing the size of the cable from the batteries to the switch and from the switch to the starter improved starting performance all that much. 

But to answer your questions, the stock cables are 4 AWG so the next size up would be 2 AWG.  From the starter, the cable goes aft around the wall with the head, forward on the other side of the same wall, through a chase under the head floor (that you can access from the door that faces aft in the head, out of the chase in the space just forward of the waste tank and runs up with the rest of the cables behind the port sliding door and makes an aft turn to the switch.  The cable from the switch follows the same path back to the space aft of the waste tank, under the salon floor, and makes an aft turn into the battery compartment. 

I did run a 2 AWG cable from our starting battery to the switch but only because I installed it forward of the starboard water tank so the length dictated the size of the cable.  I also ran a new 2 AWG cable from the alternator to the house battery bank (bypassing the switch) - I probably could have gone with 4 AWG but it was marginal and I decided to err on the side of caution.  But that was not to improve starting - it was to improve the efficiency of the alternator in recharging the batteries.


Hope that helps.

[mregan]

Also check where the negative wire connects to the engine block.  The terminal on mine looked pretty good but where it contacted the engine was rusted.  Once I cleaned that off, it started beautifully.  Unfortunately I figured this out after I replaced the glow plugs.

[Stu Jackson]

clay and mregan have it correctly, Cliff.  I also suggest you read the Critical Upgrades topic, which includes a "hard starting" discussion.  In a vast majority of cases, it's the main ground on the back of the engine, starboard side, that is a poor connection.  The solenoid is always a good starting pl;ace and is extensively described in the C34 Tech wiki.

Running the new cable doesn't have to follow the path of the old one.  For the ground, I'd run it down to where the hot water heater is and then use a couple of wire coat hangers to run it under the engine and back.  No need to go the extra length to go under the head sole.  That's why it's hard to answer your question about length, 'cuz folks have different routes they can take.

[crieders]

Where is the glow plug selenoid and how difficult to replace?

[Noah]

Here are photos of my new glow plug solenoid. I opted for a heavy duty "marine" model that I grounded, instead of using a non-grounded automotive model mounted to to the HX, as some have done/suggested. Mine works quite well.

Also, note, I installed the dual alarm engine overheat temp. switch/sender kit from Catalina Direct. New shiny silver module center with pressure relief valve on top. Replaces old-style single unit.

[Stu Jackson]

Where is the glow plug selenoid and how difficult to replace?

Cliff,

There is no solenoid installed on M25 or M25XP engines, one has to ADD it.  The later engines come with it.

You might want to read the C34 Tech wikis, like this one:

http://www.c34.org/wiki/index.php?title=Faster%2C_More_Efficient_Glow_Plug_Heating_with_a_Solenoid

[Steve W10]

Cliff, unfortunately I think you've got some big decisions ahead of you.  Sounds like you have the factory set-up on your boat.

A couple quick things first....
- Ground connection – excellent place to start
- Terminal ends are certainly a good thing to check, but personally with the age of our boats, it's probably not a bad time for an upgrade anyway
- I will politely disagree with Clagr with respect to the Glow Plug Solenoid helping your engine turn over better; the Glow Plug Solenoid upgrade is an excellent idea, but it will not improve cranking of your starter at all (and I think that's what you are really looking for here).  It will certainly get more juice to your Glow Plugs and help the engine fire up more easily, but doesn't help the starter motor.
- Increasing wire size will help turn that motor over better.  There are many charts around describing voltage loss over a given run for varying cable sizes, and our factory run is very long so it is significant.
- I've also pulled my starter motor and cleaned up the commutator as has worked in many cars I've owned, but in the end the wire run is a much bigger factor so it was pretty much a waste of time.

In my opinion, the simplest and least expensive solution for you is to
- check the existing ground and terminal ends
- double up (add another 4 gauge wire to the existing paths for the starter, battery-to-switch, switch-to-starter and the appropriate negative as well)  I experimented with this before committing to my full-blown electrical upgrade and it worked very well.
- doubling up can be challenging to get wires through and it will get a little messy in there so I'd be more apt to replace it with new, heavier gauge wire than doubling up.

From there the solutions step up through many permutations to some pretty expensive options.
- Glow Plug Solenoid
- Dedicated Start Battery, some will call and use it as a Reserve
- Varying levels of Shore Chargers
- Combiner, or some method of topping up your Start Battery while underway. (I use a ProIsoCharger, but the combiner is great too)
- Battery Monitor
- Alternator upgrade
- External Alternator Regulator
- Bigger House Bank

How much money have you got?  

If you're not spending too much time on the hook and want to keep it inexpensive, I think I'd just recommend bigger wires and following the guy's advice wrt the 1-2-both switch and wiring the alternator directly to the House Bank.  If your engine then turns over really well but doesn't light off quickly enough for you, the Glow Plug Solenoid is a good next step.

Stu and the guys have put together tonnes of great information, so you've got lots of reading ahead of you if you want to ensure a good decision.

Just my thoughts.

Steve

[Clay Greene]

Steve raises a good point - is your difficulty with the engine turning over or actually starting?  I agree that the glow plug solenoid is not going to help if it is an issue with the engine turning over (i.e., delivering power to the starter motor). 

I get the point about voltage drop over the length of the run from the batteries to the switch and from the switch to the starter but we had the stock 4 AWG cable and the boat turned over fine.  We'd all be having this problem if the 4 AWG cable was the cause of a hard starting issue.  It seems more likely that it is a connection issue. 

[mark_53]

The standard factory installation should be adequate for starting the engine.  The problem is that over time "stuff happens", i.e. connections corrode, wires get stressed, fuses blow or develop insufficent conductivity. I had a similar problem when I purschased my boat.  Turns out it was the large ANL fuse in the battery box. A hairline crack would cause it to start slowly or not start at all.  Look very carefully at your fuses.  The one in the engine compartment and the large one in the battery box.

from the peanut gallery.

[Ken Juul]

Not sure if this might be the problem, but it hasn't been said in a long while so I will repeat.  It is not necessary to use the glow plugs and the starter at the same time.....too much amp draw.  Heat the glow plugs for 10 seconds with the selenoid, maybe 20 without it.  release the key to the on position and push the start button.  Glow plugs are a huge draw, starter is a huge draw.  Don't need them both at the same time. Glow plugs will stay hot for 15-20 seconds.  Engine should start right up.   Also if the engine temp is over about 100 degrees you don't need the glow plugs at all.

[Clay Greene]

To be fair, I came across this post from Maine Sail while looking for something else:

Catalina used to ship the M-25's with 4GA wire. They now ship that same engine with 2/0 gauge wire. That is a HUGE difference. If you have small gauge wire an upgrade to larger wire can be a very good investment and your engine will start a lot quicker and the starter will see a lot less voltage drop. Nearly every sailboat I went aboard during the last boat show was using 1GA or larger wire with 1/0 and 2/0 being the most popular in boats over 30'..

[Lance Jones]

All are great comments that often overlap and compliment each other. I had that issue as well. Check connections first. This oft times solves the problem. Addition of the solenoid really helped mine start quicker. I also rewired my electrical system based on the options offered in the Must Do thread. I rewired the short runs with 0/0 and the long runs with 2 ga.