Maxum 1800 SR3 - Battery Cable Lengths and AWG Sizes

[_jp]

Hi all,

My Maxum 1800 SR3 has a Mercruiser 4.3L (Carb version) and I'm having a little trouble starting it. Narrowed it down to the Starter Motor and / or Battery Cables.

I've read that battery cables should be the same length, even if one needs to be loosely looped. My Positive cable is 3m in length and the Negative is only 1m in length. Both are AWG 2 size and look original (with some signs of corrosion inside).

Is the above a standard setup? As the lengths are different and the AWG 2 is right on the limit for that length of run and amps needed.

I'm considering upgrading the cables to AGW 0, just to rule that out as an issue, before moving on to replacing the Starter Motor. Unless the above is a normal setup??

Thanks

James

[mmwjr]

The difference in length should not be a problem. The key is to have the proper wire gauge for the amount of current that will be flowing through it to ensure that a voltage drop doesn’t occur. A 3meter run should not be an issue as long as the connections and battery are good. Is the starting issue a new problem?

[_jp]

It played up last year, but after I cleaned up all the terminals on both positive and earth it did turnover and fire up. Once started it worked every time.

However, I've got the issue again this year and all terminals have been cleaned. So, I think the issue is either the cables themselves or the starter, both look to be original and could do with replacing.

[mmwjr]

Are the cable terminals copper or tin plated copper? If plain copper they will continue to corrode. Also how do the terminal crimps look, any green corrosion?

[_jp]

Yes, I think they're plain copper, or if tinned, then it's worn off. The crimps were green last year and I had to sand them back to fresh/bare metal. I did paste them with electrical grease.

There is some green'ing on the cables at the ends, which was there last year. I think it's only on the outer side of the exposed cable. I've just ordered new cables.

[mmwjr]

I would replace them. Good that you ordered new ones.

[shrew]

When you turn the key, do you hear a loud 'CLICK'? That should be the starting solenoid. Locate the starting solenoid. It should have external terminals. Trying jumping the solenoid. If the starter spins, it might be a bad solenoid. That is a COMMON problem.

If the starter is spinning but the engine isn't cranking, it might be the bendix on the starter

[yahoo82]

The only time battery cable lengths really need to match is when 2 battery’s are wired in parallel. In that case a difference in resistance from each battery to the load could result in one draining/charging slightly faster than the other. In a single battery circuit the round trip path only cares about the total length (which translates to total resistance) and not differences in length to or from the load.