Engine slow turnover

[mark_53]

Stu. Our boats are 30 years old. By now we all have differences in existing systems. What works for one may not work for another.  I'm retired so my time is cheap. I agree if you have to hire someone to mount your battery and you have a clean slate to work with, choices may have been different.  My preference is to use the start battery for starting. House battery for house loads. Whether you use a short run or a long run makes no difference technically as long as wire is sized correctly. Your boat your choice.

[mark_53]

Ron. I chose not to start off the house battery. Doing so, according to my MFD manufacturer could induce a voltage spike to the MFD rendering a restart. The start battery is isolated from the house so no MFD dropouts.

[jonathanc34]

My boat came w a dedicated emergency/start battery as bank 2 and a large 4x 6v as bank 1, but I still suffered from slow start under certain conditions (esp when the engine was hot) that I could not diagnose, even when using the fully charged start battery.

I replaced my engine compartment wiring harness connector strip and restripped the wire ends in the process, which improved the glow plug current and start signal.
The fuel pump and fuel gauge would still occasionally flutter, which turned out to be the engine block ground, which had a poor crimp connector and was undersized. The original #4 awg wires were copper only, not tinned.

I replaced the starter positive, alternator positive, and engine block ground with #2 awg tinned copper and high quality crimp connectors, and now absolutely everything works properly under all conditions: fast crank, quick start, and higher current flow when charging.

[KWKloeber]

I replaced the starter positive, alternator positive, and engine block ground

Along with lugs/cable size upgrades - it's best to NOT use the engine for the harness/panel ground because heat / terminal and fastener expansion-contraction /corrosion can cause issues.  It's best to run the battery neg cable to the starter bolt (so current goes directly where it's needed), run a heavy alt neg cable to that bolt, and jumper to a buss for (harness and other) lnegative connections directly to the battery cable.  It could jumper from either the starter bolt or Alt neg post.
The battery neg cable on the bell housing is not the best location.

[jonathanc34]

Along with lugs/cable size upgrades - it's best to NOT use the engine for the harness/panel ground because heat / terminal and fastener expansion-contraction /corrosion can cause issues.  It's best to run the battery neg cable to the starter bolt (so current goes directly where it's needed), run a heavy alt neg cable to that bolt, and jumper to a buss for (harness and other) lnegative connections directly to the battery cable.  It could jumper from either the starter bolt or Alt neg post.
The battery neg cable on the bell housing is not the best location.

That makes a lot of sense and most likely contributed to the issues I was experiencing. I don't believe my starter has an official ground terminal.
There are two bolts and two screws on the forward side of the motor housing. Which would be best?

Would a grounding bus in the engine bay be a good option, have one place for all of the grounds to land?

[Ron Hill]

Mark : Guess I don't know what a MFD induced voltage spike or MFD rendering a restart or MFD dropouts is/are?????

When C34s were new all of the cabling and contacts were tight and CLEAN, so there were no problems. 

Catalina gladly installed refrigeration in our boats, but would NOT address what was really needed to support a 24/7 refrigerator!!  I know because I asked Many Many times!!

A few thoughts

[mark_53]

Mark : Guess I don't know what a MFD induced voltage spike or MFD rendering a restart or MFD dropouts is/are?????

Ron, In laymens terms, when you start the engine, If your both starting and running the MFD off the house bank, it could cause the MFD to go tits up. At least according to my instal instructiions.  That's also the point of SiACR (start isolation)

[KWKloeber]

MultiFunction Display - for old folks.

[KWKloeber]

@jonathanc34

See the diagram.

The battery cable would go on the most accessible (outside) starter bolt, which is the same M8 bolt as the bell housing.

At a minimum, you'd have the btty cable and a jumper to a neg buss but there are two ways to do it.  Cutting down on connections there is why I said one way is to pick up the harness neg at the alt neg post.  Depending on how many negs you want/need to pull together to one point a buss (or blue sea "Power Post") may or may not be required. 
On my 30 I have virtually everything on the port side running to a neg buss (bilge pump neg, galley and saloon lighting, four 12v outlets, etc.)

[Stu Jackson]

Thanks, Ken, very helpful visual.

[Ron Hill]

Mark : Guess that I've never had a MFD or MFD problem because I've always had a Balmar External Voltage regulator that eliminated any of the spikes you may have experienced!!
Also all of the negative wires are gaged on the negative shunt for the Link 10 battery Monitor.  I further ran a separate #8 from that gang to the DC negative buss bar on the top inside of the Main Electrical Panel.

A thought

[Jon W]

I believe that Mark is referring to the inrush current of the start motor, not the alternator voltage regulated by the Balmar external voltage regulator in the charging system.

[mark_53]

Mark : Guess that I've never had a MFD or MFD problem because I've always had a Balmar External Voltage regulator that eliminated any of the spikes you may have experienced!!
A thought

Ron, your Balmar regulates current going into the battery not current going out.  You are right though, if you have no sensitive electronics to protect, then connecting to the house bank is fine.

Here is a link that explains better than I can.

https://shop.pkys.com/What-is-the-Start-Isolation-feature-of-an-ACR-for_b_40.html

[Stu Jackson]

Mark : Guess that I've never had a MFD or MFD problem because I've always had a Balmar External Voltage regulator that eliminated any of the spikes you may have experienced!!
A thought

Ron, your Balmar regulates current going into the battery not current going out.  You are right though, if you have no sensitive electronics to protect, then connecting to the house bank is fine.

Here is a link that explains better than I can.

https://shop.pkys.com/What-is-the-Start-Isolation-feature-of-an-ACR-for_b_40.html

Mark is right.

In addition to hsi link, the very concept of separating electronic loads from inrush starting voltage drop is a key feature of how to choose how you switch your battery banks.  This is covered in great detail in the Electrical Systems 101 Topic in the Battery Wiring options.  That's why there ARE options! 

[Ron Hill]

Mark : My Balmar has a delay so that the engine is running about 5 seconds before it allows the alternator to kick in. 

Guess those with 4 Trojan Golf Cart batteries, best never start in the ALL position!!

A thought