[C320-list] Alternator Fuse on Yanmar 3YM30 powered 320 MK II

[Ian Neale]

Hi,

In starting the engine this morning the voltmeter flickers up to 18 v on the instrument panel. I suspect I have a blown regulator but my house batteries were 70% run down so are wondering if I blew an alternator fuse with a surge in charge current.

Does anyone know where the alternator fuse on a 320 MkII with a Yanmar 3YM30 engine is?

Thanks, Ian.

Sent from. my iPhone

[Troy Dunn]

Ian

Hopefully someone with a MK II hull will come along and confirm. I don’t
believe the stock alternator is fused on a 320. I believe on later
model 320s there is an 80A breaker (or maybe a fuse) located at the
battery combiner/selector switch. If this is blown however I think your
house loads would not work either. 18V does seem quite high. If the
alternator is not an upgrade, the internal VR seems like a possible culprit
for sure. If your batteries aren’t charging at all, even on shore
power,.check and make sure the fuses for the shore power aren't blown,
these should be located within 7” of the batteries. If both the fuses are
blown AND the VR is blown...that's unusual...lightening strike?

Regards

Troy Dunn
Hull #514

[Stephen Cox]

>
> Hopefully someone with a MK II hull will come along and
> confirm. I don't
> believe the stock alternator is fused on a 320. I believe on later
> model 320s there is an 80A breaker (or maybe a fuse) located at the
> battery combiner/selector switch.

I haven't found any fuses for the stock alternator on my C320 MK II and neither is there any fuse or circuit breaker on the
electrical panel.

There are Limitron KTK-40 inline fuses (40a) near the batteries on the positive cables from the mains charger.


Stephen Cox
Tegwen #1141

[Jack Brennan]

I didn’t see the start of this thread, but I think I can contribute.

These stock alternators are aftermarket, not made by Yanmar, despite the sticker. Do some searches on the Internet. You can buy a 50 amp for $120 or so. There might be 80s out there, too. The same one with the Yanmar sticker will cost you $800.

Even though it seems illogical, there’s not a large difference between the 50 and 80 stock units unless you have a huge battery bank.

That’s because the charging rate slows as the alternator heats up and because the acceptance rate slows for your batteries as they fill up. You might start at 80, but you’ll soon be at 50 or 30 or less.

My alternator is not fused. It is wired to the common pole on the switch. If you switch through off when the diesel is running, you kill the alternator. I have 200 amp fuses on the positive battery posts to protect from short circuit and fire.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.



Sent from Mail for Windows 10

[Stephen Cox]

> These stock alternators are aftermarket, not made by Yanmar,
> despite the sticker. Do some searches on the Internet. You
> can buy a 50 amp for $120 or so. There might be 80s out
> there, too. The same one with the Yanmar sticker will cost you $800.
>

They are made by Hitachi.

Regards,

Stephen Cox
Tegwen #1141

[Jack Brennan]

Used to be. The ones on the Internet are now made by a factory in China. Other companies rebrand them. I think Hitachi got undercut.

I tried to buy a Hitachi two years ago and couldn’t find one.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.

Sent from Mail for Windows 10

From: Stephen Cox
Sent: Thursday, March 18, 2021 9:24 AM
To: C320...@Catalina320.com
Subject: Re: [C320-list] Alternator Fuse on Yanmar 3YM30 powered 320 MK II

[Ian Neale]

Thanks everyone for your comments.

The issue turned out to be the earth cable on the block of the engine coming out of the crimped lug. Initially it must have been high resistance and then as I got to the berth the engine meter panel died and I could shut the engine down without using the manual shut off.

The biggest issue was the problems meant we missed the last race of the Americas Cup 😩. We did see the others from the water which was great.

Now today I have had tach issues as described in another chain of emails although it is intermittent. It does seem if the alternator is still charging. I will see how performs over the next day while at sea and report back to let you n in is what I find.

Thanks, Ian.

Hull # 1122. Solutions.
New Zealand.

Sent from. my iPhone

> On Mar 19, 2021, at 2:41 AM, Jack Brennan <jackb...@bellsouth.net> wrote:
>
> Used to be. The ones on the Internet are now made by a factory in China. Other companies rebrand them. I think Hitachi got undercut.