Amps cut in half?

[kloudie1]

Consider that at 2000 RPM on the diesel, the ripple frequency from a hard working alternator will be around 200 Hz.. Enough to cause me to distrust a DC clamp ammeter (that has since been discontinued by Fluke).. ( I like Fluke products, and have used them professionally) The 60 reading from the panel meter is not absolutely accurate, but it certainly sounds to be in the ballpark more than 30 in this case.. Need a third opinion meter on this one .. :~)
but until you get one .. have a Dos Eques .. and trust that the batts are charging.

 

[Stu Jackson]

Cockpit Ammeter

Stephen, you really need to do two things. Get rid of your cockpit ammeter and replace it with a voltmeter. (You could also get a cockpit ammeter with a remote shunt and only run the shunt wiring to the ammeter.)

The reason? ALL of your charging is running from the alternator output (AO) all the way to the cockpit and then back to your batteries. This is usually done in relatively small wire, with large voltage drop.

We have been discussing this "design" for many years here on this and other forums. That design was workable back when there weren't many electrical loads on boats. It's at least 30 years old. The age of your boat, unless modified by a PO or by you, is a dead giveaway that you have this old system.

Think about it: you want to have all the current going from the AO to your house bank as cleanly and quickly as possible.

For some reading, try the "explanation" that Catalina/Seaward provided in the early 90's about why their "enhanced" engine panel was necessary:

http://www.c34.org/wiki/index.php?title=Engine_Harness_Upgrade

While it relates to the Catalina wiring harness issue (bad connectors) it's really the BASIC DESIGN FLAW of cockpit ammeters.

Also check out my article on Ammeters & Shunts 101 which is linked at the top of that article.

I have an ammeter in my boat (in addition to my Link 2000), it is located on the positive side of the system, down at the nav station. It is on the positive wire between the 1-2-B switch and the DC distribution panel. Anything that goes "On" passes through the ammeter and shows up. Simple. It's completely OUT of the AO charging circuit. Where it belongs.

 

[Bill Roosa]

Hey Stu. With that setup you cannot monitor the battery charging except to note the voltage. Apparently this is by design. What is your thinking behind not wanting the AO measued by the shunt?

 

[Mark Maulden]

since you're a distance from the boat, find out the wattage of the headlights/taillights of your car and divide by the measured voltage with engine on and that's what your flulke should read. fluke clamped around the battery positive only at battery. Give or take......That would tell you if the Fluke is correct. I would guess in the area of 20a

 

[Stu Jackson]

Hey Stu. With that setup you cannot monitor the battery charging except to note the voltage. Apparently this is by design. What is your thinking behind not wanting the AO measued by the shunt?

Bill,

Good question.

1. The ammeter was there when I bought the boat.

2. It's a 0-25A internally shunted meter, so based on my link to the Ammeter 101 article, it's never overloaded with HOUSE DC loads (NOT including the higher AO amperage)

3. I have a Link 2000 which takes care of the AO measurement. The panel ammeter reads DC draw. So if the fridge is on (5A on the ammeter) and the engine is running with the AO and my Link reads 20A, I know the AO is 25A.

4. By only measuring DC panel loads, and not the larger AO or shorepower charger input amperage, I can keep the internally shunted simple ammeter

5. I had an AutoMac before I upgraded the alternator, new external regulator and installed my AutoMac, so I knew from the ammeter on the AutoMac what my AO was

Stu

 

[Mark Maulden]

since you're a distance from the boat, find out the wattage of the headlights/taillights of your car and divide by the measured voltage with engine on and that's what your flulke should read. fluke clamped around the battery positive only at battery. Give or take......That would tell you if the Fluke is correct. I would guess in the area of 20a

whoops.. Sorry... Engine off