Reply
 
Thread Tools Display Modes
 
Old 01-09-2015, 02:51 PM   #1
Senior Member
 
Lutarious's Avatar
 
City: Oakland,Ca
Country: USA
Join Date: Sep 2014
Posts: 108
How do I MEASURE Alternator Output.

I know about checking battery voltage and then running the motor to see that the Alternator is actually working, but I'm curious to know how to measure the amps being produced by the Alternator at any given time.

I have a bank of 5 AGM house batteries charged by a single alternator only Starboard Volvo. There's a Blue Seas ACR in line to serve the starting battery on that side, and a Xantrex freedom 10 inverter/charger on that bank too. I have a No. Lights 8kw genset which hasn't ben working lately... More on that later.

A bit of history....

At one point, I ran the house batteries down quite low. Low enough that I got a warning of low voltage from the display on the VHF while I was out at sea. I believe that the switch for the ACR was in the off position. I can't be sure. I kicked on the generator and got them back up, but in an odd coincidence, the genset suffered a mechanical catastrophe. Luckily, we got to shore, where we found a blown 150 amp fuse between the ACR and the house bank. Replaced that one, charged up and made it home without the genset, but the Xantrex remote was reading 12.0v for the entire three day trip. So, the problem seems to be that the alternator is charging, but after a couple hours under way, the house bank gets down to 12-volts just hangs there. They don't drop real low, but they never get up to 13-13.5 that I would like. Even when they are connected to the shore power the Xantrex can only get them up to about 13. Maybe that's not a problem, but it seems weird that they run down to a certain point and then kinda hang like that forever.
__________________
Advertisement

Lutarious is offline   Reply With Quote
Old 01-09-2015, 03:24 PM   #2
Guru
 
No Mast's Avatar
 
City: Atlantic Highlands, NJ
Country: US
Vessel Name: Moana Huaka'i
Vessel Model: Selene 53
Join Date: Dec 2014
Posts: 816
Quickest way to measure amps will be with a clamp style meter.

Have you a copy of Nigel Calders "Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems" Extensive troubleshooting guides in there
__________________

No Mast is offline   Reply With Quote
Old 01-09-2015, 04:08 PM   #3
Guru
 
Edelweiss's Avatar
 
City: PNW
Country: USA
Vessel Model: 1976 Californian Tricabin LRC
Join Date: May 2011
Posts: 1,834
Are you sure your batteries in question are good?? Charger/alternator will not charge bad batteries. You'll get just a surface charge and then they will stop charging.
__________________
Larry B
Careful . . .I Have a Generator and I'm not afraid to use it !
Edelweiss is offline   Reply With Quote
Old 01-09-2015, 04:15 PM   #4
Guru
 
Bacchus's Avatar
 
City: Seneca Lake NY
Country: US
Vessel Name: Bacchus
Vessel Model: MS 34 HT Trawler
Join Date: Nov 2014
Posts: 1,407
Take a look at this recent post in this section "A path to redemption for an electrical idiot"
There is a link to a PDF of "Boatowner's Illutrated Electrical Handbook" that has good sections on batteries & alternators along with troubleshooting guides.

Are there any diode type isolators in the charging circuits?
__________________
Don
MS 34 HT Trawler
"Bacchus"
Bacchus is offline   Reply With Quote
Old 01-09-2015, 05:23 PM   #5
TF Site Team
 
FlyWright's Avatar
 
City: California Delta and SF Bay
Country: Sacramento, CA, USA (boat in Vallejo)
Vessel Name: FlyWright
Vessel Model: Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 10,170
One surefire way to confirm your alternator output is with a State of Charge (SOC) meter. Mine monitors two banks for voltage and one bank for amps in/out and AH remaining. My house bank get the full monitoring and voltage-only on the start battery. It's enough on the start battery to see that it's getting alternator charging and to spot check the voltage during anchoring.
__________________
Al

Custom Google Trawler Forum Search
FlyWright is offline   Reply With Quote
Old 01-09-2015, 07:54 PM   #6
Senior Member
 
Martin J's Avatar
 
City: Mt Crested Butte
Country: USA
Vessel Name: St Christopher
Vessel Model: Cheoy Lee 50ft tri-cabin
Join Date: Feb 2013
Posts: 243
Ammeter

One of the most useful pieces of equipment I've owned has been a clamp on DC ammeter. You can buy one from sears for about $60. Extech also make a good cheap one. I have owned both over the years and they have saved me many headaches. Just clamp on a wire and it will show the amperage going down the wire. JUST MAKE SURE it's a DC NOT AC clamp on meter!
Martin J is offline   Reply With Quote
Old 01-09-2015, 08:14 PM   #7
TF Site Team
 
Bay Pelican's Avatar
 
City: Chicago, IL
Country: USA
Vessel Name: Bay Pelican
Vessel Model: Krogen 42
Join Date: Oct 2007
Posts: 2,781
Installed in line ammeters on my alternators so that I can watch the output. Very useful as the engines vary the output depending on their rpm. Also gives me an immediate gauge if anything is going wrong.
__________________
Marty
Bay Pelican is offline   Reply With Quote
Old 01-09-2015, 10:27 PM   #8
Guru
 
No Mast's Avatar
 
City: Atlantic Highlands, NJ
Country: US
Vessel Name: Moana Huaka'i
Vessel Model: Selene 53
Join Date: Dec 2014
Posts: 816
I'm hoping someone can either corroborate or correct me on this. I definitely have much to learn with regards to electric systems.

1. Batteries not getting past 12V for three days while running without the genset. Sounds to me either the engine alternator is too small to handle boats load AND charge or there's an issue with one of the batteries.

2. Batteries not fully charging under shore power point to either a problem with the batteries themselves or the charger either perhaps being incorrectly setup.

One thing may be important that is unknown is where are these measurements being taken. They could be measured at the charger, at the battey or someplace else such as at a bus. It could partly be a voltage drop issue caused by a cable being sized wrong.

In any event load testing the batteries sounds like a solid first step.

Having recently moved from the sailing side, the difference in electrical system complexity is a learning curve for me. Any critique of my thoughts would help me learn and maybe the OP troubleshoot.
No Mast is offline   Reply With Quote
Old 01-09-2015, 10:47 PM   #9
Senior Member
 
Lutarious's Avatar
 
City: Oakland,Ca
Country: USA
Join Date: Sep 2014
Posts: 108
Quote:
Originally Posted by No Mast View Post
I'm hoping someone can either corroborate or correct me on this. I definitely have much to learn with regards to electric systems.

1. Batteries not getting past 12V for three days while running without the genset. Sounds to me either the engine alternator is too small to handle boats load AND charge or there's an issue with one of the batteries.

2. Batteries not fully charging under shore power point to either a problem with the batteries themselves or the charger either perhaps being incorrectly setup.

One thing may be important that is unknown is where are these measurements being taken. They could be measured at the charger, at the battey or someplace else such as at a bus. It could partly be a voltage drop issue caused by a cable being sized wrong.

In any event load testing the batteries sounds like a solid first step.

Having recently moved from the sailing side, the difference in electrical system complexity is a learning curve for me. Any critique of my thoughts would help me learn and maybe the OP troubleshoot.
Yea, NoMast, I had the same thoughts, which is why I originally asked about measuring Alternator output. I have been testing the batteries both from the remote, which reads the charge from the xantrex unit, and also with a multi meter at the batteries directly. I recently tried charging them for 24 hours with no loads, disconnecting them from each other, and testing them individually with the full charge and 12 hours later - still completely disconnected. No one battery showed a significant loss of charge, leading me to believe that they are probably okay.

The entire system, is new within a couple of years, and the wire sizes, fuse sizes, etc are all correct. It was done by a certified electrician who did it very much by the book.

At this point, I think load testing the batteries and taking the alternator in to the genius is the best bet. Im still going to buy or borrow a clamp type meter and see what that tells me before I surrender to the professionals though.
Lutarious is offline   Reply With Quote
Old 01-10-2015, 01:27 AM   #10
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,251
Isn't a battery monitor sufficient?


__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 01-10-2015, 07:12 AM   #11
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
Weather a battery is charged is best done with a hydrometer , although a SOC meter will work.

Just looking at voltage will not tell the state of the battery , only weather it is being charged.

Sounds like you ran the batts to low and now one or more cells is shorted so the bank will not charge.

Low cost check is a portable charger , disconnect the bat from the boats electrics and charge over night.

13.5 V at charge finish , 12.8 sitting disconnected after a day or two, is what you need. Check them all, one at a time.
FF is offline   Reply With Quote
Old 01-10-2015, 07:49 AM   #12
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,422
Quote:
Originally Posted by FF View Post
Weather a battery is charged is best done with a hydrometer
He has AGM batteries I believe. Which are sealed. So that option is out.

To the OP, is your charging system properly tuned for AGM batteries? The higher fix float voltage used with flooded batteries can shorten the life of AGMs.
Capt.Bill11 is offline   Reply With Quote
Old 01-10-2015, 08:51 AM   #13
Guru
 
No Mast's Avatar
 
City: Atlantic Highlands, NJ
Country: US
Vessel Name: Moana Huaka'i
Vessel Model: Selene 53
Join Date: Dec 2014
Posts: 816
From what I remember, to properly test these batteries in this circumstance the open circuit test already performed is insufficient to determine the batteries are fine. What is needed is either a load test or a capacity test on them.

Another question also is when your batteries are charging have you monitored their temperature? At the posts?

Markpierce: I'm reading that AMP hr meters are "incapable of accurately reflecting this ever changing efficiency factor and need some form of periodic recalibration to bring them back in line with the actual state of charge of the Battery. Between calibrations the meter will tend to become less and less in sync with the battery's state of charge." - Nigel Calder
-- news to me
No Mast is offline   Reply With Quote
Old 01-10-2015, 09:54 AM   #14
Guru
 
Heron's Avatar
 
City: Cypress Landing Marina (NC)
Country: USA
Vessel Name: Heron (2)
Vessel Model: '88 Cape Dory 28 Flybridge #115
Join Date: Nov 2014
Posts: 1,077
Quote:
Originally Posted by No Mast View Post

Markpierce: I'm reading that AMP hr meters are "incapable of accurately reflecting this ever changing efficiency factor and need some form of periodic recalibration to bring them back in line with the actual state of charge of the Battery. Between calibrations the meter will tend to become less and less in sync with the battery's state of charge." - Nigel Calder
-- news to me
I've done some reading on this. Review the Balmar Smartgauge. Seems to be the solution to accurate SOC with no need for calibration:

Smart Gauge Battery Monitoring Unit Photo Gallery by Compass Marine How To at pbase.com
__________________
Steve
Heron is offline   Reply With Quote
Old 01-10-2015, 10:05 AM   #15
Guru
 
Codger2's Avatar
 
City: San Diego
Country: US
Vessel Name: "Sandpiper"
Vessel Model: 2006 42' Ocean Alexander Sedan
Join Date: Oct 2007
Posts: 5,420
Quote:
Originally Posted by Heron View Post
I've done some reading on this. Review the Balmar Smartgauge. Seems to be the solution to accurate SOC with no need for calibration:

Smart Gauge Battery Monitoring Unit Photo Gallery by Compass Marine How To at pbase.com
The Smart Gauge only gives you "voltage" data .......no amp values.

I have a Victron for "Amps" and a Smart Gauge for "Volts".
Attached Thumbnails
Click image for larger version

Name:	IMG_5694.jpg
Views:	53
Size:	171.2 KB
ID:	36217  
__________________
Codger2

My passion for improving my boat(s) exceeds my desire to constantly cruise them.
Codger2 is offline   Reply With Quote
Old 01-10-2015, 10:14 AM   #16
Guru
 
Heron's Avatar
 
City: Cypress Landing Marina (NC)
Country: USA
Vessel Name: Heron (2)
Vessel Model: '88 Cape Dory 28 Flybridge #115
Join Date: Nov 2014
Posts: 1,077
Quote:
Originally Posted by Codger2 View Post
The Smart Gauge only gives you "voltage" data .......no amp values.
No it doesn't...But seems the most accurate gauge available for measuring SOC which was what I was referencing in the quote in my post..Like a gas gauge for your housebank..

As you mention, having both will give you the most info..
__________________
Steve
Heron is offline   Reply With Quote
Old 01-10-2015, 10:42 AM   #17
Guru
 
Codger2's Avatar
 
City: San Diego
Country: US
Vessel Name: "Sandpiper"
Vessel Model: 2006 42' Ocean Alexander Sedan
Join Date: Oct 2007
Posts: 5,420
[QUOTE
As you mention, having both will give you the most info..[/QUOTE]

Although the Victron will show a "Voltage" value, it often is not accurate. It does show you amps in, amps out and total amps consumed The synchonization for the Victron can be done by simply holding the + & - buttons simultaneously for 3 seconds.

The Smart Gauge, as Steve has mentioned, does give you accurate "Voltage" values but no amp info. No synchronization is necessary with the Smart Gauge.
Attached Thumbnails
Click image for larger version

Name:	Victron.jpg
Views:	60
Size:	71.2 KB
ID:	36226  
__________________
Codger2

My passion for improving my boat(s) exceeds my desire to constantly cruise them.
Codger2 is offline   Reply With Quote
Old 01-10-2015, 10:53 AM   #18
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,197
If you cant measure specific gravity uncouple all batts wait 24 hours and measure voltage. The one that reads 10.5 volts or so is bad and draining charge.
bayview is offline   Reply With Quote
Old 01-10-2015, 10:56 AM   #19
Guru
 
Heron's Avatar
 
City: Cypress Landing Marina (NC)
Country: USA
Vessel Name: Heron (2)
Vessel Model: '88 Cape Dory 28 Flybridge #115
Join Date: Nov 2014
Posts: 1,077
I like the simple % SOC feature of the Balmar and it's accuracy....when it hits 50% on your primary housebank, time to recharge or run the risk of shortening battery life and the beer getting warm!
My boat has very simple systems...Refrigerator and lighting so I know how long I can hang on the hook before I need to re-charge the system.
For best battery life don't drop below 50% before recharging...

Here are some relative Voltages VS. SOC. From the reading I've done, the "Gel" scale is pretty close to AGM numbers..

__________________
Steve
Heron is offline   Reply With Quote
Old 01-10-2015, 11:01 AM   #20
Senior Member
 
Lutarious's Avatar
 
City: Oakland,Ca
Country: USA
Join Date: Sep 2014
Posts: 108
Does anyone know of a "real-time" alternator monitor that would show me, at a glance, what my alternator output is (amps)? In combination with an accurate SOC (volts), it seems like it would be useful to know.
__________________

Lutarious is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 11:52 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012