Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 25-11-2019, 14:40   #1
Registered User

Join Date: Oct 2010
Location: El Salvador/ Vancouver Canada
Boat: Beneteau First 435
Posts: 30
Measuring ripple voltage

Iím having a problem measuring ripple voltage on my system.

I have 3 multi meters, a cheap one, a Ďgoodí (more expensive, autoranging, more measuring modes, etc.) one and a clamp one (also autoranging) with probes

Using all three, the dc voltage is the same on my system.

Measuring ac in the dc system (ripple voltage), the cheap one measures 28.6vac, the expensive one 0.06vac, and the clamp on meter (using the probes) canít decide, but see-saws between a low value and over range alarm.

Values donít change when the shoreside battery charger is turned on and off, or the shore power is disconnected completely. The specs on the three meters for vac measurement are essentially identical.

Iím at a bit of a loss as to whatís going on here, the values being so out of whack. Anyone have any wisdom to offer up as to what might be happening?
avant is offline   Reply With Quote
Old 25-11-2019, 15:11   #2
Registered User

Join Date: Dec 2007
Location: West Virginia
Boat: Cape Dory, Cutter,30
Posts: 185
Re: Measuring ripple voltage

I think you can only see the AC component on the DC line with an oscilloscope. Then, you could see the frequency too.
moctrams is offline   Reply With Quote
Old 25-11-2019, 15:20   #3
Registered User

Join Date: Oct 2010
Location: El Salvador/ Vancouver Canada
Boat: Beneteau First 435
Posts: 30
Re: Measuring ripple voltage

Numerous online forums and instructional posts in electrical and boating forums mention and describe using a multi meter to quantify ripple.
avant is offline   Reply With Quote
Old 25-11-2019, 22:04   #4
Registered User
 
AKA-None's Avatar

Join Date: Oct 2013
Location: Lake City MN
Boat: C&C 27 Mk III
Posts: 2,269
Re: Measuring ripple voltage

Meters will show you rms ac voltage but it depends on the frequency of the ac. Otherwise you really need an oscilloscope
__________________
Special knowledge can be a terrible disadvantage if it leads you too far along a path that you cannot explain anymore.
Frank Herbert 'Dune'
AKA-None is offline   Reply With Quote
Old 25-11-2019, 23:14   #5
Registered User

Join Date: Jun 2019
Location: Bay of Islands New Zealand
Boat: Morgan 44 CC
Posts: 1,136
Re: Measuring ripple voltage

Quote:
Originally Posted by avant View Post
Iím having a problem measuring ripple voltage on my system.
Iím having a problem understanding the need to measure ripple voltage on my system?
CassidyNZ is offline   Reply With Quote
Old 26-11-2019, 04:54   #6
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 6,008
Re: Measuring ripple voltage

The ďcheapĒ one must not be blocking DC. Some cheap RMS meters will measure DC+AC when in AC RMS mode.

Why do you think itís important to measure AC ripple on your DC system? If you have batteries then AC ripple will be very low.

Are you searching for the source of AC hum on your radio?
transmitterdan is offline   Reply With Quote
Old 26-11-2019, 05:58   #7
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 47,077
Images: 241
Re: Measuring ripple voltage

Checking Alternator Ripple Voltage or (AC voltage) can be measured by switching your DMM to AC, and connecting the black lead to a good ground, and the red lead to the "BAT" terminal on the back of the alternator (not at the battery).
A good alternator should measure less than 0.5 VAC, with the engine running. A higher reading indicates damaged alternator diodes.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low voltage vs higer voltage solar Singleprop Electrical: Batteries, Generators & Solar 11 06-07-2015 19:35
Measuring Voltage Drop US1Fountain Electrical: Batteries, Generators & Solar 5 15-05-2011 20:25

Advertise Here


All times are GMT -7. The time now is 07:23.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.