Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 05-03-2015, 07:43   #1
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
Expensive vs Cheap Amp Meters

After reading the outstanding guidance of Maine Sail and others on CF, I am about to install a SmartGauge.

This gauge is great but it will not show connected load. The existing ammeter is shot and several large power users are wired (with fuses) off the house battery.

My current plan is to add a shunt between the engine (system ground) and the common battery ground/DC bus ground. Then connect an ammeter.

This will let me see current DC load on the system.

Question to the "team". What is the difference between a $125 ammeter and shunt vs. a $30 meter and shunt------ okay aside from $95.

Why not go with the low bid item??

Thanks


Sent from my iPhone using Cruisers Sailing Forum
__________________

__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 05-03-2015, 07:48   #2
Registered User
 
wingless's Avatar

Join Date: Aug 2013
Boat: 2000 Searay 380 Sundancer
Posts: 487
Re: Expensive vs Cheap Amp Meters

Here is one for $10.

Post links to the two products to permit a better comparison.
__________________

__________________
2000 SeaRay 380 Sundancer Mercruiser
454 MAG MPI Horizon 380hp / Westerbeke 7.0KW BCGB
many cool mods
wingless is offline   Reply With Quote
Old 05-03-2015, 11:05   #3
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
Expensive vs Cheap Amp Meters

The iPhone app does allow for links.



But generally what is the difference between any amp meter from blue sea or defender vs the $10 one you found on eBay.



Sent from my iPhone using Cruisers Sailing Forum
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 05-03-2015, 11:13   #4
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,389
Re: Expensive vs Cheap Amp Meters

The difference would be the quality of the shunt and the meter. Without being able to see the ones you're comparing (and I understand your inability to provide links) there's pretty not much more we can say.

The only other difference I can think of is the RANGE of the ammeters. The ones with built-in shunts are less expensive, but would have a smaller range.

Ammeters & Shunts 101 Ammeters & Shunts 101

So you have to figure out how much current you're planning to measure.

For example, we have a built-in 0 - 25 A ammeter that measure output of our distribution panel. If I turned every single DC load I have connected to the panel, it would be hard to exceed the 25A.

OTOH, that meter would be toast if I placed it where you're planning yours, because I have a 100A alternator (OK only sees 50A when charging) but our shorepower charger can get up at 75 A on startup on a discharged bank.

Plan accordingly.

Good luck.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 05-03-2015, 11:31   #5
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,815
Re: Expensive vs Cheap Amp Meters

While not a cheap amp meter, I have a cheap $10 volt meter that is almost 2 years and still reads the same as my VOA meter.

The $10 amp meter is direct from china, the defender unit has probably an importer and distributor markup as well as defenders mark up. So $10+$20+$40+$60 = $120.

Myself I've found the $10 volt meter well made. One day I'll splurge on a $10 amp meter.
__________________
sailorchic34 is offline   Reply With Quote
Old 05-03-2015, 16:24   #6
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
Re: Expensive vs Cheap Amp Meters

Finally got home and did some research


This is the Defender Ammeter Defender.com Search Results: digital ammeter


Here is an eBay one for $38 DC 5 40V 0 100A Volt Amp AH Power Combo Meter Charge Discharge Battery Monitor | eBay





And one for $26.50 http://www.ebay.com/itm/DC-150A-200V...item2a30ea87c0

Aside from being openly Chinese (vs rebranded)


What is the difference??


Thanks
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 05-03-2015, 20:12   #7
Registered User
 
Sailorman Ed's Avatar

Join Date: Jun 2010
Boat: Polynesia 40/42
Posts: 685
Images: 15
Send a message via Skype™ to Sailorman Ed
Re: Expensive vs Cheap Amp Meters- shunts

Question - do shunts add resistance to a circuit? And does adding a second shunt in series have any effect?
__________________
Sailorman Ed is offline   Reply With Quote
Old 05-03-2015, 20:35   #8
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Martinique
Boat: Fortuna Island Spirit 40
Posts: 1,726
Re: Expensive vs Cheap Amp Meters

Quote:
Originally Posted by Snore View Post
Finally got home and did some research


This is the Defender Ammeter Defender.com Search Results: digital ammeter


Here is an eBay one for $38 DC 5 40V 0 100A Volt Amp AH Power Combo Meter Charge Discharge Battery Monitor | eBay





And one for $26.50 DC 150A 200V Current Voltage Combo Meter Battery Monitor Charge Discharge | eBay

Aside from being openly Chinese (vs rebranded)


What is the difference??


Thanks
You should search the forum about that Chinese meter. There was a post a couple of months back about that exact amp meter. The post could not get the amp meter to be accurate. Another user was trying to help him as he had just installed the exact meter.

I can't seem to find the thread right now.
__________________
travellerw is offline   Reply With Quote
Old 05-03-2015, 20:35   #9
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Expensive vs Cheap Amp Meters

Yes, shunts do add a small resistance to the cct. They are just highly accurate, high power, low resistance resistors. Adding a second one in series shouldn't be a problem, although I don't think I would do it. Some people have one in the positive lead from the alternator to read the alternator current directly. That is effectively in series to the negative side shunt for a battery monitor.
__________________
DeepFrz is offline   Reply With Quote
Old 05-03-2015, 20:39   #10
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Martinique
Boat: Fortuna Island Spirit 40
Posts: 1,726
Re: Expensive vs Cheap Amp Meters

Found it.. 3 pages of information about that particular meter..

Low Cost Battery Monitor
__________________
travellerw is offline   Reply With Quote
Old 06-03-2015, 04:53   #11
Registered User
 
wingless's Avatar

Join Date: Aug 2013
Boat: 2000 Searay 380 Sundancer
Posts: 487
Re: Expensive vs Cheap Amp Meters

Quote:
Originally Posted by Snore View Post
The Blue Sea Systems 8236 Ammeter is a quality marine gauge w/ a list price of $245. They also offer a positive-side shunt for $46 to permit measuring from the positive side instead of negative side.

The $10-$38 Chinese meters are not marine parts and provide functionality.

All should work.

My prior experience w/ Blue Sea System products is positive and I wouldn't hesitate to use / recommend their other products.

Saving money is good, so a cheap Chinese device for $10-$38, versus a qualtity product for ~$200 is worthy of consideration for some applications.
__________________
2000 SeaRay 380 Sundancer Mercruiser
454 MAG MPI Horizon 380hp / Westerbeke 7.0KW BCGB
many cool mods
wingless is offline   Reply With Quote
Old 06-03-2015, 05:07   #12
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
Re: Expensive vs Cheap Amp Meters

Quote:
Originally Posted by Snore View Post

This gauge is great but it will not show connected load. The existing ammeter is shot and several large power users are wired (with fuses) off the house battery.
I have been on the hunt (on CF and elsewhere) for the elusive positive and negative recording amp meter for less than $100 for months. No one has given me a straight answer that their amp meter will do it.

I opt for the smartgauge, due to superior SOC monitoring and added BMV702 only for the amp recording.

Quote:
Originally Posted by Snore View Post
Finally got home and did some research
This is the Defender Ammeter Defender.com Search Results: digital ammeter


Here is an eBay one for $38 DC 5 40V 0 100A Volt Amp AH Power Combo Meter Charge Discharge Battery Monitor | eBay

And one for $26.50 DC 150A 200V Current Voltage Combo Meter Battery Monitor Charge Discharge | eBay

Aside from being openly Chinese (vs rebranded)
The defender one is too expensive

The $38 appears to record but does not appear to negative range. i.e It will record the amps going out of the battery for example but not amps going in. So if you drew 120 amp/hr one day and produced 100 amp/hr of solar it would report 20 amp/hr? The next day you drew 100 amp/hr and produced 120 amp/hr it would report 0 a/h not -20 amp/hr? - I don't know but that is the thing no one can tell me.

The $26 one does not record but it does negative range.

If you just want to know the immediate volts and amp draw the $26 one appears to be it. I sure wish I could find a recording one.
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 06-03-2015, 06:04   #13
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Expensive vs Cheap Amp Meters

Just one caution....

Be sure your shunt can handle the system loads for where you place it in the system. I have seen undersized shunts get whacked with high current and lose accuracy and in one case actually lose solder.......

If your highest system load is your engine cranking circuit you want a shunt that can handle that with ease. If it is a bow thruster, electric winches, windlass etc. it too needs to handle those with ease... Most reputable Ah counter manufacturers ship 500A rated shunts and most often 50mV.

To me one of the best values, for what you get, is the Victron BMV-700....
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 06-03-2015, 07:29   #14
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Expensive vs Cheap Amp Meters- shunts

Quote:
Originally Posted by Sailorman Ed View Post
Question - do shunts add resistance to a circuit? And does adding a second shunt in series have any effect?
Yes. The meter determines the current through the shunt by measuring the voltage drop of the shunt and displaying it as current. It's a small resistance though.
__________________
rwidman is offline   Reply With Quote
Old 06-03-2015, 13:25   #15
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Expensive vs Cheap Amp Meters- shunts

Quote:
Originally Posted by Sailorman Ed View Post
Question - do shunts add resistance to a circuit? And does adding a second shunt in series have any effect?
A 50mV X 500A shunt will impart a 50mV drop (0.05V) at 500A. At normal house loads it is at the opposite end of 50mV...
__________________

__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Reply

Tags
cheap

Thread Tools
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
Want To Buy: Need a Cheap, Cheap, Cheap Boat . . . Did I Mention Cheap ? TheScarab Classifieds Archive 52 05-02-2012 13:29
Moisture Meters marty9876 Construction, Maintenance & Refit 18 05-04-2008 09:22
Buy cheap & repair ... or buy expensive and go? j9gillik General Sailing Forum 22 23-10-2007 15:02
Depth Meters Jimske Marine Electronics 16 28-08-2006 19:25
Advice on Tachs and Hour meters Volvo 2030 JJ Engines and Propulsion Systems 8 04-07-2006 15:20



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:48.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.