Ammeter installation

Weasel

Weasel

.
May 23, 2004
152
Beneteau 331 Iuka, MS
Hi Gang,
I need some advice on installing a DC ammeter to keep tabs on my DC energy use. Nothing special on my boat, std battery charger and alternator. I have all LED lighting and have the standard wind, autopilot and depthsounder. I do have a fridge unit that is DC as well as a pressure water system. Question is how do I hook up an ammeter to my 2 house batteries. What size ammeter? 100 amps, 50 amps, and what is a shunt?
I am a mechanical engineer but I know nothing about the ammeter stuff. A schematic would help and a brief description.

Thanks in advance for any help,

Weasel
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
22,770
Catalina 34 224 Maple Bay, BC, Canada
Gunni mentions a competitive product, but wiring the Victron is a heckuva lot easier. I have a Heart Interface Link 2000 and it required running 16 wires!!! The Link Lite has lots less wires, but compered to the simple telephone plug on the Victron, it's like night and day.

Try this:
How to Wire a Battery Monitor by Maine Sail:
http://forums.catalina.sailboatowners.com/showthread.php?t=12560

You should also read this:

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

http://c34.org/bbs/index.php/topic,4922.0.html

DEFAULTS are factory settings that are made to be modified to suit your setup.

Also read this one:

Programming a Battery Monitor (by Maine Sail)

http://www.pbase.com/mainecruising/programming_a_battery_monitor
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
22,770
Catalina 34 224 Maple Bay, BC, Canada
Gunni

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
The Balmar SmartGuage is a very simple to install product but it does not give you Amps and Amp/hours, which is the currency by which we manage our house electrical budget. I may install one as a second data feed for accurate battery voltage.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Gunni said:
The Balmar SmartGuage is a very simple to install product but it does not give you Amps and Amp/hours, which is the currency by which we manage our house electrical budget. I may install one as a second data feed for accurate battery voltage.
Click to expand
The SmartGauge is not just for voltage. It delivers significantly more accurate SOC measurements, something which the vast majority of installed Ah counters do not do..

Ah's in to Ah's out are only relevant if your bank is actually the size you program it for and the monitor is painstakingly set up and calibrated fairly routinely. If an owner is not doing bi-yearly or yearly 20 hour capacity tests, and about 99.99% of boaters using Ah counters are not, then there is no way the Ah counter is delivering anywhere close to accurate SOC....

For the average boater who is asking what a shunt is, the SmartGauge is the easiest and best choice, if saving your batteries from over discharge is what you are looking to accomplish.

Ah counters are great for some but not great for others who don't want to take an active roll. SmartGauge is literally set it and forget it..
 
kloudie1

kloudie1

.
Nov 6, 2006
9,892
Hunter 34 Mandeville Louisiana
But it does give you a great read on battery charge state.. which is ultimately the info that ya need to know. My main problem with it is that it can only calculate one battery (yes it looks at volts on another, but does not calculate state of charge)
EDIT: Maine beat me by six seconds
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
kloudie1 said:
But it does give you a great read on battery charge state.. which is ultimately the info that ya need to know. My main problem with it is that it can only calculate one battery (yes it looks at volts on another, but does not calculate state of charge)
Click to expand

Why would you have more than one house bank?
 
kloudie1

kloudie1

.
Nov 6, 2006
9,892
Hunter 34 Mandeville Louisiana
Laughing.. it is an anachronism that I am comfortable with. My batteries are still in the old 1-2-Both set up.. and both are deep cycle 31's with a smidge over 100 AH each. My loads are small and I am on shore power almost always. If I ever re-install refrigeration, I will go back to golf carts and a start batt, but for now, this works.
EDIT I learned that a long time ago (mid 1950's) on dad's power cruiser and have been OK with that so far.. No one else uses the boat.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Weasel said:
Hi Gang,
I need some advice on installing a DC ammeter to keep tabs on my DC energy use. Nothing special on my boat, std battery charger and alternator. I have all LED lighting and have the standard wind, autopilot and depthsounder. I do have a fridge unit that is DC as well as a pressure water system.
Click to expand

An ammeter is not going to tell you much unless you count the ampere hours being removed and returned. The best value in an Ah counter is the Victron BMV-700 (it comes with everything you need to install it including the shunt).

That said you would be much better served by a Balmar SmartGauge. It is very, very simple, stays accurate over time and tracks and stays in sync with your battery even as it ages. Ah counters do not do this and require considerable owner input to remain anywhere close to accurate for SOC predictions.

In terms of simplicity look at the SmartGauge once in the morning before charging, and once at bed time after charging has stopped. Adjust your charging times accordingly. It is a simple three wire hook up, if you want to monitor the voltage of a second bank, otherwise it is a two wire hook up direct to the house bank...

Weasel said:
Question is how do I hook up an ammeter to my 2 house batteries.What size ammeter? 100 amps, 50 amps, and what is a shunt?
I am a mechanical engineer but I know nothing about the ammeter stuff. A schematic would help and a brief description.

Thanks in advance for any help,

Weasel
Click to expand
When you say "two house batteries" I am assuming you mean two batteries permanently wired in parallel? You should not have two house "banks" but you can have multiple batteries all in one permanently wired contiguous bank. You do not want to "split" house banks. One start bank and one house bank. Even with two identical batteries, start and house, pick a battery as house and allow your other battery to remain healthy for starting purposes. The house bank is the one you monitor for SOC and the start bank is fine just looking at voltage.

Minimum size for a shunt, for main battery bank monitoring, where starting loads may be expected, should be 500A.

If you want the ultimate in simplicity buy an accurate volt meter that reads to the hundredths position and do not ever discharge your bank, at your average house discharge loads, below 12.15V or preferably 12.20V... For example if your average house load is 4.0A begin charging anytime you see 12.20V...

.
 
Gunni

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
I don't trust any of these elaborate state-of-charge calculator meters, and see them as a nominal feature. But I do use and value the +/- amperage readout, and the amp/hour recorder to assess where my energy budget is in relation to my usable 225 amp/hours of DC battery power. It is particularly useful for determining how much power some DC load may be drawing, and it helps me identify DC motors that are dying and loading up on resistance. On the charge side, having an amp meter lets me know how much charge I am sending to the battery, and where the battery is in the charge cycle. This is the tool that will tell you how much that OEM engine alternator really delivers to your battery, or when you might as well quit burning fuel through your generator.
 
druid

druid

.
Apr 22, 2009
837
Ontario 32 Pender Harbour
Wow - talk about making a simple thing complex! A simple ammeter will tell you a LOT about how much you are drawing from the batteries (more than a voltmeter). I suspect you have a separate (big!) wire going to your engine for starting and alternator charging. You should also have a smaller wire (should be red) going from your battery switch to your DC panel. Cut that one and install a $20 ammeter in it. Unless you have some VERY big draws (like an anchor winch or macerator) a 20A ammeter should be plenty - even a 10A might work. My fridge draws 2.7A, but yours may draw as much as 6 or so. If you're drawing more than 10A, your batteries won't last long...

A-h is not a hard thing to calculate: if you're drawing 5 A for 12 hrs, that's 60 A-h. Not rocket science...

druid
 
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