Hi Mark
Two concerns with that meter - it isn't likely sealed, and it does not
mention how much current it draws while on. The first you could address
by buying a couple of them for spares, and I'd wire it up in line with a
"momentary on" switch so you only have it powered when you press the
switch, thus limiting the current draw.
I've got a pair of DMS-20PC-0-DCM-C
<http://www.digikey.ca/product-search/en?KeyWords=dms-20pc-0-dcm-c&WT.z_header=search_go>
meters, they draw 13 mA and are epoxy encapsulated, just a pair of screw
terminals sticking out of the epoxy on the back. But they also cost 10x
the one you list... They are 6 years old and working perfectly.
Graham Collins
Secret Plans
C&C 35-III #11
On 2015-02-02 2:57 PM, Dr. Mark Bodnar via CnC-List wrote:
Josh,
Thanks for the info on using voltage to gauge battery level.
With my tiny bank and very limited loads it does not make sense to be
wiring in a monitor or Balmar Smart Gauge (to the tune of $360 cdn).
But I was thinking about adding a voltmeter so I could maintain some
track on drain.
Say something like
http://www.amazon.com/DROK-Voltmeter-3-50-30-0V-Anti-reverse-Protection/dp/B00DUTJXWO/ref=sr_1_8?s=automotive&ie=UTF8&qid=1422902563&sr=1-8&keywords=voltage+meter&pebp=1422902722997&peasin=B00DUTJXWO
I have to hook up and figure out how to mount my solar panel this
spring, and I will re-wire my 1-2-off switch as per MaineSail's
instructions. Rather than going to a "starting bank" and a "house
bank" - I'll likely stick with A bank and B bank - use them
interchangeably for starting and house.
Mark
There is no cure for birth and death save to enjoy the interval.
- George Santayana
On 2015-02-02 1:20 PM, Josh Muckley via CnC-List wrote:
What you are looking for is an amp-hour meter. Discharging a flooded
deep cycle battery rated at 100 Ahrs below 50% should be avoided.
This roughly equates to 50 Ahrs of use. 5amp for 10hours or 50 amps
for 1 hour....you get the jist. Discharging a flooded deep cycle
below 50% will decrease its effective useful service life. Many
batteries publish a the number of cycles and depth of discharge. One
loose rating convention is that a deep cycle will survive 200
charge/discharge cycles of 50%. The cycle number increases when the
depth of discharge is reduced.
When using a voltage meter, it is important to take a "no load"
voltage after the battery has had time to "recover". The easy way to
remember a capacity to voltage conversion is 0.1v per 10%. A fully
charged battery will read 12.7v and a fully discharged one will read
~11.7v. By this convention one should avoid voltage readings below
12.2v. I have a total of 500Ahrs between 2 banks so when one gets to
a "loaded" voltage of 12.2v I start considering a switch to the other
battery. I can go about 2 days in the middle of summer with no
charging source before I start to worry. The engine charges at
100amps so motoring on and of the hook keeps me pretty well topped up.
I put one of these in my first sailboat. It is similar to the Link
2000 that Edd suggested. I have a Link 2000 installed on my current
boat but it has never worked right. I believe the current shunt is
bad or somehow bypassed on the charge or discharge circuit.....I'll
get to it...
http://www.altestore.com/store/Meters-Communications-Site-Analysis/Meters-Battery-Monitors/Ammeters-Voltmeters-Battery-Monitors/Bogart-Engineering-TM-2025-A-F-TriMetric-Meter-Includes-fuse-and-fuse-holder/p10112/
Josh Muckley
S/V Sea Hawk
1989 C&C 37+
Solomons, MD
On Feb 2, 2015 8:27 AM, "David Knecht via CnC-List"
<cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote:
Looking at the wiring diagrams reminded me of a question I am
sure this list can answer. I have not done much cruising yet,
but plan to do more in the future. One of the things I am unsure
of is how people monitor the state of their batteries when you
know shore power is not going to be available. I have a digital
voltmeter on the panel that I can check the batteries and a chart
that translates voltage into percent charge and I have used that
as a rough guide, but that seems crude for such an important
function. My understanding is that you have let the batteries
sit for a while if they have been charging to get an accurate
reading. I am not sure if current draws also have to be off.
For instance, how would I know if it is safe to run the
refrigeration while sailing to the next destination? Can you get
a meter that gives you “hours of battery life remaining”? What
strategies to listers use to solve this problem? Thanks- Dave
Aries
1990 C&C 34+
New London, CT
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