12 volt monitor

P

Plan C

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I have considered several ways of keeping an eye on battery levels. I saw what might be the best bet for me yesterday. WalMart has a "Battery Monitor" in automotive, "Innova #3721". It just plugs into the cigarette lighter and gives you a voltage readout. $15. Haven't tried it on the boat - just the car, but it looks accurate. It would be my choice to keep the batteries over 12 volts, with a max charge at 78 degrees of 12.75.

Dave
 
Dave, Battery voltage is only part of the story if you want to know what's left in the "tank". A Link 10 or Link 20 battery monitor will tell you the Amp Hours remaining. Once programmed, they are a valuable tool for those who spend time on the hook. My 2 cents worth, for what it's worth.
 
Roger tells the truth, 100%, love the peace of mind knowing what's happening with my batteries (VHF emergencies, starting the engine...etc). Also "safety items" get a free pass around the boat bucks kitty.
 
Here is the product description, apparently you can calculate amp hours remaining from measured amp hours consumed...assuming of course, you know how many amp hours you had when you started. I assume with my two 60 amp hour house batteries in parallel I have 120 amp hours to use.



Description

Single and Dual Battery Bank Monitors

Provides Battery Status Information At-A-Glance

Link 10 (part#84-2016-01) and Link 20 (part#84-2020-00) use sophisticated microprocessor technology to provide complete battery status information for one and two battery banks, respectively. Simple and easy-to-use multicolor displays show volts, amps, amp hours consumed, and operating time remaining. The Link 10 and 20 allow you to select Automatic, Sleep and Scanning modes and automatically calculate and display charging efficiency. The Link 20 can monitor a house bank and starting bank or two house bank batteries at the same time. By adding an optional prescaler, Link 10 can monitor single battery banks up to 500 volts.

Product Features

* Digital Numeric Display - LED display shows numeric read out of volts, amps, amp-hours and time remaining
* Easy to read multi-color LED bar graph
* Splash proof panels allow for outdoor mounting and hands free operation
* Displays key historical battery information such as charge efficiency, deepest discharge, and average discharge
* Compatible with 12 and 24 volt DC systems
* Works with any battery type
* Includes DC shunt (part#84-2010-00 for Link 10 and 84-2011-00 for Link 20)
* Low battery alarm contacts
* One year warranty

Accessories

* Color-coded, twisted pair cable (eases installation). Available in 25 (part#84-2014-00) or 50 foot lengths (part#84-2015-00).
* Prescalers (0-100 or 0-500 volts) to extend voltage range covered by your meter

Not recommended for use with Xantrex MS or RS Inverter/Chargers




dogon dory":trmo33x5 said:
So what does the monitor measure to tell you how many amp hours you have?
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Although I certainly agree it is ideal to have a link 10 or 20 (or equivilant) which uses a shunt and measures the actual current taken from the battery by the systems or going into the battery thru various charging sources, I have found thru the years that a simiple digital volt meter serves well. I slightly disagree that two 60 amp batteries you 120 amps to use. I try and never discharge a lead acid battery to less than 12.20 volts (which is 50 % of capacity). This really gives one 60 amps usuable amps in a battery bank which would theoretically have 120 amps if the battery was drained completely. One of the problems with any measurement of battery capacity is how rapidly the battery is drained. The lower the current flow, proportionately, the more capacity the battery has. There are several different ways of measuring battery capacity: starting with a constant 5 amp draw. In other words, the battery which was drawn down at one amp an hour would appear to have more capacity than the battery which was loaded at 100 amps an hour.

I have found that the simple volt meter has worked very well on sail boats where I was totally dependant on 12 volt systems to power auto pilot, nav instruments, lights, radios etc 24 hours a day for up to 20 days on a passage across an ocean. Our rule of thumb was when the steady state voltage of a battery bank fell to 12.20 volts we began to recharge the battery. Doing this will allow the battery last many years. One of the problems for us, was that we had multiple battery banks--and I still do, even in small boats. For the larger boats, we had engine start, gen start, house bank, electronics bank, inverter bank and windlass bank. I could not afford a Link system for all of the banks. Even in the TC 255, I will have 4 battery banks: one for each engine, one for "house" and a fourth for freezer/refigeration.

Incidently I have tried to get information from the % meters by Marcom--and the e-mails said to call. Technical assistance was not in, and did not return my call--so I still don't know what the % means--and this is why I went with the Blue Seas battery moniter, with a multiposition switch to measure the various battery banks.

More power to those who use the Link systems, or similar accumilinating amperage used--but the simple voltage--if steady state--can give a lot of information.
 
I don't have any depth of theoretical experience, however, I bought an electric car (conversion, 120 VDC) last fall and deal on a daily basis with battery state, therefore now have some practical experience. My car, by the way, has an E Meter, which is the same as the Link 10 (Xantrex bought them out). I find watching the voltage (on the E Meter) gives me a pretty good read on what the battery state is. I have become pretty well acquainted with how my battery pack behaves.

What does a Link 10 cost - $250? More? They can very easily be fried if you mess up the wiring. For $15 and something that goes in the cigarette lighter, that can read both batteries - I think this is a cheap wonder. I'll report further when I have used it for a while, and will check it against my VOM.

The electric car, by the way, has been an absolute success. I make lots of 1 mile each way round trips. It has saved starting my car 1400 times since November, and running without the engine getting warm.

Dave
 
BlackNorth":2qb2y5g6 said:
The electric car, by the way, has been an absolute success. I make lots of 1 mile each way round trips. It has saved starting my car 1400 times since November, and running without the engine getting warm.

Dave
Click to expand...

I'm waiting for this car to drop in price before going electric.

Don
 
Sneaks":35lhsonb said:
I'm waiting for this car to drop in price before going electric.
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I did not see a price on the site for the car, so you know it has to be incredibly expensive.

Now my question about electric cars. Where will we get all the electricity for them? Also, can you imagine getting in an accident and having all the weight coming forward?
 
oldgrowth":2cc9870s said:
I did not see a price on the site for the car, so you know it has to be incredibly expensive.
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Jeeze, Dave, is a fully rigged C-25 incredibly expensive? Actually, a better writeup on it is over here and the target price for the "sedan" version is about the same as an outfitted C-22.

A typical San Francisco viewpoint is in this article.

Only the first 100 will make folks cringe (except DaNerd of course). $100,000 each, fully equipped, fully optioned and with special "Collector Series" graphics and options which include a Blaupunkt Navigation System. Hurry, there's only a few openings left....

Don
 
You're welcome, Dan. When was your Green epiphany?

Born in Berkeley, CA, with a mother who worked at UC Berkeley through the '60's (remember Forward Under Clark Kerr?) an aunt who worked for the Berkeley City Council, and a cousin who taught english in Oakland for decades, I've successfully resisted "The Calling."

Neat car, neat concept. But it won't tow a C-Dory....

Don
 
Hi Folks,

I purchased a combination battery monitor, 12 volt plug, and three fuse switches. Made by Perko. Gives me a place to plug in my GPS, spot light, and cell phone in the evening.

It has a little button, that when pushed, gives the voltage of the battery I am using.

Simple and good to have.

Fred
 
Unfortunately the analog meters are not accurate enough to be of a lot of value in battery management, even with an expanded scale in the 10 to 18 volt range. (There are accurate analog meters, but not in the combo panels in my experience)
 
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