Association Forum - Battery Strength

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

Battery Strength

New Topic

Topic Locked

Printer Friendly

Author

Topic

jerlim
Master Marine Consultant

Member Avatar

USA
1484 Posts

Initially Posted - 06/27/2007 : 07:11:19

Now that I have the solar panel, I can calculate the various loads/drains on the battery and also figure the likely recharging; allowing for inefficiencies, cloud cover etc....my question is - Are there any meters I can use to determine how well charged the battery actually is? So that when I get on-board, I can see how much 'juice' is available?
Many thanks!

Jerry

Edited by - on

DaveR
Master Marine Consultant

Members Avatar

USA
2015 Posts

Response Posted - 06/27/2007 : 07:18:30

I'm sure there are more extravagant gauges but I just use a cheap voltage meter, and Since I've become comfortable with my solar charger I rarely use that.

Edited by - on

OLarryR
Master Marine Consultant

Members Avatar

USA
3467 Posts

Response Posted - 06/27/2007 : 08:13:10

Agree the cheapest route that gives a sense of the battery strength is reading the volts off of a voltmeter. Though this does not give a real good feel for the amp drain and when under load. Still, the voltmeter is a good way to get a sense of the battery condition.

Slightly better is reading the voltage off of a solar controller. The controller has the extra benefit that you can see the readings all the time and that is a convenience. It will also indicate when the solar panel is charging or if the battery is fully charged or weak. I use a Morningstar Pro 15M controller.

Edited by - on

jerlim
Master Marine Consultant

Members Avatar

USA
1484 Posts

Response Posted - 06/27/2007 : 09:18:35

Thanks guys - great advice!

Edited by - on

Bill Arden
1st Mate

Members Avatar

USA
83 Posts

Response Posted - 06/27/2007 : 09:33:08

Here's some information I found from this site:

http://www.solarnavigator.net/battery_charging.htm

While the chemical thermodynamics people among us may bicker, I'd guess this is close enough for most of us. I use a similar chart for the solar charger on Prana.

State of Charge 12 Volt battery Volts per Cell

100% 12.7 2.12
90% 12.5 2.08
80% 12.42 2.07
70% 12.32 2.05
60% 12.20 2.03
50% 12.06 2.01
40% 11.9 1.98
30% 11.75 1.96
20% 11.58 1.93
10% 11.31 1.89
0 10.5 1.75

Edited by - on

Bill Arden
1st Mate

Members Avatar

USA
83 Posts

Response Posted - 06/27/2007 : 09:35:39

One more note: These voltages are measured with no load on the battery (i.e., everything turned off), and no charger operating. My solar charge controller is smart enough to vary the charging voltage, so all I read when it's connected is a ramping voltage that constantly varies.

Edited by - on

Bill Arden
1st Mate

Members Avatar

USA
83 Posts

Response Posted - 06/27/2007 : 09:44:08

Oh, @#$%

Sorry about the formatting of that table. I tried to do it with spaces, and didn't realize the editor would kill all the extra spaces.

The three column headings are "State of Charge", "12 Volt battery" and "Volts per Cell." The left-hand column ranges from 100% down to 0; the middle column ranges from 12.7 (at 100%) down to 10.5 (at 0%); the right-hand column ranges from 2.12 down to 1.75.

Hope that helps!

Edited by - on

OLarryR
Master Marine Consultant

Members Avatar

USA
3467 Posts

Response Posted - 06/27/2007 : 11:47:00

Bill,

I agree the solar controller measures the ramping voltage...except when the sun is not out or at a unfavorable angle. When the sun is not out or at a unfavorable angle, the controller (or at least mine) then reads the battery voltage without charging going on. If I start the motor and the sun is overhead, the solar amps on the controller goes to zero since the controller prevents the current going to/from the panel but then the controller reads the ramped up voltage from the motor charging....which i agree is not the actual battery voltage. The ramped up voltage is the voltage above the battery voltage needed to get the amps from the panel or the motor into the battery.

Edited by - on

Turk
Admiral

Members Avatar

USA
736 Posts

Response Posted - 06/27/2007 : 17:44:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jerlim
 Now that I have the solar panel, I can calculate the various loads/drains on the battery and also figure the likely recharging; allowing for inefficiencies, cloud cover etc....my question is - Are there any meters I can use to determine how well charged the battery actually is? So that when I get on-board, I can see how much 'juice' is available?
Many thanks!
<hr height="1" noshade id="quote"></blockquote id="quote">

Here is a link to a voltmeter panel I bought for my batteries for just this reason. Inexpensive and works great. I added a cheap monetary push button to view the voltage. Mounted it near my electrical panel.

http://www.marteltesttools.com/products.php?cat=113& action=detail& id=69

Edited by - on

Bubba
Admiral

Members Avatar

USA
542 Posts

Response Posted - 06/27/2007 : 18:48:18

I have the same volt meter. Since it only draws 3mA max, I didn't put a switch on it. It's on when a battery is switched on.

Edited by - on

SEAN
Admiral

Members Avatar

USA
772 Posts

Response Posted - 06/27/2007 : 18:54:54

you could get a battery moniter , xantex has one for $300 . i dont know if you want to know that much !! . But there nice tells how much amps are flowing in or out . And tells a % percentage of battery . they say not to let the battery go below 50 %
It also can calculate time left in hours or minutes .

Edited by - on

Tom Potter
Master Marine Consultant

Members Avatar

USA
1913 Posts

Response Posted - 06/27/2007 : 20:59:16

A lot of the newer depth finder/chart plotters units have "data overlays" which allows you to put the units data on the screen you have selected to use of the finder/plotter. I have my Lowrance set up to show the plotter screen when I turn the unit on, but in the corners of the screen is the water depth, boat speed, battery voltage, and the time.

Edited by - Tom Potter on 06/27/2007 21:42:48

atgep
Master Marine Consultant

Members Avatar

1009 Posts

Response Posted - 06/27/2007 : 23:05:51

I was very surprsed to find my Eagle chartplotter lacking the Voltage reading. It is available for all the lowrance products but not their stepchild brand, Eagle. The Eagle is the cats meow otherwise and costs less.

I have no problem with the batteries up here in the PNW. The motor is almost aways on!
Tom.

Edited by - on

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.