Battery charge gauge

[LFK]

After replacing a battery that wouldn't hold a charge (and not finding out until I was at the dock) I have decided to but an in-dash gauge that shows the level of my new battery's charge. I figure this way, if I'm listening to tuns or whatever I'll know when it's time to stop.... Likewise, when I get home I'll know when it's time to plug my charger in.

My question is this. For those of you who have experience with in-dash battery gauges, do you hook them up directly, or through your ignition switch?

The one I bought is backlit, so I'm leaning towards going through the ignition so that it's not sitting in my driveway draining my battery.

Suggestions? Ideas?

What's worked or hasn't worked for you..?

 

[ricksrster]

Re: Battery charge gauge

Is it a voltage gauge? if so, on the back of the gauge will be a post for 12+ IGN. This connects to your ignition on. There will be a GND for ground and another post for your light that connects to your navigation lights.

 

[Silvertip]

Re: Battery charge gauge

I must assume you are talking about a Voltmeter. If so, I doubt you will get any benefit from it if you hope it will tell you when to turn the electronics off. The battery will very likely read 12 volts but when you hit the key it drops like a rock to something under 10 volts and you get the dreaded "grunt - grunt". A voltmeter tells you what battery voltage is and when the engine is running it indicates how much the charging system is charging. It will typically read 13.5 volts or higher at speed. Unless you buy a "true battery gauge" which has a small load built into it, the voltmeter will be of little value to you. It's essential however if you want to know if the charging system is working.

 

[LFK]

Re: Battery charge gauge

Yea, I already have a voltmeter guage. The one I'm talking about is like the one I link below; it's a battery condition guage: http://www.cabelas.com/cabelas/en/t...=froogle&cm_pla=0240401&cm_ite=0001254010912a

The one I bought is a little different, but basically the same thing.

 

[LFK]

Re: Battery charge gauge

Sorry about the size of that link, using text-anchored links on this site doesn't seem to be working for me....

 

[bruceb58]

Re: Battery charge gauge

That battery condition guage is a fancy name for a voltmeter...nothing more.

You already have one of those! This will just be second guage that you really can not count on.

I suggest putting in a second battery and always starting your boat in your driveway before you set out on a trip.

 

[LFK]

Re: Battery charge gauge

That battery condition guage is a fancy name for a voltmeter...nothing more.

Your kidding?
My voltmeter looks like this, and measures the voltage of my circuit. http://shop.com.edgesuite.net/ccimg.shop.com/220000/227700/227715/products/lg_14694951.jpg

The battery condition guage should show me the current level of charge my battery has.

It's a battery tester vs a volt tester. When my boat is turned off, the voltmeter sits at zero but the battery condition meter shows the level of charge.

 

[bruceb58]

Re: Battery charge gauge

Nope...I am not kidding. They both measure volts and that's it.

Sounds like you were going to wire this one through your ignition swith too. It will also read 0 volts with the ignition off.

 

[Silvertip]

Re: Battery charge gauge

What do you think the numbers on that gauge mean? It's a common voltmeter. In other words, if you could pull the glass off your voltmeter, you could paint the three colors on the face and you'd magically have a battery condition gauge. I suggest you do an internet search for "Battery Load Testers" and "Hydrometers". Those are the only two ways to measure battery condition.

 

[LFK]

Re: Battery charge gauge

Dang it!

Okay, thanks guys...

Anyone want to buy a new Battery condition (voltmeter) gauge?

Drat!

 

[LFK]

Re: Battery charge gauge

Alright....how about this idea.

I hook up the guage I just bought to the battery via a switch. I have the empty hole for the guage in my dash, I could easily put a switch next to it. Then, on or off, I could flip the switch and check out the current charge of my battery.

Would that work?

 

[bruceb58]

Re: Battery charge gauge

Ebay!

Anyone want to buy a new Battery condition (voltmeter) gauge?

 

[Silvertip]

Re: Battery charge gauge

You seem hell-bent on making this gauge do something its not intended to do. It merely measures battery voltage. Presense of battery voltage does not tell you anything about the "condition" of the battery. There is a difference. It is no different than turning your ignition switch on and looking at the voltmeter you already have! It will tell you the same thing. Unless you measure voltage with a load (called a load test) or with a hydrometer (measures electrolyte specific gravity) the voltage means nothing. Look at it this way. At what voltage would you turn things off to ensure the engine would start? I would almost guarantee that if you let the battery get near the red on that gauge your engine would not start. The needle would drop to 8 volts the minute you hit the key. Why? Because there is no amp capacity left even if the voltage measured 10 volts. If installing this gauge is going to make you happy, install it. You'll then have two gauges that tell you your engine won't start.

 

[LFK]

Re: Battery charge gauge

Okay. Point taken. I'll leave it alone.

Thanks.

 

[jtexas]

Re: Battery charge gauge

voltmeter measures a battery's state of charge.

state of charge at 80ºF
12.65 = 100%
12.45 = 75%
12.24 = 50%
12.06 = 25%
11.89 = 0%
varies slightly with temp

But as you discovered, a battery with a weak cell or two can show good voltage while not having the power to crank your engine. Need a hydrometer to test individual cells.

Also, voltage reading will be elevated right after charging due to "surface charge" - a few seconds of cranking usually dissipates that.

 

[Silvertip]

Re: Battery charge gauge

JT's chart illustrates my point very clearly. Full charge to no charge is 0.76 volts. Chances are the voltmeter has that much error so for battery condition its a useless gauge. As a charging system gauge its valuable.

 

[jtexas]

Re: Battery charge gauge

digital...sorry, meant to say digital voltmeter measures a battery's state of charge...exactly as silvertip says...

 

[MASTER Brian]

Re: Battery charge gauge

I have a question on this subject. My fishfinder has a volt meter built in. It also has an alarm that can be set to tell when the volts drop below a certain threshold (user set), so you know your battery level has dropped below a certain level.

After reading this, that seems pretty useless does it not? It is nice to see if my battery is charging, but it would also be nice to know if battery charge level is going down too much with boat off, but accessories on.

One thing I have found is that the "LOW VOLTAGE" warning flashes when I start the boat. It stays until I clear it from the screen. Why would that be? Battery tested fine by O'reiley's and the charging system is new and apparently working fine.

Is the low volt alarm useless as a guide that battery volts are going down to where the boat won't start?

 

[Silvertip]

Re: Battery charge gauge

What do you want it to tell you? What we are trying to get across here is that a nearly dead flashlight battery will show its normal voltage until you turn it on. It then drops to zip. Same with your start battery. You simply do not know when the battery will not turn the starter. Some engines turn harder than others. That's a very fine line. Apparently with your locator, the low voltage alarm tells you voltage has dropped to the point where the locator will not work. That's totally different than whats required to spin the starter.

 

[MASTER Brian]

Re: Battery charge gauge

Silvertip, I believe I get both of your points. I just wonder why they put that feature on there if it's useless, more or less. No reason to sound an alarm telling me the locator will not work. That would be pretty obvious just by looking at it!

For what it's worth, the alarm can be set at any volt level. So I could set it at 12.45 and when it hits that point it would beep at me. I guess it's better than nothing if they do intend for it to be a low battery indicator. You could get a little warning that the battery is no longer 100% or in this example 75%. My motor also started on a battery showing 11.8V, so I guess I am lucky and have an easy starting engine.