Jump to content
Temkin

Added Volt Meters to Dual Battery Set Up

Recommended Posts

I put two cheap volt meters in small project boxes with a pulse switch and attached them to my dual battery setup.  Cost per box was about $12.

I know it's overkill but it's nice to be able to quickly check the volts on both batteries when I already have the hood raised checking the oil before each outing.

IMG_6837%20with%20text_zpskypdf4go.jpg

Edited by Temkin
Added Photo.

Share this post


Link to post
Share on other sites

I don't mean to sound like a jerk!! So please don't take it that way.....

What comes to mind is: Are the volt meter ignition protected? Do you need to open the engine compartment to read them?

I installed this just over my wet bar  http://www.defender.com/product3.jsp?path=-1|328|2289954|2289950&id=724613

I have twin engines so for the 3 banks this works. I just wished it showed more levels of the battery being drained. But for 48 bucks and a 4 wire hook up, its hard to complain.

On the other hand and just a suggestion: Install one meter in a covenant location and use a on-off-on switch. Meaning bank one "on" - meter "off" and bank 2 "on".   

Share this post


Link to post
Share on other sites

Excellent, IMO, not overkill as I plan on doing the same.....But, FWIW, for an accurate voltage reading that you can trust, the batteries MUST be under a load when checking the voltage. A "weak" battery in need of a charge can easily show 12 volts when no load is being applied, and can fail you when "cranking amps" are needed.

Share this post


Link to post
Share on other sites
59 minutes ago, Iggy said:

I don't mean to sound like a jerk!! So please don't take it that way.....

What comes to mind is: Are the volt meter ignition protected? Do you need to open the engine compartment to read them?

I installed this just over my wet bar  http://www.defender.com/product3.jsp?path=-1|328|2289954|2289950&id=724613

I have twin engines so for the 3 banks this works. I just wished it showed more levels of the battery being drained. But for 48 bucks and a 4 wire hook up, its hard to complain.

On the other hand and just a suggestion: Install one meter in a covenant location and use a on-off-on switch. Meaning bank one "on" - meter "off" and bank 2 "on".   

You don't sound like a jerk to me.  The meters are connected directly and separately to the two batteries inside the engine compartment so yes I have to open the compartment to read them.  They are inactive unless I'm pushing the pulse switches on the back of each project boxes (2 seconds each).  Once underway and under load (SNiC's valid comment above) I rely on the volt meter in my instrument panel, which I understand only tells me the status of the selected battery.

I like the Defender system you put it.  It's just more than I need.

I've been around boats for 50 years and my biggest concerns have always been; 1: running out of gas (I keep 1.5 gal. of gas in a 2.5 gal. commercial gas can on board); and 2: failing batteries.  

Along with my dual battery setup I also carry a 600 amp XP-10 jump charger in case my batts fail, or someone on the lake needs a jump start.  From experience I know better than to use jumper cables which on one occasion fried the electrical system in my SUV.

Thanks for the comments.

Share this post


Link to post
Share on other sites

You can add a battery combiner that will charge both batteries no matter how your switch is set. Just a thought.............

Share this post


Link to post
Share on other sites
3 minutes ago, Iggy said:

You can add a battery combiner that will charge both batteries no matter how your switch is set. Just a thought.............

I usually run with both batts selected which changes both.  I also have battery tenders I plug in when I leave my marina slip.

Do you have a suggestion about what battery combiner to use?

Edited by Temkin
Forgot a question.

Share this post


Link to post
Share on other sites

I have to disagree with batteries having to be under load to check voltage. Testing the static (at rest) voltage is an absolute indication of their state of charge, which is what a volt meter is there for. Testing the voltage while under load, is misleading, unless you knew the draw and had a chart to calculate what the voltage should be under said constant draw. 

 

I do agree that a battery showing 12V is in need of a charge. In fact, 12V is about 75% depleted and should be charged. 

 

If I was to make a suggestion to the OP. Move the stereo/amp B+ to the common of the switch. Install a ground BUS to reduce the number of ground lugs on that one battery.  

Share this post


Link to post
Share on other sites
11 minutes ago, Was_Wylie_Tunes said:

I have to disagree with batteries having to be under load to check voltage . Testing the static (at rest) voltage is an absolute indication of their state of charge, ... 

With all due respect, I suggest you research your opinion regarding this issue..........It also depends on the definition of "charged" vs."dependability"
I for one am more concerned with the "dependability"....

Share this post


Link to post
Share on other sites

I've heard it both ways, volts on a passive vs. a battery under load, thus why I check both.  My volt readings from the meters on the battery and the instrument panel typically are 12.4.

I agree batt 2 has too many ground connections.  Good advice and I'll look at changing that. 

Share this post


Link to post
Share on other sites

How many amps does the starter pull ? Does the motor start in less than 2 seconds everytime? Good tight clean connections ? Is the battery BIG enough  to crank for 1 minute if needed ? Is it still at 12.00 vdc or higher after 1 minute of cranking.

I am concerned if the engine cranks more than a 1/4 of a second to run. Something is going downhill.

Share this post


Link to post
Share on other sites
29 minutes ago, SNiC said:

With all due respect, I suggest you research your opinion regarding this issue..........It also depends on the definition of "charged" vs."dependability"
I for one am more concerned with the "dependability"....

I did not state an opinion, so nothing more to research. Charged is charged and dependability is a roll of the dice as a battery can take a dump at any given time. My definition of charged, is based on what the industry feels is the state of charge for a 12V battery. 12.8-13 is typically 100%. 11.5-11.8 is typically 0% give or take a couple tenths and who the source is. So, if a battery has a static charge of 12V, it nearlt depleted. Now, depleted doesnt mean bad, just means its down and needs to be recharged. 

As a battery ages, both time and cycles, its rate of recovery decreases. Meaning, that the static charge it had when new, it will not be able to reach with some age and use. Again, this doesnt mean its bad. However, it will get to a point where its dependability is questionable. Even then, its still a guess on when it will or might leave you hanging. 

There is a huge difference between load testing the health of a battery and simply monitoring the state of charge while on the water. What the OP is doing, is the later. He simply wants to know the state of the voltage, so he can either turn off the loads or fire the engines or plug the shore charger up upon returning to the dock.. 

What you are describing is a 20th century means of testing a battery. Those old toaster-tester heater grids with a needle and chart. Most people never got it right, cause they overlooked the static voltage prior to hitting the load. A low battery, good or bad, wont load test as well as a fully charged battery. 

Please explain what amperage you use, how you regulate it, how long you apply the load, and what algorithm is used to calculate what an acceptable voltage at said load x time, is. 

Share this post


Link to post
Share on other sites

 I like a separate MASSIVE minus stud for taking all the battery negative cables & equipment negative cables.  No speaker hums. Any unconnected negative cable is very obvious that way. Also tightening 1 nut,  makes every negative connection tight.

Share this post


Link to post
Share on other sites

Wyile....Once again I must say, "with all due respect"; and thanks, as I do appreciate and respect your response.

Cheers 

Share this post


Link to post
Share on other sites
8 minutes ago, cyclops2 said:

How many amps does the starter pull ? Does the motor start in less than 2 seconds everytime? Good tight clean connections ? Is the battery BIG enough  to crank for 1 minute if needed ? Is it still at 12.00 vdc or higher after 1 minute of cranking.

I am concerned if the engine cranks more than a 1/4 of a second to run. Something is going downhill.

I'm not in the fight about passive vs. under load voltages.

My 2008 Mag 350 engine with 280 hours on it starts in about 2-3 seconds.  I asked and was told this was typical for that motor.  It has consistently started like this for the 3 years I've owned it.  I've never had to run the starter for a minute but feel confident my batts could do that easily and no speaker hum.  So far, so good.

Share this post


Link to post
Share on other sites

A bit off topic, but, there should be only 1 wire connected to each battery terminal (2 if you have an onboard shorepower charger)- postive to a battery switch and negative to the common groun, and then, postivie to an electrical distribution panel or block. Everything else should be connected either to the switch terminals or distribution block. Sorry, I would never do it this way

Share this post


Link to post
Share on other sites
1 hour ago, SNiC said:

Wyile....Once again I must say, "with all due respect"; and thanks, as I do appreciate and respect your response.

Cheers 

WWT,

I too agree with your analysis. A fully charged battery would expect to see 12.8-12.9v. Moderately charged at 12.6-12.8v and a weaken charged battery at 12.4 and below.

This will easily determine the state of charge. Will it determine the true cranking amps or longevity.? Not necessarily but you stated the obvious, correctly.

Share this post


Link to post
Share on other sites

Here's a similar solution that I posted a couple of years ago:
 

Benefits: one voltage display, on/off/on momentary switch, remote mounted (on mine, mounted next to the battery switch).

 

Share this post


Link to post
Share on other sites

All this debating when all you really need is one of these.  I can charge my phones, ipads and anything else by usb as well as monitor my battery.  You can easily monitor your battery under load while charging, playing stereo...etc,  without having to raise any hatches to check batteries.  If you want to monitor each battery separately just flip the battery switch to get an instant reading.  Cost me 7 bucks.  

https://www.amazon.com/gp/product/B00EZ0A51U/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Share this post


Link to post
Share on other sites

voltage is good indicator to use, but unless under load you are not getting the whole story on the battery.

 

Cool set up, but doesn't the dash tell you the same thing?

Share this post


Link to post
Share on other sites
12 hours ago, Temkin said:

I usually run with both batts selected which changes both.  I also have battery tenders I plug in when I leave my marina slip.

Do you have a suggestion about what battery combiner to use?

https://www.bluesea.com/products/7601/m-Series__Automatic_Charging_Relay_-_12_24V_DC_65A

Now you can add a switch at the helm connecting ground. So now you can control when to use the combiner or not. But basically, if ether battery sees a charge voltage (engine running) the VSR will close. When the engine stops, the VSR will open.

Share this post


Link to post
Share on other sites
1 hour ago, IndyChap said:

Might take a look at this.  I plan on installing this outside the engine compartment for quick check of each BATT while hanging in party cove.  

https://www.amazon.com/Amarine-made-PN-TV1-4-Digital-Battery-Voltmeter/dp/B00V4MLPZC/ref=sr_1_1?ie=UTF8&qid=1467985566&sr=8-1&keywords=Amarine-made+PN-TV1-4

 

 

 

Nice find!! Very fairly priced at $24.

Only one review so far, so that's a bit of a concern. But, for the price, worth the risk.

Share this post


Link to post
Share on other sites
11 hours ago, bob and betsy said:

WWT,

I too agree with your analysis. A fully charged battery would expect to see 12.8-12.9v. Moderately charged at 12.6-12.8v and a weaken charged battery at 12.4 and below.

This will easily determine the state of charge. Will it determine the true cranking amps or longevity.? Not necessarily but you stated the obvious, correctly.

Wylie and B&B-

My Rockford Fosgate head unit has a voltage meter that will typically read around 12.3 when the motor is off. I've seen it go as low as 11.9.   When the engine (alternator) is running,  it reads between 13.9 and 14.1 The specs for the radio (PMX-5) say Operating range is 10.5V to 16V.   How could the radio play if you're saying the battery is depleted at <12V?  Also, when the meter shows 11.9, my boat still starts just as quick as it normally does.  

I'm not arguing with you, just trying to learn more.  Thanks,

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×