Install a Volt or Amp meter, or both?

[One Chance]

Looking for some advice on installing a voltage meter &/or an amp meter or both. Am considering on installing next to my circuit panel. Would like to have a way to monitor electrical system when engine is charging and after engine is stopped. Any suggestions would be much appreciated! Thanks in advance-One Chance.

[Sailmonkey]

how about both?

Victron Energy BMV700 Amp Hour Meter for one battery bank

[jeepbluetj]

Look into a battery monitor. They'll tell you volts, amps (in or out) and a pretty good idea of charge remaining. (Just google Marine Battery Monitor for an idea of what I'm talking about)

[radar_x]

I have two Victrons - the 602 and 602s. Which I guess is the previous model to the 700 series.

Here they are installed above my circuit panel: Imgur: The most awesome images on the Internet

I use the 602 to monitor my dedicated inverter house bank (2 deep cycle batteries in parallel), and the 602s to monitor my dedicated DC battery, and my dedicated starter battery. The 602s allows me to monitor two banks at once - since the DC and starting battery are separate. Although the 602s only shows voltage of the second bank - not all the details. Which is all I need for the starting battery.

Running the cables was a pain, but the installation itself was super easy. They show voltage, amp hours, state of charge, time to go, and how much power is flowing in or out.

I couldn't live without them. First thing I installed. Highly recommend.

[exMaggieDrum]

I consider a volt-amp meter absolutely mandatory equipment on my boat - digital. I am a marine electrician and understand completely how a meter that calculates battery capacity are supposed to work. In my experience they are not very useful and can be misleading. Some seem to find them useful but if you do use one you need to understand why they may not be giving you accurate readings and how to recalibrate them. I find them more trouble than they are worth. You need to understand what volts and amps mean on a boat. The voltage will tell you when you need to recharge the batteries and the amps help you understand why things are happening and how fast. Recommend you get one of the marine electricity books and study a bit. Basic cruising boat 101.

[Stu Jackson]

Coulomb counter battery monitors need to be re-calibrated regularly after a full charge.

This is NOT rocket science and simply requires a quick "reset" which may mean holding one button down until the light flashes and pushing the other reset button.

Sheez, if you can run a sailboat, ya oughta be able to figure this one out!

Seriously, the amount of drivel I've read about this on boating forums is simply nonsense. RTFM!

That said, part of RTFM is to understand the DEFAULT settings, which are usually for a 200 ah bank, and what FULL actually means as far as the algorithm in the computer chip is concerned.

Like this:

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

Link-series Charging Algorithms -- The "Gotcha" Factor!

DEFAULTS are factory settings that are made to be modified to suit your setup.

Maine Sail covers it in his battery monitor writeup but in a lot less boring detail.

Also recognize that depending on where in the circuit you install a separate ammeter, and certainly with shunts for counter monitors, you are reading the NET system current. This means:

Alternator Output 40A

Fridge load 5A

Instruments & lights 10A

Monitor reading will be 25A

If you put an ammeter inline with ONLY the alternator output, it'll read 40A, zero when the engine is off.

If you run your bilge pump off your reserve bank, but are reading the house bank on your monitor, guess what?!?

Also there's this:

Ammeters & Shunts 101: Ammeters & Shunts 101

Good luck.

[exMaggieDrum]

Originally Posted by Stu Jackson

Coulomb counter battery monitors need to be re-calibrated regularly after a full charge.

This is NOT rocket science and simply requires a quick "reset" which may mean holding one button down until the light flashes and pushing the other reset button.

Sheez, if you can run a sailboat, ya oughta be able to figure this one out!

Seriously, the amount of drivel I've read about this on boating forums is simply nonsense. RTFM!

That said, part of RTFM is to understand the DEFAULT settings, which are usually for a 200 ah bank, and what FULL actually means as far as the algorithm in the computer chip is concerned.

Like this:

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

Link-series Charging Algorithms -- The "Gotcha" Factor!

DEFAULTS are factory settings that are made to be modified to suit your setup.

Maine Sail covers it in his battery monitor writeup but in a lot less boring detail.

Also recognize that depending on where in the circuit you install a separate ammeter, and certainly with shunts for counter monitors, you are reading the NET system current. This means:

Alternator Output 40A

Fridge load 5A

Instruments & lights 10A

Monitor reading will be 25A

If you put an ammeter inline with ONLY the alternator output, it'll read 40A, zero when the engine is off.

If you run your bilge pump off your reserve bank, but are reading the house bank on your monitor, guess what?!?

Also there's this:

Ammeters & Shunts 101: Ammeters & Shunts 101

Good luck.

Gotta love it when someone dismisses a someone else's point by calling it drivel and then produces their own as if it isn't.

Please enlighten the rest of us why one should go through the trouble of setting strange parameters on these non-rocket science devices. If it gave someone some essential bit of information that is not available through any other means that would be one thing (if the info was in fact correct). But the issue I have is: what decision would or should you make based on having the calculated battery capacity - which is likely incorrect unless you go through repeated resets of these devices - that you could not decide by the voltage?

I went through that for two years with my own Link 20 dutifully resetting the little guy and finally decided it was a waste of my time. I still had to recharge the batteries when they got to a certain voltage. I still had to monitor my amp uses and sources. I still had to worry that I was losing capacity or not. But if the Link 20 is so good at determining true battery capacity then the pro shops would be using them to do so - and they aren't. At least so far as I have ever seen.

And a good battery capacity tester for deep cycle batteries would be a huge benefit to the industry. As of right now the only good test is to set up a constant known drain after rigorously fully charging a battery for a set time, and then measure the voltage!

We had the fancy, and very expensive, capacitance battery testers and found them to be essentially useless. Carbon pile testers are OK for start batteries. But nothing has come out of the drawing boards to provide good, reliable capacity testing of deep cycle batteries. Call up the battery manufacturers (like Trojan) and that is what they will tell you.

I am very willing to use something that benefits me and my precious batteries but so far, IMHO, battery monitors are not one of them. That's my drivel and I am sticking to it. BTW - I loved my Link 20 and wish I had one for my current boat. I have a Link 10 left over I may put in. They are very nice for what they do best.

The discussion on net amps is spot on. When troubleshooting or just trying to understand what is happening with your battery system you need to isolate sources and uses of the batteries to see where your amps are really coming or going. Net amps is good info but not enough.

[Stu Jackson]

exMD, sorry about the drivel comment. I should have used the phrase "misinformation bandied about" which is what I hear many times about the difficulties people have with counters. It was particularly addressed to the " In my experience they are not very useful and can be misleading" which you followed by saying yes, one needs to learn how to use them. Well...???

They aren't perfect, but if a skipper reads the manual and helpful internet posts about the way they work, it is rather simple.

Unfortunately, the Link 10 and 20 units left a lot to be desired. The transition from Heart to Xantrex went from knowledgeable assistance to dumb & dumber. The failure rate on those was very high.

The manuals had less & less information about how they worked, and folks like Maine Sail provided important information not found elsewhere.

Many of his posts told the story of when he bought his current boat from the prior owners who had cruised for many years with no sophisticated instrumentation and the batteries remained in good shape when cycled between 50% and 85%.

I also agree with you that a voltmeter and an ammeter (not the OEM in the cockpit unless one understands) on board are the first thing to do, followed by anything else.

I've been involved in boat electric systems for almost 20 years. I admire your posts. I just find it somewhat disconcerting when the counters, which can help most boaters understand their systems much better, seem to dismissed for the wrong reasons.

Maine Sail and I have both seen, first hand, how incorrect installations and wrong settings mess them up. That simply isn't the fault of the instruments.

One of the things they do best is to show boaters that what goes back in takes a lot longer than what comes out. You & I call it battery acceptance, and many still do not understand the concept.

Glad we agree on net amps! In many discussions, when folks install solar systems, they have posted indicating they don't understand this concept either. We'd be rich if we shared $1 for each time we heard or read: "I just installed my solar system and am showing 10A when motoring. What does this mean?"

If you have a V & A and know how to read them and HOW AND WHERE THEY ARE INSTALLED in the system, especially the A, then information is available. I simply find a counter to be helpful, especially when determining when a bank reaches full or when the engine can be turned off to avoid wasteful running.

Thanks again for helping me to clarify.

[onestepcsy37]

You guys are working way too hard. I've been using a digital voltmeter wired directly to the battery bank - 4 golf carts - for the past ten years. Tells me everything I need to know. Last set of golf carts lasted 6 years. No resetting or calculating involved.

[exMaggieDrum]

Stu - we are on the same page.

One of my concerns, from experience, is that some owners try to use the battery capacity readings as all they need to know. Then they get upset when the batteries never get up to 100%, or how it shows them they are at 80% and then the lights dim when they turn on the "whatever".

We used to carry Heart Interface inverters and the Link 10/20, etc. But after Xantrex came along the quality of the gear went down and customer support (even worse vendor support) went down the tubes. They wouldn't return phone calls or emails. We dropped them from our parts room. We would install them if a customer insisted but told then they would have to deal with Xantrex for any repairs and other support. Too bad since they had some good gear. I just got an email from the new owner of my old boat. I installed a Freedom 20 in it in 2002. He thought the inverter had finally gone bad but just heard it is working now, so it has had a long useful life. We full time cruised with it and they do to.

Any way, all good. I share your frustrations with people who do not take the time to understand their boat systems, and, a lot of the misinformation out there.

[Stu Jackson]

Originally Posted by exMaggieDrum

Stu - we are on the same page. ................

Any way, all good. I share your frustrations with people who do not take the time to understand their boat systems, and, a lot of the misinformation out there.

Yup, sounds all good. Maybe we can help Dockhead with his multiple ammeter concept.

[Snore]

When I upgraded I followed Maine Sails logic. A Balmar Smart Gauge wired to the house batteries as primary bank to monitor and a Victron 700 wired to the start battery, but tracking watts across th common ground.

Works Great!!

[exMaggieDrum]

Another "essential" piece of gear in my boat is a clamp-on ammeter, so I can measure solar amps, or alternator amps, or whatever amps, direct and not "net" as a boat wide ammeter would do. If I am suspicious of something or just want to make sure I understand how the boat systems are doing, I whip it out.

I actually prefer a separate ammeter built in to a solar charge regulator but the clamp-on works too if I can get to the wires easily.