Battery Monitor Manufacturers

Richard19068 · May 4, 2009

I just read about these. Don't know anything about them but looks interesting.

http://www.argusanalyzers.com/

Chuckbear · May 4, 2009

IMO the Victron are the absolute best available

http://shop.pkys.com/index.asp?PageAction=MFGSEARCH&ManfID=4&Page=1

Chuck

sailingdog · May 4, 2009

Victron makes a good battery monitor, as does Blue Sea.

There are also some more expensive ones like the Pentametric and Trimetric battery monitors, made by Bogart Engineering.

Maine Sail · May 4, 2009

Victron !!

I vote Victron too. They actually made the Xantrex XBM for Xantrex. The Victron's cost less money are very, very reliable and easier to hook up (cat 5 type connector). Jamestown Distributors sells them.. My XBM is a Victron and it replaced a faulty and buggy Link 10...

tsmwebb · May 4, 2009

The Victron looks like good kit.

The potential buyer might be advised to read their doc :http://www.victronenergy.com/upload/documents/Manual - BMV 600 602 - rev 07 - EN NL FR DE ES.pdf

Note that the monitor must have a correct Peukert value to work. It is an exponential value so very small errors in this value will be strongly amplified in the results. It changes with age and ought to be updated regularly. It can only be correctly found by completely discharging the battery bank twice. Implementing Peukert is not trivial and I know that some manufactures have mucked it up. I'm a little concerned that the Victron uses both a Perkert and an efficiency rating as the later should be included in the former. It would be very nice to see their code.

Even if you do all of that, the monitor requires resetting on a regular basis to clear out errors. (I've included a quote from their manual below).

These kinds of issues are common to all state of charge monitors. Monitors can be very helpful, but users should be aware of the shortcomings of these devices. They will collect errors over time. It is important to keep an eye on the fundamentals (amps, volts acceptance &c) and not to blindly follow a percent of capacity display.

--Tom.

2.3.4 Synchronizing the BMV
For a reliable readout of the state of charge of your battery, the battery
monitor has to be synchronized regularly with the battery and charger. This
is accomplished by fully charging the battery. When the charger is operating
in the ‘float’ stage, the charger considers the battery full. At this moment the
BMV must also determine that the battery is full. Now the Amp hour count
can be reset to zero and the state-of-charge reading can be set to 100.0%.
By precisely adjusting the charged-parameters in the BMV, the battery
monitor can automatically synchronize with the charger when the ‘float’
stage is reached. The range of the charged parameters is wide enough to
adjust the BMV to most battery charging methods.

When the voltage supply to the BMV has been interrupted, the battery
monitor must be resynchronized before it can operate correctly.

Please note that regularly (at least once per month) fully charging your
battery not only keeps it in sync with the BMV, but also prevents substantial
capacity loss of your battery which limits it’s lifetime.

Chuckbear · May 4, 2009

Almost all monitors need the correct Peukert value to provide accurate information. Setting up and maintaining the Victron is not much different from other monitors except it seems to me to be a better built, better engineered piece of equipment. Not sure why you see that as a negative. Chuck

Maine Sail · May 4, 2009

tsmwebb said:
It is important to keep an eye on the fundamentals (amps, volts acceptance &c) and not to blindly follow a percent of capacity display.

Personally battery % of charge is a screen I rarely use. The only time I totally trust it is when I am at 100% after a few days of solar charging and non boat use. When I know it is at 100% for sure I then recalibrate it. From there I simply monitor amps out and amps in. I've never seen much use in monitoring the volts because when I am on board I am drawing current so volts will be inaccurate for judging SOC. I only use the % of charge as a very rough guide line and usually just monitor how many amp hours I am down...

tsmwebb · May 4, 2009

Chuckbear said:
Almost all monitors need the correct Peukert value to provide accurate information. Setting up and maintaining the Victron is not much different from other monitors except it seems to me to be a better built, better engineered piece of equipment. Not sure why you see that as a negative. Chuck

Sorry, my bad.

All functional monitors need a correct Peukert. I'm not picking on Victron at all. They were kind enough to put their manual on the net and folks are recommending them so I was just using them as an example. Assuming they are the best in class and they document that they must be reset frequently in order to zero out their errors it follows that all energy monitors must be frequently reset. There are a couple of statements in their manual that make me cringe a little but I'll take it on faith that they work as well as any other battery monitors.

My fear is that naive folks will assume an energy monitor is like a tank gage. That it measures the contents of the battery and if there are any errors they will tend to be consistent(eg. 1/4 full will always be 1/4 full). But, energy monitors are not battery gages. They do not measure the contents of the battery. Energy monitors monitor the flow of amps in and out of a battery and from that infer the state of charge. This is somewhat like attempting to measure the contents of a water tank using an air flow sensor on the vent pipe. If you set it all up with great care it can be done, but there is lots of room for error. In practice there will be errors, and they will be cumulative. The implication is that if you look at the state of charge reading on a monitor and do not know the history of the particular charge cycle you are in, you have no idea how much error you are seeing. That is a reading of 1/4 full might mean empty or full. You just don't know. You can't even make an educated guess.

Now, properly set-up, an engergy monitor should reset itself often enough that it will not be wildly out of whack at any given time. They certainly can be used effectively. And I use one myself. However, on a long cruise when you're not fully recharging the bank your monitor may well become seriously misleading. AFIK, none of the devices available now provides an expected error reading or even a time since the last reset as a part of its main display. So, it is up to the user to be aware that there will be errors and that will get larger and larger until the unit is reset.

--Tom.

Chuckbear · May 4, 2009

OK Tom, so what would you suggest for folks to use to monitor their batteries and charging system? I think most of us understand the requirements for installing and using these types of monitors. It is our need to have this information available that we install them. I doubt anyone seriously considering installing a monitor considers it anything like a tank gage. If that were the case a simple voltage meter, which most boats already have, would be all we would need. Chuck

Deadhead · May 4, 2009

Ditto on the Victron

I installed mine this past winter. I also purchased it from Jamestown Distributors. Very prompt delivery. The kit included all wire necessary to complete the install. The shunt is mounted on a plastic base that is somewhat fragile - I mounted it on a block & ended up cracking it when I tightened the bolts.

In addition to costing less the Victron draws about half the current than the LinkPro. I am very satisfied so far.

tsmwebb · May 4, 2009

Chuckbear said:
OK Tom, so what would you suggest for folks to use to monitor their batteries and charging system?

For monitoring batteries, battery monitors are as good as it gets. They just aren't so good that you just take them at face value. The user needs to apply a little skill and thought when working with them. I use mine mostly as a dedicated multi-meter and find it provides good info on state of charge; just not so much on the state of charge screen.

Charging systems should be regulated by voltage, time, battery temperature and, perhaps, acceptance rate. They don't need energy monitors.

I think most of us understand the requirements for installing and using these types of monitors. It is our need to have this information available that we install them. I doubt anyone seriously considering installing a monitor considers it anything like a tank gage.

To be clear, I'm not suggesting that folks think the monitor has a float inside the battery that measures watt volume or something. I'm suggesting that people mistakenly assume the gage reading behaves the same way a tank gage reading does. That is, they think a 1/8 tank reading is analogous to a 1/8 energy monitor reading. I'm particularly concerned that these sad people will expect REPEATABILITY from their monitor in they way that they do of tank gages. That is, if you fill you gas tank to 3/4 every time it gets to 1/8 you might expect to be able to repeat this a great many times without any serious loss of accuracy. You can not do this with an energy monitor and expect to get accurate or consistent results.

Folks with even a semi-active geek gene will be able to grok the basic problems here. But, many folks have these kinds of systems installed by a tech and never fully understand them. I've been asked questions by people about their monitors that made it very clear that they had no grasp of the fundamentals of the units. If you look at the magazine ads these devices are advertised as gages and the readouts often can be set to show fractions or bar graphs like a gas gage. I fear that this can be quite misleading. I know that people have been confused and even distressed by it. But, perhaps boaters where you are are much better informed than they are where I sail. I'm just trying to point out some potential problems that I have seen in the field. If I'm mistaken and they are just trivia, then I apologize for wasting your time.

--Tom.

Maine Sail · May 4, 2009

tsmwebb said:
Charging systems should be regulated by voltage, time, battery temperature and, perhaps, acceptance rate. They don't need energy monitors.

Can you explain how this will be easier than looking at my monitor telling me I have drawn down -50 ah out of a 100 ah bank which puts me at 50% DOD and it is now time to re charge..? I then look at it a few hours later and I'm now back up to -15ah down off a 100 ah bank. We don't need exact numbers but a close approximation. IF you discharge to 46% a few times vs. 60% it's not the end of the world..

Voltage: Voltage can be very misleading when the system is in use and batteries need to come to a resting state before a true SOC voltage reading can be measured. This takes time.

Time: You want to talk about confusing. if you have a 100 amp alternator and run it for an hour you put 100 amps back in right.... Not...! What does time tell you..?

Temperature: Seeing as most boaters would not even know the temp conversions for SOC using reting voltage or a specific gravity test (which can't bedone on AGM's or Gels), vs. batt temp this is certainly more confusing than a monitor.

Acceptance: See time above..

The battery monitor is one of the most useful tools I have on board my boat. I was amazed at how far off my well thought out energy budget was once I got one. There are a fair number of us who were very surprised at how far off we were on what we had calculated daily consumption to be and what it really was. I was amazed to watch the differences in fridge draw from day one and a warm start to day two and already cold. Time, voltage, acceptance etc. tells you none of this and unless you have a clamp on DC meter (good ones cost as much as a monitor, you have no real way to know your amp draw as many items are variable like a fridge, laptop computer etc. The monitor keeps track of each amp in and out. As I said above I don't use the % of charge screen and find amps in/out far more telling..

Benefits of a monitor.

It teaches you how a charging system works by letting you see first hand how accptance plays a role. It also allows you to see that the last 15% of charge takes for ever no matter how big your alternator is.

It can save you money, if you install it first, because you may find you DON'T really need a big money alternator as the one you currently have may not even be working all that hard.

I can monitor my alternators behavior and it's amp output. Watching this tells me how close I am to full charge or how far away from it I am.

I can monitor the output of my solar panel and then adjust & angle the panel to maximize amp output and subsequently am input to my batteries.

I can monitor my house consumption, in amps, as it's happening.

I can monitor my house consumption, in amp hours, cumulatively.

I can tell when I am nearing a 50% DOD by watching the ah consumed screen.

I can tell what phase of charge my charger is in by watching the amps in screen or the volts screen.

I can see the net effect of what is going into my batts even when running lots of loads while charging. The monitor tells me what the net input is.

The list goes on. I find it very surprising anyone would say boats "don't need energy monitors".

My buddy Tom was going through batteries every three seasons at big $$$$. He had been monitoring battery SOC via volts based on what he had figured on paper and decided his house loads were. At my suggestion he installed a battery monitor. Needless to say he is on year five with his current bank. That right there is enough reason to buy a monitor. If he gets six years out of his bank the monitor helped him understand and double the life of his batteries. This guy is an average Joe sailor and it helped him dramatically...

tsmwebb · May 5, 2009

Maine Sail said:
Can you explain how this will be easier than looking at my monitor telling me I have drawn down -50 ah out of a 100 ah bank which puts me at 50% DOD and it is now time to re charge..? I then look at it a few hours later and I'm now back up to -15ah down off a 100 ah bank. We don't need exact numbers but a close approximation. IF you discharge to 46% a few times vs. 60% it's not the end of the world..

By charging system I mean your battery charger or the controller for your alternators or other charge sources. They should be automatic based on the factors I noted. That is, if you've got a charge source it should charge until you're batteries are full and it knows your batteries are full because the acceptance rate has fallen to zero and then it should switch to float. Because the question I was asked was two parts (monitoring and charging) I was addressing it as two parts. But, to be sure, they are parts of a complete energy system.

The question you're getting at is, I think, when should one turn on one's charging system. Thats a hard question. If you want to get the most amp/hours per battery life time you'll probably want to recharge at close to 50% rate of discharge... Another goal might be to get the longest life from a battery that will only be deep cycled very occasionally (eg. attempting to get as many years as one can with a one or two week cruise each year). In that case you'll rarely get down to 50% but will still need to periodically fully charge the battery (bi-weekly to monthly, perhaps). In my case, I want to get as much power as I can from my solar array, keep my engine time minimal and maximize battery life-time... In any of these cases one would need some insight into the state of charge to implement a strategy. For that, as I've said in each of my posts, an energy monitor is the best thing we have. But, because it is a complex indirect measuring system it has some unavoidable short comings that users need to be aware of.

Right now my battery monitor reads 4.6 (that's net amps and the screen that it lives on) my voltage is 12.8, it is morning and the sun light has just started to touch my panels. I know that my fridge compressor, lights and computer have drawn about 50-60 amps from the system and I know that I'm down about 10% on my bank. I know this without ever looking at the percent of discharge screen on my monitor. By early afternoon my panels will be able to push the bank voltage to 13.5 and the controller will start cutting them out. By the end of the day the batteries will be a ~90-95% charged. They will be accepting about 5 amps to get to 13.5 volts. They will not take a full charge because I'm limiting their voltage to prevent excessive gassing on a daily basis. Once a week or so If I'm at anchor I'll bulk charge the batteries with the engines in the morning and let the controller top them off all day. If I'm in a marina I'll hook up my three stage charger over-night. If I'm at sea I will bulk the batteries more or less daily on average (it gets complicated, if anyone cares I can put it in another post). And, of course, if the sun don't shine I try to run a full charge on them when they drop towards 50%. (Is anyone still reading this???) If so, they might say "aha, now you need an energy monitor to tell you your state of charge!" To which I answer, "sure, I do look at it, but I still don't look at the percent of charge screen because it just isn't all that reliable. Instead, I look at my net amps and volts and because I've been watching them closely over the years I have a good enough feel for the state of charge based on their relationship to each other. To be sure, when I was newer to my system I did look at the SOC screen and it helped me get a feel for these relationships. But, I know that if I've been cycling the system to less than reset levels for over a week that the SOC screen will have serious errors (on the order of tens of percentage points). In these cases, my guess isn't just as good as the monitor's, it's better." (Compelling dialog, no?

) So, once more, and with feeling, all I am saying is that SOC monitors will accumulate errors that to a naive user might be unexpected.

--Tom.

Blitz · May 5, 2009

suggestions

Battery monitor - seems like everyone needs to be cautious, but it is an essential piece of equipment. I agree - on the master list of things to add whether or not I win the lottery.

Battery Isolators - No good. Too much voltage loss...

Battery Combiner - Good but can be done with a switch...

Battery Charger; Multiple outputs to each bank or one output to the starter or house bank? Preference?

tsmwebb · May 5, 2009

Maine Sail said:
...I have drawn down -50 ah out of a 100 ah bank which puts me at 50% DOD and it is now time to re charge..?

I can tell when I am nearing a 50% DOD by watching the ah consumed screen.
...

Just for the record:

You need to know the rate at which all of those amps were drawn to know the state of charge. It is not correct to say that having drawn 50 ah from a 100ah bank that you are at 50% state of charge. You can not tell that you are at 50% DOD just by looking at the ah consumed screen. This is why you must tell the monitor the Peukert of the bank. And, that value must very, very close to correct because it is exponential. Being off by a tenth will make make your monitor's SOC reading complete garbage. That may be somewhat covered up by the fact that they reset themselves often, but it will be a problem if you let them run for a while. If monitors could just sum up the amps in/out of your battery they'd be very accurate. They can't and that is, I think, key to understanding them.

My apologies for flogging this deceased equine again.

I'll try to restrain myself in the future.

--Tom.

tsmwebb · May 5, 2009

Blitz said:
Battery monitor - ... is an essential piece of equipment.

Battery Charger; Multiple outputs to each bank or one output to the starter or house bank? Preference?

"Essential?" Hmmm, nobody had one 15 years ago, but lots of folks did lots of serious cruising. I rate them in the very nice to have category, but I forgo one before I'd forgo cruising!

On point two. Would it be better to have a single bank for starting and house with a backup?

--Tom.

tsmwebb · May 5, 2009

Stu Jackson said:
Tom,

I think it's not so much when to turn your charging sources on, but when to turn them OFF. ... What I didn't recognize was that the acceptance severely limits what can go BACK INTO the bank(s) when charging. THAT, to me, is much more important that what's goin' out, and is the real value of the battery monitors.
...

I hope someone will tell me when I'm sounding like a crank on this...

Your battery monitor resets when your charge source determines that your battery is charged. Your charger determines that your battery is full (has gone through bulk and acceptance) and goes to float as a function of acceptance rate at voltage by time. The voltages it does this at should be adjusted for battery type and temperature. Your monitor does not tell your charger to shut off.

--Tom.