Battery Monitors

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Alaskan Sea-Duction
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1988 M/Y Camargue YachtFisher
I have a 702 installed, works well. It is a one line display so there is some scrolling involved if you want to see a bunch of stuff. They have the 712, bluetooth connected to your phone which eliminates that for a price. The advantage of Victron is they have an extensive array of battery and power management stuff, all of which plays well together, if you buy into the ecosystem. I've bought it hook line and sinker: charger inverter, the excellent Color Control, solar controller, and battery monitor.

The 702 will monitor the voltage (but not AH) on a second battery. I *believe* you could hook one 702 to a 712 with their network cable, and read the info and history on both from your phone but you'd want to check on that.
 
Tom, I had an early model Blue Seas monitor installed about 10+ years ago, which i have subsequently removed.. I found that the AH information was just directly proportional to battery voltage, which I already had and I needed the dashboard space. I talked to Blue Seas before I took it out and they really didn't have much defense for it other than it uses some exotic algorithm with the result still being proportional to voltage. They may have a later and greater model now...I like Blue Seas gear. Otherwise I've heard good things about Victron and that's what I'd buy.
 
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Hi Tom,
I am not familiar with that unit personally. You might want to check out all of the info on battery monitors from Compass Marine (Rod Collins) on his site marinehowto.com.
From what I gathered, most monitors that require a negative shunt (and monitor amp hours) also need to be "zeroed" usually manually to maintain accuracy. If not "zeroed" they get less and less accurate as time goes on. However, the Balmar Smartguage does not. I have been using the 'older" model of the smartguage for several years now and it works very well, however, it only shows state of charge (percentage) and voltage for one bank and voltage only for a second bank. I understand that the new model of the smartguage does now also monitor amp hours (in and out).
Rod discusses these monitors in great detail with accompanying test results. He is not paid by any of the companies for his testing so I feel his results and statements can be trusted.
Good luck with your decision,
Tom
 
Most battery monitors use a shunt such as the Victron and Xantrex. The Balmar Smartgauge uses a "sophisticated algorithm" to figure amps and amp hours, and yes based on voltage. Some swear that the Balmar is as accurate as the others without the complexity of a shunt installation.

I do like the Victron though.

David
 
From what I gathered, most monitors that require a negative shunt (and monitor amp hours) also need to be "zeroed" usually manually to maintain accuracy. If not "zeroed" they get less and less accurate as time goes on.

Properly set up, a good battery monitor will sync itself at the top of charge. If you operate for long periods never reaching a full charge then the measurement will get less accurate with time. About the only advantage of the Smartgage is that it requires little setup, and isn't subject to this drift problem - though it might be quite inaccurate for other reasons. To me, the disadvantages of it outweigh the advantages.
 
Most battery monitors use a shunt such as the Victron and Xantrex. The Balmar Smartgauge uses a "sophisticated algorithm" to figure amps and amp hours, and yes based on voltage. Some swear that the Balmar is as accurate as the others without the complexity of a shunt installation.

I do like the Victron though.

David


The Balmar sg uses a shunt (they call it a smart shunt) the trick thing with the SG is it calculates SOH of the bank... From personal experience it takes several deep discharge cycles for the SG to learn.
 
While everyone is entitled to their own opinions and choose to buy whatever they want, I am curious why some of you "like" what you do here. What source of info did you use?
Personally, I used Compass Marine (known as Maine Sail) on several forums, a very well respected marine electrician and technician who freely gives of his time running the website I referenced above.
He states that through extensive testing:
The SG200 (Balmar Smartguage) is the most accurate battery monitor for SoC & SoH we’ve tested here at Compass Marine Inc..

This device accurately measures not only state of charge (percentage), charge/discharge current, voltage, and is the only monitor that measures battery state of health (or tells when batteries need replacement), all without user intervention. Admittedly it does take a bit of time or use for it to "learn" your batteries, but in as little as a few cycles it is about 97% accurate (according to real world testing).
When I bought my "older version" of the Balmar Smartguage, Compass Marine had recently tested it. In his review, he started out by saying that he expected it to fall short of the claims made by the manufacturer. However, after testing, he said that he had to eat his words as the device performed exactly as claimed.
I have previously owned a Xantrex Link monitor so I am familiar with the most common type of monitor. For the average boater, as time goes on and their batteries are cycled over and over, these monitors (without intervention by the user) get less accurate.
Buy what you want, just know what and why you are buying it. If my monitor wasn't only 3 years old, I would replace it with the new Smartguage!
 
SOC and SOH are perhaps the least interesting numbers to me. At least the newest version gives you instantaneous current, as they are now using a shunt. Something like the Victron 7xx supplies a whole lot more data. I think Balmar's market is owners who do not wish to understand batteries, probably a large market.
 
SOC and SOH are perhaps the least interesting numbers to me. At least the newest version gives you instantaneous current, as they are now using a shunt. Something like the Victron 7xx supplies a whole lot more data. I think Balmar's market is owners who do not wish to understand batteries, probably a large market.
I like to think of myself as someone who takes the time to research most things and to learn a reasonable amount. However, for me, I am most interested in state of charge. How full is the "gas tank" and do I need to "top it up"? I think having easy access to a state of health (are my batteries still "up to the task") would be very useful info.
However, each to their own and that is probably good news for the various manufacturers :D
 
As a person who anchor’s out a lot (like many here) I expect my battery monitor to:

1. Tell me the system voltage
2. Tell me the instantaneous current into or out of my battery bank.
3. Tell me the percentage of charge on my batteries at any given time.

I DO NOT need the monitor to tell me “battery health” I’m smart enough to figure out on my own if my bank is starting to fail and needs replacement.

In order for a battery monitor to provide me with the data I need it needs to be able to measure current.

Why... That is simple. First I want to see the level of current into or out of my bank, so it darn well better be able to measure it.

Second, in order to calculate the charge status of my bank the meter needs to have a starting point and then add and subtract amp hours, from my pre-programmed amp hour capacity.

Why is this charge state or State Of Charge information so important???

Well, I use it to time my generator use. I do not want to run my generator unnecessarily, nor do I want to discharge my batteries too much below 50% so I watch the State of Charge, and time my generator runs accordingly.

The physics of DC electricity is not rocket science. Today, comercially, in order to accurately measure DC current we need a current shunt. Any system that does not have one, is of limited use to me as it does not supply the data I need.

I use a Xantrex link pro battery monitor, but there are other brands that use a shnt like the Victron that are just as good.
 
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We installed a Victron 712 this summer. It was a learning curve - there are programming settings that you have to make sure are correct for your boat that allow it to "detect" a fully charged battery bank, IE a certain number of volts / certain % of the total house capacity being supplied as charge current that indicate the battery bank has reached its full state.

I did not pay attention to or understand all of those settings and found my bank slowly degrading despite telling me it was 100% charged because I didn't understand the monitor yet or have it configured for a shortcoming in my DC charging system (underway with all electronics running the net output from the alternators was low enough it tricked the Victron's default settings into thinking the bank was fully charged. Over several days, it led to a continued state of 50% to 70% charge instead of my desired 70% to 90%. While my experience is isolated to my partially incomplete electrical system (large capacity alternator system coming!) it shows the failing of the "give me a starting point and I'll add/subtract" or systems that plan for "tell me the condition that exists when the batteries are fully charged." Once I figured out that issue I understand it better, but the Victron does not come with a big long manual that explains it all for you! (Its a little book that tells you the settings it has.)

I can pull up the Victron on a tablet or smart phone. Unfortunately, the app does not receive or keep any historical data, so if you close the app you have to start over to be able to, for example, look at your power use over a 24 hr period. Which I've never been able to do, because I don't have a device that I can manage to leave on (with the screen on) and dedicated to the Victron for 24 hrs. I'm getting used to it, and like that its a gauge, but like any other it has its limits.

I would jump at the Balmar except I've already just bought something; the Balmar didn't have have an app last time I looked, but tonight I see they have something out or coming. But I really just want to without fail know my current amp usage, daily amp hour use and my current amp hour balance.

I am finding a lot to like about Victron though, and won't replace it. We've selected a Victron MPPT charge controller for our solar, and will likely go to a Victron inverter if/when it comes time to replace our Magnum. Having it integrate with our other future systems will be nice.

I think that since you have nothing, you would be really happy with either! My guess is the Balmar will be a point and shoot solution for you.
 
As a person who anchor’s out a lot (like many here) I expect my battery monitor to:

1. Tell me the system voltage
2. Tell me the instantaneous current into or out of my battery bank.
3. Tell me the percentage of charge on my batteries at any given time.

I DO NOT need the monitor to tell me “battery health” I’m smart enough to figure out on my own if my bank is starting to fail and needs replacement.

In order for a battery monitor to provide me with the data I need it needs to be able to measure current.

Why... That is simple. First I want to see the level of current into or out of my bank, so it darn well better be able to measure it.

Second, in order to calculate the charge status of my bank the meter needs to have a starting point and then add and subtract amp hours, from my pre-programmed amp hour capacity.

Why is this charge state or State Of Charge information so important???

Well, I use it to time my generator use. I do not want to run my generator unnecessarily, nor do I want to discharge my batteries too much below 50% so I watch the State of Charge, and time my generator runs accordingly.

The physics of DC electricity is not rocket science. Today, comercially, in order to accurately measure DC current we need a current shunt. Any system that does not have one, is of limited use to me as it does not supply the data I need.

I use a Xantrex link pro battery monitor, but there are other brands that use a shnt like the Victron that are just as good.

Good points Kevin. Having my smart phone connected to a FLA battery monitor located far away isn't a life priority for me. I've been happy with my two Magnum BMKs, more than necessary data is available.
 
Good points Kevin. Having my smart phone connected to a FLA battery monitor located far away isn't a life priority for me. I've been happy with my two Magnum BMKs, more than necessary data is available.

No disagreement there. Detailed DC information, for me is needed during the charge/discharge process.

I do feel that it is a good idea to know if your charger is working while you are not on your boat for extended periods of time but boat alarm and monitoring systems are a whole separate subject.
 
No disagreement there. Detailed DC information, for me is needed during the charge/discharge process.

I do feel that it is a good idea to know if your charger is working while you are not on your boat for extended periods of time but boat alarm and monitoring systems are a whole separate subject.

We have a regular boat watcher. It is a strong cottage industry in BC given the number of absentee owners. Battery charging is but one of many items on the checklist.
 
I think some of you are confusing the first (older) version of the Balmar Smartguage with the newest version the SG200. The new version DOES HAVE A SHUNT and measures "instantaneous current"! It is way easier to setup than a more traditional monitor and is more accurate (especially if the user does not adjust the monitor over time - which is not needed with the Balmar unit), plus it provides information about the overall condition (based on age and useage) or state of health of your batteries.

Disclaimer: I have no affiliation with Compass Marine, Balmar, etc. I just want to set the record straight and inform the OP (Tom) of this potentially better option. Admittedly, "better" is a matter of opinion.


I agree with earlier posts about what is "useful information" about your batteries, but some of the statements made about what the monitor must have or be capable of to achieve this is no longer correct (due to changing technology).

I have the older version of the Balmar. It does not have a shunt. It works great for me. It tells me voltage and state of charge very, very accurately. My charger remote panel tells me what voltage and how many amps are being input by that device, and my solar charge controller tells me even more info about what the panels are doing. If I was interested, I could calculate amp hours based on the "state of charge", but I find the percentage far easier to understand as for me it is used to decide if I need to run the generator to top up the batteries. If I do run the gen set, then I use the state of charge percentage coupled with the charger remote panel (which tells me input amperage) to decide when I have reached the point of diminishing returns for shutdown.



The newer version (of the Smartgauge) provides what I have described plus instantaneous current, and state of health (a percentage of what your battery is now capable of compared to the baseline of what a new battery is capable of). So for example, if your battery bank now is only capable of 80% of what it could hold when new, it informs you of this fact. As well, your state of charge now reflects this new, diminished capacity so you will not accidentally discharge below the (new) 50% mark, potentially damaging your already aged batteries. I don't know why this capability is something some of you have vehemently stated you don't want?
Anyway, my intent is only to inform about what for some may be "new developments", but still believe, "to each his own" :)
 
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Not sure of the algorithms in the new Balmar product, however on the old one the only way to know if it is accurate is to hook up a shunt and do a capacity test counting the AH, like traditional battery monitors do. There's nothing wrong with SOC and SOH, but these are derived numbers. Better to have the raw data too. I don't mind having an engine alarm that screams "something is wrong with your engine" but I'd also like to see the oil pressure and coolant temps myself.
 
FWIW, I like my Victron BMV 700. Shows voltage, amps in or out, and AH used. % charged too, but I pay more attention to AH.
 
Net amp hours out-in are not an accurate measurement of state of charge. Just so's ya knows.
 
Net amp hours out-in are not an accurate measurement of state of charge. Just so's ya knows.
You made my point but much more clearly :D
Again to each his own, but I find state of charge (percentage) way easier to understand and therefore to work with than amp hours. The key is to limit your depth of discharge and recharge to a full 100% as often as possible (for optimum battery life).
 
Here is what I am not understanding. You state that amp hours in and out do not accurately indicate SOC. But yet, isn't SOC calculated as a percentage of battery capacity, that is, amp hours out as a percentage of total amp hours capacity?
Net amp hours out-in are not an accurate measurement of state of charge. Just so's ya knows.
 
The advantage of any SOC system is you will be looking at it and probably will not kill the house batts to dead.

Weather in reality your bank is 55% full or 45% full is meaningless as you realize a charge is necessary .

It takes a huge amount of time to get to 100% charged up ,usually dockside or solar,but its great to know when you have done it.

Any SOC system is better than no SOC system.
 
Good points Kevin. Having my smart phone connected to a FLA battery monitor located far away isn't a life priority for me. I've been happy with my two Magnum BMKs, more than necessary data is available.

Amen to that. Magnum is a bit old-school and is hard-wired, which is exactly what I want on my boat. A good friend has a very nice 4-year old Horizon 52 powercat where household gizmos (TVs, music, A/C, electric shades, lighting, etc.) are controlled via iPad. It's pretty cool.....until it isn't or something changes and the system needs re-configuration. Apparently, when he had a Victron auto-start generator module installed, it added itself to his network and made the necessary configuration changes without regard to the rest of his network which was neutered in the process (BTW - motorized shades cannot be easily reverted to manual). So he had the Victron yanked, restored the network to a prior version, and installed a Magnum auto-start module which works like a charm but [happily] has no iPhone App interface.

In my opinion, network IP Addresses and SSIDs have no place on a cruising boat. Tough to get it to zero these days, but making sensible decisions such as Magnum over Victron has helped me balance functionality and reliability. Keeping a boat operational is tough enough without adding IT complexity. Finally, not having information displayed on an easily visible gauge tends to disenfranchise crew (wife) as they do not have access to all the boat's information. For me, the upside of App-gizmology is greatly overshadowed by the downside risk and complexity. Not even a close call.
 
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I have the Victron 712 monitor and the Bluetooth connection is very weak and intermittent. I can connect after rebooting the unit, but it fails after a few minutes or if I get more than a few feet away from it. I’m not happy with this at all.
 
I've got the Blue Sea M2 OLED monitor. It's shunt based amp hour counting. So not perfectly accurate (doesn't account for Peukert effect and such as far as I know). But it's good enough for my purposes and gives me a pretty good idea of how much power is in the batteries.
 
I have the Victron 712 monitor and the Bluetooth connection is very weak and intermittent. I can connect after rebooting the unit, but it fails after a few minutes or if I get more than a few feet away from it. I’m not happy with this at all.

Do you have a hard wired battery monitor gauge as part of the Victron 712 setup? If so, just put your phone in your pocket. Apps, blue tooth connectivity, tablets, phones etc drive too many of us crazy when all we require is a simple number or two.
 
Do you have a hard wired battery monitor gauge as part of the Victron 712 setup? If so, just put your phone in your pocket. Apps, blue tooth connectivity, tablets, phones etc drive too many of us crazy when all we require is a simple number or two.
The problem is that the actual unit is in the generator room under the galley floor. To view my state of charge I have to move the rug, open the hatch and squat under the floor to look at the monitor. I was trying to avoid this with the Bluetooth feature..... I am now waiting to hear what the Victron dealer has to say.
 
For those of you that rely on inverter charger remotes for battery charge/discharge information. I believe that they don't show the inherent energy overhead losses that occur within the inverter even when the inverter is in standby,



The shunts for these two devices are in series yet the current displayed very seldom is in agreement....
 

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Here is what I am not understanding. You state that amp hours in and out do not accurately indicate SOC. But yet, isn't SOC calculated as a percentage of battery capacity, that is, amp hours out as a percentage of total amp hours capacity?

Yes that is correct.

Starting at a full charge and a programmed in amp hour rating, then subtracting amp hours removed from the batteries yields the remaining amp hours left in the batteries.

Furthering that thought, determining the “health” or need for replacement of your batteries is easy.

Start with a full charge. Remove amp hours. Look at your battery voltage. Is it reasonable? Yes that is a judgement call but it is also a trackable value.

On my FLA 820 amp hour bank I am currently seeing 11.7 volts at a 50% discharge. That is acceptable to me, but when it goes down much it will be time to replace the bank.
 
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