Battery Monitors

[Codger2]

I am currently seeing 11.7 volts at 50% discharge.[/B] That is acceptable to me, but when it goes down much it will be time to replace the bank.

Kevin, I find the above statement interesting, especially coming from you! The below table was copied from an SAE site.

 

[DDW]

Net amp hours out-in are not an accurate measurement of state of charge. Just so's ya knows.

State of charge is defined as 1 - (AH out/capacity). So AH out is by definition accurate. Directly integrating AH in and out alone over time disregards Preukert's and internal resistance - but no decent battery monitor ignores those factors. Some users do, and don't set these parameters for their battery bank - and that is the main reason CMS likes the Smartgage: it requires less setup by unknowledgeable owners.

 

[ksanders]

Kevin, I find the above statement interesting, especially coming from you! The below table was copied from an SAE site.

The challenge is that chart is a “open circuit” battery chart.

House batteries are never open circuit. They are always either discharging or charging as we always have loads on them.

Theoretically the chart is correct, it is just not a practical way to judge a working set of batteries.

 

[sunchaser]

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....

On our Magnum station 3 "meters" shows more detail. It looks like you're on #1, #3 will likely read different for 12V amps. Also, we normally shut down inverter when on shore power.

 

[Ka_sea_ta]

On our Magnum station 3 "meters" shows more detail. It looks like you're on #1, #3 will likely read different for 12V amps. Also, we normally shut down inverter when on shore power.

This wasn't meant as a criticism of what anyone is using. it is just an observation.... The magnum is my primary battery charger for a relative large bank of AGMs I just find it curious that the two meters that measure current where the shunts are connected in series and are physically 6 inches apart very seldom show the same current.... I have seen them have as much as 40 amps difference....

 

[sunchaser]

This wasn't meant as a criticism of what anyone is using. it is just an observation.... The magnum is my primary battery charger for a relative large bank of AGMs I just find it curious that the two meters that measure current where the shunts are connected in series and are physically 6 inches apart very seldom show the same current.... I have seen them have as much as 40 amps difference....

Flip to #3 and toggle through it. The BMK provides lots of data, some useful some not. I doubt your Magnum shunt goes straight to the meter, it likely ties into the inverter. Data overload at work.

 

[CMS]

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?

The answer to this is a bit to complex to answer in a post. The article below walks through programming a Coulomb counting battery monitor and discusses the ways it can get out of sync with the bank.

Making Your Battery Monitor More Accurate (LINK)




.

 

[mvweebles]

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

As my dear departed father used to say "A man with a clock always knows what time it is. A man with two clocks is never certain."

 

[localboy]

...and that is the main reason CMS likes the Smartgage: it requires less setup by unknowledgeable owners.

Wow.

 

[DDW]

Flip to #3 and toggle through it. The BMK provides lots of data, some useful some not. I doubt your Magnum shunt goes straight to the meter, it likely ties into the inverter. Data overload at work.

The BMK meter is quite inaccurate, at least the ones I have seen?



Why two shunts in a row? One is enough for two meters.

 

[Ka_sea_ta]

The BMK meter is quite inaccurate, at least the ones I have seen?



Why two shunts in a row? One is enough for two meters.

One shunt is for the Balmar sg200 other is for the Magnum

 

[firehoser75]

The discussion in the last few posts is exactly why I favour the Balmar unit. Simple, simple, but accurate. Even you "gurus" seem to sometimes be in disagreement
I also still feel that with the new unit, having amps as well as State of Health are good things and do not "overly complicate" things. To me, having the ability to have a monitor that will inform me of where my batteries are at capacity (capability) wise compared to new batteries, as well as automatically adjusting the SoC readout to match the new (current) capacity is a great idea!!

For those who are very savvy electrically and like multiple set points that may (if not set properly) give or contribute to errors, and who like to know every little aspect of their system at all times, then the "counter units" are best, if operated properly (a big if for most boaters). For the rest of us (I would think the majority) the Balmar unit does more than enough with a far simpler set up and actually gets more accurate as you use your system.

I am not proposing anyone "drop what you have" in favour of the new Balmar (I am not doing that), but if someone is looking to add a new monitor or change out an old one, then I think it would be prudent to at least "look into" the Balmar unit.
JMHO

 

[CMS]

The BMK meter is quite inaccurate, at least the ones I have seen?



Why two shunts in a row? One is enough for two meters.

The SG200 is not a standard 50mV, 75mV or 100mV shunt that you can tap into. The SG200 shunt also houses the processor and the display is only a display or user interface.




.

 

[koliver]

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.

Many years ago I bought into the idea that a battery Monitor was a Must Have. At that time, Ample Power had a good unit out, EMON, and I wanted their Next Step Regulator, so the pair made sense.
In 2000 I did an engine swap and following that , never could get the Battery Monitor back on line. I haven't missed it a bit, as I get all the battery health information I need by checking the voltage. My Inverter panel gives me that, along with the acceptance amperage when charging. I have found no need to pursue getting the EMON back on line. I suspect the Victron gives little, if any more.
My last battery change was after 11 yrs on the house set and 12 yrs on the start.

 

[Alaskan Sea-Duction]

I currently have a Xantrex Monitor. All it shows is LED lights and only when the charger is on. I also have a DCv meter on my electrical panel. The reason I was thinking of switching was the other unit could show me better information on the condition of my battery bank.

 

[firehoser75]

Tom,
Not to be a broken record (remember those ), but sounds like you would benefit from the new Balmar Smartgauge. It is simple, accurate, and gives all (or most) of the info that is useful for monitoring your battery bank.

I am not affiliated with them in any way, just a satisfied customer of their earlier version, and new one does even more.

Good luck with your decision, as really any monitor will be an improvement from what you describe.

 

[Blazys]

Battery monitors

I have a Balmar installed. Nice feature is that it gives state of charge and health of batteries. But if you want status away from boat on your phone etc look at siren.

 

[LarryM]

I've always been partial to Mastervolt equipment. My present system is simple with House, Start and Gen batteries connected to a Mass Combi Inverter/Charger.

For battery monitoring I use the BTM - III battery monitor which provides an accurate indication of the voltage, charge/discharge rate, remaining capacity% and remaining time of battery bank 1 (House), and the current and estimated capacity only of battery banks 2 (Start) and 3 (Gen).

The built-in microprocessor calculates the remaining capacity and stores a wealth of historical data: time elapsed since the battery was last fully charged; time elapsed since the last “low battery” alarm; total number of discharge-recharge cycles; number of “abusive” cycles; total number of hours the battery has spent discharged below 20 percent; total amp-hours consumed; average depth of discharge; deepest discharge; and highest recorded voltage.

It features programmable alarms and advanced settings for the individual battery banks. It continuously recalculates the CEF (Charge Efficiency Factor) on bank 1 (House) as it is used and ages, along with the Peukert Exponent (also programmable), to calculate time remaining and SOC.

As far as I can tell, it is amazingly accurate, and Mastervolt chargers are very easy on batteries when dialed in properly.

 

[dutch-barge]

I have on two of my boats the Victron, one reason because of the whole 'eco-system....inverter, solar, control units

I see a lot of discussion about 'accuracy'. does it REALLY matter if your batteries are 77, or 74 % SOC? NO ...does your gas tank, fresh water tank give you accuracy up to to a quart, or gallon? NO...so buy the one you like, looks good and can be integrated with future systems

The one thing I like about Victron. 5 years warranty and a great distributor here in the US !!! every time I had an issue , one phone call ( even during the weekend ) and it was solved !

 

[Woodland Hills]

Kudos to Victron and to my dealer. I have been having Bluetooth connection issues from Day One a couple of months ago and yesterday I was finally able to dive into things with the dealer. After trying a few things while in phone consultation we decided to just exchange monitors for a new one. Then, an hour later I got another call from the dealer who had been on the phone with a Victron engineer. It turns out that if one connects the Bluetooth from Settings/Bluetooth on the phone, the App wil be unable to connect to the monitor even though it is all being done by the same device. The trick is to disconnect Bluetooth from the battery monitor in Settings then Connect using the Victron app: this works perfectly every time.
Anyway I thought it was pretty good customer service from both the dealer and Victron.

 

[DDW]

The built-in microprocessor calculates the remaining capacity and stores a wealth of historical data: time elapsed since the battery was last fully charged; time elapsed since the last “low battery” alarm; total number of discharge-recharge cycles; number of “abusive” cycles; total number of hours the battery has spent discharged below 20 percent; total amp-hours consumed; average depth of discharge; deepest discharge; and highest recorded voltage.

Mastervolt and Victron are top shelf, well ahead of the others in the market on all of this stuff. The data that you reference is all valuable at one time or another if you care about your batteries. The Victron will keep a complete record of battery amps/volts over time which you can access remotely. None of this available on the Smartgage.

On accuracy, any AH counter can drift significantly off IF it is improperly set up or the bank operated for long periods at a partial state of charge. The latter condition does not allow the meter to resync to the fully charged state. Operating that way will also quickly kill your AGM batteries so more an issue with FLA or LFP cells. The Smartgage does not have this disadvantage but that gain is at the expense of a lot of other functionality. Set up even remotely in the ball park, and with a full charge every week or two, the AH counter is as accurate as you could possibly need while providing much more information.

 

[Boatcrazy]

Following. We installed the V-712 (it works perfectly, shows a lot of data on my cellphone) as well as the Smart Gage (original). But between remembering to correctly (?) de-rate the bank capacity at least annually, sort out if the solar and/or wind gen are contributing or not, if the Coulomb counters have been reset/recalibrated, trying to understand some of the unexplained algorithms in the SG (how does it know??) etc, etc, I also installed a direct-reading Blue Sea digital voltmeter. Paying casual attention to each daily gives me a good idea of where my batt bank is at.....and that's really all I need to know! Measure with a micrometer, mark with a grease pencil, cut with an ax?