Balmar SG-200 Battery Monitor

[sailinglegend]

Originally Posted by Paul L

......AH counters with the typical shunt setups are accurate.

I'm really sorry you didn't understand a word of my post. I tried to keep it simple.

I made one big error and excluded the Ah capacity of the battery bank which must be input so that Peukert's formula can calculate the actual Ah it is displaying. This can give the biggest error unless of course you do a capacity test each year and enter that, as well as changing Peukert's each year, as well as only measuring Ah only when the battery is at 77C.

The bottom line is that the Ah displayed is the 'corrected' Ah based on the above criteria. If you don't input the correct data you get the wrong answers.

I can understand why you are trying to get a comparison under certain conditions:

How much energy did I use overnight?
How much energy do I burn when sailing offshore, under sail, with my autopilot and chartplotter running during a day?

My point is that the SoC will give you that comparison and much more accurately. When you burn gas in your car you don't want to compare the exact litres you use on a motorway or around town, you want to compare say half a tank to a quarter tank.

So IMHO Balmar are absolutely right in not displaying Ah because they know it is not giving accurate results.

Edit: This Ah error helps them to calculate the State of Health of the batteries.

[transmitterdan]

If you believe the SG is giving accurate SOC then it's easy to tell your net energy gain/deficit by just looking at SOC. if its going down you are not making as much as you use.

Having the amperage metered is very useful. Knowing AH not so much, as long as you believe the SOC displayed is accurate.

[john61ct]

I do not agree that an AH display is not very useful.

Its useful functionality is very different from bank SoC, assuming the latter is accurate.

Once you have accurate SoC then "overall AH in and out" becomes less necessary.

But an AH counter whose shunt can easily be moved around to specific strategic points in the boat's circuits can be invaluable in improving the design and operation of the system overall.

Just as a good solar controller displaying total useful AH produced by (drawn from) **that SC**, you essentially now have that capability for any given charge source. Or the sum total of all sources if your design includes a separate charging buss.

And of course same with loads. In deciding the LVD setpoints for the entertainment circuits vs fridge vs nav/safety Essentials, knowing their relative AH / 24hr consumption levels is **very** helpful.

[transmitterdan]

John,

It’s is not much to expect cruisers to move a shunt all around their boat. Who does that?

[ontherocks83]

Originally Posted by transmitterdan

John,

It’s is not much to expect cruisers to move a shunt all around their boat. Who does that?

None that I have ever heard of.

[ayates]

Originally Posted by rgleason

"Upcoming Nmea Gateway???" What do you mean, I don't see anything like that in the specs. I agree plotting the two state of charge curves against each other would be interesting.

From https://www.panbo.com/balmar-sg200-a...r-gets-better/

"Balmar’s planned options for the SG200 system include a Bluetooth gateway that will support a mobile app and a NMEA-2000 gateway that will make battery status and other metrics available on connected N2K instruments and MFDs. The basic SG200 gauge and shunt kit sells for $239 with limited availability until January, and the gateway prices aren’t yet known."


Allan.

[sailinglegend]

Originally Posted by john61ct

I do not agree that an AH display is not very useful........

Double negatives John are very hard to cope with.

So do you agree Balmar should or should not include an Ah count on the SG 200? Maybe only if they could included a 'corrected' Ah count which they might be able to calculate from the SoC and SoH?

[john61ct]

I think the "correction" issue only pertains to the translation from AH flow data to estimating SoC.

If Balmar chose to display an accumulation of AH flow at the bank location, I don't think adjustment is necessary.

I think useful resets would be at a fixed time each 24-hour period, since last 100% reset and anytime via user pushbutton. That timestamp should be displayed with the net AH number.

Originally Posted by transmitterdan

move a shunt all around their boat. Who does that?

As stated above, using a tiny cheap AH counter and inserting Anderson plugs in advance makes it very easy.

[Stu Jackson]

Originally Posted by john61ct

>>>>>>>>>>>>>>>>>>

But an AH counter whose shunt can easily be moved around to specific strategic points in the boat's circuits can be invaluable in improving the design and operation of the system overall.>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>

Moving a shunt around is entirely unnecessary. A single shunt measures NET current. It's easy to determine both charging and discharging actual loads. By simply turning loads off and on. When cc's first came out, many of us spent a lot of time teaching newbies at it what NET meant.

[Paul L]

Originally Posted by sailinglegend

I'm really sorry you didn't understand a word of my post. I tried to keep it simple.

I made one big error and excluded the Ah capacity of the battery bank which must be input so that Peukert's formula can calculate the actual Ah it is displaying. This can give the biggest error unless of course you do a capacity test each year and enter that, as well as changing Peukert's each year, as well as only measuring Ah only when the battery is at 77C.

The bottom line is that the Ah displayed is the 'corrected' Ah based on the above criteria. If you don't input the correct data you get the wrong answers.

I can understand why you are trying to get a comparison under certain conditions:

How much energy did I use overnight?
How much energy do I burn when sailing offshore, under sail, with my autopilot and chartplotter running during a day?

My point is that the SoC will give you that comparison and much more accurately. When you burn gas in your car you don't want to compare the exact litres you use on a motorway or around town, you want to compare say half a tank to a quarter tank.

So IMHO Balmar are absolutely right in not displaying Ah because they know it is not giving accurate results.

Edit: This Ah error helps them to calculate the State of Health of the batteries.

How does SOC tell you how much your devices used in the examples I gave is beyond me. SOC is a secondary calculated value subject to the errors you describe. If you were using the original SG and started the evening with an SOC of 85% and ended with 78% SOC, how many amp hours did your refrigeration etc use overnight? You can't answer that because the SG doesn't tell you what it thinks your current bank capacity is and because the error bands on the SOC are so high.
If you had a battery monitor that included a shunt and amp hour display it might start the evening with a reading of -75ahs, in the morning it might say -165ah. Your reefer etc used approx 90ah with probably a few percent error .

While SOC estimates are useful for live abroad cruising, there are many other uses for the battery monitor that come first.

[john61ct]

Originally Posted by Stu Jackson

It's easy to determine both charging and discharging actual loads. By simply turning loads off and on.

In that case a clamp ammeter will do.

The whole point of an AH counter is to measure actual consumption over time, when the load current varies from one minute to the next, and/or you don't even know how many min/hrs it is running per day.

For example, screen devices may easily total lots more than the fridges, but just taking amp snapshots will not tell you that.

[noelex 77]

The number of AHrs down tends to be a more important parameter than the SOC. It is also is a more accurate parameter than SOC.

[ontherocks83]

Originally Posted by john61ct

In that case a clamp ammeter will do.

The whole point of an AH counter is to measure actual consumption over time, when the load current varies from one minute to the next, and/or you don't even know how many min/hrs it is running per day.

For example, screen devices may easily total lots more than the fridges, but just taking amp snapshots will not tell you that.

Man you seem to know a lot about everything.

[Stu Jackson]

Originally Posted by john61ct

1. In that case a clamp ammeter will do.

2. The whole point of an AH counter is to measure actual consumption over time, when the load current varies from one minute to the next, and/or you don't even know how many min/hrs it is running per day.

3. For example, screen devices may easily total lots more than the fridges, but just taking amp snapshots will not tell you that.

1. Why use something that requires movement and/or connection and re-connection when using a simple switch is so much easier?


2. Of course.


3. Of course, amps and amp hours are different things. What's your point?

[john61ct]

The point is the ability to record AH/24hrs usage for specific circuits, loads or sources, while systems are in production use, without having lots of shunts permanently wired in.

I certainly don't see how "a simple switch" would get you there, obviously just turning things off and on while systems are in use does not.

If you don't want that info, or think it's not worth the effort, fine. I was pointing out how it can be more useful than a single system-wide measurement.