Battery Monitor

[75thRanger]

I'm considering a shunt based battery monitor and am wondering how accurate they are after time passes.

It seems to me that constant monitoring of amps in and amps out that any reading would become less reliable over time.

Do the higher end systems have 'smart' features that can learn how you use your power and compensate for this?

A system reset to delete data and start over?

Disconnect the battery and let it settle down after a full charge?

I'm guessing at this stuff (obvious,eh)

[cpaharley2008]

I installed a Trimetric system from Bogart years ago in my T@da, very complicated and told me things that I never really understood. I'm happy with the Go-Power info.

[tdf-texas]

Originally Posted by 75thRanger

I'm considering a shunt based battery monitor and am wondering how accurate they are after time passes.

It seems to me that constant monitoring of amps in and amps out that any reading would become less reliable over time.

Do the higher end systems have 'smart' features that can learn how you use your power and compensate for this?

A system reset to delete data and start over?

Disconnect the battery and let it settle down after a full charge?

I'm guessing at this stuff (obvious,eh)

A battery monitor such as a Victron BMV712 battery monitor doesn't lose accuracy over time. It will display the current available battery capacity based on the measured current and temperature of the battery.

"Do the higher end systems have 'smart' features that can learn how you use your power and compensate for this?"

The Victron calculates the actual available battery capacity based on Peukert's Law.

What is Peukerts Law? | All About Lead Acid Batteries

The Peukert exponent is published by the battery manufacturer and entered into the battery monitor as a factor in calculating the currently available battery capacity based on actual load. The Peukert exponent does change as the battery ages (the Peukert exponent increases as the battery ages) but determining the Peukert exponent for a battery by testing is fairly complicated and not something most people would do. By the time the Peukert exponent has changed enough to greatly affect the calculated battery capacity, it's time to buy new batteries anyway.

"A system reset to delete data and start over?"

Yes, the Victron has resets that will establish new zeros or reset the data.

By the way, The Trimetric doesn't calculate the battery charge based on Peukert's law - only a more modern battery monitor such as the Victron has this capability.

Below is a video for testing the actual capacity of a lead acid battery. Again, most people just use the published capacity of the battery from the manufacturer as testing to determine battery capacity is somewhat complicated.

https://www.youtube.com/watch?v=hrq67tYV1Pw

[75thRanger]

I checked your site on our Mr. Peukert. His equation is obvious to the most casual observer.

I'm gonna do it!

[tdf-texas]

Originally Posted by 75thRanger

I checked your site on our Mr. Peukert. His equation is obvious to the most casual observer.

I'm gonna do it!

You do know that to get an electrical engineering degree, you only have to take one additional math course to get a minor degree in math with it. I passed on that - I had already had more of triple integral math than i wanted. One course I took taught laurent expansions - used to do math proofs. Now try to use that in everyday life!
https://www.sciencedirect.com/topics...rent-expansion

That's why retired EE's can be high school / jr college math teachers.

[75thRanger]

Originally Posted by tdf-texas

You do know that to get an electrical engineering degree, you only have to take one additional math course to get a minor degree in math with it. I passed on that - I had already had more of triple integral math than i wanted. One course I taught laurent expansions - used to do math proofs. Now try to use that in everyday life!
https://www.sciencedirect.com/topics...rent-expansion

That's why retired EE's can be high school / jr college math teachers.

My degree was also EE(Power Option) but I've never worked a single day at it. Went in the Army(I was ROTC) did my active duty and returned to the farm. Stayed in the reserve tho.

Had a prof tell me once that if we could go to the middle of the Sahara and draw a huge right triangle, label the sides, and inscribe "C square = A square + B square. Anyone out there that could see us would know we were 'somewhat' intelligent.

[Lanark Camper]

I've installed and owned a few battery monitors and solar charge controllers in past years.

On our new 17B I removed the supplied charge controller right away. Then installed the Trimetric battery monitor and charge controller. I bought them because I think its a good idea if the charge controller can talk to the battery monitor. I also like the versatile programmability and available data output. Definitely not for those that want a set and forget system.

I think the best set and forget battery monitor is the Balmar,
https://marinehowto.com/balmar-sg200...ttery-monitor/
It will constantly adjust for the actual size of the battery bank and give a nice gas gauge type indication of how much juice you have left in the battery bank.

Bob

[tdf-texas]

Originally Posted by 75thRanger

My degree was also EE(Power Option) but I've never worked a single day at it. Went in the Army(I was ROTC) did my active duty and returned to the farm. Stayed in the reserve tho.

Had a prof tell me once that if we could go to the middle of the Sahara and draw a huge right triangle, label the sides, and inscribe "C square = A square + B square. Anyone out there that could see us would know we were 'somewhat' intelligent.

I still remember my first weed out course at U of H - linear algebra. Dr. Betty J. Barr taught the course - U of H had hired her to "strengthen the engineering college's math skills". She is retired now but I still remember her vividly - and the stress I went through before every exam trying to get ready.

[75thRanger]

Originally Posted by tdf-texas

I still remember my first weed out course at U of H - linear algebra. Dr. Betty J. Barr taught the course - U of H had hired her to "strengthen the engineering college's math skills". She is retired now but I still remember her vividly - and the stress I went through before every exam trying to get ready.

My favorite was 'Spherical Trig" Dr Kumins (German) would walk around during pop quizzes looking over our shoulder and mutter "Such operations are not possible"

[jeffrow]

Originally Posted by 75thRanger

My favorite was 'Spherical Trig" Dr Kumins (German) would walk around during pop quizzes looking over our shoulder and mutter "Such operations are not possible"

My wife was getting her degree in pure math at UC San Diego years ago. Sometimes for lack of a babysitter she would bring the kids to some of her 400 level classes. One of her professors used to wind down a lecture with a look at the kids and ask them if they understood what he just said. They would solemnly shake there heads no. He would reply "Thats ok.... nobody else understood it either".

[dfandrews]

You know, of course, that differential equations are our friends.

[75thRanger]

Originally Posted by dfandrews

You know, of course, that differential equations are our friends.

Differential(shudder)ain't nobody's friend!

[75thRanger]

Anyone have any experience with the Balmar monitors? They claim that they have a proprietary, self calibrating algorithm that determines how the battery has aged from its original capacity.

They claim SOH is delivered as a percentage representing the battery current capacity as opposed to design capacity.

I don't think the Victron has a similar feature. If you start with a programmed 100ah and ignore the aging of the battery I would think you are going to get less meaningful readings after a period of time.

I'm sorta feeling my way thru this stuff. Been a long time! Ah and coulomb counters indeed!

Theses things are not plug and play to get any useful info from them.

[tdf-texas]

Originally Posted by 75thRanger

Anyone have any experience with the Balmar monitors? They claim that they have a proprietary, self calibrating algorithm that determines how the battery has aged from its original capacity.

They claim SOH is delivered as a percentage representing the battery current capacity as opposed to design capacity.

I don't think the Victron has a similar feature. If you start with a programmed 100ah and ignore the aging of the battery I would think you are going to get less meaningful readings after a period of time.

I'm sorta feeling my way thru this stuff. Been a long time! Ah and coulomb counters indeed!

Theses things are not plug and play to get any useful info from them.

The Balmar SG200 is a new model that came out last year. The earlier model (SmartGuage) has the self calibrating algorithm but no shunt. The SmartGauge measures the battery voltage and calculates the SOC from that. That's why the SG200 came out - the SmartGauge cannot display realtime current use due to no current shunt. The ability to calculate the aging of the battery is interesting. Here's a review.

https://marinehowto.com/balmar-sg200...ttery-monitor/

Let me know if you find it but I can't find anywhere that says if the SG200 does the Peukert law calc. Trimetric doesn't either but it's a decades old low tech monitor.

PS. the bluetooth adapter and app are not available and Balmar is not giving an estimated availability date. PKYS is the only vendor that I can find that sells the SG200 and they are out of stock. Seems the SG200 is still in development - they state that the monitor will be able to receive flash updates once the bluetooth adapter is available.

https://shop.pkys.com/Balmar-SG200-b...or_p_7850.html

[tdf-texas]

Originally Posted by 75thRanger

Anyone have any experience with the Balmar monitors? They claim that they have a proprietary, self calibrating algorithm that determines how the battery has aged from its original capacity.

They claim SOH is delivered as a percentage representing the battery current capacity as opposed to design capacity.

I don't think the Victron has a similar feature. If you start with a programmed 100ah and ignore the aging of the battery I would think you are going to get less meaningful readings after a period of time.

I'm sorta feeling my way thru this stuff. Been a long time! Ah and coulomb counters indeed!

Theses things are not plug and play to get any useful info from them.

Here is a good discussion on the SmartGauge. From what I've read, the SmartGuage uses the same algorythm as the SG200 but without the shunt.

Balmar SmartGuage - Cruisers & Sailing Forums

[Iowa Dave]

The best professor I ever had would walk around the class while we took a test. If he noticed an arithmetic error or a formula you were using wasn’t right he’d put his finger on the mistake. You could then correct your error assuming you knew what you were doing and get credit for the question. That to me was teaching. The stiff ones with no compassion are relegated to history and forgotten but I can see George W. Thompson like it was yesterday. Even though it’s been 50 years.
Iowa Dave

[John in Santa Cruz]

and remember, Physics is just Applied Mathematics!

and everything else, and I mean everything, is applied physics.


https://xkcd.com/793/

[Lanark Camper]

I haven't used Balmar products for a few years. I did use their highoutput alternators and alternator smart charge controllers. They were extremely well engineered, well documented, and well supported.

As far a Bogart's monitor and charge controller is concerned I think it is smarter than it might first appear. It was designed years ago for sure and does look like I made in my garage (maybe that was the appeal for me). It was marked to RV owners. So maybe the manuals were designed to be more understandable to their customers. While they don't have the option to input Peukert factor,

"In addition, it has two advantages not usually offered in solar controllers to better preserve the capacity of your battery system:
1. Amp hour counting: Many battery companies recommend that when batteries are recharged they should be overcharged, so that 104 to 120 percent of the charge that was previously removed should be replaced before going into “float”. Most controllers don't measure this. When connected with the TriMetric, this controller measures the amp hours used, and allows you to specify the correct amount of amp hour overcharge when recharging. The more usual benefit of this is to insure that batteries are not undercharged. However it is also beneficial to prevent overcharging, in situations where solar panels are charging a lot during successive days but where very little battery discharge is occurring in the evenings.
2. Finish current charging: After the batteries are mostly charged, this controller has an optional “fourth” stage that is beneficial for liquid electrolyte lead acid batteries, and this is also sometimes recommended for some AGM types. This stage allows the voltage to go unusually high while it regulates the current to a specified level, to safely get more charge into the batteries. This helps to maintain the capacity of the batteries, which often begins to degrade with solar charged batteries because they don't get sufficiently charged."

I gave up on programming the Peukert factor years ago, its a moving target.
My approach with any charge controller is to reset it to 100% periodically when I know the battery bank is at 100% SOC. I try to keep my bank at 100% as much as possible. The Bogart charge controller gives two options for how 100% soc is determined. I won't go into it here.

I think the mains charger supplied in the Escape can't charge the batteries to 100%, the voltage isn't high enough and wire connecting it to the batteriesis too small. That's the advantage of a solar panel and programmable charge controller.

My long term plan is to open the converter and disconnect the 12 V supply function. Then install a proper 50 A, 12 V battery charger, connected to the batteries with wire sized for the job. So far most of the wiring I've seen on the trailer is undersized.

Bob

[rubicon327]

Originally Posted by 75thRanger

My favorite was 'Spherical Trig" Dr Kumins (German) would walk around during pop quizzes looking over our shoulder and mutter "Such operations are not possible"

This made me laugh. I had a professor in my mechanical engineering program that taught Strength of Materials and Advanced Engineering Math. He would say to us " do not eat too much before the exam or you will puke". That line coupled with his accent was pretty intimidating.

[75thRanger]

Discovered my battery switch was bad when doing something else. 12v was on regardless of switch on or off. ETI sent me another and I just changed it.

Worked fine for about 5 min. I turned lights on and then turned batt switch on and off a few times and lights were on and off also. I was pleased with that. and all was well.

I turned the batt switch off and was leaving the trailer. The ceiling light by the door came on. I leave it on so I can use the switch at the door to turn on lights before I step up in trailer.

Went back and checked the new batt switch. Same problem, always on.

When I was going to check the one I first removed to see if I got a reading of any kind. The lever switch came off in my hand when I turned it on.

Dustin said to get the switch I wanted and send him the bill. See how that works.

Looking at that switch was too funny to get real upset after a few minutes of dark thoughts.