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Here's a great Battery SOC voltage chart

Posted by tattoo

Nov 13, 2018 at 5:30pm

Here is a great Battery SOC voltage chart that's in the 60aCC manual and not in any other manuals that I have seen.... I would guess many of the new people on here haven't seen it, I posted it on the old forum but it's all but gone...


I printed it out and posted it on my wall where my solar is. It came in real handy when I first got started in solar......

Hope this is helpful to others....








 Chart.png

Posted by lindsay

Nov 14, 2018 at 12:04am

Hi Tattoo,

Thanks, this is useful. What I'd like to know is, on systems that are constantly under load, is there a calculation one can use to work out state of charge?
Maybe an online calculator that takes into account the current load in amps and/or maybe how many Ah or KWh have been pulled out of the batteries since fully charged?

Thanks

Posted by swampmonster

Nov 14, 2018 at 12:32am

lindsay Avatar

Nov 14, 2018 at 12:04am lindsay said:

Hi Tattoo,

Thanks, this is useful. What I'd like to know is, on systems that are constantly under load, is there a calculation one can use to work out state of charge?
Maybe an online calculator that takes into account the current load in amps and/or maybe how many Ah or KWh have been pulled out of the batteries since fully charged?

Thanks


Yes, there is a device that does exactly that, but the guy with the chart sez he is never concerned with his SOC and don't even dip his batteries much...That so far after 2 years they work fine, yada yada yada....And now he shows up with a chart...Hell, my battery maker publishes the chart I need for my exact batteries, like all other battery makers, so I donwanna look at some generic chart.

The fact you are seeking such info is great, because it really is something you should wanna know and check often....No chart or online calculator is capable of what you seek....The only way to get it is to install a certain device exactly as instructed and to properly set it up and routinely re zero it/reprogram it kinda....Because it is only when a proper device is properly inserted in your system can it can "see", follow, then calculate with decent accuracy, and provide you with better quality/accuracy of status.

What will do all this for you is called a "battery monitoring system"....There are many makers, Bogart, Zantrex, and so on....But they all require a properly installed shunt and the cabling to connect the shunt to the monitor panel.

Good luck!:)

Posted by lindsay

Nov 14, 2018 at 3:48am

Thanks, yes I have a shunt between my controller and the batteries and another between the load and the batteries. These are monitored from a Raspberry PI, so I know how much amps charging and load. What Sounds like I just need to know what formula these battery monitoring systems use and then I'd be able to implement it in my software. Anyone know?

Posted by tattoo

Nov 14, 2018 at 4:36am

lindsay Avatar

Nov 14, 2018 at 12:04am lindsay said:

Hi Tattoo,

Thanks, this is useful. What I'd like to know is, on systems that are constantly under load, is there a calculation one can use to work out state of charge?
Maybe an online calculator that takes into account the current load in amps and/or maybe how many Ah or KWh have been pulled out of the batteries since fully charged?

Thanks


I'm Glad this was helpful...


If it's under a load or what people call sag I don't see how that can be figured because the load varies..... This chart is the batteries at rest....


This is a battery state of charge chart, not the CC % state of charge..... Forget about the CC % state of charge it means nothing.... Like I have said many times before....


Some people need to learn to read better....

Posted by tattoo

Nov 14, 2018 at 4:41am

lindsay Avatar

Nov 14, 2018 at 3:48am lindsay said:

Thanks, yes I have a shunt between my controller and the batteries and another between the load and the batteries. These are monitored from a Raspberry PI, so I know how much amps charging and load. What Sounds like I just need to know what formula these battery monitoring systems use and then I'd be able to implement it in my software. Anyone know?


Bupkis will know the correct answer.... Wait on him to respond...

Posted by lindsay

Nov 14, 2018 at 5:08am

Thanks, yes, I never believe SOC from the controller! Will wait on Bupkis ;)

Posted by bupkis

Nov 14, 2018 at 5:12am

long battery blog on battery monitors with shunts that count in/out ...
And then the smart gauge that is shutless!

marinehowto.com/smartgauge-battery-monitoring-unit/

Posted by playersz28

Nov 14, 2018 at 5:17am

lindsay Avatar

Nov 14, 2018 at 3:48am lindsay said:

Thanks, yes I have a shunt between my controller and the batteries and another between the load and the batteries. These are monitored from a Raspberry PI, so I know how much amps charging and load. What Sounds like I just need to know what formula these battery monitoring systems use and then I'd be able to implement it in my software. Anyone know?


The SOC charts are based on a rested battery and not much good to determine what the true SOC is. You could be sitting in float chg mode with very little sun and then turn on a big load and the battery volts would drop a lot but that doesn't mean your SOC crashed.

Here's an article on calc'ing it out. www.analog.com/media/en/technical-documentation/technical-articles/A-Closer-Look-at-State-Of-Charge-and-State-Health-Estimation-Techniques-....pdf

I'm working on putting a Pi into my RV at this point. I was planning on migrating all the Arduino code onto it but I don't have a 3.3-5v shifter for the I2C and my RTC needs 5v. Until I get one I plan to keep the Arduino which broadcasts the shunt data over UDP and have the Pi pick that info up and put it in the SQL db for reporting. I already track net AH used/generated. On the Arduino I just manually reset it late in the day. With the Pi I'll reset it to zero to zero after a period of float charge unless the doc above provides a much better solution.

And if you want one person's view on AH counting (they have a reason to be against it :) )www.smartgauge.co.uk/sgvahrs.html

Posted by tattoo

Nov 14, 2018 at 5:34am

playersz28 Avatar

Nov 14, 2018 at 5:17am playersz28 said:

The SOC charts are based on a rested battery and not much good to determine what the true SOC is.


Yep that's what the chart is for like I said Batteries at rest... The chart was for the new people and not for those with your expertise... It sounds like your system is awesome.....


I just use my Hydrometer to check my battery SOC.....


Posted by tattoo

Nov 14, 2018 at 5:38am

playersz28 Avatar

Nov 14, 2018 at 5:17am playersz28 said:

  You could be sitting in float chg mode with very little sun and then turn on a big load and the battery volts would drop a lot but that doesn't mean your SOC crashed.


Yes sir that's what I was talking about checking SOC with a load... It's not accurate...

Posted by swampmonster

Nov 14, 2018 at 1:16pm

OP, what you seek is becoming more clear....You don't seek just a device, you seek the math and the science and various different methods that many BMS makers use, and also many guys like you need to perhaps make it better, or at least more to your situational requirements....Simply stated, you just wanna know mobetter exactly the most accurate status of your battery bank when using the devices already available to you, and also how to develop your own version of the software to adapt it to your Blackberry PI.

......And THAT is cool....Yeah, that is cool.

Ok then, the point of my post above was ONLY to state that NO CHART alone could tell you what you want to know....That instead, you gotta get actually INTO the flows of the system where using various devices and various methods and calculations, depending on the system insertion points of those detectors,...Be able to achieve a more confident status....Yeah, I understand....What you seek is exactly what many companies claim to offer with their many different devices....And their particular "devices" often use different points to monitor, and different calculations to finger it out, and their systems then use different proprietary programming written in different codes.

Good luck!:)

Posted by lindsay

Nov 15, 2018 at 12:45am

I always used to worry that my voltage of my batteries went too low overnight even after a full day of sun.
For example, at 1am in the morning my batteries would go to 24.4V when my fridge kicked in and pulled 4-5amps for ten minutes. Once it switches off the voltage will bounce back up to 24.8V, under the 1.5amps that I constantly draw from the batteries for lights, security cameras and cellphone chargers.
I mostly ignore the voltage unless it gets under 24V (if it didn't charge fully the previous day). If I look at how many Ah I use overnight it's only 33Ah of a 400Ah battery bank (@24v)

Posted by tattoo

Nov 15, 2018 at 4:22am

lindsay Avatar

Nov 15, 2018 at 12:45am lindsay said:

I always used to worry that my voltage of my batteries went too low overnight even after a full day of sun.
For example, at 1am in the morning my batteries would go to 24.4V when my fridge kicked in and pulled 4-5amps for ten minutes. Once it switches off the voltage will bounce back up to 24.8V, under the 1.5amps that I constantly draw from the batteries for lights, security cameras and cellphone chargers.
I mostly ignore the voltage unless it gets under 24V (if it didn't charge fully the previous day). If I look at how many Ah I use overnight it's only 33Ah of a 400Ah battery bank (@24v)


You have it figured right.... KIS is the way to go with solar.... Don't worry about what the batteries are at with a load on them all that matters is what they are at when the load is off.... Unless the voltage drops way down with a load..... Like 23v or less under a load...


It sounds like your batteries and solar system are doing just fine...

Posted by lindsay

Nov 16, 2018 at 2:08am

Yeah, I plan on doing a little bit of Ah counting, but only as a rough idea on a daily basis of how much the batteries are drained overnight. Peukert's law was interesting to read up about, but with the most I draw of a 400Ah battery bank being 8 amps I don't think it'll have much effect.



Posted by tattoo

Nov 16, 2018 at 5:37am

lindsay Avatar

Nov 16, 2018 at 2:08am lindsay said:

Yeah, I plan on doing a little bit of Ah counting, but only as a rough idea on a daily basis of how much the batteries are drained overnight. Peukert's law was interesting to read up about, but with the most I draw of a 400Ah battery bank being 8 amps I don't think it'll have much effect.


No sir, That's not much draw at all..... Like you say keep an eye on it for a while but as long as it gets fully charged everyday you will be just fine...

Posted by bupkis

Nov 16, 2018 at 6:00am

lindsay Avatar

Nov 16, 2018 at 2:08am lindsay said:

Yeah, I plan on doing a little bit of Ah counting, but only as a rough idea on a daily basis of how much the batteries are drained overnight. Peukert's law was interesting to read up about, but with the most I draw of a 400Ah battery bank being 8 amps I don't think it'll have much effect.


ah counters count in and out of the battery, not only Peukert's, but temp, and charge eff need to be considered.
Deep discharged battery suck up nearly 100% of charge while shallow discharged batteries ~50% the rest heats the battery.
Then of course SoC% is based on 20 hr capacity and that is an unknown that folks guess is the rated capacity even as capacity is lost to age, use and repetitive undercharging.

Count out/in back to full and compare!

Posted by bupkis

Nov 16, 2018 at 6:15am

www.batteryfaq.org/

The fifth link (downloads SoC.xls)

Temperature Compensated Battery State-of-Charge (SoC) Tables

When printed, this Excel spreadsheet produces a single page that contains tables with the temperature compensated Specific Gravity and Open Circuit Voltage State-of-Charge measurements for wet Standard (Sb/Sb), wet Low Maintenance (Ca/Sb), wet "Maintenance Free" (Ca/Ca), AGM VRLA (Ca/Ca), and Gel Cell VRLA (Ca/Ca) lead-acid battery types. Please see Section 7.1 for battery type descriptions. The file size is approximately 19 KBytes and was last updated on October 2, 2017.

Posted by playersz28

Nov 16, 2018 at 7:11am

Converted the XLS to PDF for Temp Comp SOC

Attachments:

SoC.pdf (33.78 KB)

Posted by swampmonster

Nov 16, 2018 at 3:58pm

lindsay Avatar

Nov 16, 2018 at 2:08am lindsay said:

Yeah, I plan on doing a little bit of Ah counting, but only as a rough idea on a daily basis of how much the batteries are drained overnight. Peukert's law was interesting to read up about, but with the most I draw of a 400Ah battery bank being 8 amps I don't think it'll have much effect.


8 amp overnight discharge from a 400 amp bank is certainly very minimal, but the problem with under recharging after the discharge is that with every under recharge, the battery walks down in total capacity....So yes, on a daily basis, the effect is minor, but over time it adds up negatively.

Seeing as how you plan to "Do a little amp hour counting" of the discharge, then you maybe think you should also count the amps you put back in?...Maybe?...Yaknow, seeing as how you agree battery voltage ain't no reliable way to determine actual level of charge so that you plan to count and track discharge amps, don't you think the only way to determine true state of charge would be if you also counted the amps you put back it?

I bet if you spent 1K a pop on Lithium batts you would.

Hey Man, it's up to you. You can use the generic voltage chart to maintain your batteries and buy new batteries more often than if you invest the money and extra time to monitor them with amps....Prolly works out the same $$ wise either way unless you really totally under recharge routinely.

As long as you understand the science and the math, you can make your decision better informed no matter what that decision is.

Posted by bupkis

Nov 16, 2018 at 5:24pm

let us not forget that lifeline batts REQUIRE 20% charge or they are undercharged. Balance wiring is a must also.

Posted by swampmonster

Nov 16, 2018 at 6:09pm

bupkis Avatar

Nov 16, 2018 at 5:24pm bupkis said:

let us not forget that lifeline batts REQUIRE 20% charge or they are undercharged. Balance wiring is a must also.


bupkis, that is total BS....I suggest that if you have the money to invest in Life Line batteries that you do just that....And only when and if you do, that you also first school yourself up, and properly equip your system up on how to monitor and protect your investment....But if you do not have the bucks and any experience with Life Line batteries, and if you ain't willing or able to do that, then perhaps you need to shut up and remain on your front porch and let the big boys run that race.

In that process, you may become VERY familiar with the very PARTICULAR characteristics, and the very particular best practices concerning your very particular batteries...But then again, YOU maybe will not.

Balanced battery connection wiring is ALWAYS a must, no matter the battery bank or type....Especially if batteries are connected in parallel.

Go back to rvnet and check..maybe they there have the experience I do...Maybe.

Posted by bupkis

Nov 17, 2018 at 5:09am

more swamp drivel to be ignored, directly against the manufacturer! it has become SOP, ie pushing pablum.

sorry swampy but your previous lies and bad information lives on and will haunt you. No one should even waste the time on your ramblings.

Posted by playersz28

Nov 17, 2018 at 10:21am

lindsay Avatar

Nov 16, 2018 at 2:08am lindsay said:

Yeah, I plan on doing a little bit of Ah counting, but only as a rough idea on a daily basis of how much the batteries are drained overnight. Peukert's law was interesting to read up about, but with the most I draw of a 400Ah battery bank being 8 amps I don't think it'll have much effect.


I changed the code on my ESP8266 to take 90% of positive current values towards the net and 100% of the neg values as I track the running net Ah. After the charger has been in float for a min 4 hrs with a small net chrg current then it'll reset the cum Ah when the CC indicates night. I'll see how that works out once the trailer is in a suitable solar loc'n which won't be until Jan. Then I can adjust my programming as necessary to see how it works out.

Posted by lindsay

Nov 19, 2018 at 7:48am

swampmonster Yes, as mentioned earlier I plan to count Ah in and out of the batteries. No plans to upgrade my battery pack since I bought 8 sealed lead acid only about a year ago.

playersz28 Cool, my batteries usually slow down charging around midday (the amps trail off), which indicates to me they are close to full. I don't have a flag from the controller I now use (no longer using SRNE/Renogy) so I wait until there has been no charge coming in for 15 minutes and consider that night. Then I reset the count of Ah used. When the battery starts charging in the morning I reset the Ah coming in.
I'm also colour coding the backlight on my Raspberry PI connected LCD - RED means not even close to being charged, ORANGE - within 8Ah, WHITE - within 3Ah, GREEN - within 1Ah. I reset the colour when the sun comes in in the morning.
At the moment we've had multiple sunny days and by the end of the day my Ah has been anywhere between 5% under charged and 5% over charged even though it certainly seems close to full by midday. I guess it's always going to be a bit rough maybe partly due to me only sampling the shunts every 10 seconds and assuming those amps were constant over the last 10 seconds.

Posted by playersz28

Nov 19, 2018 at 12:15pm

lindsay Avatar

Nov 19, 2018 at 7:48am lindsay said:

playersz28 Cool, my batteries usually slow down charging around midday (the amps trail off), which indicates to me they are close to full. I don't have a flag from the controller I now use (no longer using SRNE/Renogy) so I wait until there has been no charge coming in for 15 minutes and consider that night. Then I reset the count of Ah used. When the battery starts charging in the morning I reset the Ah coming in.
I'm also colour coding the backlight on my Raspberry PI connected LCD - RED means not even close to being charged, ORANGE - within 8Ah, WHITE - within 3Ah, GREEN - within 1Ah. I reset the colour when the sun comes in in the morning.
At the moment we've had multiple sunny days and by the end of the day my Ah has been anywhere between 5% under charged and 5% over charged even though it certainly seems close to full by midday. I guess it's always going to be a bit rough maybe partly due to me only sampling the shunts every 10 seconds and assuming those amps were constant over the last 10 seconds.


I query the INA219 every 2 seconds but it also averages itself within that period.

Nice trick with the backlight display color as an indicator :)We've got snow here so I've been sweeping off the panels when I can to get some readings. I'll play with the code more to see if I can tweak it when we are travelling in the winter and have SW USA sun. I figure if I can get a value that is pretty close then that's good enough. 

Posted by swampmonster

Nov 19, 2018 at 2:30pm

I'm gonna tone down my replies to stay friends, BUT.
Try to keep it simple in your mind, a few facts about ALL lead acid batteries we use today in our cars and RV solar. ALL of them.

A. Under recharging a lead acid battery causes sulfide build up on the plates, = walkdown in capacity
B. Over recharging causes the plates to lose lead alloys where they fall to the bottom of the battery, = destruction of plates
C. leaving a lead acid battery discharged for long periods of time reduces it ability to fully recharge, = walkdown in capacity
D. ALL LEAD ACID BATTERIES HAVE A LIFE SPAN MEASURED IN CYCLES...ALL OF THEM.
E. All batteries will suffer shortened life spans if not properly maintained
F. NO method we might employ outside a LAB can truly determine the condition, remaining life, or the true State of Charge of the battery...Amp counters help lots, but none of them are accurate, and all of them require you to be religious in programming, monitoring, and reprogramming them routinely.

Posted by lindsay

Nov 21, 2018 at 7:38am

playersz28 Avatar

Nov 19, 2018 at 12:15pm playersz28 said:

lindsay Avatar

Nov 19, 2018 at 7:48am lindsay said:


I query the INA219 every 2 seconds but it also averages itself within that period.

Nice trick with the backlight display color as an indicator :)We've got snow here so I've been sweeping off the panels when I can to get some readings. I'll play with the code more to see if I can tweak it when we are travelling in the winter and have SW USA sun. I figure if I can get a value that is pretty close then that's good enough. 


I'll change mine to every 5 seconds and see if I get more reliable values ;)

Posted by playersz28

Nov 23, 2018 at 6:15am

Still working on the charts and what I display. Screen shot from my phone.



Pi maintains the db and talks to the Rover. Gets shunt reading info from ESP8266 via UDP. Pi serves the Web page.



Working on porting the Arduino INA219 C++ lib to the Pi but not done. There's a Python one.

Attachments:

trailer_mon.jpg

Posted by tattoo

Nov 23, 2018 at 7:51am

^^^^^^ Damn that is awesome Z28......^^^^


Posted by lindsay

Nov 28, 2018 at 4:42am

Very cool :)

Posted by AKSKIFFfER

Jan 13, 2019 at 10:53pm

lINDSAY, You can get your batteries state with a hydrometer. They are calibrated for Batteries and use the Specific Gravity to calculate charge.
You check each cell in a wet battery.

Hope that helps

TK

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