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crazy-marty avatar image
crazy-marty asked

BMV-712 Settings for Battle Born batteries

BMV-712 SOC is always wrong. 3 Battleborn Batteries.

Hello everyone. I sure this has been covered somewhere but I haven’t found the answer yet.

I have the BMV-712 smart monitor and it seems it’s never correct on the SOC. I have charged the batteries several times to full charge. During this process I run nothing off of them and charge them to the point it shows 0.2 Amps or less going into them and 14.4 volts. At that point I synchronize the BMV to 100%.

Now one would think the SOC would go up and down correctly with the voltage but the BMV-712 shows a low SOC all the time.

All of the settings are correct for the battleborn batteries firmware is up to date.





The system has 800 watts of solar and generator that can charge the battery bank.


One would think that when the system is charging and it’s only dumping in 10 amps via the generator it would show it’s nearly full on the SOC. But it always seems lower then expected.

So if anyone can please give me some ideas on what makes or ideas on what to change or make adjustments to I would appreciate It.

Thanks in advance. Crazy Marty.


BMV Battery Monitor
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Hi Cm,

"Now one would think the SOC would go up and down correctly with the voltage but the BMV-712 shows a low SOC all the time."

The BMV does not work out the soc based on voltage, it counts ah going in/out of the battery.

The most important thing is to fully charge the battery regularly (you have done that), and for the bmv to sync when that happens.

To get the bmv to sync reliably requires some tinkering with the "Charged voltage" value. The charged voltage is normally set a little lower than the mppt absorption voltage setting. If you are charging your battery up to 14.4v, set the bmv "charged voltage" at around 14v.

You have not mentioned what settings your mppt has.

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crazy-marty avatar image crazy-marty klim8skeptic ♦ commented ·

Thanks for the reply.

I have fully charged several times and the MPPT is set up according to the battleborne and morning star engineering information below. Everything works the way it should and all power that flows through or to the batteries must go through the shunt.

The batteries are being discharged relatively deep overnight but not to the point of auto disconnect. So I’m just trying to figure out how the battery monitor tracks the SOC.

As a mechanic I rely on the rule of thumb. As voltage increases amps decrease. So one would think that if it’s only wanting 10 amps or under it would show a higher SOC.

https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2019/01/morningstar-battleborn-compatibility-technote.pdf

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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Crazy Marty

I've resized the images in your post to make it a bit easier to read.

Did you already try:

-setting peukert factor to 1.00

-charged voltage a bit lower (14.3?)


Please also note: when at 14 volt for a bit, your battery is very much fully charged also.

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crazy-marty avatar image crazy-marty commented ·

I have not tried that yet. I know the charger from the generator will easily reach the 14.4 the manufacturer wants things set to. Since this trip is an operational test it makes it easier to make adjustments and changes. This is my reading at the moment. I will try and add another tonight when I loose sun.



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crazy-marty avatar image crazy-marty commented ·

What does the peukert factor determine or do?

The more I understand in engineering the better.

Thanks.

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ crazy-marty commented ·

It's in the manual, section 5.1:

https://www.victronenergy.com/upload/documents/Manual-BMV-700-700H-702-712-EN-NL-FR-DE-ES-SE-PT-IT.pdf

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crazy-marty avatar image
crazy-marty answered ·

Well I guess things are working the way they should. I just need to let it do it’s thing and monitor it closely for now.


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blond2silver avatar image
blond2silver answered ·

Hello, I have a battleborn bank - here are setting that are functioning properly:


1.) match the battery capacity to be exactly the same as battery bank.


Battery:

* charge voltage = 14.00 volts

* tail current = 2.00%

* charge detection time = 3m

* peukert exponent = 1.10

* charge efficiency = 97%

* current threshold = 0.10A

* time to go averaging period = 3m


Relay:

set the low SOC relay to 20% 20%


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mdbrown avatar image mdbrown commented ·

blond2silver: Interesting set of settings. How did you arrive at these, in particular the peukert setting? Thank you

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sglad avatar image
sglad answered ·

See this link for settings.

https://amsolar.com/rv-solar/support

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crazy-marty avatar image
crazy-marty answered ·

Final outcome. So what was happening finally showed it’s head several years later. I found one battery that had a bad internal connection. I found it with the use of a Flir camera. It showed up as a hot spot. Every time I moved the cable on the outside. That battery would start charging.

This caused the other batteries to become out of balance and subsequently caused a warranty of all 3.

The warning signs are out there if you know where to look.

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