question

Lionel SEYDOUX avatar image
Lionel SEYDOUX asked

Soc 100% at absorbtion beginning

Hi folks!

On my system, SOC reaches 100% about 1 hour before the end of Bulk while full sun at 10:00. I thought that Bulk could only fill 80% of the battery capacity and that absorption was designed to fill in the remaining 20% and reach fuil SOC. I set BMV with the C20 Ah capacité Where am I wrong?

battery chargingSOC
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5 Answers
michelg avatar image
michelg answered ·

Hi Lionel, any changes on the Peukert Coeff ? Or in the tail current ?

Michel

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Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Hi Michelg,

No change from the default values

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klim8skeptic avatar image klim8skeptic ♦ commented ·

How do you charge your batteries?

Solar? Multi?? B2B??? Mains charger???? Alternator?????

Each of those^ charging sources would require slightly different BMV settings.

Different battery chemistry also require slightly different settings..

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michelg avatar image
michelg answered ·

Hi Lionel, I just checked my BMV-702, it is using the 3.11 firmware. I will suggest to input again the parameters you usually use on your BMV, if for any reason they are displaying fine, but they are somehow corrupted.

If this does'nt work, you could check you battery bank (2V units ? ) to see if there is 1 or more units whose voltage is not consistent with the rest of them. Also, check the mppt side, to see if there are any changes on it or not. I mean, the mppt can still provide the correct charge (or not) and the BMV detects it in a wrong (or not) way.

I remember I had such issues when installing the BMV and Ihad to modify the Peukert / tail. Since then, there is more or less a difference between the absorption and the 100% SOC in the BMV of 45m/1h, which is acceptable.

Michel

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Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Hi klim8skeptic

Thanks for your questions. Some answers

Charging is done with solar panels. In difficult times, rare, a generator bur rarely more than 2h/week

My batt bank: 12 OPzS 2V open, liquid electrolyte TYS11, 9 years old

Over & Bye

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klim8skeptic avatar image klim8skeptic ♦ commented ·

Page 12 of the manual could reveal some clues.

bmv-sync.png


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bmv-sync.png (80.2 KiB)
Lionel SEYDOUX avatar image Lionel SEYDOUX klim8skeptic ♦ commented ·

Thanks,

This confirms my programm when I manage to get there (mid april?)

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klim8skeptic avatar image klim8skeptic ♦ Lionel SEYDOUX commented ·

I would wait for the thaw.. I'm soft.

Could the batteries temp ? be stuffing up the SOC??

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Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Hi Michel,

My BMV is BMV 712 and runs on 4.01firmware. I shall do as suggested:

  1. Reset BMV in case some values are corrupt;
  2. Check each unit of my 12 OPzS 2V units (TYS11);
  3. Check my MPPTs;
  4. Check Peukert value (presently default). Does that value change when the batteries age?
  5. Check and possibly lower the tail amps;

Quite a program to be done when I manage to reach my house, prently under 1m of snow with a 1.5 hour run on snowshoes..

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michelg avatar image michelg commented ·

1m of snow => so temperature is low, this could also prevent the batteries to charge correctly. Take a look at : https://batteryuniversity.com/learn/article/bu_503_how_to_calculate_battery_runtime

Currently I can't check my Peukert value, but I remember that I did a change on it, not sure if 1.25 or 1.30... You could also run an equalization, as the symptoms seem to be related to sulfation.

Hard to get to your place, so better to have a full list of steps to do, there is an article written by Steven from Rolls about issues with sulfation :

http://support.rollsbattery.com/en/support/solutions/articles/5964-battery-sulfation

I'll take a look deeper this afternoon if I can find any other details. Remember to adapt your refractometre to the current temperature (putting distilled water on the test area, and changing the 0 position).

Michel

I'll recommend you to follow this YT webinar :


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