xdorland avatar image
xdorland asked

SMartshunt says the (lithium) battery is full after a few minutes of charge from the solar panel/ Bad setting of parameters?

A professionnal installed me the SMartshunt 500A last week.

I remarked two things :

1) the discharges are a little bit less than I expected (example : when I turn 2 2Watts lights, the smartshunt says count only 2Watts)

2) more important (but point 1) is maybe linked to point 2)) : a few minutes after the solar panels start charging the battery...the smartshunt say the battery is full...but it clearly does not correspond to the sun power I have^^ (the VE.Direct SMart on my MPPT charger said around 2-3 Amps go to the the 15 Ah that needed to be charged cannot be charged in 10 minutes^^)

I live in a motorhome. The battery is a 110 Ah Lithium.

I think the professionnal installed weel the shunt.

I think there is something wrong with the parameters of the shunt (At the beginning, I forgot the to set the "Charged voltage" was 0.0V ^^)

==> I set the "charged voltage" parameter at 13.2V as said in the manual...but the manual is only about lead-acid battery...and I have a lithium battery. Maybe is it because of this?

==> How would you set the "Charge voltage " parameter for my lithium battery (considering that the "Absorbtion voltage" of my MPPT charger is set as "14.2V" (default value for lithium batteri". Do I try to set the "charge voltage" of the shunt at 14.0V as said in paragraph 10.3.8 of the manual?

(I set the "Additional settings for lithium batteries": Charge efficiency at 99% , Peukert exponent at 1.05)

Best regards.

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2 Answers
seb71 avatar image
seb71 answered ·

You can start with 14.0V for "charged voltage", observe for a few days at least, then adjust as needed.

Also look at tail current and charged detection time.

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xdorland avatar image
xdorland answered ·

Thank you for your answer.

It seems to work!

But, I have a funny question : why would I rather set "charged voltage" with...100V?

...I do not care if it do not synchronized as I prefer to resynchronized it myself sometimes (I live in a camper and the shunt is not supposed to be disconnected before years)...and I do not want to take the risk that the shint think the battery is full if it is not the day where, for some reason, there will be a voltage of 14.0 for a few minutes.

Thank you again.

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seb71 avatar image seb71 commented ·

You can set the "Charged voltage" from the SmartShunt settings to a higher value if you want to avoid automatic synchronization of SOC to 100% and then manually synchronize from time to time if you notice that the SOC value drifts away from reality, if you prefer it this way.

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xdorland avatar image xdorland seb71 commented ·

Thank you for your answer.

I have a last question : the voltage of my lithium is decresing (for exemple...12,3V now), even when (almost) nothing use it (just a few lights)...but the shunt says it is 77% full (and 77% is in OK considering m'y production and consommation of today).

This " low voltage" (for a lithium battery) occuree several time last days. The battery was bought in last october...I had 5-6 complet shuntdowns because we used it too much (no shunt at this time^^)...even if a few of these shuntdowns were quite strange.

...normally, a lithium battery stay at 13V almost until it is very Can I explain it?

(I will maybe create an other post has or does not concern specifically the shunt).

Thank you in advance

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seb71 avatar image seb71 xdorland commented ·

Maybe the battery is defective.

Can you monitor or measure each cell voltage?

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