question

andy13 avatar image
andy13 asked

Shunt not same reading as Ultimatron

Hello,please find my wiring diagram. The issue is the reading of the shunt is not the same as the Ultimatron, over night the soc of the battery can go down but the shunt will not have the same reading. Also the mppt over charges the battery and the bms kicks in to stop the charge from the mppt

Thank you for your help 1d75e637-60b3-4a68-96cc-03a73bf098d4.jpeg

SmartShunt
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Alexandra avatar image Alexandra ♦ commented ·
@Andy13

Knowing what bettery you have and your shunt settings would be helpful.

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andy13 avatar image andy13 Alexandra ♦ commented ·

Hi the battery is an Ultimatron 150 amp hrs

thanks for helping1663910189469.jpeg

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1663910189469.jpeg (47.2 KiB)
andy13 avatar image andy13 andy13 commented ·
The battery reading last night was 88% and this morning 61%
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3 Answers
snoobler avatar image
snoobler answered ·

Program smart shunt to:

14.2V charged voltage

Peukert 1.05

Efficiency 99%


Fully charge your battery to 14.4V, hold there for 30 minutes.


The two should both sync to 100%, and they should stay reasonably close provided you fully charge at least a couple times a month.


If those breakers are cheap Chinese ones from Amazon, return them. Get Littlefuse, BlueSea or some other reputable brand.


If that's an audio style fuse, trash it. Get a Class T.



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andy13 avatar image
andy13 answered ·

Thanks I'll modifiy the settings, Any idea why the MPPT is over charging the battery ?

1663920744439.jpeg


1663920744439.jpeg (380.7 KiB)
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snoobler avatar image
snoobler answered ·

I'm sorry. I missed that the BMS was cutting out. The MPPT is not overcharging the battery. The typical cause of this is the battery CELLS are out of balance, and the BMS is cutting off the charger because a single cell has gone over-voltage.


Recommend the following:

Absorption 13.8V

float 13.6V

Under Expert, absorption time: 6 hours.


To resolve this, the battery must be held at elevated voltage to allow the BMS to balance the cells.

After a few days, try 14.0V absorption again. If it works, use that voltage and increase every few days until you can get to 14.4V.

If this doesn't resolve quickly, you need to contact the battery manufacturer for replacement.


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