Electricity follows the path of least resistance. The shunt measures amps by using resistance. NOTHING should get to the battery without first going through the shunt of you want an accurate measurement. If the above is the case, amps are going into the battery but not through the shunt. Ok, you have a lot going on here, but I think I'm seeing what's going on.įirst, it sounds like negative of the battery is connected to ground (the vehicle frame) and doesnt go through the shunt. Is this the issue? Should it be plugged in directly to battery minus or system minus of the smart shunt since? I'm guessing this would show a higher charge current which would prevent the 2nd paramater from checking off auto syncronization.ītw, I gave you a gold star for all the help! THANK YOU! ![]() And now as I'm typing this, I'm realizing the ground cable is still plugged in directly to the car battery. With that being said, my fridge only draws 4 amps which would fall under the charge current parameter (135AH x 4% = 5.4 amps). So theoretically, if I were to go camping having my fridge all night running off my Lithium Car Battery and draining to X% the next morning, I can drive for 3 minutes and the State of Charge would show 100%. 3 minutes have passed while both the voltage and current conditions are met.the charge current is less than 4.0% of the total battery capacity (e.g.In the case of a 12V battery, the battery monitor will reset the battery’s state of charge to 100% when all these parameters have been met: And after reading the Victron manual further it's because it's hitting 3 paramaters for it to set the charge value to 100%: From what I'm experiencing, any drain I perform even when 20%+ discharge, after a few minutes of driving the app will report the State of Charge being 100%. So in a scenario where I have a 100AH hour battery and I drain it to 50% being 50AH left, the smart shunt would be accurate in regards to State of Charge because this is the issue I'm not truly understanding. Wow thank you for this info! As you can tell I'm a bit new to this stuff. I had to take a moment to think and double check when I set up the BMV. I just installed a 300ah bank in my camper with Lifepo4 batteries and a Victron BMV-712. ![]() Once it does, the battery is considered fully charged. In other words, after the bulk phase, the absorption phase will remain at the charged voltage for a while until the amp input falls to a certain threshold. The voltage is part of the equation so the shunt understands the charging profiles and when the battery is truly fully charged. So you have to monitor amps in and out (a little over simplified but hopefully you understand). The reason the shunt is even necessary is because lithium batteries don't have a linear discharge curve like lead acid. What it does is, once the battery is charged, it will start monitoring the amp draw, it doesn't care the voltage, it just knows that once charged to 100%, it's at 100 unless amps are drawn out of the battery. The shunt won't care what the voltage says after charging (i.e, the voltage sag), it's smart enough to understand what's going on. This is different than the resting charged voltage which will be the voltage the battery rests at after being charged and taken off the charger. ![]() Now, for your smart shunt, your fully charged voltage setting will reflect the bulk charging voltage (check the battery manual, it will be around 14.4-14.6v). ill let you look up why newer cars do this. If your vehicle is new enough, you probably have a smart charging system meaning, once the battery is charged (and there are no significant loads on the system) the voltage will drop to around 13.0-13.4v. Lead acid batteries also do the same thing.
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