Good day.
I have set up VE Networking using SmartShunt and am charging a LiFePO4 battery via an IPBlue 30A charger.
The IPBlue profile is set to the default Smart LiFePO4 profile; however, while connecting to VE Networking, the IPBlue is pushing a high voltage of up to 15.7V. There is about 23 feet (7 meters) between the battery and the charger. Is this normal? see screenshots
7 meters one-way? If so, there’s going to be a critical amount of voltage drop from the charger to the batteries, so it’s likely that the SmartShunt is telling the charger (via VE.Smart Networking) to increase its output voltage to make sure that by the time it gets to the batteries you’ll still have usable charging voltage.
Yes, 7 meters one way. However, if I were to charge without joining VeNetworking, the battery would still charge. I also have a Bluetooth battery app, which shows that the voltage goes all the way up to 14.2V (that is what I have set up for the BMS disconnect)
Remember that if you have a run with a large voltage drop, that drop starts to reduce as the current reduces, so if you start pushing 15v at 15A but only 13v is getting to the end, by the time the current drops to say 1.5A, you will be getting a significantly higher voltage at the battery, maybe even too high.
This is what the dynamic voltage code allows for - you measure at the battery and adjust from there, but you keep adjusting so that as the current comes down, or the cable temperature changes, or other things happen, you keep the voltage at the battery in the target range.
@guystewart mentioned;
During battery charging, the MultiPlus will compensate the voltage drop over the DC cables up to a maximum of 1 Volt (i.e. 1 V over the positive connection and 1 V over the negative connection). If the voltage drop threatens to become larger than 1 V, the charging current is limited in such a way that the voltage drop remains limited to 1 V.
Guy: Is this code in the IP Blue 30A chargers as well, if they are connected to a smart network? I could imagine it is, because the shunt has the true battery voltage, and the network allows the IP Blue to access that data, so it could bump up its voltage to compensate. If it does, does it also have the max 1v over each cable limit?
The numbers seem to suggest this - the 30A has lowered the charge rate to 26.8A, so that +1v on each cable can be allowed for, giving an actual charging voltage at the battery terminals of 13.7v (15.7 - 1v - 1v)
