Hello All.
I am new here and not great with electronics. I have tinkered around with 555 timers, comparators, voltage regulators, counters, LED display drivers, mosfets, transistors etc but that is about my limit.
My Son has a project to do, with my help.
We live completely off grid and have about 4kw(peak) solar array with panels in series pairs so have feeds into our battery shed at near battery voltage. About 70v open circuit but the batteries pull that down to between 48v (flat) and 60v (equalisation charge). Charge is controlled by a fairly simple PWM charge controller. The lead acid battery bank is nominally 48v. This feeds three Victron inverters to provide our 230v AC supply to our temporary caravan home, until I build the house.
My Son, Toby, wants to use an Arduino to show the charging current, battery voltage and inverter draw current. He wants to do this numerically and graphically.
Ideally he wants the display panel in our caravan but the current measurement shunts will need to be in our battery shed about 30 metres away.
The rough plan is to run something like cat5 network cable between the shed and the caravan carrying the signals and the high current shunts in an enclosure in the shed and then another box in the caravan with the arduino and displays.
We have just started this project so I have scrawled a quick sketch and a bit of information. Hopefully you guys can help steer us towards the most suitable components and methods. I have searched the internet and an INA240A3 device with an amplification of 100 V/V seems like a posible contender to bring the shunt mV signals upto a level that could be sent along the long cat5 cable without too much of a problem.
Power comes in at the left from our solar charge controller to the batteries at the bottom. There is a lot of PWM noise from the charge controller which the INA240 device might be able to deal with. I don't know how much noise but know that hwen the sun is shining and the charge controller is doing its pwm switching, at an audible frequency, the inverter buzzes at the same frequency. I have added a smoothing capacitor and switch and the smoothing capacitor quietens the inverter down so there is a good bit of ripple on the dc but I don't know how much.
The Victron inverters I have have their negative battery feed connected, or connected with some resistance, to the earth/ground side on the AC output. This would then be connected to my PC and then the Arduino ground via the USB cable so I am wanting my shunts and circuits on the negative side of the battery so I don't create a 50 odd volt path and zap some electronics or PC.
I do have a couple of 70v to 5v voltage regulators. I can't remember the number but will have to dig those out. I shall get the Arduino to send a signal to 'wake up' the voltage regulator and sensing circuits. I don't want to be dropping 45v over a device continuously so will get it to have a few seconds running every 15 minutes or so.
I did think there may be a bit of an error in which side of the shunts my grounding and Arduino are located but if my output signals are amplified into the 0v-5v range then the odd few mV error lost across the shunts might not be much of an issue and I could maybe write out the error in the arduino programming.
It is early in thinking about this project so nothing is fixed yet.