I have a new SmartSolar MPPT 75/10 connected to a 12V LiFePO battery only. I updated the battery in the VictronConnect app and can turn on/off the load without issue. The problem is that in the Always Off state, there is about .30v on the terminals measured with a multimeter. This causes the attached device not to turn on once proper voltage is applied.
I have the load connected to a Linovision Industrial 5 port gigabit switch rated for a 9-54v input. If I unplug the switch and plug it back in after I set the load to Always On, it powers up and operates fine. However, if I set the load to Always Off, the power light on the switch flickers on once every few seconds.
I tried to factory reset the unit and re-program but the behaviour remains. Is this normal?
This would not be unusual to have a low level leakage current from the load output.
If this is causing a problem, then a shunt resistor can be connected in parallel with the load, this will reduce the “off” voltage. Value of the resistor can be selected to solve the issue.
Thank you for the reply and suggestion. Upon further troubleshooting, I have narrowed it down to when I command the load on by changing the load output through the app to always on, if my 12v switch is connected to the load, it will not come on. I have verified this with a multimeter attached. If I only connect the mm to the load terminals and command the load on/off, it will power on/off. As I mentioned before, it is a 12v switch made to accept 9-54v input using a built in voltage booster. The unit itself has an operating wattage of less than 6w and I am testing it with nothing plugged in. Could the voltage booster be causing an issue causing the MPPT to not provide power when there is a load?
12v automotive headlight bulb - 2 amps - power on/off without issue multiple times
12v marine pump - same issue as the switch, briefly attempted to spin up but then the load from mppt switched load off, it would cycled through this a few times
12v motor from a kids power wheel, same as marine pump - attempt to start but then mppt switched load off
Both the motor and marine pump both start and run fine directly connected to the same battery connected to the mppt.
You will find that loads like a pump or motor have a very high start up current and this is probably going into overload on the mppt which shuts the load down. Remember it is only rated for 10A, motor start up current can be 6 times higher than the motor rated current.
Also you said the issue was with a voltage booster. A lot of items like voltage boosters have capacitors on the input, which create a high surge current when initially connected as the capacitors charge instantaneously. As with the motors, this may well overload the mppt and shut down on high current. DC to DC converters are not suitable for the load output.
I understand that but if that were the case, in the example of the small switch with built in voltage booster, wouldn’t I experience the same issue if I were to connect the switch to the load terminals when there is load output is already on? That same rush of current would overload and shutdown the mppt upon connection? That is not happening. The issue is only when going from a load always off to load always on scenario from the app. If I set the load to always on, then connect the switch, it powers up fine.
You were correct. It was the high startup current of the device. Obviously, the mppt cut power to the load terminals, but did I miss an error or warning message in the app or through the lights that this was happening?