Hi,
I’m aiming to test the worst case scenario of how much energy can be harvested in a shaded location in Northern Europe in winter. A BlueSolar MPPT 75 ¦ 15 Charge Controller is used with the VE.Direct Bluetooth device and the Victron android app. Battery charging is working perfectly as expected with MPPT correctly optimising the current and voltage drawn from the photovoltaic panel in low light levels to optimise efficiency. Battery charging seems to be working correctly as well with float, abs. and bulk charging being used automatically.
I set Load Output to “Conv. algorithm 1” to automatically drain the battery into a 12 V, 50 W light bulb as a test load without taking the battery charge level too low and this correctly displayed “off < 11.1V, on > 13.1V.”
I’d planned to use this to test the worst case scenario of how much energy could be harvested in shade when the battery is repeatedly drained to 11.1 V. After a few tries this worked on the first day but the next day (today) the battery voltage came up to 14.6 V but the test load stayed off with no power at all being sent to the load.
I’d expected Load Output “Conv. algorithm 1” to automatically switch the load on whenever the battery voltage goes above 13.1 V and automatically switch it off whenever the battery voltage goes under 11.1 V but this doesn’t seem to have happened today.
Perhaps my c. 50 W test load is too large?
“Always on” sometimes works as expected and sometimes doesn’t - with the load sometimes switching on and sometimes remaining off. I don’t want to use “always on” because of the risk of damaging the lead acid battery by discharging it too much.
This is the documentation I followed:
12V system: OFF when Vbatt < 11.1V, ON when Vbatt > 13.1V.
The battery voltage in settings is set to 12 V, Max charge current set to 5 A (less than the default 15 A) and Battery preset is left at Factory Default “Gel Victron Deep Discharge(2)”
I’m using a new BlueSolar MPPT 75 ¦ 15 Charge Controller with firmware updated connected to a new photovoltaic panel (445 W nominal, 39 V open circuit) and new 12 V 7 Ah lead acid battery. Connection to the Victron app. on an Android mobile is via a VE.Direct Bluetooth device. The test load is a 50W 12 V lamp. The maximum charge current for the battery is set to 5 A. I understand that this is a very large solar panel for this size of battery - I’m only testing the worst case scenario of a solar panel working in shade in a European winter - not the full output of the solar panel in direct sun in the summer - which would be much higher.
The VE.Direct Bluetooth device was left connected to the BlueSolar MPPT 75 ¦ 15 Charge Controller all the time but my mobile was only in Bluetooth range occasionally.
Will