MosFet leakage from Battery Protect activates Orion-Tr Isolated DC-DC converter remote switch

Q&A and troubleshooting
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1

I am setting up a system for an unattended operation where the Battery Protect is controlled using the VE.direct cable as virtual load control from the SmartSolar MPPT 100/50 Charge Controller which in turn controls the remote switch on the Orion-Tr 12|24-5 DC-DC converter. The only loads on the output side are a PoE injector which uses about 10 uA at low voltage and the Orion-Tr 12|24-5 Isolated DC-DC converter remote switch which also draws very low current. The Orion-Tr is used to power a Starlink Mini.

My problem is the leakage current from the BatteryProtect raises the voltage on the output side above approximately 2.2 volts and activates the remote switch on the Orion-Tr. Solutions tried are 1. Load output with two 10 K Ohm resistors. Current draw about 200 uA and voltage reduced to 1 volt; 2. use a slave relay 1 mA draw; and 3. use the Orion-Tr-Isolated-DC-DC-Charger-remote-cable which draws about 100 uA when inactive and requires 4 volts for pull-down. I chose the Remote switch for deployment; however, I am concerned that MosFet leakage may change with temperature. Unit deployed in Alaska with expected temperatures below 35 C at all times and below +15 C for critical time period where unit will be unattended. Observation of voltages and current conducted at 15 C. Expected MosFet leakage at lower temperatures is lower.

Reference Document: BatteryProtect_12V_24V/114439-Smart_BatteryProtect-pdf. Drawing Page 4

2

Yes, it will. However, the temperature coefficient is positive - leakage increases with temperature.
Best solution is to use a small enough resistor to get the voltage produced by the leakage current to under 0.5V - worst case. looks like a 1k ohm load would be sufficient.

3

Perfect. Will test different resistor values for best fit.

4

Solution: 1.8 k resistor worked fine for no-load condition. MOSFET leakage at 20 C measured at 290 uA. No-Load (except voltmeter) voltage Vbat - 0.8.

Smart Battery Protect had leakage of 10 uA with no-load voltage of 0.5 Volts.

Best solution is to use Smart Battery Protect. Did not check with Bluetooth disabled as I can tolerate extra 300 uA current draw.