strud
Active Member
- Joined
- Jul 1, 2019
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I posted a photo of my HPV4PoC Avbay and have had a question or two about the SmartSwitch device I mentioned.
This is a little board I made up to serve a number of functions in a small footprint.
1. Provide mutilple (3) channels of independent real battery/electrical isolation and use a simple pull pin mechanism
2. Allow monitoring of each battery/channel voltage, current, power and accumulated energy, primarily so that prior to launch one can get feedback on not just battery voltage but the current being drawn and gain confidence that everything is in order
3. Be low mass and as shock/vibration insensitive
So this is what it looks like currently:
PCB layout
Gnd (0v) connections are all common, while +ve inputs are isolated
Power monitoring chip is a PAC1934 device from Microchip
PAC1934 datasheet
Interface to the system reading the values from the SmartSwitch is I2C. In my case it is connected to my RocTrak module where the results are both displayed on a webpage that can be connected to by any browser (WAP also implemented) AND the results are saved in the log file along with GPS and other information.
The spring loaded contacts have a high preload and very low mass, hence require a very high shock/impulse/acceleration to break them free. I am yet to determine that number but will test.
Even so, when aligned to the X or Y axis of the vehicle (Z along long axis) then achieving this level of acceleration/shock etc would be most difficult.
However, it is also possible to use these inputs to drive a set of 3 low leakage low on resistance high side drive mosfets or similar, where the gates have capacitance added and hence a bounce in these contacts would be ignored. I will wait to implement that option after I determine the shock level required to make these contacts bounce....
This is a little board I made up to serve a number of functions in a small footprint.
1. Provide mutilple (3) channels of independent real battery/electrical isolation and use a simple pull pin mechanism
2. Allow monitoring of each battery/channel voltage, current, power and accumulated energy, primarily so that prior to launch one can get feedback on not just battery voltage but the current being drawn and gain confidence that everything is in order
3. Be low mass and as shock/vibration insensitive
So this is what it looks like currently:
PCB layout
Gnd (0v) connections are all common, while +ve inputs are isolated
Power monitoring chip is a PAC1934 device from Microchip
PAC1934 datasheet
Interface to the system reading the values from the SmartSwitch is I2C. In my case it is connected to my RocTrak module where the results are both displayed on a webpage that can be connected to by any browser (WAP also implemented) AND the results are saved in the log file along with GPS and other information.
The spring loaded contacts have a high preload and very low mass, hence require a very high shock/impulse/acceleration to break them free. I am yet to determine that number but will test.
Even so, when aligned to the X or Y axis of the vehicle (Z along long axis) then achieving this level of acceleration/shock etc would be most difficult.
However, it is also possible to use these inputs to drive a set of 3 low leakage low on resistance high side drive mosfets or similar, where the gates have capacitance added and hence a bounce in these contacts would be ignored. I will wait to implement that option after I determine the shock level required to make these contacts bounce....
