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SmartSwitch for battery isolation and power monitoring

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strud

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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:

SmartSwitch1.jpg


PCB layout

SmartPowerDisconnect_pcb_rev2.jpg



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.

IMG_0365.PNG



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....
 

WillMarchant

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Looks great! Dimensions? Will this be a product?
 

VernK

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Would you be willing to share the part number for that switch assembly with the spring loaded contacts? I have never seen one like it.
 

strud

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Dimensions are 33.2 x 38.1

A simpler version without monitoring capability can be much smaller at 1" x 1" footprint

IMG_9716.jpg IMG_9691.jpg


Would you be willing to share the part number for that switch assembly with the spring loaded contacts? I have never seen one like it.
it is a unique one for sure. Supplied by rs-components https://au.rs-online.com/web/p/jack-plugs-sockets/9131018/

Regarding if this could become a product? I guess so
 

markjos

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Aha! That’s a 3.5mm jack masquerading as a 3PST switch. Good use of the switch contacts. I hope that it proves to be reliable, mechanically.
 

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