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help needed in determining materials list

mstng_67

Hello. I am very new to hardware development and am in need of some professional help determining what parts I need to accomplish my goal. I am looking to build a power management system for use inside a car. The system will be used to manage power to a Raspberry Pi. Attached is an accurate (yet I'm sure very crude...please pardon my ignorance) representation of what I'm trying to accomplish. The goal of this is to maintain a constant stream of clean power to the RasPi while the vehicle is in operation. Could I get some guidance on what materials I need in order to make this a success?

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    I didn't understand the exact requirement, did you intend the RPI to gracefully power off when the vehicle is not in operation?

    If so, there are alternate ways that do not require the LiPo and step-up DC-DC converter - the sleepy pi would then likely meet the need.

  • 0 in reply to shabaz

    Well, that's part of it. I also want to ensure no vehicle battery drain when the system is not in use. In addition, I need some mechanism to ensure the RPi is getting clean power in the hostile power environment present in a car. That was the thought behind the LiPO. The LiPO is meant to ensure a clean stream of power to the RPi no matter what the power condition is in the vehicle.

     

    The requirements are:

     

    1) Ensure that the system can completely power off such that there is not drain on the automotive battery.

    2) Ensure a clean and steady power supply to the RPi.

    3) Provide a mechanism to allow the RPi to shut itself down gracefully and then "wake up" when the vehicle key is switched to the "run" position. Note the IGN wire in my drawing. That's what starts the whole process.

     

    The sleepy pi may be an option. I am unsure if it the entire system can be completely shut down...meaning does the arduino stay powered on the whole time? If so, that would cause a drain on the automotive battery. Lastly, I see that it provides the power management I'm looking for; however, I really need to be able to fend off the spikes, brownouts, and sustained voltage craziness in the vehicle. I would still need some kind of battery to provide the consistent power I'm looking for...correct?

  • 0 in reply to mstng_67

    Sat-Nav and in car entertainment equipment operate from the vehicle battery. They contain processors too, and a LiPo is not needed for cleanliness with these devices.

    The sleepy pi website specifies "Extend RPi battery life from hours -> weeks / months" so I'm confident it won't drain the vehicle battery when powered off gracefully (which

    is what the sleepy pi does). Basically relays, LiPo's and step-up converters are not needed - saves a lot of effort!

    You should take steps to ensure the input won't exceed 17V (the sleepy pi limit) - perhaps using a varistor, TVS or both.

  • 0 in reply to shabaz

    I have been experiencing power-related problems with my RPi project. Log messages harvested from the SD card suggest power-related issues that cause a bunch of horrible things to happen like the network interface to stop functioning. Over and over again I have come to realize that the RPi seems to be sensitive to in-vehicle power fluctuations. This is the largest impediment to my project. If I'm wrong, do you have any ideas what I may be experiencing and why? For example, when the RPi is running off of the vehicle battery and the vehicle is started, the only LED on the Pi that lights up is the second one and it stays red. Nothing else happens. The device will not function until I completely pull the power for several seconds and then re-apply power.

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  • 0 in reply to shabaz

    I have been experiencing power-related problems with my RPi project. Log messages harvested from the SD card suggest power-related issues that cause a bunch of horrible things to happen like the network interface to stop functioning. Over and over again I have come to realize that the RPi seems to be sensitive to in-vehicle power fluctuations. This is the largest impediment to my project. If I'm wrong, do you have any ideas what I may be experiencing and why? For example, when the RPi is running off of the vehicle battery and the vehicle is started, the only LED on the Pi that lights up is the second one and it stays red. Nothing else happens. The device will not function until I completely pull the power for several seconds and then re-apply power.

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