Solar Powered / LoRa Controlled 12v Solenoid

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toddmandude
 
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Solar Powered / LoRa Controlled 12v Solenoid

Post by toddmandude »

Hi, I'm looking for any advice with my power schematic for a Solar Powered LoRa project that uses a relay to activate a 12v water solenoid. I'm not totally out of my depth, but I may have overcomplicated this. The 12v solenoid will work down to 6v. For this project, I'm looking at 9v lipo. However, I also want my LoRa feather to have a 3.7v backup battery (use case: 9v completely discharges/fails, the feather can still communicate with home base).

The attached schematic makes sense to me, but I'm open to any advice on simplifying. Also open to critiques if there is an issue I'm missing.

Thanks!

Project (major) component list:
  • Adafruit Latching Mini Relay FeatherWing PID: 2923
  • Adafruit Feather 32u4 RFM95 LoRa Radio- 868 or 915 MHz - RadioFruit PID: 3078
  • Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger - bq24074 PID: 4755
  • Plastic Water Solenoid Valve - 12V - 1/2" Nominal PID: 997
  • 9V 2000mAh LiPo
LoRA_Relay_Schem.png
LoRA_Relay_Schem.png (22.67 KiB) Viewed 87 times

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adafruit_support_bill
 
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Re: Solar Powered / LoRa Controlled 12v Solenoid

Post by adafruit_support_bill »

The #4755 bq24074 charger in your component list can handle up to 10v input. But the #259 charger shown in your schematic has a max input voltage of 6v.

Assuming that you are using the #4755, that should work.

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toddmandude
 
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Re: Solar Powered / LoRa Controlled 12v Solenoid

Post by toddmandude »

Thanks Bill! Typo on my part. I intend to use the #4755.

I was also considering a buck to bring the 9v down to board voltage. Then I could use the built in LiPo charger on the feather. But I have no experience with bucks and I'm not sure how consistent or prone to failure they might be with varying temperatures and prolonged usage.

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adafruit_support_bill
 
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Re: Solar Powered / LoRa Controlled 12v Solenoid

Post by adafruit_support_bill »

Buck regulators are generally efficient and reliable. Especially if you are not pushing them to the limits. The charge rate of the on-board Feather charger is pretty low, so a unit like this one would not be under any stress:
https://www.adafruit.com/product/4739

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toddmandude
 
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Re: Solar Powered / LoRa Controlled 12v Solenoid

Post by toddmandude »

Cool. I think that could declutter this project a bit. I appreciate the help.

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