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Solar Powered Wyze CAM
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Solar Powered Wyze CAM

by mirichards on Mon May 31, 2021 9:26 am

I want to power my Wyze CAM with a solar panel and LiPoly/Li-ion battery 24-7. I would like the set up to power the Wyze CAM throughout daytime via the solar panel while charging my LiPoly/Li-ion at the same time. Once it gets dark, I want the LiPoly to take over the power requirement until we get sun the next day.

The Wyze CAM requirements are 5V 1A DC via USB-C. Wyze indicates a 10000mAh power bank will power my Wyze CAM for 16 hours; 20000mAh for 33 hours.

I am thinking I can use the bq24074 along with a PowerBoost 500 to achieve the controls. Any issues that I should be concerned about for this application?

1. What size battery should I use? I am leaning toward a 20000mAh to cover those cloudy or winter days when solar power will be minimal. Should the battery be 3.7V dc? Does Adafruit have a battery this size or can I achieve with multiple smaller batteries?
2. What size solar panel should I use to power the CAM thru the day while charging the appropriately sized battery?
3. Is this too big a requirement for the bq24074 or PowerBoost 500?

All of this will be outside at the end of my 700ft driveway. So, I am a bit concerned with the temperature limitations of the battery. I am in Pennsylvania, so the ambient temps should not get any higher than 100 degF (37.7C), but on the cold side we may see 0 degF (-17.8C)--are there issues at the low end to address?

mirichards
 
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Re: Solar Powered Wyze CAM

by adafruit_support_bill on Mon May 31, 2021 9:58 am

The Wyze CAM requirements are 5V 1A DC via USB-C. Wyze indicates a 10000mAh power bank will power my Wyze CAM for 16 hours; 20000mAh for 33 hours.

10000 mAh / 16 h @5v = 625 mA @5v. That is the expected average current draw from the camera.

625 mA * 24 h @5v = 15000 mAh @ 5v. That is how much 5v power you need to get through the day.

Since the nominal battery voltage is 3.7v, you will need to boost the voltage from 3.7v to 5v. That will incur a proportional decrease in current - plus some additional loss in the conversion process. So to get 15000 mA @ 5v out, you will need closer to 25000 mAh input at 3.7v.

The bq24074 has a maximum charge rate of 1500 mA. 25000 mAh / 1500 mA = 16 hours. Even the sunniest parts of Pennsylvania are not going to have enough hours of prime sunshine to store 25000 mAh per day using the bq24074.

You are probably better off going with one of the many off-the-shelf 12v systems out there and use a buck converter like this one to get the 5v you need for the cam: https://www.adafruit.com/product/4739

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Re: Solar Powered Wyze CAM

by mirichards on Sat Jun 12, 2021 10:55 am

Thanks for the response and details Bill.

I found a 12V solar panel to connect to the Buck converter and a 12V Lithium battery that can output 12kmaH at 5V. My thinking is to use these with the Buck converter so that I get solar power thru the day on the Wyze CAM. However, it looks like I need a device/circuit to select between the 12V/5V battery output and the 5v Buck converter output to the Wyze CAM. Otherwise, how can I connect the battery output at 5V to the Buck 5V output to power the Wyze CAM?

Does Adafruit offer a device for this "selector"?

mirichards
 
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Re: Solar Powered Wyze CAM

by adafruit_support_bill on Sat Jun 12, 2021 12:03 pm

How are you planning to charge the lithium battery?

Instead of two separate systems like that, I think what you want is an integrated 12v solar charging system - these are usually designed for charging SLA batteries. Then you can feed that directly into the buck converter to power the camera.

The good news is that the laws of physics work both ways. So a decrease in voltage yields an increase in current. So, to get 15000mAh at 5v, you will only need about 7000 mAh at 12v.

Assuming 4 hours of good sunlight per day on average, you would need a system capable of charging at a 1750mA rate. That translates to 21 Watts at 12v.

Looks like this one has a built-in 5v (USB) buck converter output: https://www.amazon.com/ECO-WORTHY-IP65- ... B00PFGP0EA

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Re: Solar Powered Wyze CAM

by mirichards on Mon Jun 14, 2021 7:10 pm

Excellent find Bill! Your Amazon reference was what I was looking for, pretty much all in one package! I don't know why I did not find this one sooner. Thanks again.

mirichards
 
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Please be positive and constructive with your questions and comments.