I am running a LTC3588 energy harvester as pictured in the simple solar example [below] with the 4 caps, only I am using a 3.7V 700mAh Li Ion battery in place of the caps. My solar film is outputting 4V @ 80-100mA. My project I am trying to run requires 25mA.
https://cdn.sparkfun.com/assets/9/0/7/6 … 000001.jpg
I am trying to charge the battery and power the device while the solar film is active, and run the device off of the battery while the solar film is not active.
I am getting no V at the VCC, and I have 3.7V at the VIN. I do not have any other pins hooked up as I cannot find the datasheet for THIS device. The only one I can find is for a different device similar to this one. I have the on-board D0 and D1 still in the factory positions.
What am I missing to make this work?
Why are you using the LTC3588 in that circuit, and what is it supposed to do?
It makes no sense to use a lithium based battery in that circuit. They require a special charge controller and low voltage shutoff circuit, and there are no charge controllers on the hobby market that allow a load to be driven while the battery is being charged. If you ignore those issues, the battery will very quickly be destroyed.
I’m new to using solar power. I am powering a device that gets 12 hours of light and 12 hours of dark in the room. I’d like to be able to run the device off the solar in the light, and battery in the dark. Do you have any suggestions on how to accomplish this not using the battery?
The starting point is to determine how much power and energy (powertime) the “device” consumes. If it is 25 mA TOTAL, as mentioned in your first post, then it consumes 2512 = 300 mAh. Multiply by the voltage to get mWh total energy.
Then pick a solar panel that can provide at least that much energy given the lighting conditions you expect to encounter. Plan for periods of cloudy and rainy days if necessary.
The storage component comes after all that, and for solar power, supercaps, sealed lead acid or NiMH batteries are much preferred as they don’t require fancy charge controllers.
It consumes 25mA. So 300mAh would be bare minimum I could go. There will be no cloudy days as it will be indoors and light will be on for 12 hours continuously at a minimum. The closer to 500mAh the better. Thank you in advance for your help.
Solar panels are rated in full sun at noon, so under ordinary room lighting, the output of your panel will probably be a tiny fraction of what you stated in your first post.
The conditions at which the solar panel will be placed meet that requirement. It will be under a 600W - 2000W light bulb for at least 12 hours a day.
I will be testing this before sending, so i can adjust the solar panel size accordingly later on. I’m just trying to get the right storage option and wiring using this module. Once this testing is done I will be reverse engineering the harvester board and building one to spec that I need.
I found some NiMH batteries that will work for the storage I need. A little overkill @ 2000mAh each x 3, but better to be safe than sorry. Now Im just looking for a wiring diagram for this harvesting module.
Why do you want to use the “harvesting module”?
I dont have to. Like I said, I’m new to solar. So if I can get away with just the batteries and the solar film hooked up to the device you would save me some $$ - which is GREATLY appreciated. LOL
If the device requires a regulated voltage, you can choose from a large variety of voltage converters (https://www.pololu.com/category/136/voltage-regulators) for a fraction the price of the LTC3588.
This is perfect! Thank you!
