UPDATED SEPT 28, 2019: I added a new electrical contact frame design based on Keystone 209 hardware. See further below for more details.
What is the Ryobi Power Deck? It is an accurate, portable, rechargeable, DC power supply for your projects. This solution adapts a readily available Ryobi battery (~20Volts fully charged) down to a lower voltage (0.00-18.00V), and current (0.000-5.000A), which are selected by the user depending on the application. The power supply is very accurate and is high resolution (can set values to 1/100ths of a volt). The shell is contoured to fit to left hand grip while adjusting power settings with the right. It is well balanced in the hand with the Ryobi battery in it. The shell fits very well on the Ryobi battery and it locks into place. The banana plug jacks are recessed for a cleaner design.
So, why would you need this as part of your electronics tool kit? It's an accurate power supply with a good range of Voltage and Amperage. You can use this solution to power ESP8266 IOT boards. Use it to power led strings, or laser modules. These sensitive electronic devices can be easily damaged if the supplied power is not correct. It can also be used to recharge 18650 batteries. I've even used it to run a DC to AC inverter (very lightly loaded) to run a small water pump in a remote area with no grid 120v power available. I've also used it to revive individual AA and AAA rechargeable batteries which have been discharged so far a standard charger will not recognize them and therefore will not recharge them until they are brought up to a minimum charge of around 1volt (for example: expensive Eneloop rechargeable batteries).
There is a DIY contact insert (Contact-R1.stl) that holds solar tab wire which makes the actual contact with the battery terminals. The insert locks into the shell with a satisfying click and stays in place. It could be glued in place but I have not found that necessary. I used tinned copper solar cell tabbing (5mm wide) in the insert for the connection to the battery. Keep the un-insulated tabbing lengths short so they cannot touch each other while in the shell. Solder insulated wire leads to the short tabbing to supply the battery power to the regulated power supply module.
UPDATE March 31, 2019: I updated the shell print to an "enhanced" version which includes a provision for a 3 way switch and a USB port charger! This enhanced version is called "Shell-R2.stl". The first version is still available as "Shell-R1.stl" and, unlike the enhanced version, it turns on the moment it is attached to a battery and does not include the USB charge port.
UPDATE Sept 28, 2019: I added the Contact-R2.stl variant to my design. This contact insert uses Keystone 209 connectors and is an alternative to the DIY contact. The fit is great. Build the contact insert first (solder the wires to the 209 contacts, put them in the insert, then install the contact assembly onto printed frame) before putting it into the shell. The contact clicks into place within the shell with a very positive latch/sound. The contact is hard to remove without breaking.
I appreciate any monetary tips. Alternatively to the Tip Designer button, tips can be made here too: https://paypal.me/vivap2p . Both work. Enjoy!
Power supply: https://www.amazon.com/gp/product/B01N0VKTC2/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B01N0VKTC2&linkCode=as2&tag=vivap2p-20&linkId=93dfd0df81250f792d7d18a062adbf6d
Banana Plug Jack: https://www.amazon.com/gp/product/B00D6AICR4/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B00D6AICR4&linkCode=as2&tag=vivap2p-20&linkId=d89bf2fd280b093136d68a9f63e44330
USB Charge Board: https://www.amazon.com/gp/product/B01HXU1C6U/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B01HXU1C6U&linkCode=as2&tag=vivap2p-20&linkId=58bc5c5430736a374d363228aafd1820
3 Way Switch: https://www.amazon.com/gp/product/B06XJHGM4B/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B06XJHGM4B&linkCode=as2&tag=vivap2p-20&linkId=d450163a01ed67133b85e31636321808
Keystone 209 battery Contact: https://www.amazon.com/gp/product/B06VTPWM6M/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B06VTPWM6M&linkCode=as2&tag=vivap2p-20&linkId=e70f8d329eff8e738d6d17ea81e2d413
A great soldering iron kit: https://www.amazon.com/gp/product/B074W3W55T/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B074W3W55T&linkCode=as2&tag=vivap2p-20&linkId=fb125059768fab105d54e00b292be777
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