We were planning to create a DIY battery from 18650 cells for our off-grid project for a long time but as always low priority experimental tasks have to wait. The goal was to reuse some 18650 cells from previous builds to test their capability and be environment friendly. We also wanted to create the biggest battery that would fit in the box for obviouse reasons, and before I forgot we wanted to created a 12v battery pack.Let’s see what we have created in our free time!
We prepared for a build with the followings:
- 18650 cells
- Charge controller
- Nickel plated steel belt
- 12V car battery charger
- test load device [a car h4 bulb with 65W which requires ~5A]
These are the steps we did:
- we charged / test all the cells so make sure we have the same condition cells in one series
- with this information we were able to determine which cells were not usable
- then we packed them in a group
- we used our spot welder to weld the nickel belt to a series
- then one by one we connected to the series to each other carefully making sure no short will happen
- soldered the charge controller to the battery pack
- tested the load and charge process
- tested the load and charge process with 10 times the current which we will need
- tested the balancing option within the charge controller by cycling the battery and checking the voltage level of each pack[in the series] within the battery
Summary of our DIY battery from 18650 cells:
- we completed the task without any major issues 🙂
- we were able to created a 65Ah battery which is huge
- it fits into the required space with the plastic holders [they were not counted…]
- with this capacity, we estimate that our device can operate for three weeks without having any sunshine
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