This blog post describes improvements and additional features for the Open Source Outdoor Robot platform JECCbot mini which was introduced here: Open Source Outdoor Robot platform JECCbot mini
For the next revision we decided to give the option to use power tool batteries. We used the Einhell Power X-Change System ( https://www.einhell.de/en-de/innovations/power-x-change-platform.html ) because we already had some batteries and chargers at hand.
These batteries seem to consist of five LiIon batteries in series. They have a nominal voltage of 18 V and little bit over 20 V when fully charged and down to 16 V when empty. The batteries also have some electronics included which cuts the power when the battery is empty. They also have some status LED which show the state of charge. So we think the batteries are quite handy and there is little chance to destroy the battery with bad handling like deep discharging. Additionally the mechanical connection to the tool / robot is solid and no additional mounting is needed. (in contrast to LiPo pouch cells like in RC cars).
At the moment the files for the adapter are in the "dev_v0.4"-branch of the repository and will be merged when testing is finished and the new revision is released.
Here are two fotos of the adapter:
Until now we only used wheels with a diameter of 12 to 13 cm. Now we added bigger wheels with a diameter of 17 cm ( https://www.conrad.de/de/p/reely-1-5-buggy-komplettraeder-big-spike-5-star-schwarz-2-st-235815.html ). This adds 2.5 cm to the ground clearance and allows us to use a bigger roller wheel. The old one had a total height of 10 cm, the new one has 12.5 cm. These changes improve the performance in rough terrain.
Here are three images with the bigger wheels: