JECCbot mini - battery adapter and bigger wheels

16 Feb 2020

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

Battery adapter for Einhell Power X-Change

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:

Bigger wheels

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:

Top Comments

dubbie over 5 years ago in reply to bernhardmayer

Bernhard,

Thanks, this is useful. Not being familiar with GitHub I did find it a bit confusing but if the information is there then I will eventually find it.

I do like the idea though and might well try it out, it seems a good solution for a mobile robot. I have been thinking of getting a new cordless drill so I might take the opportunity to get a spare battery pack as well.

Dubbie
- Cancel
- Vote Up +1 Vote Down
- Sign in to reply
- More
- Cancel
bernhardmayer over 5 years ago in reply to dubbie

Dubbie,

I think a smaller version would also be strong enough. In fact only the upper 10 mm hold the battery pack. The lower part is only there to have enough space to hide the screw heads and not collide with the battery pack. But you can find all the source data in the github repo and you can modify them. The part was built using FreeCAD.

The battery holder needs about 2 hours to print.

Bernhard
- Cancel
- Vote Up +2 Vote Down
- Sign in to reply
- More
- Cancel
dubbie over 5 years ago in reply to bernhardmayer

Bernhard,

Thanks for this information. It looks interesting. The 3D printed part looks very chunky, is all that necessary or do you think a slimmed down version might still be strong enough? How long does it take to print?

Dubbie
- Cancel
- Vote Up +1 Vote Down
- Sign in to reply
- More
- Cancel
DAB over 5 years ago

Nice approach.

DAB
- Cancel
- Vote Up +2 Vote Down
- Sign in to reply
- More
- Cancel
bernhardmayer over 5 years ago in reply to dubbie

Hi Dubbie,

the battery adapter is a 3D printed part (like the whole robot). You can find the data here: https://github.com/generationmake/JECCbot_mini/tree/dev_v0.4/productiondata
You just need to add two 6.3mm Faston connectors like this one https://de.farnell.com/jst-japan-solderless-terminals/vdadm1-25-250-lf/crimpanschluss-stecker-63mm-rot/dp/9993479 to make the electrical connection to the battery.

We designed our own adapter to fit to the mounting grid (50 x 25 mm) on the JECCbot mini.

Bernhard
- Cancel
- Vote Up +2 Vote Down
- Sign in to reply
- More
- Cancel