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Power Supply & Batteries
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Topic starter
2021-02-11 12:56 am
I have this weird fixation on creating "walking" robots. My latest design uses 6 of those (cheap knockoffs, I confess) 9g servos from Amazon. But now I am struggling a bit with how best to power them. I want the batteries to be onboard, because I want the robot to be able to move freely under radio control. I notice that these servos can take up to 800mA at a maximum each.
Can someone suggest a good way forward for choosing batteries and supporting circuits that can be carried onboard?
Thanks!
2021-02-11 2:23 am
My first thought is making a little custom pack of 18650 Lithium Ions with 3-series configuration for 12v. And add a (Battery Management System) like this:
Then you can add a charger system, either on the robot, or separately. And use a BUC down converter to obtain 5v and/or 3v. You will want to double check all the math on amp hours and your expected needs. But off the cuff, a battery set-up like this seems like a reasonable start.
Having said all that about brand new 18650 Lions... I also scrounge these up at our local salvage yard.
They are old-school, but work if you find ones with some life left in them. I bring a volt meter and small motor to the salvage yard, and test the batteries to see if they are near 12v and can run a motor. If so, I gamble and pay a few bucks for the batteries. Some end up no holding a charge when I get home. Worst-case, I recycle them and get some portion of my investment back. Might be an option if you are on a budget and have a good salvage yard near you.
Project sounds like fun! Keep us up to date. I want to follow your build. 🙂
Scott
Imagine by thought, create, don't wait, Scott.
Topic starter
2021-02-13 7:31 pm
18650 Lithium Ions seem like a good idea. I will take a look at them.
Thanks!
2021-04-10 12:22 am
That is almost exactly what I did. I did a 4P(instead of a 5P showed here) 3S power supply using 3AH Lipo baterry with a 25A BMS.I use a buck converter to get 5V . I did a second pack just for the motors.
2021-04-13 5:26 am
So since 2021-02-10 7:23 pm, I have acquired quite a few more of those batteries shown above. I now have re-recycled a few, that didn't hold up to charging and discharging. But I have also assembled a nice little 48v 4s bank, of batteries that test good, and hold a good charge. They cost almost nothing at the salvage yard. Just takes time. Apparently, some batts are recycled before their time. (just gotta find'em)
Imagine by thought, create, don't wait, Scott.