Lithium Battery Pack for GoPiGo3 and ROS

GoPiGo
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Husband: “I’m going to build a second robot”
Wife: “How much is that going to be?”
H: “Around $250”
W: “I thought it was going to be $550?”
H: “That was turtlebot, this will be GoPiGo3 based”
W: “$250 includes the battery?”
H: “Yes, (hope she doesn’t ask what type)”
W: “I don’t understand why do it, but it sounds like you are excited, so go for it”

@jimrh also did a great review of the ModRobotics battery

One important negative about the battery included with the GoPiGo3 is that it is single voltage output, and the LIDAR for a ROSbot needs a strong 5v.

I have a Pololu 5v switching voltage regulator that I can mount to split out power for the LIDAR. I have to check if it has a logic level enable input to turn it off when I don’t need the LIDAR.

Note: Amazon has a “similar to the ModRobotics battery” which includes a 5v output, but I am more trusting ModRobotics on battery safety, than Amazon third party sales.

As to the “short cable” noted by @jimrh, I have a “Y” cable that will be in the path to split out power to the 5V regulator, so I think the short cable will end up perfect for my use.

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Far be it from me to dis the GoPiGo, but you folks may be running into territory where a different robotics platform might be a better choice, since it looks like you will need a better/more capable power source and the physical space to attach things to.

The GoPiGo is a great 'bot, and I appreciate the heck out of it, but as has been said before - you can only do so much with it before you out-grow it - especially if you want to attach more sensors than Hans Solo has on the Millennium Falcon.

Correct me if I am wrong, but it’s the same battery with six extra parts soldered onto the output metering module.

The one M/R sells is the TalentCell YB1203000 (12v 3000 mAh).

There is also the TalentCell YB1203000-USB which includes the USB output.

If you want to drive anything more power hungry than a set of USB speakers, I’d go with the YB1206000-USB, or even the monster sized YB12011000-USB.

Here’s the product page out of the batteries I received.

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IMG_20210609_195700137~22448×3264 1.72 MB

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By the way, Charlie has weighed in on the whole rechargeable battery issue, giving the Modular Robotics rechargeable battery module a BIG “two antennae up!” :wink:

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IMG_20201231_193345666~21494×1908 386 KB

“Your honor, the prosecution rests. . .”

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ROSbot power budget:

  • Processing, distance sensor: 2.5W
  • Motoring about 50% duty cycle: 0.8W
  • Servo (10% usage max): 0.1W
  • LIDAR (100% duty max ): 2.5W

If the MR pack will deliver 90% of “rated”, say 2700 mAh at an average of 11.1v, that should be 30Wh?

30WH / 6W would seem to predict 4-5 hours?

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That assumes everything is linear.

Heck! Benzine isn’t even linear anymore. :roll_eyes::wink:

Seriously, I’d take a calculation like that with about 10lbs of salt until proved.

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That’s the one I have. Works fine with the lidar. Much easier to use than the system I had kludged together before.

https://www.amazon.com/gp/product/B01M7Z9Z1N/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

/K

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Turtlebot Burger which is RPi3 based and weighs 2.2lbs, runs the same LIDAR and two (Dynamix) motors at the same max speed as a GoPiGo3, comes with an 1800mAh 11.1v battery and claims 2.5 hrs operating time and 2.5h charging time. (It also has a 32-bit Cortex M7 with an FPU on the driver board.)

The GoPiGo3 weighs a little less, and has a bigger battery, adding some support to my 4-5 hour guess.

You can bet my first platform tests will be to measure actual power consumption of the LIDAR, and characterize the battery voltage over time with a few motor duty cycle values - (0%, 50%, 100%).

Mapping is probably an 80-90% percent motor duty cycle but once the bot thinks it knows its environment, it will have to drudge up an excuse to navigate, period. (I’m still holding onto the idea that one day Carl will start looking around, asking “what is this?”, and announcing “Did you know there are XXX feet of followable walls in this house?”, or “The smoke detector in the bedroom is only blinking every 90 seconds, maybe you should replace the battery so it won’t wake you up in the middle of the night.” (Those darn things always start complaining when the temperature drops a little in the middle of the night, and the beep is so high frequency it bounces around so I can’t tell which one is complaining.)

Not really, the MR battery fits just fine on the back deck, but turning accuracy is so much better with the weight closer to the drive wheels than the castor.

(ROSbot will have lots of empty space on the back deck. I considered maybe moving the upper-deck(s) backward some and chopping off the front deck, but then it wouldn’t be a “stock GoPiGo3”, but then adding another upper deck isn’t going to be exactly stock either, but that I feel compelled to do for accuracy.

Now if the day comes that I want to add an Intel RealSense Depth Camera (and a fan so I can really load the RPi3B+ processor), then I may need to consider the 6000mAh monster battery, which might just be too much weight on the GoPiGo3’s cantilevered motor axles. (The Turtlebot Burger with Dynamixel motors probably wouldn’t notice the extra weight, but we’re talking $300 more for the bot.)

BUT, before ROSbot gets visual depth perception, Carl will be calling for my attention, so I think GoPiGo3 as a ROSbot platform makes good sense - albeit only a few people have recognized that so far.

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I think I want to investigate a logic controlled 5v supply so I can turn the LIDAR on only when needed, but then again full-time LIDAR could be a fair motion detector, but then again the PiCam does a somewhat limited FOV motion detect, so I don’t know what I’m going to do - have to see what’s in my junk box.

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Hopefully I am one of those few, as I have been championing the GoPiGo, (and the gigglebot!), for a while now.

IMHO the only reason I could possibly have to change ‘bots is if I decide to go for a huge-honkin’ DARPA class outdoor 'bot with Caterpillar tracks or those wonky wheels with twenty little sideways rollers on 'em, and a setup that requires a 750 Cold Cranking Amps Di-Hard battery to run.

And a small gasoline powered motor to haul all the weight.

Just think:  Gasoline fumes.  And you thought lithium batteries were dangerous? :exploding_head:

Until then, I have enough stuff in the pipeline for Charlie that my heirs won’t even have time to finish!

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DigiKey might be a good source for something like that.  Since I’m on their mailing list, (along with Adafruit and SparkFun :wink:), I will mention it if I see something.

What would be better would be a monolithic supply that can be controlled for both 12 & 5 volts.

I’ll keep my eyes open.

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Sheesh!

I should have a wife that understanding! :wink:

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Sometimes my memory does work wonders.

In my junk box was a Pololu S18V20ALV 2A 4-12v step up/down power supply with a pull-up default “Enable” input.

Pulling that low puts the supply in a 30uV sleep (with back-flow prevention as well).

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We thoroughly tested the big battery found on Amazon and it passed the same tests as our main rechargeable battery. Same manufacturer, same protection circuit board, same results.

We don’t carry the one from Amazon because of a couple of reasons:

  1. I can totally imagine kids in a classroom plugging anything into that USB port, including another battery. And that scares me. So we sell a battery without a USB port.
  2. I can also imagine someone trying to connect the Raspberry Pi usb port to the battery USB port.
  3. the battery on Amazon is 6000mAh, which is overkill if the only thing you power is the GoPiGo.
  4. Its dimensions are a lot bigger than the 3000mAh (there are more cells in it, so makes sense that it would be bigger). It’s a pain, honestly, because of its size. You’ll have to come up with a proper method to hold it in place.

However anyone knowledgeable enough to consider a LIDAR is able to understand how to connect the battery properly. So feel free to pick that battery from Amazon.

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I ran a BrickPi / Pi4 combo with 4 of the LEGO big motors non stop for 3 hours.
I also ran a GoPiGo / Pi4 combo with the motors running full power for 25 seconds and off for 5 seconds. That ran for 6 hours.

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I like you.  You’re evil.  Just like me.

That’s the kind of broad and expansive thinking you have to have when dealing with international terrorists or school children.  (Which are substantially similar in many ways. :wink:)

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I have led classroom workshops before. I speak from experience. (not with terrorists thankfully!)

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You can do that programmatically in ROS I think. Although the board gets power, I’m guessing it doesn’t use much until the motor is running, which doesn’t happen until I launch the lidar node. And it turns off when I kill the node. I usually do that with ctrl-c from the command line, but there are ways to do that programmatically, which I’m guessing will also kill the motor.
/K

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Amazon also had a 3000 mAh version with USB, which is what I ended up using. You’re right - the other is just too big. But handy to have if I need the extra capacity.
/K

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Have you seen The Mitchells vs. the Machines on Netflix? If you have Netflix it’s worth watching. Don’t be fooled by the fact that it’s animated – it’s hilarious. The reason I mention it is that there is a line in there to that effect in terms of teachers being used to dealing with chaos.

/K

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Good to know - Thanks, that simplifies things a bit.

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