MDD10 PiHAT

Interesting.  Does this mean Bill is using the Pi4 to control the motors and scraping his idea to use two 328P microcontrollers?

@bif99

I doubt it.

It just means that I found something cool and compatible and wanted to share it

OK, got it.  I'm still waiting for a test sketch to check out the two nano motor driver board as you are, also.  In the meantime, check out my post in DB-1 about soldering aviation connector cable assemblies.  I'm interested in your opinion.  If you like it, pass it on.  I think there are guys out there that need help with soldering in tight places.

Posted by: @bif99

I'm still waiting for a test sketch to check out the two nano motor driver board as you are

Count me in on this waiting list!   I've been waiting for this wiring and sketch since early summer!  I'm almost ready to give up and just design my own system from scratch.   I was hoping to get on the same page with Bill's DB1 project so when he does more things in the future this will all be compatible with his overall design.

I'm not building a DB1 replica,  but I was hoping to build something along the same lines as Bill's design just so his DB1 series doesn't become too alien to my robot.   But the wait is becoming intolerable.  I want to get my robots up and running pretty soon.   I hope he gets this info out fairly soon.  Even just a schematic and sketch would be super appreciated.   A video explanation would be nice, but any info at all is better than none.

 So yeah, I'm waiting for this too. 

@dronebot-workshop

When can we expect to see this information Bill?  Can you give us an expectation date?

@robo-pi

Good to know others are waiting patiently for the motor controller.  My robot is a duplicate of DB-1 to this point except for the name.  I call mine RB-1 (R for Riley, my grandson and Bill for me).  When Bill announces his choice on batteries I will chime in with info on the care and feeding of rechargeables.  During my career, I designed primary lithium batteries for use in implantable medical devices so I have knowledge that will help with safety, etc. 

Posted by: @bif99

When Bill announces his choice on batteries I will chime in with info on the care and feeding of rechargeables.

I'll be looking forward to that as well.   I'd like to learn as much as possible how to build an efficient batter charger.   My current prototype robots are very small, and I've been using standard flashlight batteries to run them:

But I'd like to replace these batteries with rechargeable batteries.   And then I'll need a way to charge them up without  overcharging them, etc.    My current plan is to just use a commercial battery charger and just modify it so that my robot can drive up to it and plug itself into the charger.   In fact, I'll probably go that route anyway just because it's easy.   But it would be nice to learn how to build my own onboard battery charger.  Later I might want to build a robot that can just plug itself into any 120 volt AC outlet and charge itself up from there. ? 

@robo-pi

Very nice.  My grandson and I built one of those and controlled it with a joystick and nRF24L01.  We followed Bill's video.  My grandson is now building the 4 wheel drive version of the robot car.  We might use Bluetooth to control it.  May I suggest that you use NiMH batteries for your robot.  They can be charged from any charge state without danger of over-charging provided you use a charger designed for NiMH batts.  They have a higher self discharge rate than NiCad batts but do not exhibit charging memory like NiCADs.  This means a NiMH batt when left unused after being fully charged will self-discharge up to 15% in the first 24 hours after charging and continue to discharge 3-4% per day thereafter.  While a NiCad will not self-discharge as fast it is susceptible to capacity loss when repeatedly charged from a partially depleted state.  The NiCad must be cycled (fully discharged and charged) to ensure it charges completely.  NiMH and NiCad batts are safer to use and charge than LiPo batts.  Also, LiPo batts must be put in a "storage" state when not in use.  Otherwise, outgassing will occur and cause the battery to swell.  This can be dangerous and cause a catastrophic failure, what my competitors used to call "venting with flame".  I call it "explosion".  Sorry I got a little long winded here.  Guess I chimed in a little too early.

Posted by: @bif99

May I suggest that you use NiMH batteries for your robot.  They can be charged from any charge state without danger of over-charging provided you use a charger designed for NiMH batts.

That's interesting.   I currently have an Energizer NiMH batter charger that will charge either four AAA or four AA batteries. I've actually been using this to recharge the AA  batteries for my Kodak Digital Camera.  I'm currently using Rayovac NiMH batteries.  The problem is that they don't seem to last very long in the camera.   And these are brand new batteries that I just bought too.

I was thinking of using these NiMH batteries in my robot and just use this charger.  I can set the charger up near the floor and create a cradle that my robot can park itself in to charge up using this charger.

But like I say, I was a little disappointed at how quickly the batteries die in my camera.   Not sure why that is.  I have even been removing the batteries from the camera thinking that maybe the camera is somehow discharging the batteries when it isn't on.  But even that didn't help.  They still seemed to not last very long.

I haven't tried them in the robot yet.  The robot is on a back-burner awaiting Bill's  magic motor controller code. ?  I wanted to get them set  up with nice  acceleration routines and emergency stop, etc.   So I'm still waiting for Bill to get his Round Tuit.  I think he's soundproofing the Workshop so his neighbors don't accidentally learn about Arduino programming when he's making videos for us.? 

@robo-pi

Interesting problem.  You may have one weak cell.  The only way to know for sure is to set up a breadboard to test the capacity of each individual cell.  Run down each cell using a resistive load that produces 1C,2C and 5C currents at the start of the test.  Take periodic voltage measurements until voltage begins dropping rapidly.  Plot the voltage curve.  Each cell should perform identically with the other cells.  If you have a spreadsheet, you can calculate the average capacity delivered during each time period then total the results for total capacity delivered to EOL (end of life).  If this sounds like a lot of work, it is.  If you have confidence in the battery pack you can run it down as a pack to save time.  Check this out to familiarize yourself with NiMH characteristics. http://shdesigns.org/batts/battcyc.html . Also search on Amazon "Tenergy TB6-B".  This smart charger/discharger is very versatile and can save you a lot of time.

@bif99,

That sounds like a  good project for an Arduino. ?   The whole process could be automated using analog pins to read the voltages, etc.   The data could be stored on an SD card and then plotted using a serial plotter.   It's  probably a worthwhile project  that could be used to test a lot of batteries.  I actually have quite a few older rechargeable batteries that I would like to test to see if any of them are still worth using.

I also have bags of standard  AAA batteries.  These are not rechargeable.  They were used in mice and/flashlights.  Often times I replaced them before they were completely dead.   I was thinking of  setting up a circuit to test their voltages with a load to see where they are.   I was thinking that if I found a lot of them that had the same voltage across the same load I could pick those out and put them in a large battery pack, maybe even enough of them to get 24volts.   Then use one of those switching regulators to drop the voltage down to a few volts to drive LEDs, or something (maybe even a mouse).    Just a way to squeak out the last bit of juice before disposing them altogether.  ? 

I'm one of those people who hates to see anything go to waste. ? 

Just on the camera deal, I should probably mention the following:

The camera  only uses two AA cells.  I've tried using different combinations of pairs of batteries to see if there was a problem cell.   But it seemed that no matter how I rotate them I get the same results.   This camera used to run a good week on two fully charged batteries.   But now it tends to go dead in just a few hours.

It could be the camera itself?  That's what I'm suspecting.

But the battery tester sounds like an interesting project.   It could  probably be programmed into an Arduino with the same effort it would take to do it by hand.  In fact, I'd be surprised if someone hasn't already done that.

@robo-pi

Interesting idea.  Keep me posted.  Would like to try out your solution when you complete the project.

Posted by: @bif99

Interesting idea.  Keep me posted.  Would like to try out your solution when you complete the project.

It will probably be a while as I am working on other projects at the moment.   But I did do a search for "Arduino NiMH battery tester" and got a ton of results, from articles to YouTube videos.   So apparently this is a quite popular project.

@bif99

Bill,

How are you making out with the two Nano motor controller?  Have you accomplished any testing yet.

And did you make your two Nano board on perf board?

I've been able to send I2C commands to my controller board from the Mega2560 to move DB1 (or Willy Nilly in my case) forwards, backwards, and spin CW & CCW.  And stop of course.

I working on ver 2 of my motor controller design to move to just the 328P chips instead of using the Nanos, but may wait for some more info from the DroneBot Workshop Guru before committing to making five more PCBs.  No one ever took me up on the other two boards I had made so I'm still sitting here with four extra of each. 

P.S. looks like I have actually posted this in the wrong thread!? ? 

@codecage

You may have posted to the wrong thread but the subject matter is interesting.  My two nano motor controller is hand wired on perf board.  I'm still waiting for Bill to supply the test code.  The long delay has caused me to spend more time on other projects.  I recently downloaded KiCAD and have been spending a lot of time reading the ebook and watching videos.  I may be interested in one of your PCBs if Bill ever re-engages with DB-1.  Did you have any luck with the websites I sent you for butt connectors and 6 conductor shielded cable?