Go to Post I've done enough preaching to the choir. Let's carry on changing the culture. - StevenB [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rating: Thread Rating: 2 votes, 5.00 average. Display Modes
  #1   Spotlight this post!  
Unread 28-07-2011, 14:27
dudefise dudefise is offline
Registered User
FRC #2637 (Panthers)
Team Role: College Student
 
Join Date: Feb 2011
Rookie Year: 2011
Location: CA
Posts: 92
dudefise is an unknown quantity at this point
Off-Board power

Is it possible to equip your robot to legally be capable of using power from an off-board source (i.e. a charger or something) for testing purposes? The power would not be used during competition, just to save batteries for practice.
I was thinking about putting 2 Anderson connectors on the PD board, 1 for the battery, one for the external power. Would it work continuously if I disconnected the external and switch immediately to the battery? or would it run off of both or something?
__________________
2010 VRC 2453B - Team Captain
2011 FRC 2637 - Electrical - Las Vegas Regional Semifinalists with 1726 and 166
2012 FRC 2637 - Electronics Captain - Las Vegas Regional Semifinalists with 1661 and 2984
2013 FRC 2637 - Build Captain - Inland Empire Quarterfinalists with 3925 and 207
2014 FRC 2637 - College Mentor - Central Valley Quarterfinalists with 2085 and 5136 / LA Regional Semifinalists with 696 and 5102
2015 FRC 2637 - Lazy Schmuck - Couch Sitting Quarterfinalist
2016 FRC 2637 - College Mentor - SD Regional Finalist with 1572 and 2443, Excellence in Engineering, Wildcard
  #2   Spotlight this post!  
Unread 28-07-2011, 15:25
iblis432 iblis432 is offline
Co Captain/Chief Programmer
AKA: Bobby
FRC #2106 (Junkyard Dogs)
Team Role: Programmer
 
Join Date: Feb 2009
Rookie Year: 2008
Location: Virginia
Posts: 146
iblis432 is a splendid one to beholdiblis432 is a splendid one to beholdiblis432 is a splendid one to beholdiblis432 is a splendid one to beholdiblis432 is a splendid one to beholdiblis432 is a splendid one to beholdiblis432 is a splendid one to behold
Re: Off-Board power

If my understanding of what you want is correct, having both plugged in would fry just about every circuit on the robot, and the battery and charger. I'm not sure if the charger plugged directly to the robot would work or not, but I know i have used a power covertor before to power the robot from a wall socket. Don't know if its legal in the pits or not though, and having two anderson connections seems not needed to me, since you would never want to have both plugged in at once.
__________________
"Don't worry, programming can fix it"
  #3   Spotlight this post!  
Unread 28-07-2011, 15:39
Ether's Avatar
Ether Ether is offline
systems engineer (retired)
no team
 
Join Date: Nov 2009
Rookie Year: 1969
Location: US
Posts: 8,125
Ether has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond repute
Re: Off-Board power


Quote:
Originally Posted by dudefise View Post
Is it possible to equip your robot to legally be capable of using power from an off-board source (i.e. a charger or something) for testing purposes?
A standard 6-amp charger would not be capable of running the robot.

A single CIM, stalled at 12 volts, will draw 133 amps.


  #4   Spotlight this post!  
Unread 28-07-2011, 15:44
Jon Stratis's Avatar
Jon Stratis Jon Stratis is offline
Mentor, LRI, MN RPC
FRC #2177 (The Robettes)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2006
Location: Minnesota
Posts: 3,835
Jon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond repute
Re: Off-Board power

DO NOT DO THIS. First, don't put 2 Anderson connectors on your robot. The second one only introduces a perfect place for a short during the match. Second, the battery chargers we have in the KoP are designed to charge batteries, not power robots. They can only put out 6A max, which isn't enough to drive your robot around (40-60A would be more appropriate for running a robot, but even that isn't enough when you start talking about stalling CIM motors). They also don't put out a straight 12V - in order to charge a 12V battery, it needs to put out more than 12V... Having 14 or 16V going into the robot might damage something.

Also, please consider the possible safety implications of running a robot off an extension cord. How do you manage that cord across a practice field? What happens if the cord gets caught in a moving mechanism and is crushed/cut? The risk of electrocution or other serious, damaging accidents is much greater. Do you want to be the one to explain to a dozen other teams why their pits suddenly lost power at competition? Do you want to have to explain to the rest of your team why the expensive electronics on the robot are burned out from a sudden 120V short?

Last edited by Jon Stratis : 29-07-2011 at 09:44.
  #5   Spotlight this post!  
Unread 28-07-2011, 15:54
DarrinMunter's Avatar
DarrinMunter DarrinMunter is offline
Fixes parts that leak smoke
AKA: Darrin Munter
no team
Team Role: Mentor
 
Join Date: Aug 2010
Rookie Year: 2009
Location: Peoria, IL
Posts: 151
DarrinMunter is a splendid one to beholdDarrinMunter is a splendid one to beholdDarrinMunter is a splendid one to beholdDarrinMunter is a splendid one to beholdDarrinMunter is a splendid one to beholdDarrinMunter is a splendid one to beholdDarrinMunter is a splendid one to behold
Re: Off-Board power

Your best bet is to have your older batteries used for testing, and save the new ones for competition.
__________________
2014 Wisconsin Engineering Inspiration Award, CIR Engineering Excellence Award
2013 Croosroads Engineering Inspiration Award

2012 BMR Judge's Award, 2011 BMR Regional Champions, BMR Motorola Quality Award, BMR Autodesk Excellence in Design Award, 2010 BMR Regional finalists; 2009 BMR General Motors Industrial Design Award; 2008 BMR Engineering Inspiration Award; 2007 BMR Rookie All-Star Award

Darrin Munter - N9SDD
Advanced Technology Services
  #6   Spotlight this post!  
Unread 28-07-2011, 16:00
dudefise dudefise is offline
Registered User
FRC #2637 (Panthers)
Team Role: College Student
 
Join Date: Feb 2011
Rookie Year: 2011
Location: CA
Posts: 92
dudefise is an unknown quantity at this point
Re: Off-Board power

this is now sounding like a bad idea. it seems that off-board power isn't strong enough + and it would be dangerous and complex to wire properly=not worth it. also old batteries are easier to use.
__________________
2010 VRC 2453B - Team Captain
2011 FRC 2637 - Electrical - Las Vegas Regional Semifinalists with 1726 and 166
2012 FRC 2637 - Electronics Captain - Las Vegas Regional Semifinalists with 1661 and 2984
2013 FRC 2637 - Build Captain - Inland Empire Quarterfinalists with 3925 and 207
2014 FRC 2637 - College Mentor - Central Valley Quarterfinalists with 2085 and 5136 / LA Regional Semifinalists with 696 and 5102
2015 FRC 2637 - Lazy Schmuck - Couch Sitting Quarterfinalist
2016 FRC 2637 - College Mentor - SD Regional Finalist with 1572 and 2443, Excellence in Engineering, Wildcard
  #7   Spotlight this post!  
Unread 28-07-2011, 16:12
EricVanWyk EricVanWyk is offline
Registered User
no team
 
Join Date: Jan 2007
Rookie Year: 2000
Location: Boston
Posts: 1,597
EricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond repute
Send a message via AIM to EricVanWyk
Re: Off-Board power

For what it is worth, I did a lot of the PD testing using a giant programmable power supply so that I could easily push the voltage around and test corner cases.

As long as you don't need to move motors (or only move them unloaded/on blocks), you might be able to use a high power computer power supply.


As everyone else has already said, do not attempt to use a battery charger for this.
  #8   Spotlight this post!  
Unread 28-07-2011, 16:19
AdamHeard's Avatar
AdamHeard AdamHeard is offline
Lead Mentor
FRC #0973 (Greybots)
Team Role: Mentor
 
Join Date: Oct 2004
Rookie Year: 2004
Location: Atascadero
Posts: 5,526
AdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond repute
Send a message via AIM to AdamHeard
Re: Off-Board power

In the past we've wired a charger in parrallel with the battery.

Make an anderson "extension" cable using proper gauge wire a few inches long. Plug the battery in using this. Inline on the extension cable, hook up the charger.

If you're average current draw over time is low, this will work. It's great for programming.
  #9   Spotlight this post!  
Unread 28-07-2011, 18:14
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Off-Board power

In general, using a battery charger in parallel with the battery while connected to a load, is a bad idea for the electronics that are connected as part of the load. The charger (even smart chargers) are confused by the varying load/battery combined and will on occasion produce the maximum voltage the charger is capable of generating. This condition is bad for both the electronics and battery. A high current power supply as Erik has suggested might be available from your mentoring organization but these items are rare for most businesses. You can substitute a larger battery, i.e. a automotive battery, for testing purposes if you need extended battery times. Please be sure to insulate any wiring you choose to make. With the battery disconnected from the robot, you can then charge the larger battery with an appropriate rated charger.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #10   Spotlight this post!  
Unread 28-07-2011, 19:59
Trent B Trent B is offline
College Mentor
AKA: Trent Borman
no team (Surviving Grad School)
Team Role: Alumni
 
Join Date: Dec 2008
Rookie Year: 2008
Location: Ames, IA
Posts: 479
Trent B is a splendid one to beholdTrent B is a splendid one to beholdTrent B is a splendid one to beholdTrent B is a splendid one to beholdTrent B is a splendid one to beholdTrent B is a splendid one to beholdTrent B is a splendid one to beholdTrent B is a splendid one to behold
Send a message via AIM to Trent B Send a message via Yahoo to Trent B
Re: Off-Board power

Quote:
Originally Posted by Al Skierkiewicz View Post
With the battery disconnected from the robot, you can then charge the larger battery with an appropriate rated charger.
I was going to suggest the same, if you need a battery to last an extended period of time for a workbench time scenario go for a marine or car battery (The robot batteries are 18Amp-Hours so choose accordingly). If you don't need a lot of current, a deep cycle battery should allow you to run even longer between chargings (correct me if I am wrong but deep cycles have less cold cranking amps at the cost of greater capacity)

Al, I was under the impression that even with no load on the battery chargers aren't a very clean source of power, is this true?
__________________
Former 2502 (Talon) Captain and 3928 (Neutrino) Mentor, currently teamless and attending Penn State for graduate school.
Have questions about Iowa State University or Penn State University? Feel free to email or PM me

Last edited by Trent B : 28-07-2011 at 20:05.
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 18:51.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi