Go to Post Safe zones are for the weak. - ChristopherSD [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
  #16   Spotlight this post!  
Unread 25-03-2014, 11:19
barn34's Avatar
barn34 barn34 is offline
Isn't this how Skynet got started?
AKA: William Barnickel
FRC #2481 (Roboteers)
Team Role: Mentor
 
Join Date: Feb 2012
Rookie Year: 2009
Location: Metamora, IL
Posts: 243
barn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond reputebarn34 has a reputation beyond repute
Re: Legal battery chargers this year.

Big thanks, Al! We did make some subtle adjustments to our drive style and the issue did not occur once after we made the breaker swap like Kyle mentioned. We were icing it down between matches, as well, and are looking at all of our options for making sure we keep that breaker cool and untripped in St. Louis whenever that defensive intensity cranks up. Thanks again for all your help!
  #17   Spotlight this post!  
Unread 25-03-2014, 11:44
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: Legal battery chargers this year.

Anytime, Good Luck!
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #18   Spotlight this post!  
Unread 25-03-2014, 12:07
marccenter's Avatar
marccenter marccenter is offline
Registered User
FRC #3548 (RoboRavens2)
Team Role: Coach
 
Join Date: Sep 2004
Rookie Year: 2004
Location: Royal Oak
Posts: 406
marccenter has a spectacular aura aboutmarccenter has a spectacular aura about
Lightbulb Re: Legal battery chargers this year.

I guess I'm hijacking the thread a bit but want to capture a potentially important "gotcha" issue related to battery connections that Alan's post helped to job some cobwebs in my brain.
Quote:
Loose main power connections -- on battery terminals, SB-50 connectors, main circuit breakers, and/or Power Distribution Board inputs -- were unfortunately very common. It'll be interesting to see if the logging feature of next year's PDB will help convince certain teams that their general animosity toward "the FMS" is misplaced, and that their loss of robot control on the field can usually be prevented with a bit more attention in the pits to checking and maintaining the robot's electrical system
Alan,
At the MI Howell district event we even had someone (FTA?, Inspector?) come by and inspect our PD distribution board connections (12V & ground) to the battery to help eliminate this potential problem issue (assume he was going around to all teams.. we had not reported any issue). I can't remember precisely but he quoted something like "teams commonly place a lock washer underneath the battery connection to the PD board when, if used, it should be placed on the top, next to the nut".

Al S, is there any "best practice" on this battery connection to the PD board and main breaker that teams are missing?
I assume there should be a direct connection from the battery connector to the PD board post. Should the FRC
documentation trail capture this somewhere?
__________________
Marc Center
FIRST FRC Mentor/Coach - Team 3548 Royal Oak RoboRavens#2 - on Sabbatical 2017 season
marc.center@gmail.com
Mobile: 248-255-7377

Last edited by marccenter : 25-03-2014 at 12:10. Reason: grammar
  #19   Spotlight this post!  
Unread 25-03-2014, 16:45
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: Legal battery chargers this year.

Marc,
It is likely that someone visited you because the tracking logs showed you undervolt. The terminals on the main breaker and the PD are hard metal compared to the soft material used for the battery terminals and they don't get handled as much. The lock washer between the battery terminal an the wire terminals keep the terminals from twisting and loosening the hardware. Both the PD and the main breaker have substantial hardware with lock washers. Most often these wires are also tied into the robot so that they cannot move and twist unlike the battery. Any loose connection in the primary wiring (All the #6 AWG) will cause significant voltage loss under the current demands of our typical robot. These losses are what shows as melted SB50 plugs and wiring and to a much lesser degree, tripped main breakers.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #20   Spotlight this post!  
Unread 28-03-2014, 21:06
swootton swootton is offline
Registered User
AKA: Steve Wootton
FRC #4055 (NRG4055)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2012
Location: Barkhamsted, CT
Posts: 50
swootton is on a distinguished road
Re: Legal battery chargers this year.

Quote:
Originally Posted by Nirvash View Post
You can not charge a battery at a rate higher then 6 amps, (about the max charge rate of the batteries we use) This is stated in the safety manual.

This is generally enforced by limiting chargers to a max rate of 6 amps. However certain special conditions could allow a charger with a max rate greater then 6 amps to be used.
I hate to disagree with all of you but if you read the Enersys application manual for our batteries it does clearly state the maximum charging rates on page 6. The confusion seems to be the fact that the bolted terminal line says 6CA. All the other columns are specifically amps. If you go to page 17 you will see the definition of CA and the line above with c-rate.

The actual max charging rate on our battery is 6 times the Ah rating or 6*17.2 for a max of 103.2A. Would anyone ever charge at that high a rate? I would expect not. If you look at the other columns in the chart on page 6, why on earth would you be able to charge at 75A maximum through a normal spade terminal and only 6A through a physically bolted connection. That just doesn't make any sense at all. The most important thing with these batteries is not the amperage that you charge at, it's the voltage which should be 2.35-2.45 volts per cell or 14.1-14.7 volts.

It's all about reading the manual correctly.
__________________
  #21   Spotlight this post!  
Unread 28-03-2014, 22:29
Alan Anderson's Avatar
Alan Anderson Alan Anderson is offline
Software Architect
FRC #0045 (TechnoKats)
Team Role: Mentor
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Kokomo, Indiana
Posts: 9,113
Alan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond repute
Re: Legal battery chargers this year.

Quote:
Originally Posted by swootton View Post
It's all about reading the manual correctly.
What manual are you reading? The one I see says the maximum suggested charging current is 0.25CA, and it says the battery won't accept more than 2CA in any case.
  #22   Spotlight this post!  
Unread 28-03-2014, 23:06
swootton swootton is offline
Registered User
AKA: Steve Wootton
FRC #4055 (NRG4055)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2012
Location: Barkhamsted, CT
Posts: 50
swootton is on a distinguished road
Re: Legal battery chargers this year.

Quote:
Originally Posted by Alan Anderson View Post
What manual are you reading? The one I see says the maximum suggested charging current is 0.25CA, and it says the battery won't accept more than 2CA in any case.
You are reading page 11 under initial charge current limit. Go to page 6 in the chart at the bottom which lists "Maximum Permissable Current(Amps)"
You will see "All bolt or recpetacle" lists 6CA which is 6 time the Ah rating of the battery. In our case 17.2 times 6 = 103.2A maximum Amps.

The battery charger should be a smart charger with voltage limiting based upon state of charge. I verified all this information with my battery supplier and was told that you cannot overcharge these batteries unless you charge at too high a voltage. He recommended no more than 30A or so, but for longer battery life 10-20A max would be ideal.
__________________
  #23   Spotlight this post!  
Unread 28-03-2014, 23:47
Alan Anderson's Avatar
Alan Anderson Alan Anderson is offline
Software Architect
FRC #0045 (TechnoKats)
Team Role: Mentor
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Kokomo, Indiana
Posts: 9,113
Alan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond repute
Re: Legal battery chargers this year.

Quote:
Originally Posted by swootton View Post
You are reading page 11 under initial charge current limit. Go to page 6 in the chart at the bottom which lists "Maximum Permissable Current(Amps)"
You will see "All bolt or recpetacle" lists 6CA which is 6 time the Ah rating of the battery. In our case 17.2 times 6 = 103.2A maximum Amps.
That sure looks like a maximum discharge current spec to me. The maximum charge current of 0.25CA appears immediately below it, as well as being repeated in the charging section on pages 10-12.

Quote:
The battery charger should be a smart charger with voltage limiting based upon state of charge. I verified all this information with my battery supplier and was told that you cannot overcharge these batteries unless you charge at too high a voltage. He recommended no more than 30A or so, but for longer battery life 10-20A max would be ideal.
I don't know what your battery supplier thinks he's telling you, but 30A is more than five times the recommended value. "High charging current can cause abnormal internal heating which may damage the battery."
  #24   Spotlight this post!  
Unread 29-03-2014, 00:15
Tristan Lall's Avatar
Tristan Lall Tristan Lall is offline
Registered User
FRC #0188 (Woburn Robotics)
 
Join Date: Aug 2001
Rookie Year: 1999
Location: Toronto, ON
Posts: 2,484
Tristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond repute
Re: Legal battery chargers this year.

Here's the document in question.

Quote:
Originally Posted by Alan Anderson View Post
That sure looks like a maximum discharge current spec to me.
I agree. That's the current that can safely flow through that particular type of terminal, which basically has to be a discharge (except in the standby case).

We should consult the charts and data in the rest of that manual for the actual recommended charge current for the entire battery, which in normal service is 4.3 A (i.e. 17.2 A·h capacity at a 0.25 C rate of charge).

Charging at 6 A may not necessarily kill the battery or be unsafe, but it is outside the manufacturer's specifications for normal use. You should contact an EnerSys application engineer for guidance; they may be able to advise that 6 A or more is acceptable, at the cost of shorter battery life. (If that's indeed what EnerSys says, feel free to post the correspondence here and forward it to frcparts@usfirst.org so that they can keep it in mind for future years' rules/safety manuals.)
  #25   Spotlight this post!  
Unread 29-03-2014, 01:10
philso philso is offline
Mentor
FRC #2587
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Houston, Tx
Posts: 940
philso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond repute
Re: Legal battery chargers this year.

Quote:
Originally Posted by swootton View Post
You are reading page 11 under initial charge current limit. Go to page 6 in the chart at the bottom which lists "Maximum Permissable Current(Amps)"
You will see "All bolt or recpetacle" lists 6CA which is 6 time the Ah rating of the battery. In our case 17.2 times 6 = 103.2A maximum Amps.

The battery charger should be a smart charger with voltage limiting based upon state of charge. I verified all this information with my battery supplier and was told that you cannot overcharge these batteries unless you charge at too high a voltage. He recommended no more than 30A or so, but for longer battery life 10-20A max would be ideal.
The table with the "6CA" reference gives the current ratings of the various types of terminals available with the Genesis product family. It is NOT any sort of current rating for any of their batteries, in any mode of operation.

The section below, titled "Charging", shows how to choose the charging current.

We install about a ton or two (literally) of batteries from this series each week in the industrial grade UPS' we manufacture where I work. Our UPS' charge the batteries at about 0.1CA to maximize the service life of the batteries. I have spoken with the Application Engineers at Enersys multiple times about service life issues. Using a charging current that is too high is one of the major factors that WILL reduce service life (along with over-charging, discharging too deeply, discharging at very high currents, operating in high ambient temperatures and not cycling the batteries).
  #26   Spotlight this post!  
Unread 29-03-2014, 03:27
Bill_B Bill_B is offline
You cannot not make a difference
FRC #2170
 
Join Date: Jan 2010
Rookie Year: 2004
Location: Connecticut
Posts: 1,099
Bill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond reputeBill_B has a reputation beyond repute
Re: Legal battery chargers this year.

I've heard that term "cycling the batteries" before but I'm still uncertain of its precise meaning. I'm sure it has nothing to do with certain popular two-wheeled vehicles.
__________________
Nature's Fury FLL team 830 - F L eLements
FRC team 2170 - Titanium Tomahawks
  #27   Spotlight this post!  
Unread 29-03-2014, 09:43
MrForbes's Avatar
MrForbes MrForbes is offline
Registered User
AKA: Jim
FRC #1726 (N.E.R.D.S.)
Team Role: Mentor
 
Join Date: Feb 2006
Rookie Year: 2006
Location: Sierra Vista AZ
Posts: 6,033
MrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond repute
Re: Legal battery chargers this year.

Cycling the batteries, just means to use them occasionally. Don't let them sit for half a year without being discharged and then recharged.

And never let them sit after being discharged...always recharge before storing.
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 19:23.

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