Go to Post Hello... I need one order of Thunderchicken, extra crispy. Yes, I would like fries with that. OK... go ahead and super-size it. What, only $2.17!? Sweet. - Andy Baker [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 Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 06-05-2013, 22:07
tuXguy15's Avatar
tuXguy15 tuXguy15 is offline
Team Mentor
AKA: Devin Kolarac
FRC #2559 (Normality Zero)
 
Join Date: Apr 2012
Rookie Year: 2012
Location: Harrisburg, PA
Posts: 127
tuXguy15 is an unknown quantity at this point
Battery Chargers

This past season we used the 6amp charger on our batteries from andy mark. This gave us up to 13 volts for a full charge but the FRC batteries can go up to 15 max. Our team knew this would happen and knew that our batteries would be destroyed by the end of the season. Well we were right. So over the off season we plan to develop a battery charging cart that will charge the battery at 2 Amps for a while, then 4 Amps, and then 6 Amps to get our batteries at full complicity and keep them living longer. Does anyone have any ideas on how we can make this possible?
__________________
  #2   Spotlight this post!  
Unread 06-05-2013, 22:25
jbsmithtx's Avatar
jbsmithtx jbsmithtx is offline
FIRST Fanatic
AKA: Josh Smith
FRC #4206 (RoboVikes)
Team Role: Engineer
 
Join Date: Aug 2012
Rookie Year: 2012
Location: Fort Worth, TX
Posts: 91
jbsmithtx is a jewel in the roughjbsmithtx is a jewel in the roughjbsmithtx is a jewel in the rough
Re: Battery Chargers

Your batteries were zapped after one season? I think there's a bigger problem here.. We've had 8 batteries now, and after 2 seasons none of them show any signs of slowing up any time soon... Nearly all of them charge up to about 13 every time.. Do you leave them on the charger over night? Was your robot intensely power draining?
  #3   Spotlight this post!  
Unread 06-05-2013, 22:46
mman1506's Avatar
mman1506 mman1506 is offline
Hater of Tiny Molex Connectors
AKA: Marcus Quintilian
no team (WARP7)
Team Role: Alumni
 
Join Date: Mar 2012
Rookie Year: 2012
Location: Toronto
Posts: 807
mman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond repute
Re: Battery Chargers

Quote:
Originally Posted by tuXguy15 View Post
This past season we used the 6amp charger on our batteries from andy mark. This gave us up to 13 volts for a full charge but the FRC batteries can go up to 15 max. Our team knew this would happen and knew that our batteries would be destroyed by the end of the season. Well we were right. So over the off season we plan to develop a battery charging cart that will charge the battery at 2 Amps for a while, then 4 Amps, and then 6 Amps to get our batteries at full complicity and keep them living longer. Does anyone have any ideas on how we can make this possible?
Charging a battery to 15v will not make it last longer, it is the other way around. The 6 amp charger will go green at 13v but will charge up to 14.6 if you leave it to maintain the battery. The best way to charge a battery is by charging the battery at 6 amps then slowly lowering the amperage as it gets closer to a full charge.

If you want to charge to 15v every time get one of these (http://www.hobbyking.com/hobbyking/s...er_w_acc_.html (It dosen't list lead acid charging in the ad but it does have it). It has adjustable endpoints and charge rates.
__________________
2014-2015: FRC 865 Warp7 Team Captain
2016: FRC 865 Mentor

2017: Free Agent Mentor, Inspector
  #4   Spotlight this post!  
Unread 06-05-2013, 23:01
tuXguy15's Avatar
tuXguy15 tuXguy15 is offline
Team Mentor
AKA: Devin Kolarac
FRC #2559 (Normality Zero)
 
Join Date: Apr 2012
Rookie Year: 2012
Location: Harrisburg, PA
Posts: 127
tuXguy15 is an unknown quantity at this point
Re: Battery Chargers

This year our robot drew a lot of current and it killed the batteries when we had to keep recharging them constantly. Also i know that 15 volts wont last longer. My point is that we are not managing our batteries right if we arent getting 15 volts. The 6 amps wont get it there because doing a 6 amp charge does not allow a peak and level type of charge that those types of batteries need. You do 2 amp until it peaks then 4 until it peaks then6 to finish charging it's.
__________________
  #5   Spotlight this post!  
Unread 06-05-2013, 23:03
fb39ca4 fb39ca4 is offline
Registered User
FRC #1899
 
Join Date: Jan 2012
Location: Bellevue, WA
Posts: 195
fb39ca4 is a name known to allfb39ca4 is a name known to allfb39ca4 is a name known to allfb39ca4 is a name known to allfb39ca4 is a name known to allfb39ca4 is a name known to all
Re: Battery Chargers

This charger from HobbyKing is about half the price when you factor in shipping weight, and also charges at 6 amps. I have one for charging Li-Po batteries at home, but I brought it to a competition, and it works great for FRC batteries. http://www.hobbyking.com/hobbyking/s...cessories.html

Keep in mind for either one you will still need to find a power supply. Laptop chargers as long as they are >6A and 12V and ATX power supplies both work great.
  #6   Spotlight this post!  
Unread 06-05-2013, 23:22
spydan's Avatar
spydan spydan is offline
Dan
FRC #0708 (Hatters Robotics)
Team Role: Marketing
 
Join Date: Aug 2012
Rookie Year: 2011
Location: Horsham, PA
Posts: 105
spydan is on a distinguished road
Exclamation Re: Battery Chargers

This thread may be of use, our team purchases from this company:
http://www.chiefdelphi.com/forums/sh...d.php?t=110031
__________________

www.team708.org

FLL Student: Food Factor, Senior Solutions
FRC Student: Ultimate Ascent, Aerial Assist, Recycle Rush, FIRST Stronghold
Volunteer: Ultimate Ascent, Aerial Assist, Nature's Fury (FLL), Recycle Rush, World Class (FLL), Trash Trek (FLL), FIRST Stronghold


My posts do not necessarily reflect the views & opinions of affiliated teams.
  #7   Spotlight this post!  
Unread 06-05-2013, 23:26
mman1506's Avatar
mman1506 mman1506 is offline
Hater of Tiny Molex Connectors
AKA: Marcus Quintilian
no team (WARP7)
Team Role: Alumni
 
Join Date: Mar 2012
Rookie Year: 2012
Location: Toronto
Posts: 807
mman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond repute
Re: Battery Chargers

Quote:
Originally Posted by fb39ca4 View Post
This charger from HobbyKing is about half the price when you factor in shipping weight, and also charges at 6 amps. I have one for charging Li-Po batteries at home, but I brought it to a competition, and it works great for FRC batteries. http://www.hobbyking.com/hobbyking/s...cessories.html

Keep in mind for either one you will still need to find a power supply. Laptop chargers as long as they are >6A and 12V and ATX power supplies both work great.
I have that charger but it only changers at 50w vs 150w on the other one(Meaning on a 12v battery it will charge up to 4.1 amps on the 50w or 12.5 amps on the 150w) A boat battery makes a great portable power source.
__________________
2014-2015: FRC 865 Warp7 Team Captain
2016: FRC 865 Mentor

2017: Free Agent Mentor, Inspector

Last edited by mman1506 : 06-05-2013 at 23:29.
  #8   Spotlight this post!  
Unread 06-05-2013, 23:29
mman1506's Avatar
mman1506 mman1506 is offline
Hater of Tiny Molex Connectors
AKA: Marcus Quintilian
no team (WARP7)
Team Role: Alumni
 
Join Date: Mar 2012
Rookie Year: 2012
Location: Toronto
Posts: 807
mman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond reputemman1506 has a reputation beyond repute
Re: Battery Chargers

Quote:
Originally Posted by tuXguy15 View Post
This year our robot drew a lot of current and it killed the batteries when we had to keep recharging them constantly. Also i know that 15 volts wont last longer. My point is that we are not managing our batteries right if we arent getting 15 volts. The 6 amps wont get it there because doing a 6 amp charge does not allow a peak and level type of charge that those types of batteries need. You do 2 amp until it peaks then 4 until it peaks then6 to finish charging it's.
No it's the other way around. once it peaks you lower the current, lowering the voltage under load allowing you to put more power in. http://batteryuniversity.com/learn/a...d_acid_battery
__________________
2014-2015: FRC 865 Warp7 Team Captain
2016: FRC 865 Mentor

2017: Free Agent Mentor, Inspector
  #9   Spotlight this post!  
Unread 06-05-2013, 23:36
Billfred's Avatar
Billfred Billfred is offline
...and you can't! teach! that!
FRC #5402 (Iron Kings); no team (AndyMark)
Team Role: Mentor
 
Join Date: Feb 2004
Rookie Year: 2004
Location: The Land of the Kokomese, IN
Posts: 8,563
Billfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond reputeBillfred has a reputation beyond repute
Re: Battery Chargers

Mind you, many other things (current draw on the robot, cycles of use on the robot, physical abuse seen on and off the robot, storage conditions) can also determine how long a battery will last before it's due to retire from the match rotation.

On 2815, our standard procedure is to charge at 2A at home and overnight at competitions, then 6A during the day at competitions to ensure we have enough batteries ready. We also started using a Battery Beak to spot-check battery health; if you don't have one, another team nearby might.

For the capacity of these batteries, 6A until automatic cutoff shouldn't have serious negative effects...but we figure it's better not to tempt fate.

And even if your batteries have weakened to the point that they're not optimal for match use, never underestimate the utility of batteries for powering your electrical board during testing, or for powering an inverter for laptops in the stands. (I've seen a scouting team with a small cart that held a robot battery, an inverter, and a network switch for their laptop-based scouting network. Kinda slick.)
__________________
William "Billfred" Leverette - Gamecock/Jessica Boucher victim/Marketing & Sales Specialist at AndyMark

2004-2006: FRC 1293 (D5 Robotics) - Student, Mentor, Coach
2007-2009: FRC 1618 (Capital Robotics) - Mentor, Coach
2009-2013: FRC 2815 (Los Pollos Locos) - Mentor, Coach - Palmetto '09, Peachtree '11, Palmetto '11, Palmetto '12
2010: FRC 1398 (Keenan Robo-Raiders) - Mentor - Palmetto '10
2014-2016: FRC 4901 (Garnet Squadron) - Co-Founder and Head Bot Coach - Orlando '14, SCRIW '16
2017-: FRC 5402 (Iron Kings) - Mentor

94 events (more than will fit in a ChiefDelphi signature), 14 seasons, over 61,000 miles, and still on a mission from Bob.

Rule #1: Do not die. Rule #2: Be respectful. Rule #3: Be safe. Rule #4: Follow the handbook.
  #10   Spotlight this post!  
Unread 06-05-2013, 23:40
Tom Line's Avatar
Tom Line Tom Line is offline
Raptors can't turn doorknobs.
FRC #1718 (The Fighting Pi)
Team Role: Mentor
 
Join Date: Jan 2007
Rookie Year: 1999
Location: Armada, Michigan
Posts: 2,554
Tom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond repute
Re: Battery Chargers

Quote:
Originally Posted by tuXguy15 View Post
This year our robot drew a lot of current and it killed the batteries when we had to keep recharging them constantly. Also i know that 15 volts wont last longer. My point is that we are not managing our batteries right if we arent getting 15 volts. The 6 amps wont get it there because doing a 6 amp charge does not allow a peak and level type of charge that those types of batteries need. You do 2 amp until it peaks then 4 until it peaks then6 to finish charging it's.
Something is fishy.

We constantly charge our batteries. We have 10 'competition' batteries, with another couple that we keep to charge the inverter on our cart. We draw plenty of current from the battery, and it's not unheard of for us to see the batteries drop to 6-7 volts when we're driving on our practice field. Nothing you've said leads me to believe that your batteries should be dying.

Our batteries fresh off the charger come in at just a touch over 13 volts, but let sit for a couple minutes for the surface charges to drop, they go down to 12.8 - 12.6. When our batteries are not on the robot, they are always on charge. I question your assertion that the batteries should be at 15 volts. I have never once seen an FRC battery come off a charger at 15 volts, and would worry if they did.

I think we need some more info. Are you running matches on the batteries without fully charging them? Are you overheating them?

Again: these batteries (generally speaking) should not die after a season of FIRST use if handled correctly. We have heavily used batteries from 2008 still going strong, and our last 2007 ones just failed this past year.

Last edited by Tom Line : 06-05-2013 at 23:44.
  #11   Spotlight this post!  
Unread 07-05-2013, 00:42
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: Battery Chargers

Quote:
Originally Posted by tuXguy15 View Post
This past season we used the 6amp charger on our batteries from andy mark. This gave us up to 13 volts for a full charge but the FRC batteries can go up to 15 max.
While you can safely charge AGM 12 V batteries at 15 V in certain conditions (smart charger, proper current and relatively low ambient temperature), they won't hold 15 V for long, if at all.

Test them under a small load like the Battery Beak does to get a more reliable voltage measurement. Test them under a moderate load like the CBA tester does to get an idea of voltage performance throughout a full discharge cycle.

Here's some data for the MK batteries, and the old (no longer FRC-legal) Exides.

Also, Al will likely be around shortly to explain more thoroughly why various forms of overcharging are contraindicated.
  #12   Spotlight this post!  
Unread 07-05-2013, 07:09
tuXguy15's Avatar
tuXguy15 tuXguy15 is offline
Team Mentor
AKA: Devin Kolarac
FRC #2559 (Normality Zero)
 
Join Date: Apr 2012
Rookie Year: 2012
Location: Harrisburg, PA
Posts: 127
tuXguy15 is an unknown quantity at this point
Re: Battery Chargers

Ok thanks guys ill check into these and Billfred the issue is that when you constantly do a direct 6 Amp charge and not 2 and 4 it damages the batteries. The second we take them off the charger they start dropping voltage even when not being used. That is the effect of the constant 6 amp charge.
__________________
  #13   Spotlight this post!  
Unread 07-05-2013, 07:37
protoserge's Avatar
protoserge protoserge is offline
CAD, machining, circuits, fun!
AKA: Some call me... Tim?
FRC #0365 (MOE) & former 836 Mentor)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2002
Location: Wilmington, DE
Posts: 754
protoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond reputeprotoserge has a reputation beyond repute
Re: Battery Chargers

Can you answer some more basic questions?
  1. How many batteries did you use this season?
  2. Did you have a process for use such as a serial number and a cycle schedule?
  3. Were you fully charging batteries before taking them off the charger?
  4. Were you putting them back on charge immediately after use?
  5. Did you Battery Beak them before and after use?
  6. Did you maintain their charge through the pre-season?
  7. Did you fully charge them before first use?
You easily can kill batteries by the method you described if you are not cycling (keeping an even usage) and charging them appropriately.

I'm paging our battery experts. Hopefully they will chime in soon.
  #14   Spotlight this post!  
Unread 07-05-2013, 07:43
adciv adciv is offline
One Eyed Man
FRC #0836 (RoboBees)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2010
Location: Southern Maryland
Posts: 478
adciv is a name known to alladciv is a name known to alladciv is a name known to alladciv is a name known to alladciv is a name known to alladciv is a name known to all
Re: Battery Chargers

What voltage are you discharging your batteries down to? I suspect you are over-discharging the batteries and causing damage.

Charging the batteries to 15V will not kill them, 12V Lead Acids today are designed for this. Also, charging the batteries at 2A, will not do anything for you over a standard 6A charge.

Other things which will kill your battery life:
- Storage in hot areas
- Letting your batteries sit uncharged for months at a time
- Charging/Draining batteries while they are hot or cold (est. >90 & <40)
__________________
Quote:
Originally Posted by texarkana View Post
I would not want the task of devising a system that 50,000 very smart people try to outwit.
  #15   Spotlight this post!  
Unread 07-05-2013, 07:48
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: Battery Chargers

Guys,
There are a few things about batteries you need to know. A battery might show something above 12 volts (no load) when it comes off the charger due to a condition known as 'surface charge'. This voltage will drain back down to the 12 volts as soon as you start to draw current from the battery. That is why no load battery testing is inconclusive when checking the state of charge or the condition of the battery. Charging SLA/AGM cells requires that a voltage higher than the cell voltage be forced on the battery. The higher the voltage, the more charge current is pushed into the battery to reverse the chemical reaction that takes place inside. The manufacturers state that currents in excess of six amps will damage the battery. However, the smart chargers provided in the KOP and equivalents will back down from the six amp maximum as needed during the charge cycle. So setting the charger at 6 amps does not mean it will provide six amps during the entire charge cycle. Any additional current in excess of what can be used to reverse the chemical reaction will generate heat. In our batteries this excess heat can cause boiling of the electrolyte within the cell, deformation of cell plates, leaking of the battery and explosion in rare cases. That is why inspectors will ask you to remove battery chargers that are in excess of six amps and are not smart chargers. We regularly will find teams trying to use 50 amp car chargers in the pits. These are extremely dangerous for use in the pit and will guarantee early battery failure with no warning. While the KOP charger does allow current selection below 6 amps (i.e.4 and 2 amps) selecting these lower settings will not measurably extend the life of the battery but if you have the time to wait, the lower current may be a more efficient charge method.
The best method of checking battery state of charge is under a controlled load. The Battery Beak is an excellent simple charge tester that you can carry in your pocket. For really accurate checks that mimic the manufacturer's specification, use a West Mountain Radio CBAIII.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
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 20:03.

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