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Author Topic: Watch your BATTERIES!!!  (Read 6996 times)

Kims Robot

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Watch your BATTERIES!!!
« on: August 30, 2010, 09:08:30 AM »

From Bill's Blog:

First the lesson:
It is a good practice to inspect your robot batteries for damage at the end of the season and a good idea to monitor your batteries throughout the off season.  Batteries need to be stored and/or charged in a well-ventilated area away from sparks, open flame and direct sunlight.  Persons handling batteries are to wear safety glasses (preferably non-vented goggles) and acid resistant gloves. If you use metal tools on the battery, remove metal jewelry such as rings and bracelets first. Have an eye wash station nearby and have supplies on hand to clean up in the event of a spill. The batteries are factory sealed.  Do not attempt to open or “service” recycle any battery that will not hold a charge.

Then the reason I mention this now:
Last week the occupants of 200 Bedford Street were greeted by a really unpleasant odor when we arrived at work one morning.  It took us a while to track it down, (we’ve had some work done recently on the AC which turned out to be a red herring), but we found a swollen 2008 robot battery plugged into a charger on the game floor.  We always have a few batteries charging.  We use them when we’re trying out GDC game ideas, when we prototype robots, and when we’re working on the FMS and scoring systems.  No one was hurt, nothing was damaged and we had the air quality in the building tested.   The battery has been retired with thanks for its long service.  We’ve updated our battery process and procedures and thought now was a good time to remind teams to do the same.
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~kim~
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BlueBlitz

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Re: Watch your BATTERIES!!!
« Reply #1 on: August 30, 2010, 09:50:58 AM »

Kim brings up a very good point by sending this out.  We need to make sure we never keep batteries charging unattended for multiple days.  I will go out on a limb and say that usually one night overnight is fine but more than that is a risk. 
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Valkyrie

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Re: Watch your BATTERIES!!!
« Reply #2 on: August 31, 2010, 07:26:47 AM »

Yeah - when we fully charged up ALL the batteries earlier this year, we had them in the detached garage (NOT the house!) and checked them every couple of hours.  Still, some had to be left overnight to charge, because they were pretty much dead and it took a loooooooong time to get them up to full...
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c0baltHa1l

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Re: Watch your BATTERIES!!!
« Reply #3 on: August 31, 2010, 09:39:14 AM »

Yea, I really hate the we-ran-out-of-batteries-because-they-take-forever-to-charge problem.
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Justin



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Crystal

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Re: Watch your BATTERIES!!!
« Reply #4 on: August 31, 2010, 09:45:41 PM »

I. Really. Think. It's. Un. Necessary. For. You. To. Mis. Use. Your. Hyphens. Like. That.
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c0baltHa1l

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Re: Watch your BATTERIES!!!
« Reply #5 on: August 31, 2010, 10:34:09 PM »

but-I-like-to-because-it's-fun

ha
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Justin



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Ramerez

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Re: Watch your BATTERIES!!!
« Reply #6 on: September 06, 2010, 11:40:18 AM »

Thankfully, we use lead-acid batteries because of their safety over other types of batteries. However, I wish we would consider using Lithium-Ion batteries for demos because of their superior power to weight ratio. They would require extra safety (maybe even contingency programming that shuts off the robot to prevent us from over discharging the batteries), but I think that they would help us not run out of batteries during long demos.
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c0baltHa1l

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Re: Watch your BATTERIES!!!
« Reply #7 on: September 06, 2010, 06:45:12 PM »

Thankfully, we use lead-acid batteries because of their safety over other types of batteries. However, I wish we would consider using Lithium-Ion batteries for demos because of their superior power to weight ratio. They would require extra safety (maybe even contingency programming that shuts off the robot to prevent us from over discharging the batteries), but I think that they would help us not run out of batteries during long demos.

That would be great, but sadly 12v lithium ion batteries aren't too cheap  :(
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Justin



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Ramerez

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Re: Watch your BATTERIES!!!
« Reply #8 on: September 06, 2010, 07:18:17 PM »

We might be able to get a company to sponsor us with some free batteries. We did get an offer for that at Simcona last year, after all. And yes, you're right - Lithium-Ion batteries don't come cheap (not even the Wegmans version).
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dave_roc

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Re: Watch your BATTERIES!!!
« Reply #9 on: September 06, 2010, 07:58:04 PM »

Lion batteries probably require a different charger also.  They have a fairly specific current versus voltage charging profile to get full capacity and full lifetime out of them.
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Ramerez

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Re: Watch your BATTERIES!!!
« Reply #10 on: September 07, 2010, 08:26:46 PM »

I would hope so. I know that my model helicopter has very specific instructions on how to charge the Lithium-Ion batteries, saying that you have to use a specific charger at a specific voltage and current for a certain amount of time (its a good thing the charger auto regulates all of those details). If we do decide to use these batteries, I think we'd have to get specialty chargers for those batteries as well. Not outside the realm of possibility in my opinion.
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Dino

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Re: Watch your BATTERIES!!!
« Reply #11 on: September 27, 2010, 06:16:50 PM »

One thing I have been learning about batteries is different types have different discharge rates usually denoted as C. When we test our batteries and parse out the best of the best we should also measure this. C will have an effect on how much current can be supplies at any one time and how quickly it can be supplied.

A new type of battery that I would love to get my hands on are Li-Po, it is a more "dangerous" the Li-Ion.

Dean
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c0baltHa1l

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Re: Watch your BATTERIES!!!
« Reply #12 on: September 27, 2010, 07:54:19 PM »

I've got one of those (6.5v) on order along with a charger for a project in working on.
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Justin



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Ramerez

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Re: Watch your BATTERIES!!!
« Reply #13 on: October 07, 2010, 02:00:28 PM »

Another interesting fact that I learned about batteries (Lithium-Ion) is how to keep their performance high all through their lifespan. Apparently, it is good practice to fully discharge a battery (to the point that the device it powers shuts off) twice a month, and then fully charge it without interruption. I learned this from an Engadget editor through their podcast. He also metioned that you don't want to deplete the battery to completely empty (as that's bad for the battery), but low enough to shut off the device that uses it (he was talking about cell phones, so the robot would be a bit different).
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