Batteries Required??

[KTorak]

We brought 3 batteries for seeding, 2 new and one old (old was for running robot to make repairs). We borrowed one new battery from a team for the quarter/semi/final rounds so we had 3 new ones total.

[Shu Song]

We brought 8 or 9 batteries to competition and always had a fresh battery for a match. If your electrical system runs a lot of motors, the batteries tend to run out pretty quickly, but if its mostly pneumatic except for the drive, then 4 or 5 batteries are plenty.

[DougHogg]

If you need more battery chargers, we found one at Walmart for about $25.00 that fits the FIRST requirements. We have been using three of this model and find that they work well, although now and then, one of them will show a red light when first connected, an error signal meaning that the charger didn't like the battery or the connection.

One other thing to be aware of: If you interrupt the charging cycle part way through and then restart the charger with the same battery, the charger may look at the surface charge and think that the battery is fully charged, even though the charging cycle wasn't completed. The answer is to prevent such interruptions and allow the charging process to complete until the green light comes on. (The list price of $46.25 below is from the manufacturer's web site):

6/4/2 Amp Charger/Maintainer
For 6 and 12 Volt Batteries...more
Price: $46.25
SC-600A

For more info on this charger, see
http://www.schumacherelectric.com/itemlist.cfm?cid=2

[nobrakes8]

We get about a match and a half out of our battery then it dies..

We won the regionals after 7 elimination matches and we did fine with 4 batteries as long as you have a battery runner to keep going to the pit with a dead battery and takeing a new one...

Also I believe FIRST had battery charges in the area..

At UTC i saw like 3 or 4 chargers where the blue alliance worked on their robots, they might have been our alliance partner's though, but it said "FIRST" on a piece of masking tape, but i dont remeber seeing our alliance partner bringing chargers to the red side when we were on the red alliance..
I should have asked

[Denman]

the best thing to do, is to get a battery reader thing. We borrowed one that tells you the voltage, the amp hours left and the temperature of the battery. it means you can tell which re the most charged...

[DougHogg]

Originally Posted by Denman

the best thing to do, is to get a battery reader thing. We borrowed one that tells you the voltage, the amp hours left and the temperature of the battery. it means you can tell which re the most charged...

We bought two different types of battery tester this year, but neither of them shows the "amp hours left". What was the make and model of the "battery reader thing"?

I suspect that your tester was basing its amp-hours-left reading on the battery voltage. One possible problem: if you start charging a battery and then test it part way through the charging cycle, the battery will have a surface charge which would throw off the tester.

What I am saying is, watch out for half-charged batteries. The voltage on a battery will register high if you take the battery off a charger in the middle of the charging cycle (as the charger was putting a high voltage on the battery to charge it and thus creating a surface charge on the battery), but the charging process won't be complete, so the battery could die during a match if your robot uses more current than the battery got from the partial charge. (We experienced this first hand in the third match of the finals at the S. Calif. Regional this year.)

[Denman]

i'll find out. It is pretty nice tester....

[pludodog]

We brought 7, had six chargers, only use five of the batteries though. It becomes rather annoying in the finals, when you have to either keep running back and forth between the pits and the robots, or try to steal an electrical outlet around the field for plugging in the charger. That's what I saw a few teams doing in NYC. Either way, we got a good 5-6 practice matches out of a battery before it was dead, but lately we've taken to powering up the robot and monitoring the voltage under some load for a few seconds, just to make sure that the battery is fully charged.

Team 375 had to have the best cart I've seen; they put a marine battery on their cart, put an inverter on there, and then carried around all their chargers and batteries with them.

[Denman]

yeh that was good lol

[Heretic121]

we replace the battery every match and check the volatage of each battery before connecting it to the bot.

Also we run the systems check on a seperate charged battery so that it has full power when doing the check, and goes back on the charger for either a following match or a following systems check.

for the elims, we bring about 4 to the quaterfinals, and at least 4-6 for semi's-finals so there is minimal rnning between the pits and the field...

*also if nessecary, we bring the chargers to the stands near the field so that we can charge batteries as welll *IE nats 2004*

[DougHogg]

Originally Posted by Denman

the best thing to do, is to get a battery reader thing. We borrowed one that tells you the voltage, the amp hours left and the temperature of the battery. it means you can tell which re the most charged....

Originally Posted by Denman

i'll find out. It is pretty nice tester....

I am still trying to find out the make and model of your mysterious battery tester. If it can really predict the amp-hours remaining in a battery, I am sure that a lot of team would find that valuable.

Doug Hogg

[Denman]

yes, i'm still trying to find out too. the person who owns it isn't sure and it seems to hvae gone walkies, hopefully its in the crate, which i will try and get opened today if i have time

[DougHogg]

Originally Posted by Denman

yes, i'm still trying to find out too. the person who owns it isn't sure and it seems to hvae gone walkies, hopefully its in the crate, which i will try and get opened today if i have time

Thanks for letting us know about your battery tester.

I received an email from one of your team members, Dave Garnett, and he referred me to

http://www.batterytester.co.uk/actmeters.htm - see Product-Index/GOLD-IBT Intelligent Battery Tester.

This tester looks very promising. For sure, it has been tough for us to reliably predict the amp-hour capacity of a battery without running the battery down. We actually bought two other types of tester this year which are helpful, but they do not tell us the amp-hours that are in the battery. Our robot is an electricity guzzler this year, and the IBT Intelligent Battery Tester seems to be exactly what we want to make sure that our battery won't poop out near the end of a match. If anyone else has used the above tester, I would be interested in hearing about your experiences with it.

Doug Hogg

[Denman]

glad we could help,
you also beat me to posting after you emailed me lol