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batteries
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Glen
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Joined: 16 Jun 2004
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batteries

just a general topic for questions and things.

heres my question:

will i be able to run a pair of 12v drills off 2x 7.2v 1400mAh car racing packs? main reason is i can get them for $15 each.

i did some basic load method calculations for the drive and i figured 1.93ah. but i figured in a load of pushing. so im inclined to think i might get a way with it.

if anyone has firm data that would be appreciated.

also charger wise i noted jake was using a power supply to charge his nicads. anyone care to comment on how id go about doing the same?

Post Wed Jul 07, 2004 9:53 pm 
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DumHed
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with nicad packs you can charge them very fast as long as you cut the charge current at the right point.

The most reliable way is to discharge the battery completely (0.9-1v per cell), then do a constant current charge for the appropriate amount of time.

The other way it to monitor the cell temperature, and cancel the charge when the temperature starts rising rapidly.

I often do that just by feeling how hot the battery is every few minutes Smile
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Post Wed Jul 07, 2004 10:56 pm 
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timmeh
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to glen yes you would be able to run 2x 12 volt drills of 2x 7.2v 1400mAh car racing packs since the cells in drill packs are usaly 1200 to 1400mAh if you run them in series you would get about half the run time as you would get out of a drill but if you run them in paralel you would get about the same time you would in a drill if that makes sence but your motors would go slowwer in paralel Laughing
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Post Sun Jul 25, 2004 9:23 pm 
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andrew



Joined: 16 Jun 2004
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Location: Castle Hill, Sydney. N.S.W


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Hey all. spent the best part of today modifying a drill nicad 12 volt pack as a ghetto battlepack. and wanted to share some tips for anybody thinking of doing the same. It reduces height, makes it easy to mount a fan too if need be and enables wired to be run off them eliminating clip on stuff.

One thing to do when resoldering the 2 cells on the top of everything flat with the rest is to cut the conecting tags in half and solder some 12 gauge if possible (or thinner but makes sure not too thin) wire between them as it is much easier to solder the tag bits and it also lets there be some flexibility. Its near impossible to solder wire properly onto the cell.

Also with 12 volt ux1 drill battery case. The top can be removed and thrown out and the resoldered 2 stray cells can be played in the front section as theres space. this enables no need for a purpose made box and saves time/effort.

Then all thats needed is to make a lexan (or any non conductive material, but lexan looks cooler) top and drill holes for battery wires to poke out of and holes where the original screws screw the top piece on. These can be used to screw the new lexan piece onto.

Now theres a batery pack to slide in a robot all ready to go and best still. weighs about 500 grams.
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Post Sat Jul 31, 2004 6:28 pm 
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timmeh
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Just a tip for soldering wire or tabs on to batterys use BAKERS SOLDER FLUID it makes it a whole lot easyer just dab a bit on where you want the solder to go and solder "It fizzez a bit then sticks real good it stops the solder going all over the place other then where you want it to go but dont dab too much on as it will rust the battery termanal a bit you can find it in plumbing stores if i remember correctly its about $8 for 250ml it lasts you a very long time.
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Post Sun Aug 01, 2004 1:55 pm 
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Shaunington III



Joined: 18 Jan 2006
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Does anyone know where I can get cheap nicad batteries?

Razz

Post Tue Jan 24, 2006 3:37 pm 
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timmeh
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What ones?
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Post Tue Jan 24, 2006 3:40 pm 
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DumHed
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cordless drills are the best source of nearly everything robot related Razz
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Post Tue Jan 24, 2006 3:43 pm 
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Spockie-Tech
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Battery Drill's from Bunnings/Super Cheap/etc.

Also, Rick (Moth) found a surplus place in Moorabbin / Melbourne that had a trailer full of "unknown" (possibly second hand / returns ?) drill packs for about $5 each.

BUT, if you're serious about being competitive, Drill packs wont do it reliably.

You CAN get by with old drill packs or other sources of cheap cells if you are prepared to disassemble them, test each cell individually with a computerised charger, turf the bad ones, match the good ones, reassemble them into a pack and periodically re-test them to make sure none of the cells have died.

Of course, this presumes you have a $200 capacity checking battery charger and weeks of your spare time available.

Its usually much less frustrating to stump up the $$ for quality cells in the end.
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Post Tue Jan 24, 2006 3:53 pm 
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dyrodium
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Yeah i must admit most of my 12v packs have a single bad cell... you can usualy tell it when your fast charging, its the first to heat up. It was a big leap for me. but the 2400mah sub c nicads pack plenty of power for your adverage robot. Smile
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Post Tue Jan 24, 2006 3:57 pm 
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DumHed
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Speedbump won the lightweight comp running drill packs Razz
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Post Tue Jan 24, 2006 4:01 pm 
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timmeh
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LOL that thing keeps amasing me Very Happy
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Post Tue Jan 24, 2006 4:03 pm 
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Spockie-Tech
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I didnt say it cant be done.. Wink
Just that it requires patience, time and lots of testing if you want to be reliable on 50cent Drill Cells.
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Post Tue Jan 24, 2006 4:04 pm 
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Glen
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drill cells go okay if you use like 3 - 4 in parrallel and keep the drills at the rated voltage.
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Post Tue Jan 24, 2006 4:11 pm 
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dyrodium
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quote:
Originally posted by DumHed:
Speedbump won the lightweight comp running drill packs Razz

He had four whole packs which means the dud cells don't get to do much! Razz
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Post Tue Jan 24, 2006 4:11 pm 
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