actually in retrospect plan b used to run its drive off drill nicads for quite a while (2 in parrallel?) and i had a pair on cobra in parrallel that lasted longer than the 2.3ah SLAs in parrallel.

i just discharged the cells by sandwhiching them between two bits of metal then soldered them all again and cycled them 3 times... works good for keeping the dead cells out.
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Thanks =)

I've found that some proper cycling of the drill packs helps a lot.

They suffer from voltage depression bigtime when they're new (this is what most people call memory effect)
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The Engine Whisperer - fixer of things

Plan B got through every event except the final at the last robowars on drill packs.
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Mechanical engineers build weapons, civil engineers build targets

My local Bunnings (Maroochydore, 150km from home, real local) has a wicked "Marked down or scratched" section. I had a dig through some of the bins until I found a bucket with oodles of drill packs....

Each pack had a $10 label slapped onto them....


I bought the 5 biggest GMC packs there, 2 x 24v, 2 x 18v and a 12v (80cells)


They all looked the same, so I pulled them apart




Well, they looked the same, but I was wrong.. I found both 24v and the 12v packs were 1200mAh NiCD's.... But the 18v's, they were different... One 18v pack was a 1500mAh stocked pack, while the other, with closer inspection is actually a 1700mAh Pack. Post conclusions, the 18v pack that had the 1700's in it had a grey trim on the casing comapred to the others with yellow, it also had T10 screws locking the case together, and had copper contacts, this pack actually belongs to the $200 GMC 18v Platinum drill combo... So, I've now got 50 x 1200mAh NiCD's 15 x 1500mAh and 15 x 1700mAh Can you say 300watt scooter motor on 96v BOOM!
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https://www.halfdonethings.com/

Well done . Any 18v left at the store? If so i'll pick up some in the morning. They were in the power tools section?

There 1 x 18v pack, it was from an older model, there is 2 x 14.4v ones same case as my lot, there is a pair of 12v with charger clipped onto them, there is half a Ryobi drill, and a bunch of ryobi batteries in the box. I saw 1 or 2 12v 2000mAh Ryobi packs, so grab them if you want something with a little more kick

Walk into the store at Maroochydore (Right next door to SuperCheap), take a left when you go through the automatic swinging door things and keep walking down the aisle, looking to your left, you should see a pallet about 20m down the aisle with various things with majorly reduced prices

These aren't the worlds best NiCd's but they are great for testing things and they can be used for competative bots (Plan B, SpeedHump, Retread)
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https://www.halfdonethings.com/

If you are going to compete with them, make sure you test each cell, or run a couple of packs in parallel (if you have the weight/space points left).

I dont know if the GMC packs are any better than other chinese ones, but from Garys experiences so far, Open-circuit cells are the most common failure mode with them.

If you're running a single pack and one cell goes open, you're dead in the water. With 2 in parallel the current load on the packs is lighter and if one does go open circuit, you will at least have *some* power left to keep moving. and 2 x 1200mah packs gives you 2400mah, about equivalent capacity to the good sanyo nicads. a bit heavier with twin packs though.
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Great minds discuss ideas. Average minds discuss events. Small minds discuss people

quote:

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Originally posted by Spockie-Tech:
a bit heavier with twin packs though.

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lol and how oftern is that exactally??
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as a shadow is seen and not heard i am here
-Waddy the phoenix

Once a year abouts.,.. getting a bit boring now though
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YEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH

quote:

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i should go bot shopping next time i go on holidays in maroochydore

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how much mAh?

I want to order a battlepack from robotmarketplace for my not yet complete featherweight. Its running two 200watt scooter motors, chain drive, 150mm wheels(rammer). 24volts Brick.

Is there a way to work this out, i'm guessing not. I'm hoping someone can give me a experienced guess. thank you. Also Nicad or NiMh. NiMh is better as in lighter but the battery has a limited life?

For the scooter motors, you can get away with drill nicds or even look at RC car packs. You can buy 3000mAh NiMH RC Car packs for as cheap as $20 each off Ebay and you only need 4 packs for 28.8v which will make the scooter motors hum a little bit more
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https://www.halfdonethings.com/

nice