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Li Pol batteries
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Spockie-Tech
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Joined: 31 May 2004
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Location: Melbourne, Australia


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true, but "suck" = "trust me, I have reasons for not liking them"

I prefer to explain the reasons to people rather than asking them to just believe me..
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Post Fri Feb 18, 2005 2:22 pm 
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Valen
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Joined: 07 Jul 2004
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i'd rather they didnt believe me and kept using their SLA's making their pwonzorage that much easier muwhahaha
and then i can say "i toldja so"
MUWHAHAHAHAH

btw Plan-B's new 3600's are getting baught today ;->
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Post Fri Feb 18, 2005 3:25 pm 
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Nick
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So why is everyone saying that LiPoly batteries are only good for low current? The largest cells on RMP are good for 90A continuous and even if Continuous really meant 1 minute, its still a heap of current and 6AH of capacity in a tiny weight & space. The weight saving more than compensates for a small cooling fan and the packs are able to be safely charged with an accessory.

True, these are the most expensive cells on RMP and true, you could still blow the crap out of them more easily than NiCads, but I would say they are now valid for anyone willing to push the envelope of featherweight design...
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Post Fri Feb 18, 2005 3:26 pm 
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Valen
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i wouldnt view it so much as "push the envelope" as spend the cash ;->

to get enough batteries to run a 24v bot with 2 or 3 packs would cost ~$1000 - $1500
thats a bit more than the $401.09 we paid for our new batteries
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Post Fri Feb 18, 2005 3:43 pm 
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Nick
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Push you credit limit as well as the envelope then? Very Happy

How will you be making your new packs? with spacers like the old ones or with the cast urethane idea?
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Post Fri Feb 18, 2005 3:46 pm 
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Nick
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Not that I'm saying everyone should convert to LiPoly but you could last a whole event with 2 of those 6.6Ah packs and only pay $700. If your bot used about 1/3 of the capacity and you could recharge thm at 1/2 C or more, then two packs should last an even as long as they were cooled and charged between matches.

Pairing the Lipoly pack with either smaller drill motors or a current limiting controller like the RS80D in a pushy bot or even better in a pneumatic lifter would allow the design to have a stronger weapon or armour without stressing the battery.
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Post Fri Feb 18, 2005 4:09 pm 
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Glen
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quote:
but you could last a whole event with 2 of those 6.6Ah packs and only pay $700


err was that joke or was that serious lol.

second the notion to SLAs sucking as well
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Post Fri Feb 18, 2005 4:28 pm 
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Philip
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Joined: 18 Jun 2004
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The other draw back to the LiPol is that they die if they drop much below 3 v / cell.You would need to build yourself a voltage monitor to turn off your robot if the voltage sagged. They have a life expectancy of 500 cycles.

I think that they will be the go in the future, but not just jet.
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Post Fri Feb 18, 2005 7:45 pm 
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Totaly_Recycled
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Heres an interesting link http://www.sionpower.com/pages/sion_technologysummary.php

Post Fri Feb 18, 2005 9:39 pm 
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Philip
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Good link, Andrew. Li S batteries will be another technology to keep an eye on.
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Post Sat Feb 19, 2005 5:19 am 
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Andy



Joined: 22 Mar 2005
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Location: Canberra


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General Li+ info

I have just built a bot with two oatley scooter motors and I'm using a 25.2 volt Li+ pack made up from cells from a second hand laptop battery.
I have been making my own packs for about 4 years but mainly for my mtb lights. They can be charged using a good benchtop PSU and just setting the voltage at 4.2 volts per cell (4.1 for some older types) and setting the current limiting at less than 1C. My bot is light, less than 5Kgs and it was going to have a weapon but now that the weight categories have changed, it will have to be a pushy bot in the 4.45?? Kg category.
I hope to be able to have it ready for whenever the next event is. It would be nice to know when that is as I need a deadline to work to, otherwise I'm a lazy bastard.

Post Tue Mar 22, 2005 2:52 pm 
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dyrodium
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Sounds way cool!
But just to let you know, the only comps in australia at the moment are for featherweights (13 odd kgs). If the Lipols can cope though, you could upgrade it pretty easy (scooter motors can power feathers well). It gives you a full 8kg to think about your weapon! Very Happy
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Post Tue Mar 22, 2005 3:30 pm 
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Glen
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glad to see you on the forum andy, theres a lot of 6kg robots floating around.. space ship 1, waddy, mouse wedge, woody wedge would be close, so would cataclysm.

im quite amazed you managed to get a pair of scooters into a 5kg robot, theres a comp in NSW on the 16th of april and im not quite sure when the melbourne one is, would be great to get a few new robots at an event (although i know the hell of driving from sydney to canberra.. that roadhouse resteraunt on the highway was getting fairly nasty after a while heh)
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Post Tue Mar 22, 2005 3:35 pm 
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dyrodium
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Lol, that's true, cataclysms way underweight. Didn't think of those bots (don't know why). lol, waydes bots always going to be refered to as "waddy" no matter what he does! You know, now there's almost enough bots in sydney for a hobbyweight comp! Smile
Aww, but i want to be in both! Crying or Very sad Very Happy
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Post Tue Mar 22, 2005 3:44 pm 
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Andy



Joined: 22 Mar 2005
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Location: Canberra


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It was meant to be a 6Kg bot with a spinning blade weapon. But I thought the weight categories had changed to 12 lbs which is around 4.45Kgs or so.

Mmmhh a weapon that ways more than the bot.... Then I could be a featherweight. LOL

Post Tue Mar 22, 2005 5:19 pm 
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