Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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.. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
Fri Feb 18, 2005 2:22 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
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 ;-> _________________ Mechanical engineers build weapons, civil engineers build targets
Fri Feb 18, 2005 3:25 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
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... _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Fri Feb 18, 2005 3:26 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
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 _________________ Mechanical engineers build weapons, civil engineers build targets
Fri Feb 18, 2005 3:43 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Push you credit limit as well as the envelope then?
How will you be making your new packs? with spacers like the old ones or with the cast urethane idea? _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Fri Feb 18, 2005 3:46 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
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. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Fri Feb 18, 2005 4:09 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
quote:
but you could last a whole event with 2 of those 6.6Ah packs and only pay $700
Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
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. _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
Good link, Andrew. Li S batteries will be another technology to keep an eye on. _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Sat Feb 19, 2005 5:19 am
Andy
Joined: 22 Mar 2005
Posts: 2
Location: Canberra
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.
Tue Mar 22, 2005 2:52 pm
dyrodium Experienced Roboteer
Joined: 24 Aug 2004
Posts: 6476
Location: Sydney
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! _________________ ( •_•)
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
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) _________________ www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz
Tue Mar 22, 2005 3:35 pm
dyrodium Experienced Roboteer
Joined: 24 Aug 2004
Posts: 6476
Location: Sydney
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!
Aww, but i want to be in both! _________________ ( •_•)
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