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Group buy - A123s
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Valen
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Joined: 07 Jul 2004
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The 3.6A ones are li-ion not li-fe.
Higher Amp-Hour ratings aren't necessarily what you want either. what your really after most in RW is higher current draw/lower internal resistance.
Unless your 2.2Ah cells are going flat then more Ah won't help, you need to suck what amps you have out faster.
Plan-G has run for several rounds (with weapon) with minimal discharge of battery.
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Post Mon Mar 31, 2008 8:21 pm 
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Nick
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I totally agree - I use a big Lipo pack that will realistically never run down in a 3 minute match. It has a tiny internal resistance and low voltage sag under load, which really gets the Mag motor spinning and that's what counts, not the AH. Bigger batteries generally have lower internal resistance, but you need to do your research on what fits your current draw vs weight allowance.
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Post Mon Mar 31, 2008 8:29 pm 
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dyrodium
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Speaking of which, those smaller packs of yours were about $200 wern't they Nick? Where bouts did you source them from? Smile
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Post Mon Mar 31, 2008 9:59 pm 
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Nick
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They are Duralite 3700 / 6S packs costing $249 USD. Thunderpower make very similar packs for around the same price - if a similar AH pack is about the same dimensions, it is definitely using the same calls and will have the same electrical performance. The main difference is performance; some packs use circut boards to connect the cells and others crimp or weld the cell tabs. The PCBs used by Polyquest & others definitely have a lower reputation.

At the moment, the 25C cells are the sweet spot for bots; the 30S packs are still too expensive while the 20S and lower packs are hardly an improvement on A123 calls for much more money.
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Post Mon Mar 31, 2008 10:41 pm 
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NMO
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Further to the 3200mAH cells on robotmarketplace, I got playing in a photo editor because I noticed a website adress on the side of the cells in the picture.

http://store.peakbattery.com/index.html

Post Fri Apr 04, 2008 12:53 pm 
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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http://store.peakbattery.com/lfp26.html


quote:
Our new EV rechargeable patented Li Iron Phophate battery that can handle over 12 Amps continous and 28 Amps for at least 30 seconds. This battery has the highest energy in it's class. The nominal operating voltage is 3.2 volts and 3200mAhrs at C/5 discharge. Add $2.00 per battery if you would like tabs welded to battery. The internal impedance is less than 19 mohms. This battery is 26.2 mm D x 65.2 mm H and it weights 82 grams.


Not much chop for the price...

https://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=6444

Still looks like the cheapest place to get A123's them bar ebay whoring... Ebay has fluctuated a fair bit lately, I've seen packs go for $120USD and others for $160USD.
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Post Fri Apr 04, 2008 1:14 pm 
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