I'm a no show till i have money Brett. But I'm basically looking for the packs that will supply the the highest amount of amps continously for Annihilation's 400amp start ups.
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https://www.halfdonethings.com/

Theres more to it than just the amps number though Aaron.

The NiCd's will supposedly supply higher peak currents than the NimH's will, but wont do it for as long due to their lower capacity for a given size/weight.

ie. The 2400 Nicd's weigh about 60grams each in a sub-C size and will supposedly supply a reasonably solid 80 amps with peaks over 100..

the 3600 NimH's weigh about the same 60g, but have another 1200mah's of capacity for that same weight. supposedly the trade-off is that they wont supply as high a peak as the nicads will.

So for annihlation, the choice for nicd's or nimh's would be determined on whether you wanted higher peaks or longer duration. the higher peak current would give you a shorter spin up time, but the longer duration cells would give you more spin-ups.

For example, a hammer-bot that requires a sudden burst of high current would appear to be better off with the NiCd's higher current peaks, but a saw-bot with lower, but sustained current draw, the NimH's seem to be better..

Supposedly.

As a matter of fact, I'm starting to get a little suspicious after looking at endless data sheets over the last week or so. They seem to be doing their best to NOT give you any solid comparable data.. some give you the internal impedance at charged state, others at 50% charged, and others at discharged state. some sheets list the discharge curves in terms on minutes, others list it in terms of "capacity" which seems weird to me.

The NiCd's are supposed to have higher discharge rates than the NimH's are, but the data sheets show internal impedances about the same..

I'm beginning to wonder if its all a big marketing con.. especially in the "RC" style cells which are aimed at the hype-heavy radio control car market where pretty "race look" stickers seem to be more important than hard data..

thats why I'm going to buy some of the "boring industrial" CP and N style nicad cells, and some of the "race pretty" RC style RC cells and see if I can get some better data on which one suits our application better.

Anyway, "till I have money" doesnt tell me much about when that might be.. are we talking weeks or months here ?
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Have you read your pm brett?

I sed id take 45 but iv been doing some more working out AND!!!!!!!!

Ill take 60 rc3300hv cells and ill put the money in your bank account wednesday or friday at the very latest cos the bank is open later and i will be able to get there after work so please send me your details pm or email:D

Hope we can buy our cells now
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Tim Team Reaper.

Do we have a time-frame for buying the cells yet? I have some solid plans for the CP3600 Nicads and 36 cells seems a bare minimum. If Nat. Instruments sells it, I would be interested in some heatshrink too - something a bit over 80mm diameter
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I just got some updated prices to include the lower quantities since we have only reached 100 cells on the rc3300hv's that Tim and I want..

Sanyo NimH
...Order Quantity ......<100./..>100./.>500
rc3000h......sub C = ........./........./ $8.25
rc3300hv....sub C = ........./ $7.72 / $6.79
rc3600hv....sub C = $9.62 / $9.32 / $8.20

Sanyo NiCd
...Order Quantity ......<100./..>100./.>500./.>1000
.rc2400.......sub C = ........./ $5.77 / $5.56
cp2400scr...sub C = $5.77 / $4.24 / $4.02 / $3.86
.n3000.cr....Csize = $9.00 / $7.15
cp3600.cr....Csize = $9.48 / $7.52 / $6.59

Gold Peak NimH
...Order Quantity ......<100./..>100
gp3300...............= $9.31 / $8.75

Current Orders
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cp2400scr x 40 (40 for brett)
cp3600cr x 36 (36 for Nick)
rc3300hv x 100 (40 for brett, 60 for tim)
rc3600hv x 60 (60 for Ajax)
-----------------------------

Ajax, you'd save a fair few $ (with only a 10% drop in capacity) if you went for rc3300's in stead of rc3600's since Tim and my order combined already puts us over the 100 cells mark on that model, want to join us in that, or would you prefer to stay with the 3600's at the higher (<100) price ?

Nick, are you sure you want the cp3600's ? They are very expensive for their capacity (because they're Csize rather than the more common sub-C according to the guy at Master Instruments). They are nearly twice the price of the cp2400's..

If you changed to 2xcp2400scr's you would get another 33% capacity (4800mah) for less than the price of the cp3600's, plus using twice the amount of cells in parallel would likely give you higher peak currents than a single set of 3600's would. They would probably be a bit larger, but not too much since the cp2400scr's are sub-C while the 3600's are C.

That also explains the surprisingly high price I got on the N3000Cr's (since they're a C-size), which makes those 2nd-hand K-packs mentioned in the other thread look better value if you dont mind the added size/weight of a C-Size.

Plus, if you changed your 36 x cp3600's to 72x cp2400's, then with my 40, we could get the >100 price on the cp2400's which makes me happy..

I'm ready to order now, Tim says he will be this week (wed or Fri), and I assume you are ?
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Hi Brett. That's some great detail, I was going with the CP3600 cells to fit into a specific size and using more sub-C cells might not work. I will do som CAD and simulation to see. Either way, I get paid tomorrow so I will pick something by then. No word on heatshrink? I looked around and sizes over 50mm are rare & expensive locally. Perhaps a bulk order from the KAN guy or Hilltop batteries? I am also looking around for copper braid as suggested in the KAN pack thread, it sounds ideal. I was thinking about buying a 25m reel and selling it off to interested builders. 10 x 2mm carried 63 amps continuous (probably more in short, solder-filled lengths)
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Master Instruments do have heatshrink.

They measure the width of the shrink when it is folded flat, rather than the diameter (I guess the diameter is hard to measure accurately with the bigger stuff).

The biggest is 163mm width and is $1.65/meter and it gets cheaper as you get smaller.

They said that larger shrink can be had from HeatShrink Australia (www.heatshrink.com.au), but its very expensive from them.

You can get some very strong stuff from builders supply shops, but they dont reccomend it, since it is quite a good insulator and traps the heat from the cells in the pack. Apparently the Army tried it for some heavy duty packs they had Master Instruments make, and they abandoned it after a while, because the packs were getting too hot.

I'm not going to worry about the heatshrink since Gary and I are standardizing on a jiffy box to enclose our cells which makes them easy to mount in the bots, offers protection, and if we need cooling, we can easily add a fan to the box for an intercooled pack. If you would like some, let me know..
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Measuring the heatshrink flat would give me approx 1/2 the circumference, right? My pack size has about 160mm circumference so tube in the 100mm flat and up size will be great.

I also need to repair severl old Battle packs and 150mm flat would be good, with the max 163 OK assuming it does at least 2:1 shrink. I would be getting 3 metres of each. Thanks for making the enquiry, my source was way more expensive.
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For anyone else who is interested in heatshrink, Master instruments has a very handy table in the accessories section listing pack sizes and the required tube size - I found it seconds after the last post...
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Brett, that box sounds great, when u build oen could u please post a pick.
i will be getting those KAN packs, for a already assembled nicad pack of 3 amp for taht price i wont give up the opporunity.
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Andrew Welch, Team Unconventional Robotics

$1.23\meter SHIT!!!!!!!!!!!!!!!!

I paid not long aggo $65 for a meter of 100mm shrink tube.

Can any one send me a link for master ins?

And brett can you send me your bank details please ASAP
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Tim Team Reaper.

LMAO, you have been shopping at RS Components, haven't you?

have a look here: http://www.master-instruments.com.au/browse/Category/Battery_Parts/Heatshrink.html

The size table is particularly helpful.
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I got myn from electrical wholesalers in baywatter.

So much for the wholesale bit!!!!!!!!!!
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Tim Team Reaper.

How do you buy stuff from them?

I cant find a shopping cart?
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Tim Team Reaper.

Brett, where are you getting the peak current specs on the batteries from? I searched through the Master Instrument and Sanyo sites looking for the peak current for the KR5000DEL cells (yes, I am power mad) with no luck. Google hasn't found the answer yet either.

I see that the internal impedance is about the same as the CP3600, but usually a bigger battery appears to have higher peak current. Any suggestions? The reason for asking is that these bad boys pack into my design more efficiently, so if their energy density and current capacity are the same or higher than a CP3600 I will get a more efficient bot.
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