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battery group buy
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Valen
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Joined: 07 Jul 2004
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battery group buy

it seems that one of the larger problems we as robot builders face is batterys
they are probbly the largest single unit cost aside from IBC and radio.

so what i am thinking is some sort of group buy of individual cells.
if we can get togther a large enough order we can probbly get some fairly decent discounts.

I am thinking something like the 2.2ah nicads (or the 3.3 if they can be had for the right price) or the 3.3 nimh's

it seems that the Sub-C size is the most acceptablle and widley used though i have seen some very funky Sub-D sized cells

looking for expressions of interest, i will buy X at $Y kinda things, any information you have on possible suppliers and anything else relating to it post that here too,

Post Thu Aug 26, 2004 8:50 pm 
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andrew



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Yeah sure, well when i get my charger stuff roagnised (getting power supply from jeff ferrara) and figuring out whether i am doing something wrong with teh charger and how to condition the batteries and go aboutr everything (long chats with yourself and jeff, nick on saturday) then ill get some if u can help me solder a pack up. Something like 2 2-3 amp nicad packs (ghettopacks Smile ) would be sweet as.
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Post Thu Aug 26, 2004 10:12 pm 
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Knightrous
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I wouldn't mind getting around 20 x Sanyo 3000mAh NICD. I'm prepared to pay $4 a Cell. Once we have the cells who here is experinced enough to put them together with out damaging the cells?
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Post Fri Aug 27, 2004 11:00 am 
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DumHed
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I've dealt a fair bit with Master Instruments, who build battery packs using mainly Sanyo cells.
I actually sent them a question a short while back about doing a semi custom "Robot pack".

I haven't heard back, but I might find some more info and chase it up.

Assuming that we were getting full packs made up, what configuration suits most people?
If I can send them a design that'll work for the majority of people, and some specs on the cell capacity to use I can get a quote pretty quickly.
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Post Fri Aug 27, 2004 12:06 pm 
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ffej
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quote:
Originally posted by teamvertex:
I wouldn't mind getting around 20 x Sanyo 3000mAh NICD. I'm prepared to pay $4 a Cell. Once we have the cells who here is experinced enough to put them together with out damaging the cells?


Good luck . . .

The cheapest price I could get out of the importers, Master Instruments, was $7.80/cell for the 3600's and that was the over 100 cell price.
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Post Fri Aug 27, 2004 1:57 pm 
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Nick
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$7.80 is relatively good - much better than the $8.90-ish from Robot Marketplace (before postage too). We are talking about blue-ribbon product here, not XU1 drill batteries - expect to pay accordingly.

I might be interested in some cells if we can also get the propper connector bars - using just the spot-welded tags makes for delicate packs.
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Post Fri Aug 27, 2004 3:18 pm 
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Valen
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ok did some talking to master instruments
the scr cells are the ones you find in the bosh type drills
apparently slightly less current but better cycle life etc

code order cost per cell
nimh
rc3000h 500 $8.25
rc3300hv 500 $6.79
rc3600hv 500 $8.20

nicad
rc2400 500 $5.56
cp2400scr 500 4.02
cp2400scr 1000 3.86

nicad
C-size
cp3600cr 500 6.59

40c per cell for high current tags

assembled into packs
12cell pack $10 + cells

Post Fri Aug 27, 2004 3:31 pm 
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timmeh
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At jaycar you can get 25+ high qulity c size 2.7amp nihm cells for $6.95 each
Or 25+ 4.5amp c size nihm cells for $10.35

You might be able to get them cheaper if you buy a large order and they are better qulity then the ones in drills
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Post Fri Aug 27, 2004 5:26 pm 
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Valen
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http://www.powerstream.com/NiB.htm

some good prices on batteries in here
subC nicad 2AH $1.44
subC nimh 3AH $3.21
halfD nicad 2.5AH $2.33

MOQ of $200

Post Wed Sep 01, 2004 11:06 am 
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Spockie-Tech
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I'd like to buy somewhere between 60-120 cells..

but from what I can see on the datasheets from those pages, it looks like they have an internal resistance more than twice as high as the sanyo cells, which would probably translate into about half the available peak and sustained currents.. if thats so, I'd rather go for the sanyo cells.
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Post Wed Sep 01, 2004 12:05 pm 
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Valen
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where is the info in the datasheet about the internal resistance of the sanyo's?
i can only see their impedance at 1khz?

those half D's are speced to 98A peak

Post Wed Sep 01, 2004 12:09 pm 
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timmeh
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valen

I wonder what the internal resistance is "they sound two good to be true Confused
why dont they have charts on em? i wonder how good a quality they are.




BATTLE PACKS Cant we still get em from http://www.battlepack.com/ if the R.M.P stops selling them
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Post Wed Sep 01, 2004 7:18 pm 
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Spockie-Tech
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Sorry, I meant impedance (which is only frequency sensitive resistance anyway).

AFAIK, most batteries spec the 1Khz impedance, since its usually directly related to the DC resistance and its hard to measure the DC resistance of a cell that will put out 100's of amps if you short it..

The sanyo RC3600's spec'd here
http://www.master-instruments.com.au/Data%20Sheets/Hobby/Sanyo%20RC-3600HV.pdf
show an impedance of <4 milliohms at 1Khz

The Powerstream GH2500 spec'd here (the closest ones they list data for)
http://www.powerstream.com/p/GH-Sc2500P.pdf
show an impedance of <10 milliohms at 1Khz (more than twice as high).

I dont think a 1/2D's peak currents can be fairly compared to a sub-C's peak current.

Also for comparison, the price of $3.21 is in US$ ($4.60 Aus), and you have to pay shipping from china with a delivery time of 3-6 weeks, plus GST (and duty if applicable) when it gets here, plus minimum order of $200 (~60 cells) for a 3000mAh cell.

The Master Instruments quote you got of $7.80 (for 100) for the lower impedance sanyo cells is is Australian $ for a 3600 mAh cell (600mAh more), is local here in Australia (low shipping) and is available now ex-stock (not sure about GST though).

Put that way, the Sanyo's dont seem so pricey. I'm not being pedantic (I hope Wink just making sure we comapre apples with apples, not just price)
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Post Wed Sep 01, 2004 10:04 pm 
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timmeh
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The desighn your own pack battle packs on the R.M.P only go up to 12v now that sucks
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Post Mon Sep 06, 2004 10:10 pm 
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Nick
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Wow, Jim has really had to cut back on the custom batteries! They are all welded tab construction and far fewer cell types are available. It looks like the packs are coming from an RC car accessory place.

Count me in for at least 20 Sanyo CP3600 cells.
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Post Mon Sep 06, 2004 11:10 pm 
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