They should be in the next few days AFAIK Nick.

I've picked up all of the others, its just the CP3600's we are waiting on now. They were supposed to be in on the 1st, but when I picked up the RC3300's they told me the 8th for the 3600's. I'll harass them friday and see whats news
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Great minds discuss ideas. Average minds discuss events. Small minds discuss people

Thanks Brett, really no hurry at all since the next comp and Robowars is some way off yet.

While the subject of pack construction is hot (pun not intended), has anyone seen "high temperature" glue guns for sale? The stuff that is used in the original Battlepacks is way better than the standard hot melt glue and is still fairly easy to remove for repairs.

I had an idea about estimating the current capacity of copper braid, please feel free to flame me if the reasoning is off:

Everything else being equal, current capacity of a wire is linear to its cross section area. For a given lengh, the cross section and weight relation is also linear. SO, if you weigh a lengh of a known wire gauge (without insulation) and the same length of braid you will get a ratio of their weight and therefore cross section area. You don't need to work out the exact area, although it can be looked up fairly easily. Once you have the ratio, you can look up a supplier's data on the web, get the current capacity of the known wire and multiply that by the weight ratio to get an estimate for the braid.

I am just guessing here, but the capacity of the braid will probably be higher than a similar round wire due to its greater surface area and better heat dissipation. this is all rather rough but hopefully good enough for our needs as long as the rating is higher than the continuous current rating of the cells.
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Australian 2015 Featherweight champion
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IF you look inside every large electric motor (EV, B&S, Etek) you will see they all use braids between the power terminal and the brush. Why, because they obviously can take the power. You always hear of brushes blowing up, but very rare do you hear about the braids blowing.
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Nick
The material rolls are great as they are a firm fit.

I found the best way is to cut them into a bit less then a cm wide rings and sit the ring on a table and push the cell into it and that way they slide streaght on.
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Tim Team Reaper.

Braid is mainly used on motor tails and brushes because it is more flexable than a twisted wire. Brushes need to be able to move in as the brush wears down with out restricting the presure of the brush spring tensioner spring ect also brushes move a slight bit from side to side as the motor changes direction so the wire needs to be as flexible as posible to stop brekage from metal fatigue .
As for the brushes blowing up some times its the brush tail that burns off first causeing the brush to blow out as the copper rapidly expands inside the carbon as it melts or plasmerises .. most times a motors windings will melt before a brush blows out or the braid fails in older high current motors its usualy the slder that metls from the com segments that conect to the armuture windings .Gary or some into auto electrics can corect me iff i am wrong ...

quote:

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Originally posted by Nick:
While the subject of pack construction is hot (pun not intended), has anyone seen "high temperature" glue guns for sale? The stuff that is used in the original Battlepacks is way better than the standard hot melt glue and is still fairly easy to remove for repairs.

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We've significantly expanded our Tech Tips page for NiCd/NiMH battery pack users, adding quite a few new topics: http://www.camlight.com/techinfo/techtips.html
Also available from a link at the top of the page, or the Downloads page, is a PDF-format version of the Tech Tips.

Thanks!
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John Muchow, CamLight Systems
http://www.camlight.com

in an unloaded pack a self discharging vell couldnt "reverse" at all
there is no current flow that would drive the reverse reacion?
the cell would discharge to 0V and stop, with no load its like having a bunch of free cells yes?
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Mechanical engineers build weapons, civil engineers build targets

Incorrect information removed...see my later post for explanation.
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John Muchow, CamLight Systems
http://www.camlight.com

Last edited by JohnMuchow on Mon Oct 18, 2004 1:42 pm; edited 1 time in total

but how can they force the current?
there is no circuit.
unless there is a circut how/why would current flow from one cell to another?
leakage through the air would be something akin to pico amps i'd imagine
(i'm not arguing with your information i'm trying to find out "why is it so")
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Mechanical engineers build weapons, civil engineers build targets

Incorrect information removed...see my later post for explanation.

Last edited by JohnMuchow on Mon Oct 18, 2004 1:49 pm; edited 1 time in total

Incorrect information removed...see my later post for explanation.

Last edited by JohnMuchow on Mon Oct 18, 2004 1:52 pm; edited 1 time in total

you thaught yours would be fugly

+|--|+|--|+|--|+

cell is |--|, + is a connector
left hand cell has say 1V across it
right hand cell also 1V
middle cell has 0V

so the string has 2V from end to end.
on this we all agree.
the right end terminal is 2V above the left end terminal
but there is no current path, there is only half a circuit.

if you put a wire from rightmost terminal to leftmost terminal then you will have a potential difference *and* current flow. without the wire there is no return path for the current to drive the center cell into reverse.
the cells *should* just sit there with their potentials floating and only their self discharge dropping their voltage.

might have another way of explaning my position
you have one bare cell
measure its voltage
now put an ammeter on one end and the other to air, 0A flow yes?
get another bare cell with any voltage you care to have, connect the ammeter to either pole of the battery aside from capactive effects 0 current will flow.

my point is unless there is some form of circut *around* the 0v cell then the batteries on either side cant push current in either direction.
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Mechanical engineers build weapons, civil engineers build targets

Incorrect information removed...see my later post for explanation.

Last edited by JohnMuchow on Mon Oct 18, 2004 1:56 pm; edited 1 time in total

Before i solder all my cells together what do i do?

Please put it simply

Brett was saying to discharge all the cells separetly at about 100mah untill they reach was it 0.5v or 0.9v or something but no lower then 0.5?
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Tim Team Reaper.