astroboycp

Wow that's one huge batt. Any video of the run?

simplecj

Yes, I posted a link several posts back... look for it..

astroboycp

Ok great will check it out.

simplecj

Here's an updated picture of my welder... hooked up more capacitors for a total of 21F (probably more like 10 cause the Audio industry likes to exaggerate).

I also have a 12v 25A Pyramid Lab Power Supply hooked up to power it.

Getting very good welds on the NEG terminal, but the POS terminal is still giving me problems. Seems OK if I make sure and put down as many welds as I can.

ALSO, I've determined that BOTH ends are nickel plated, but the POS terminal has a small thin disc stuck to it that is nickel coated. This thin disk sitting on top of a solid aluminum case is what is making the welds so weak. I have a bunch of cells where that disc was too damaged to spot weld to, so I removed it completely to expose the solid aluminum bottom. I've ordered a 260W soldering gun and a few different soldering fluxs and solder to attempt to connect them that way.

Main thing is that you're not supposed to heat the cell to much and you shouldn't solder over the NEG terminals center which is the vent for the cell. Since I can weld the NEG terminal fine, I'm ok there, now just need to get a really hot gun that will solder on the aluminum. My 140W gun just doesn't cut it....

everydayflyer

hat little blue dot in the center of the neg. terminal is not a vent. That is where the cell is sealed after assembly using a UV actived sealant.

You do not need a 260 watt soldering gun. You should not be using a soldering gun at all. You need an soldering iron with a large tip (thermal mass). A 40 watt iron with a good hammer head tip works OK . A 100 watt iron with a large chisel tip works great.

Clean the ends (burnish with 400 grit sandpaper) ,apply rosin soldering paste very lightly and use 63/37 solder.


To solder to the aluinum can use Zinc Aluinum flux from Cheap battery Packs .Com or aluinum soldering paste such as Harris from a welding supply source..


Charles

simplecj

It is a vent in case of failure, the weak point for pressure to escape without exploding, you do not want to seal it closed with solder!

I got the Zinc solder and flux from CheapBatteryPacks.com, but it just won't make a solid connection. Also, the zinc solder refuses to bond to my nickelplated battery strips. Tried to get a dob of zinc on the battery to join with my lead solder on the tab, but it refused... I think I need a hotter gun. Why can't I use a 260W gun with a big tip on it? I made a bigger tip out of copper grounding wire, but it almost smoked my 140W gun... Should work good with the 260W gun and has more mass than the standard tip that comes with the gun.

I've got the 60/40 rosin solder for soldering all the wires, but that wont stick to aluminum.

I just ordered some chemical solder flux from Allied Electronics that says it's good for soldering to aluminum with either lead or zinc solder... hopefully be able to try it out in a few days.

You got a link for the kind of soldering iron you're talking about? Only one's I've seen around here are those little piece of junk ones that take FOREVER to heat up...

I also was thinking about a tip that would fit my propane torch. I swear I've seen something like that, but I can't find one.

simplecj

SUCCESS!!!

I just got my new 260W solder gun. With this gun I was able to get good adherence to the aluminum can. Then I have to lay down some lead solder on top of that, then place a tinned piece of battery tab over and with the gun really hot push it together.

I have to put lead solder on top of the zinc first or else the tinned tab will not join. It sticks up a bit from the small pile of solder, but appears to be a good solid connection and the battery itself doesn't get overly heated.

everydayflyer

That dot is not the safety vent, believe me or not. I have soldered many cells / packs with equipment I described. I have never had any problems what so ever.

Good luck.
Charles

simplecj

Well, I did lots of research on these cells and I swear I remember reading that that dot is a safety vent and should not be covered... I could be wrong, but I'm pretty sure I read that somewhere...

It's only an actual vent in the case where a cell gets overheated or for some reason the cell becomes pressurized internally. You can cover it and be ok, but that doesn't mean it's not a safety vent.

[email protected]

I, too, have built an electric motorcycle, but a trials bike, not a world speed record or drag bike. The initial version used 4 12v small lead acid batteries. Then I switched to A123s, starting at 36, then 48, and now 72 volt packs (66v essentially). I build the packs 20x5 so I get 66v, 11ah pack. The mileage I get is highly dependent on terrain and what I am doing. Hill climbs take lots of power. Though I haven't updated my website in quite a while, you can check it out at www.ecotrials.com.

Trials riding is like off road obstacle course riding, tons of fun. And this project has been lots of fun. In 2007 I rode Saturday events on the electric, and Sunday events on the gasoline version. I ended up 2nd in my class on the electric. Last year I only rode the electric (both days) and ended up winning my classs on Saturday, and placing 2nd in my class on Sunday. I am still working out final mounting of the packs, and look forward to another fun year in 2009.

The reason I am posting is I just redesigned the pack. I was using MEC Solderless Power Tubes, but have switched to my own design using polycarbonate tubes.
I decided I wanted something a little more robust for my application, although I have to say I didn't have any failures with the packs I built using the power tubes.

So I have a bunch of power tubes that I am willing to sell. A few have been used, a few have not. I am asking $10 each for the 2x5 power tubes (MEC sells them for just under $16) and would be willing to make a deal on a volume purchase. I think I bought around 50 of them.

If anyone is interested, please drop me an email [email protected].

everydayflyer

I am sure you did read that. I have read it also but fact is it is wrong. I hate to sound like a know it all but few know more about these cells than I do.

http://www.slkelectronics.com/DeWalt/packs.htm

Snip Charles

simplecj

Very interesting. Thanks for setting the record straight!