docnjoj wrote:I'm waiting for my agniusm kits to arrive but in the meantime I;'ve used my No-Ox ID-A on all my plugs and outlets outdoors and by the pool. It seems to really help conductivity since when I do a before and after with a Killowatt meter the current draw seems to be about 1 amp in 10 lower. Maybe a fluke but I will swear by this stuff and use it on my 12S battery when the kit comes. Seems like good stuff.
whatever wrote:I'm not sure if it was this thread or another thread on 20ah a123s that I mentioned I had a spark on one pack when a metal object touched an aluminium tab and part of the plastic outer case. I've just finished off a 48v 20ahr a123 pack and I found the source of this spark.
The plastic outer sleeving of the cells appears to have a connection to the copper in the pack. There is a very very thin ( a few microns) clear plastic that is the first layer touching the the inner cells/tabs. If you interfer with the plastic outer covering when connecting cells together there is a very good chance of developing a short.
I'll give a bit of detail how I found the issue.
In my 48v pack, I needed to disonnect in the middle of the pack for charging ( using turnigy/hobbyking chargers) so that I have two 24v packs for charging.
The high amp switch inbetween the two 24v packs when 'off' I was still getting some voltage going through the pack, hence there was a short somewhere.
The source of the short was where I had punched a hole in the aluminium tab, since my tabs were very short, the hole I punched for a bolt went maybe 2mm across the plastic at the base of the aluminium tab.
After the bolt was done up tight it turns out the outerplastic ( having a connection to the copper somehow) was shorting with the aluminium tab.
With a very small screw driver i could see a tiny spark if I touched the aluminium tab and where the plastic outer casing had been interferred with by my hole punching. I think the aluminium within the plastic outer covering ( probably vapour deposited) being very thin layer of aluminium ( or similar metal) can carry a tiny current ( probably high resistance) so even though its a tiny current the voltage across the short could be quite high.
Any how if any one else has issue with some hard to find shorts, check the outerplastic covering in particular anywhere where its been cut, I landed up using nuetral cure silastic along any parts of the outer plastic that might be potential problem.
Because the plastic layer that insulates the aluminium outer plastic from the cells is only a few micron thick I suspect others will also see similar problems.
Cells that haven't had tabs cut shouldn't be a problem but any of the seconds that have very short tabs may have this issue.
A picture of what i've tried to describe would help I know, will try to organise one.
999zip999 wrote:o.k. charged my 24s twrice. The first run at 25amp was disapointingS. it went down fast. The second charge a little better, but. I stopped at 3.34v. They charge fast at 12a. to 3.59v then my 1420 shut off at 100%, all very even. Running bareback and all keep balance, but go flat fast. So a couple more cycles. Sorry can't down load pic's. ?
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