A123 20AHr Pouch Cell Battery Build & Info Thread

[steelmesh]

Correct, but the point I was making too is how does this PSI rating relate to a static environment vs the hostile vibration and shock environment of riding by bicycle? Automobiles are Full Suspension and don't transmit the vibrations and shocks that bicycles do transmit over a larger variety of terrains.

No test specs are more rigorous than automotive specs. Your bike application will not exceed what is tested for in a car, suspension or not. The mechanical shock testing these are subjected to is very intense. You will not have a greater pressure requirement due to the bike environment, I am quite confident of that.

I've been to an automotive proving ground before, they beat the piss out of the cars so bad that the human drivers can get internal bleeding and the robots they use to replace them can't hack it either. This was almost a decade ago though...but I would think the test procedures are similar; beat the shit out of the car and see what fails.

 

[xenodius]

ejonesss, the problem with that is you would be applying compression to the entire pouch and not just the z-axis.

 

[ejonesss]

i would think that would be good because then the pouch could not expand out to the top bottom and sides.

if you fill a balloon with air and put it in a pressure chamber and pressurize it then the balloon would appear to get smaller.

ejonesss, the problem with that is you would be applying compression to the entire pouch and not just the z-axis.

 

[wb9k]

As easily as air is compressed, I would not think this a suitable method. I would expect a swelling battery to just push back hard enough to displace the air just a bit more. You might be able to make it work with very high air pressure, but that will have problems of its own. Our packs have Gore vents in them to keep internal pressure within a few psi of ambient. If you don't do that, your enclosure will swell and shrink with temperature (as will your internal air pressure.)

 

[agniusm]

Pressurised container? Nitrogen gas? You have to have some imagination to come up with such ideas. The question is how you gonna make it happen? To me it sounds like total absurd. I dont know why people want to reinvent the wheel? A123 shows you how to do it plane and simple. Make pressure plates and strap it. The only thing needed is to figure out method of measuring compression force.
I have asked here but no one who received free samples of oem pressure plates have not posted single line of measurements. This could be replicated and tested but most go on asking questions that were ansvered, posting ideas which are "Alice in wonderland" theme. Maybe I woke up on the wrong foot or the solution to the issue isn't moving anywhere..

 

[wb9k]

A sealed pack filled with inert gas would be a big deal, indeed. The idea isn't that far out though. Big contactors for automotive use are sealed and have either nitrogen (Tyco) or hydrogen (Panasonic) in the contact chamber along with magnets just outside the chamber, all for the purpose of quenching arcs and limiting oxidation of contacts. Of course, I wouldn't expect anyone to be able to build something like that in their garage.

Back on topic, I think the bands in your picture are a little too far apart after taking another look. I can get dimensions for you next week if nobody else chimes in. I don't consider those dimensions to be proprietary in any meaningful way.

 

[ejonesss]

i know nitrogen is used to chase the air and moisture out of refrigeration systems prior to charging them and i know some gasses are used to displace the air needed to support fire should a cell vent any gas or at least throw off the fuel to air mix enough to make it not burn.

mythbusters tested natural gas used in appliances and determined that a certain air to gas ratio is need to support an explosion/fire when they tested both can a fireball produce enough force to blow manhole covers off the underground pipes and can firing a gun into a carton of milk blunt the flash from the gun to prevent blowing up the house from the movie kiss the girls

so i figure maybe some inerting gas in the battery pack enclosure may do the same thing.

this is just a theory i came up with

i am just trying to get all the info together for when it is time to replace/upgrade the battery i have now using these newer cells.

 

[ejonesss]

i have seen pressurized boxes on the telephone poles that have a warning saying to remove the screws in a certain order to release the pressure safely.

i believe they are white and have 6 or 8 bolts to hold them together

A sealed pack filled with inert gas would be a big deal, indeed. The idea isn't that far out though. Big contactors for automotive use are sealed and have either nitrogen (Tyco) or hydrogen (Panasonic) in the contact chamber along with magnets just outside the chamber, all for the purpose of quenching arcs and limiting oxidation of contacts. Of course, I wouldn't expect anyone to be able to build something like that in their garage.

Back on topic, I think the bands in your picture are a little too far apart after taking another look. I can get dimensions for you next week if nobody else chimes in. I don't consider those dimensions to be proprietary in any meaningful way.

 

[megacycle]

Could be overkill but thin film FSR's or piezoresistive film or pads, might be used for accurate pressure sensing, if they can be sourced.

 

[deVries]

i have seen pressurized boxes on the telephone poles that have a warning saying to remove the screws in a certain order to release the pressure safely.

What voltage and Ah battery are you planning on building? For what application?

Thanks.

 

[agniusm]

Could be overkill but thin film FSR's or piezoresistive film or pads, might be used for accurate pressure sensing, if they can be sourced.

Most I found was 100kg tops.

 

[IamIan]

Could be overkill but thin film FSR's or piezoresistive film or pads, might be used for accurate pressure sensing, if they can be sourced.

An alternative ... PVDF like Kynar is Piezoelectric ... Kynar Thin Films are fairly easy to source down to 0.001" thick

 

[deVries]

WB9K, is there a way to "decode" the manufacturing date by the markings printed on these cells? Anyone know how to do this?

Thanks.

 

[wb9k]

THere is a way, but I'm reluctant to share that here without some kind of clearance. I'll try to find out if I can share. Figuring out the year of manufacture should be relatively easy if you look and think a bit. Getting beyond that would likely require a little guidance.

 

[ejonesss]

probably a replacement or upgrade to the 48v 20 a battery i have now it is getting close to 5 years old.

i bought the cells way back when andy heckler (remember him he is the one with the hunchback of noter dame like avatar) bought some 40138 cells from taiwan i think in 2008 to 2009 range and i am not sure what the life span on them are


electric bike

i have seen pressurized boxes on the telephone poles that have a warning saying to remove the screws in a certain order to release the pressure safely.

What voltage and Ah battery are you planning on building? For what application?

Thanks.

 

[ejonesss]

regarding the pressure do you just have to squeeze the battery enough to prevent the cells from puffing?

sort of like what women would wear to make their fat belly fit into normal person's clothing or give the hourglass look?

 

[wb9k]

regarding the pressure do you just have to squeeze the battery enough to prevent the cells from puffing?

sort of like what women would wear to make their fat belly fit into normal person's clothing or give the hourglass look?

See the "thoughts on pressure" thread I started a few weeks ago.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=52244

 

[ejonesss]

would the specs be in the white paper on the site?

and how easy is it to download the white paper?

also couldnt someone just buy one of them

https://www.technologyreview.com/sites/default/files/legacy/auto_x600.jpg

and reverse engineer it for example put a force meter on the bands as they cut them and see how much force the is as it is let off.

regarding the pressure do you just have to squeeze the battery enough to prevent the cells from puffing?

sort of like what women would wear to make their fat belly fit into normal person's clothing or give the hourglass look?

See the "thoughts on pressure" thread I started a few weeks ago.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=52244

 

[deVries]

What voltage and Ah battery are you planning on building? For what application?

electric bike 48v 20Ah

I would suggest to continue to follow Doctorbass and his method to package these cells. Your ebike application is not putting much demand on these cells vs their intended car applications usage. Definitely use the principle of KISS.

 

[arkmundi]

FYI: A123 AMP20 Cells, new, legit, factory direct!

 

[ejonesss]

back when i started into electric bike the recommended battery was the eonyx battery but at $2000+ for a 48 volt 20 amp battery i built my own equiv.

What voltage and Ah battery are you planning on building? For what application?

electric bike 48v 20Ah

I would suggest to continue to follow Doctorbass and his method to package these cells. Your ebike application is not putting much demand on these cells vs their intended car applications usage. Definitely use the principle of KISS.

 

[oatnet]

What voltage and Ah battery are you planning on building? For what application?

electric bike 48v 20Ah

I would suggest to continue to follow Doctorbass and his method to package these cells. Your ebike application is not putting much demand on these cells vs their intended car applications usage. Definitely use the principle of KISS.

Devries where did you end up buying your a123 20ah pouch cells from?

 

[deVries]

Devries where did you end up buying your a123 20ah pouch cells from?

Sorry to say I never got any, ever, though I would like to get 32 confirmed good cells for Rachel's two trikes. (She is disabled, and I'm trying to help her w/battery, etc.)

 

[ejonesss]

anyone know the c rating on these cells?

 

[agniusm]

I'd say 10C. Something higher and you need cooling. I discharged them at ~210A and temps on the cells went to ~55C