Farasis 58 and 60ah 20s1p build questions

[Longshot]

Hello, im thinking about replacing my EIG battery pack with these new Farasis cells. Does anyone have a 3d print file for the frames/holders? Is there anything i need to know before I pull the trigger? Unfortunately, my EIG battery in my NYX committed suicide. I always had 1 cell that wouldnt balance. Cedrick always said dont worry but that cell shorted out and then killed the other cells ovwr the winter. The MXUS they modded for me lasted 3 days before the phases shorted out. Thanks for your response!

 

[amberwolf]

While I don't have the info you need, I am curious if you will be reusing the busbars/interconnects from your EIG cells.

(I have EIG cells here I need to get or make busbars for to use in packs for various projects).


I'm also curious about how the failed cell killed the other ones (so I can avoid this situation). It should only be possible for it to kill ones paralleled with it, unless it has a BMS that balances by capacity-redistribution and doesn't have a safety shutdown limit for this process....

 

[Longshot]

Im not sure, maybe it was just the BMS. I will probably replace the EIG cells with Farasis. I attemped to revive some dead EIG cells but while the voltage goes up, they arent storing much power at all.
Im asking about the frames because Im considering the 60ah cells which are 10mm thick. The EIG is about 7mm thick. The 10mm cells can discharge at a much faster rate. The farasis pouch tabs are soldered to he busbar which might actually be helpful in fitting the larger cells into my battery space.
I could cut my own busbars but I dont want to CAD the frames. But Ill print the frames
Do you know if the EIG/Farasis chemistry requires a metal containment to keep the pouches from expanding? I read that somewhere.

 

[amberwolf]

I attemped to revive some dead EIG cells but while the voltage goes up, they arent storing much power at all.

They're pretty tolerant, but when they're killed dead (like 0v dead) they're like any other cell-a potential fire hazard from possible internal damage you can't even know about until something happens because of it.

I revived a set of four(?) I'd been using as a 12v lighting pack way back on CrazyBike2 that got drained to dead dead (someone turned my lights on and left them, playing with the bike while I was at work), by very slowly bringing them up from 0v to something within the normal range, but they were never the same; couldn't handle much of a load, etc. Still worked ok as a lighting pack for some long time, but retired at some point.

Im asking about the frames because Im considering the 60ah cells which are 10mm thick. The EIG is about 7mm thick.
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I could cut my own busbars but I dont want to CAD the frames. But Ill print the frames

I poked around a little bit but didnt' see any projects for Farasis cell holders of any type...but I bet you could adapt the design of the EIG holders to these, measuring those, adapting the measurements to fit the new cells, then making a 3d-printable model for them. If you don't want to do the CAD, you might check with LewTwo here on ES; he's good at CAD if you have data for him to go on.

The farasis pouch tabs are soldered to he busbar which might actually be helpful in fitting the larger cells into my battery space.

Something to consider is that solder may be a worse conductor than a good clamped or crimped connection, if you need really high current thru them (increases voltage drop and wasted power as heat inside the pack). Depends on the specific connection methods in each case.

Do you know if the EIG/Farasis chemistry requires a metal containment to keep the pouches from expanding?

In general, all the pouches (and prismatics) need some form of compression on the largest cell faces, though to what degree varies per model. The only cell with any data on it here on ES I know of is the A123 20Ah pouch cells from ages ago, but I can't recall the specifics--the thread *was* recently brought up, though, so should be in the active topics for the last couple of weeks.

My EIGs don't usually see more than 1 or 2C, even peak, vs the 5C they're capable of, and they just have the standard EIG plastic carriers with the aluminum between-cell covers, and the plastic endcap cover, so there is not really any compression, but no misbehavior from any of the cells yet. If I were running them harder I might want to setup compression just in case.

The only cell I have had that puffed up at all was one that actually reversed during a (different) lighting pack failure from leaving my headlight on accidentally after I got home. (the others were ok); IIRC it was the same pack I'd revived before (been a while, so not certain).

 

[Longshot]

Theres so many different pouches available, any chance you can narrow down the best pouches that will fit the EIG holders? Im running an adaptto Max-E into QS205. I want battery amps and 20S

 

[amberwolf]

I wish I could, but I don't know which would direclty fit them (though there probably are some).

Myself, I'd be more inclined to find a well-characterized cell that is available in well-matched sets (like the EIGs used to be). When my EIGs eventually become unuseful for my EV applications I will probably get some of the various used EV modules available from places like Batteryhookup, and just "rewire" them for the voltage/capacity required on whatever my present EV system is at the time. Which ones I'd get will depend on what they have available, but they're only likely to get better....