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[mryan]

Has there been any attempt to rebuild or custom design batteries for the FX or SR? For the FX, it should be possible if the cells fit and the old battery board can be reused.

[Specter]

if you are good with that kind of thing the boards should be fine but check them, many times they use cheaper components because its not designed to last a long long time, look for burnt coils, puffy caps, darkening, stuff that may signal problem parts.  depending on how the batteries are secured, make suee that is intact too.   i just got done rebuilding a 48v 300 ah battery for storage, yah its a bit of work, but in your case you are playing with close to 100 volts on those, that'll flash burn you, arc blast and the voltage alone can kill you so always assume it is trying to@@

aaron

[MrBlc]

Like Specter said, i think the reason why you won't get a lot of response on this topic is that it is quite dangerous if you don't know what you're doing. The existing packs are potted, so repairing them isn't really an option. recreating with newer tech is the only point where it's possible to do something, but the requirements to get there is quite high.
I am about to embark on a project close to what Specter did, but my battery will have a system voltage of 495 volts. the problem of arcing and killing you increase quite a lot at this level, but then again, i AM certified.
That said, trying to build a pack that will be in movement and able to handle this level of vibration and shock? eh.. it's not the first battery build i would try to do.. :/

[T.S. Zarathustra]

The first gen Zeros had some creative battery rebuilds. I'm not aware of any for the newer bikes. The issue is that they are usually potted so rebuild (as in each cell being tested and replaced if low on specs) is difficult. Full rebuild, that I have personally looked into, is less difficult. But you need to know what you are doing. There is a lot of power potential in those cell. If that power is released in uncontrolled manner it can cause damage or fire.

[thebes]

Has there been any attempt to rebuild or custom design batteries for the FX or SR? For the FX, it should be possible if the cells fit and the old battery board can be reused.

Bit of a fair warning, if you dont have previous experience building large packs and knowhow when it comes to evs, please disregard and dont follow any of this advice, I really wouldnt recommend you do any of this. With that said, if you pull out the farasis pouches out of a brick, youre left with the shell in which you can fairly easily fit ~168 21700s. If you are using the new tabless 5ah cylindricals that have been hitting the market recently, that should yield ~3.1kwhs or right around the same capacity as a 3.6 brick. Do that twice and you have an fx pack, do it four times and you have a monolith. if you keep the original form factor and pinout of the brick you can reuse all the electronics and not have to come up with some hacky solution.

I did something similar for my 2009 x project and the same principle applies to the newer bricks. I have a few dead bricks, one of which Ive already pulled the pouches from leaving me with the case, I intend to build the aforementioned 28s6p pack out of molicel p42as and use it as a range extender for the X thatll mount to a rear rack. Im aware of just one other person who has done something similar and that is Rio Cole. He built a replacement pack for his 2013 mx out of (coincidently also) p42as. Ill see if I can dig up some pictures of his pack.

[Specter]

one thing i do, while it is NOT approved gear for this tyoe of work, i wear very thick latex gloves, i want to say they are 7mm or something, i use them for beekeeping because its very hard for the little bitches to get thru if you piss them off to that point, but when working on big battery packs, having them on gives you the dexterity you need, but most importantly a bit of protection, some battery packs they are in layers and folded over on each other, with nickel ribbon welding to connect the sections. when you re unfolding these to work on them, having the rubber gloves on protect you from accidental brushes against adjacent packs / runs/ components at (other side potential) i call it.  can help you from getting a nasty shock but you must never let it ...let you become complacent.  if you feel yourself brushing, you need to stop and remind yourself, good thing you got these gloves on, that'd been your ass touching that shit.  re assess why you errored and correct the procedure.  flipping 20 lb trays of batteries back to back to back, plenty of room for oopsies.  now when you re dealing with packs like an energica or cars or stuff that can get into the 100s of volts, that touch can be lethal, especially if you are not working one handed.  and shorting something... yah that green plasma ball will consume everything.  even if you do manage to break it, get that pack outside asap, the damage has been done internally and don't be surprised if a pack sympathetically touches off a few minutes later and takes the whole subsection with it.  my point being, this is very dangerous even when you do know what you are doing, please be careful.

aaron

[MrBlc]

Considering lithium fires are self-fuelled, using PPE is underrated.. i'd recommend adding a screen to your face as well.
i have seen what electrical shorts and subsequent fires can do to skin. it's not pleasant..

[T.S. Zarathustra]

If you use 21700, like suggested by thebes, make sure you get high current cells. Those are not readily available in 5 Ah in 21700 size. You'd be safer with 4-4,5 Ah.
While 5 Ah cells are available in 21700 size, they are usually limited to 5-10 Amp current draw. 4-4,5 Ah cells are usually good for 10-20 amps. Then you have high power cells, 25-40 amps. These usually top out at 4 Ah in 21700 size.

[thebes]

If you use 21700, like suggested by thebes, make sure you get high current cells. Those are not readily available in 5 Ah in 21700 size. You'd be safer with 4-4,5 Ah.
While 5 Ah cells are available in 21700 size, they are usually limited to 5-10 Amp current draw. 4-4,5 Ah cells are usually good for 10-20 amps. Then you have high power cells, 25-40 amps. These usually top out at 4 Ah in 21700 size.

There has actually been a bit of a renaissance in the past year or two with tabless cells that enable a very low ir and higher discharge than youd get with the more conventional 'power' cells. Take a look at (to name a few) the reliance rs50, tenpower 50xg, and the eve pl50 (though this cell has some issues with some particular batches its fairly solid overall). Theres also the molicel p50b which isnt tabless but it and all the afformentioned cells do at least 10c discharge and 2c charge and have been independently verified by multiple parties. The older power cells like the p42a, p45b, samsung 40t etc are pretty outdated when compared to tabless cells (though they can be had for very cheap, thats mainly why Im using p42as for my projects!).

[T.S. Zarathustra]

There has actually been a bit of a renaissance in the past year or two with tabless cells that enable a very low ir and higher discharge than youd get with the more conventional 'power' cells. Take a look at (to name a few) the reliance rs50, tenpower 50xg, and the eve pl50 (though this cell has some issues with some particular batches its fairly solid overall). Theres also the molicel p50b which isnt tabless but it and all the afformentioned cells do at least 10c discharge and 2c charge. The older power cells like the p42a, p45b, samsung 40t etc are pretty outdated when compared to tabless cells (though they can be had for very cheap, thats mainly why Im using p42as for my projects!).

Technoligia is always improving. Today's state of the art is tomorrows outdated technology.
It's important to check all the parameters/specifications, buy cells from a reputable brand, from a respectable seller, and do your basic homework. It's not just volts and amperes. It's also chemistry, "resistance", cooling, energy density (Wh/kg), and so on and so forth (and C). There was a video circulating recently where results of testing of hundreds of cells from various manufacturers was revealed, including x-rays of the cells. Alarmingly high portion did poorly. Some were dangerously bad.
As you point out, the higher current cells tend to be more expensive. An inexperienced person asking for an advise in an internet forum and only looks at Ah might end up with more easily available but less suitable cells. If not counterfeit cells that fail within days.

Personally, if I was discarding all the cells in my Zeros battery, and rebuilding from scrap, I'd use large pouch cells. Each cell about 20-40 Ah and around 3,7 V. That reduces connections (work, materials) and greatly simplifies build. Last time I checked I could get all the materials (reusing the BMS and housing) for 13 kWh battery for less than two grand.

[Specter]

t.s.  you have to take your bms into account too.  rebuilding that too or using old one?  if using old, how is it going to react to having empty stations?
as you said, many nuances one has to take into consideration, and no two batteries is ever going to be the same,  the moment you think you figured out a 'good' way to do something, well... ol mr.murphy is going to have to have a word with you.

thats one thing for sure you have to be a person who has patience because these projects can sure test it, but a lot of fun and of course very rewarding when you can take a pile of basically junk at this point, and turn it useful and into a product, and save yourself thousands of dollars in the process.

aaron