And the seven cents I would rake in from all those views!
Videos like that would definitely get 100x the number of views I get now.
12 Likes
Sorry for off topic, but if you’re in the Bay area, I will gladly volunteer to be your camera crew for free because I love explosions
8 Likes
Thanks but New York City. In Manhattan, where they call SWAT if you start battery fires and explosions in city parks. 
11 Likes
Sorry if this is a dumb question, but how long can I have new cells just sitting at 3.7V before they’re sort of useless? Also, does building them into a pack (say a 12s4p) increase the longevity/decrease the rate at deterioration for usability?
3 Likes
Long long time, making them into a pack won’t change that unless you have a bad cell that self discharges and drain the other on the P group
Store them somewhere that doesn’t get hot
5 Likes
Yeah, every once in a while you should run them through a cycle to keep their capacity, but they can sit at storage for a long time
2 Likes
No need to use up one the limited number of cycles doing this. NiCd/NiMH chemistry cells greatly benefited from this but li-ion doesn’t have much recoverable capacity loss due to aging during storage.
Just using the pack will get you back the small amount of recoverable capacity. The rest of the lost capacity cannot be recovered by cycling though.
8 Likes
Thanks for the advice, what you’re saying makes sense. I haven’t had a refresher for liion
1 Like
Do you have examples of cells you put into storage and how much of their cap has been rendered lost from storage?
1 Like
I almost never measure the lost capacity since, for me, what is important is the loss in run time at the power levels I typically use. Capacity loss at a nominal discharge current level won’t show the effect of any increase in internal resistance as well as a discharge at typical power levels would do.
But I recently tested the capacity loss for three Molicel P26A’s, dated mid-2018, that had been sitting at room temperature since I received them in late 2018. They were never charged.
All three cells were at about 3.35V and had lost less than 100mAh when compared to the average capacity of four March 2020-dated P26A cells I used for comparison.
When discharged at 20A the performance of the 2018 cells was essentially identical to the 2020 cells down to about 3.10V. This indicates that only a minimal change in internal resistance occurred. Below about 3.10V the lower capacity of the older cells caused their voltage to drop faster and resulted in less delivered Wh/mAh.
These results only hint that Molicel P26A’s can handle room temp storage well. We can’t say all cells will do this well. Especially salvaged cells or those from the smaller China factories, both of which typically have higher self-discharge rates and accelerated aging versus new cells from the big manufacturers.
20 Likes
HELL YEah thank you dude!!
1 Like
Where have you been all of my esk8 life…
15 Likes
Literally–im loving this so much
5 Likes
Yeah this of course presumes there were no gains on the process level at the factory with these cells no?.. The 2018 cells could have just sucked a little more to begin with right? 
FWIW I’ve revived a lot of old salvaged packs, many reading zero volts and being nearly 10 years old, although mostly medical packs with really low cycle lives, and I’ve seen plenty of empirical evidence that you will see some capacity recovery after a few full cycles. The lithium ions seem to show some movement atrophy after being in a state for so long, I’m guessing there’s some complex chemistries that can take place internally under these conditions, but it’s amazing how well these can recover in many cases.
Although I agree that it would do no good to be cycling packs in storage to avoid losing capacity, this simply won’t apply to lithium. EDIT: In proper storage. It definitely would have been good if many of the packs I’ve revived weren’t left in storage depleted or randomly fucked up states lol.
Glad to see you here with us Mooch, didn’t realize someone talked you into joining us!
1 Like
why didn’t I get a card when I bought 120 of those?!?
That’s a fair assumption. 
5 Likes
4 Likes
That’s an interesting idea. Would it be possible to make a structural battery skateboard? Take ~36 or 48 of these new batteries, epoxy them together in the shape of the deck, weld the electrical connections on, test them, then epoxy on some Baja-like suspension.
3 Likes
Not really, they are doing that with careful engineering so that the cells are only subject to the loads they were designed in the first place, and probably the case is made with that intent
Don’t glue cells to a board as a mean to stiffen a deck
2 Likes
Yeah I agree… I mean “possible” ? Yes, anything is possible, I’m sure Tesla’s engineers could handle it for us with enough relevant understanding of the types of loads and impacts generally expected of esk8 scenarios, and leveraged specifically against one type of esk8 and with a board they designed in conjunction…
Doubt they’re gonna do that for us though… 
Cool idea though, could happen if someone wanted it bad enough, but I don’t think the ROI is likely to be there myself.
I’m just hoping whatever adhesives (or etc.) they use for these packs is something we’ll be able to dissolve easily without damaging the cells. I personally expect this will be the case, since they also mentioned a push to start directly recycling packs from their cars. However, this makes me worry about it becoming more difficult to acquire surplus cells from their cars long term…
Short term though, I guarantee we’ll see some of these new cells in the wild sooner than many of you expect. Word is they’re already in test vehicles, Tesla is known for bringing new configs and products to market before reaching full economies of scale, so all we gotta do is wait for someone to wreck one lol, and the guys out in Cali will be ripping them apart.
Bigclive had a good video yesterday about what he thinks the new cell design is utilizing to go tab-less btw. I bet it’s a little more specific, but I think he’s definitely on the right track.
3 Likes