Though I don't live in NYC, nor New York State, they often are trend-setters for lots of examples. One trend that is not positive--the occurrences of e-bike / lithium battery fires. The media is all along for the ride it seems. It is easy for them to just repeat police and fire reports (while) not going into great details (that news bureaus are increasingly understaffed is another matter). What we can gather it is near inevitably the case that it's operator errors--wrong charger, an exhausted delivery person leaving the charger on overnight, or cheap batteries / refurbished batteries + combos of those examples listed. There is currently a push to regulate, or outright restrict batteries being put forward by the NYC City Council.
Myself? I purchase only high quality batteries, such as EM3EV or Luna cycles. But I live in an apartment building, with many others in the building. I can imagine that at some point there might be an event with someone else, in another building nearby or such and in swoop the regulators. I would love it, actually if there was a standardized and logical regulation to the ebike battery market. At the same time I don't want to be punished for bad actors.
Hence, the reason for the title LiFePo4 batteries. These are the older style lithium batteries that chemically rely on iron, different from the newest generations of lithium batteries. (And I'm not completely familiar with the chemistry involved) The newer ones are lighter, more energy dense and far more popular than the older LiFePo4 batteries--but could not be considered as safe as LiFePo4. I think both are great. But I'm torn. I am shopping for a new battery, the choices for LiFePo are few and far between. I realize I will have a great weight penalty should I choose a LiFePo4 battery--but whatever I'm not a speed demon it's for my cargo bike that can carry 450 pounds + on.
I am just looking for general advice from the JNO community on this subject--any of you who have an ear to the ground about the points I presented. Thanks.
I actually came on here looking for anything related to shipping state of charge and whether or not they were actually being cycled to <30 SoC or if some other feature of the pack was allowing that rule to be negated (i.e. not air shipped).
LiFePO4 are generally harder to 'light off' largely due to the lower energy density / volatility related to the Fe content. That doesn't make it 'safer' exactly; but you'd probably have a bit more time from thermal venting to thermal runaway.
How the cell is built into the pack along with the pack protection electronics is just (or more) important than the cell build quality (within reason). A good cell has at least 2 internal protections: a thermal separator and a thermal vent. A good pack has at least 5 protections: thermal (sometimes in multiple locations), overcurrent, short circuit (both charge and discharge), overvoltage (both pack and cell level) and cell imbalance (since you aren't looking at any 1s packs). The pack protections are all basically reliant on inline MOSFET switches to open the pack and series MOSFET switches to facilitate cell level balancing.
You could take the highest end cell from a Samsung/LG Chem/Panasonic, store it poorly, 14s it mismatched, with poor welds and random glue (over the vents) with 70V protection electronics and it wouldn't be a very good battery. Less so on a poorly regulating charger when the FETs open and the output shoots up turning the protection FETs into semiconductor resistors. But you'd still have voltage and it would support a load.
The reality is that all of the Lithium chemistries have safety concerns for the same reason that petrol has safety concerns. If you store it improperly or give it the conditions for thermal runaway, 'fun' stuff happens. Plenty of people handle petrol without incident... Although, you're probably not buying your petrol crude home-stilled from a person on a corner selling it in 2L bottles, either.
Love this topic! I’ve been kicking around making a video discussing this exact issue as well as others. I also would like to see a safety/quality standard on batteries. When people tell me they got a 1kwh battery for $300, I go 😬 “be careful with that thing!”
id say theres no point going back to older battery tech for some perceived safety benefits. there are new battery tech just around the corner, with the use of more graphene in lithium, and other tech that will likely improve safety and reliablity too. for now stick with known quality manufacturers or trusted custom battery makers and make sure you learn to charge and care for the battery optimally for long life and safety
im actually starting to nerd out about batteries and custom batteries, the latest best 21700 size cell technology, and how to build your own batteries. not for an amateur but very useful to learn, theres a lot of videos and info out there. im always for the highest capacity, highest power in the lowest weight and size, esp for ebikes.