Why L-ion and why not LifePO4 for an E-bike?

[BiggKidd]

I know size and weight are the two big negatives. Then again neither are all that much more for LifePO4 than they are for L-ion. Maybe 20-30% larger and heavier for LifePO4 than L-ion. The really big difference between them is the number of cycles. L-ion seem to top out between 800 and 2,000 cycles where as LifePO4 last upwards of 6,000 to 10,000 cycles. Price wise I just don't see a lot of difference in the two. 20 to 30% weight and size savings for less than a quarter of the lifespan it just doesn't make good $ sense to me. Maybe you guys can explain it to me! But for me in my way of thinking the LifePO4 have it all over L-ion in performance because they have a fairly small operating window of about 1.5-2 volts @16s in comparison with L-ion's window of about 10 volts. In other words my (48V) 105AH 16s1p LifePO4 at mostly full where I like to charge to is at 53.5V down to about 52V about as low as I like to take them. Where as a (48V) L-lion uses it's full range from about 53 volts down to about 43 volts. The power and performance is so much better with that flat curve from 53.5 to 52 it's almost steady throughout compared to L-ions 53 to 43 where you get a HUGE power loss in the bottom 2/3rds of your charge!

What say you?

 

[E-HP]

Yes, it’s size and weight vs everything you said, and the buying decision goes overwhelming to lower size and weight. Energy density will always have greater demand unless it’s for a stationary application. For ebike batteries, the supply equals the demand for LifePO4 packs.

I remember carrying one of these everywhere, but with a huge extended battery, back when my wife was pregnant. Maybe had a half hour talk time, but enough standby to make it through a workday. It was a couple of pounds. I guess I could have tried to make a NiMH backpack.

But even if it had infinite battery life, I’d opt for carrying my iPhone.

 

[e-beach]

Size, weight and sag. I run LiFePo4 Headways. I have been doing it for years. They are big and heavy and I have a hard time making them fit on my bikes is a safe manner where the bike is balanced the way I like it. No rear rack battery packs for me. I want a well balanced bike. I also sleep well at night knowing I can get home late, plug my bike in and go to sleep without worrying about a battery fire.

Most people just want something smaller and lighter that fits in there bike and don't think about any negatives about the chemistry.

 

[BlueSwordM]

Well, the main reason that people choose lithium-ion over LiFePO4... is that LiFePO4 cathodes are still lithium ion.

I believe you should rewrite the title to "Why NMC(A) and why not LFP cells for an ebike?"