Hope for LiPo?

[anotherkiwi]

https://www.engadget.com/2017/01/15/built-in-flame-retardant-lithium-ion/

If you can remove the fire risk from the LiPo equation their advantages must out number their shortcomings? (modern, lighter more energy dense LiPo d8veh )

 

[Woosh]

Fire retardant is much needed but Lipo in e-bikes?
I can't see it though. The range of power requirement for legal e-bikes is less than 1.000W which is well served by current batteries.

 

[anotherkiwi]

We have forum members using in excess of 40 Ah. My trike project includes 40 Ah nominative of 44.4 V LiPo, that's 1500 Wh for 744 € and which can be charged from empty in just over 2 hours. I am still looking for a Li-ion battery that has those specs for that price.

It will be using a 250 W continuous rated motor with a 17 Amp controller and limited to 25 km/h assisted so most probably legal...

 

[Woosh]

Going to Lipo, you only save the cost of a BMS, worth about $20.

 

[anotherkiwi]

Lunacycle is around $700 for a 21 Ah 48 V battery that = $1400 for 42 Ah
or 1323 €.
HK Graphene 10000 mAh is 94€ a pop so in 2P2S (20 Ah) x 2 = 744€ or just under half. (I corrected above where I had only calculated one 20 Ah pack)

Graphene Slightly heavier - about 400g per 20 Ah battery
Lunacycle you have to add a charger to the price, I already have the 250 W lipo chargers. 7 hour charging time per 21 Ah Li-ion so you need two chargers @ $60 each. At 1C the Lipo charger charges each 10 Ah pack in about an hour (Graphene slightly less than an hour in real world use), I have 2 chargeurs so about 2 hours for the 4 packs. But I charge with a parallel charging board on each charger so same time for the 8...
Battery life about the same: lunacycle claims 400-1000 cycles and HK over 600 cycles

Still waiting on the address for 20 Ah of Li-ion @ around 375€

 

[Woosh]

Cell prices vary. You can find Chinese packs (soft pouch cells) around $400 for 48V 20AH without casing.

 

[Fordulike]

I am still looking for a Li-ion battery that has those specs for that price.

But what price is the safety of a family or house. I've thought about the benefits of LiPo on many occasions, but the fire issue always puts me off.

As Woosh says, 18650's are all that's needed on legal bikes. If more current is required, then Samsung 30Q's will be more than enough. Heavier and more expensive than LiPo, yes, but safer, definitely.

 

[anotherkiwi]

The safety issue is the subject of the first post. I am not trying to sell the idea just saying that it works for me. I keep my LiPos safe in a fire resistant place despite my not mistreating them and making them unstable.

My bike is legal, Woosh sold me the 250 W maximum nominative GSM motor, they know (you all do) which 15 Amp controller I am using and also that my cut-off is set to 25 km/h and the reasons it is set to that limit - all that has been documented in these pages and private e-mails. I run with either a dying 10.4 Ah Li-ion battery (on the flat around town) or 20 Ah of LiPo. 40 Ah = double the range, not always double the power...

 

[Deleted member 4366]

The main things against lipo:

Not plug-and-play charging
Compexity of wiring
Easily bricked
Short lifetime
Very heavy unless you buy the very expensive ones.
Not easy to mount to your bike safely and securely.

Advantages:

Can be cheaper
Modular, so easy to change voltage and capacity

In the past, using lipos was the only practical way to get a high power battery light enough for an ebike, which is why many of us used to use them, but now you have 18650s running at a true 5C at half the weight of lipo. A three pound 18650 battery can give 10Ah and 30 amps, so its no contest.