Why no Lithium Iron Phosphate on Wispers/Ezee/Other bikes?

[OneWayTraffic]

Just what it says. I know this has come up before in the last year or so, but with the technology changing and improving continuously I'd like to know why no one has used this battery chemistry on a mainstream bike. With the longer life time I'd have thought it would be a no brainer?

Hoping that Mr Wisper Or Mr Ezee will weigh in here.

 

[torrent99]

Just what it says. I know this has come up before in the last year or so, but with the technology changing and improving continuously I'd like to know why no one has used this battery chemistry on a mainstream bike. With the longer life time I'd have thought it would be a no brainer?

Hoping that Mr Wisper Or Mr Ezee will weigh in here.

Well aside from the fact that it's relatively new and untried (in comparison to the other Lithium technologies in use), I can think of the following DISADVANTAGES of LiFePO4:

1) Bulk/Weight. For the same capacity you need a bigger, heavier battery compared to existing Lithium technologies.
2) Current delivery. Most LiFePO4 can't deliver as much current (C rating). [One exception to this is the M1 cell found in DeWalt power tools which supposedly has a 30C rating]. This means that to get the same performance of voltage drop vs current you will need a larger Ah battery...which means more bulk/weight.

However, I suspect the main problem is that of relative immaturity, which potentially leads to unreliability, which doesn't do much good for bike manufacturers.

Of course many DIYers have used LiFePO4 with great success, but not all without problems.

 

[flecc]

I can tell you what they say.

Wai Won Ching, the eZee principal has stated that his trials of acceptably priced production batteries result in an unacceptable failure rate. I know that he has been experimenting with them since before November 2006 and would love to have them if they were practical for his bikes.

David Miall of Wisper is on record as saying that in agreement with their battery supplier, the situation is also "not ready just yet", but hopefully in due course.

There is a consensus amongst manufacturers, most importers and most retailers that Li-polymer is the way to go at present.

I know all the arguments about the present successful uses for lithium iron phosphate batteries such as in power tools and RC models, but their working conditions are radically different from those in an e-bike.

On the e-car front it's noticeable that designers are now turning their back on LiFePO4 and using "salt" batteries such as natrium-nickel-chloride instead, the Smart and Think e-cars being examples. Only Chrysler with the Volt model and BYD in China are using LiFePO4, and they are both hybrids incorporating petrol engines as well. Since they have only just been introduced, we don't know how they will perform in service.

One e-bike manufacturer, Sun Cycles did try LiFePO4 in small capacity sizes on a couple of low powered bikes, but they quickly disappeared from the market.

So you can see that the signs overall are not good.
.

 

[Mark/Cytronex]

Cytronex Battery

Just a quick post as I came across this thread about LiFePO4.

I don't have a lot to add to what Flecc and torrent99 have said but we are asked frequently about this. In fact the energy density of the quality LiFePO4 cells (i.e. those that are viable for a quality commercial product) is, for example, 25% less than our high discharge NiMh cells, so it is currently not a runner for us.

Whilst I'm sure this will improve, as Flecc indicates, it is possible that LiFePO4 may be overtaken by other chemistries. I am sure other manufacturers, like us, are keeping a careful eye on developments, but the technology is not there yet.