Has anybody got direct experience of LiFePO4 batteries on ebikes?

[Ghost1951]

Just curious about the advantage of potentially a few thousand charge cycles offered by that technology and negligible fire risk set against lower capacity. Has anyone had direct experience in recent times. I read somewhere that NielS had used them some long time ago.

I looked around a bit online and found plenty of utility batteries for caravans and boats - 12 volt chunky things not suitable at all and about one battery that would mount behind the seat post. Not a lot on offer, but a technology that offers 3000 charge cycles and doesn't catch fire has got to have something to offer - or maybe not, in this application.

 

[saneagle]

Just curious about the advantage of potentially a few thousand charge cycles offered by that technology and negligible fire risk set against lower capacity. Has anyone had direct experience in recent times. I read somewhere that NielS had used them some long time ago.

I looked around a bit online and found plenty of utility batteries for caravans and boats - 12 volt chunky things not suitable at all and about one battery that would mount behind the seat post. Not a lot on offer, but a technology that offers 3000 charge cycles and doesn't catch fire has got to have something to offer - or maybe not, in this application.

Normal lithium ion batteries are very safe. Nobody here has ever had one burn. Don't get sucked in by the hysteria. They're also cheap, light, powerful and last for years.

LiFePO4 batteries are heavy. In theory, they last a long time, but in practice get all sorts of problems. I've got loads of them and I fixed many more. I think it was Kudos that gave me a pallet full of them that were all defective in one way or another, from which I made a load of good ones by mixing and matching the parts. One of my first ebike batteries was a Ping LiFePO4 one because they were highly reputed, but it only lasted a year before the cells started swelling.

My advice is to stick with what you're good at and forget all this forum intellectual masturbation.

I can see some advantage with life batteries for home power, boats and cars, where weight and size doesn't matter, but small and light batteries are much better for ebikes.

 

[matthewslack]

My impression is that weight penalty may be less than it used to be. +50% instead of +100%.

But I might be wrong.

 

[Bogmonster666]

If I remember correctly my 1st e-bike build used a ping LiFePO4. Can’t remember the capacity. It worked ok until it didn’t. Appeared to lose capscity quickly. It happened over winter so I put it down to the cold weather but in hindsight I suspect some cells went bad. My circumstances changed a bit and the battery was neglected for a bit and when I next tried to charge, nada.

Given the high quality cells around now I wouldn’t give LiFePO4 a second glance based on my previous experience - albeit a long time ago.

 

[Ghost1951]

Thanks to all for the answers.

Not too rosey a history then....

 

[Bogmonster666]

I just checked, mine was a10Ah 36v Ping battery. I had a 42 mile round trip commute but could charge in the day so 21 miles on a charge. It was more uphill on the way back. Motor was front hub. At first it was fine with the 21 miles but very quickly it started suffering voltage sag and cutout around 15 miles, usually on one of the steeper hills. I recall thinking that lugging this stupid heavy bike with stupid heavy battery up the hill unassisted was not any fun at all. My current 48v 10Ah battery in my current mid-drive gets me easily over 50 miles and it’s not ever cutout. Admittedly I’ve not tried that particular route on the new bike. I know it’s an apples and oranges comparison - but really there is no comparison at all. In both cases I put a fair amount of pedal power in.