Yesa LiFePO4 Battery

[john]

I am thinking of getting a Yesa LiFePO4 Battery 10Ah 36V battery. Not quite as cheap as Ping batteries and not as light but he is not shipping at the moment and the Yesa cells will fit better in my case.

Here are the discharge curves:



I need 15A max.

I asked about cycle life and was told that:

The capacity on end of 400 cycles is 91.3% with 0.5 C for charging and discharging

What do people think?

[Jeremy]

The YESA packs have a good reputation on the ES, John, so I reckon it should be fine.

I'm super impressed with my Ping 36V 10Ah pack; I haven't come close to finding out it's true range yet, but it's way over 20 miles on my Tongxin powered 'bent.

I rarely draw more than about 12A for short periods from the pack (the controller tops out at about 14.5A), my average current draw is pretty low, it fluctuates around the 2 to 4A zone for a lot of the time on the watt meter display, although I'm not quite sure how accurate the instantaneous current readings are. I'm guessing that I could ride for at least two hours on a charge, maybe three if the terrain was fairly flat.

I'd guess that the YESA packs are slightly better than the Ping packs, if only because they are more robustly constructed, with better connections.

My Ping pack has now been through about eight complete charge/discharge cycles and seems to be as good, or even slightly better, than it was when new. Straight off charge it sits at around 44V, but even after a weeks riding, with no charging, it still rests at around 39V (I only need to charge it about once every ten days.............). I've seen the voltage drop as low as 36V (!) when pulling about 14.5A from the pack on a sustained hill, but generally the pack voltage is around 38V or more when cruising along.

Jeremy

[frank9755]

I know, John, you are asking about YESA packs but for what its worth I can second Jeremy's experience regarding the technology from my 10Ah Ping LiFePO4. I don't have figures but range is well over 20 miles on my Wisper, and hill climbing performance is better than the original battery on my 6-month old Wisper.

Frank

[coops]

Does the Yesa still use '10Ah' (they look higher!) cells only in series while the Ping packs use parallelled 5Ah cells, and would that make any difference?

There's still a bit of a question mark for me over the longevity of li cells: despite the claims by some makes of LiFePO4 of 10yrs, 5000 cycles etc. I've not heard of anyone using them in ebike-type use long enough to confirm that, so I'd rather buy with a few years guarantee for ebike use if possible.

Those do look under-rated at 10Ah though: they are very similar in discharge characteristics to the 12Ah cells sold at www.ebikes.ca (scroll about half way down)... . Maybe they have a bit more capacity than Pings aswell as weight? I've seen other '12Ah' cells for sale, maybe they are all the same capacity, just rated differently?!

What is the weight John? About 4.5kg?

Stuart.

[Jeremy]

It's very difficult to find out precisely which cells these Chinese packs use, but I've found three general types, of which only two are in common use. The YESA packs seem to be made up from 10Ah cells that are rectangular, with screw terminals, but I have a strong suspicion that inside these rectangular packs there are some pouch-type cells connected in parallel. The Ping packs (and the other "duct tape" packs) mostly seem to use the 5Ah pouch-type cells, connected up in parallel to give 10, 15, 20 Ah etc.

I have found some different shape pouch cells, which are 6Ah capacity, that I believe are used in those packs that are advertised as 12Ah.

It's far too early to tell what the life of these cells will be, but I doubt that cycle life will be the determining factor. I would imagine that ageing will reduce the cells capacity way before cycle degradation, at least for those who only charge a pack every day or two. If I had to guess, I'd say that the life of a well-cared for LiFePO4 battery should be two or three years, which seems reasonable.

It's quite possible that the useful life of a LiFePO4 pack could stretch out beyond this, but this is still very good when compared with SLA batteries. SLAs struggle to get more than a few hundred cycles, or a couple of years, of useful life, less if they are repeatedly allowed to discharge close to their lower limit. NiMH has the edge for overall longevity, I suspect, but at the expense of added weight and lower capacity, plus their rather nasty self-discharge trait. I went for a month without using my bike a while ago and the battery appeared to be at exactly the same state of charge as it was when I left it. A NiMH pack would have lost a fair bit of charge over the same period, I'm sure.

Jeremy

[john]

I have a bit of a concern about the life too, I don't think they are going to be anything like as good as A123, but those are just outstanding. sadly not really an option at the moment. The cycle life quote I was give seems a bit low compared to other LiFePO4's but it is hard to compare without all the detailed conditions. However, I think it is good that I was obviously given real figures rather than just made up headlines.

400 cycles would be about 2 years use, and if they are still giving over 90% capacity at that point then I would be more than happy. Probably ready for better technology by then anyway.

I don't know why they are 1 kg heavier than Ping's. The cell cases will be some of it, perhaps the plates are thicker or something. People do seem to be reporting around 10Ah capacity from them.

Anyway, thanks for the advice guys, I think I will be ordering one in the morning.

John

[bersh]

I believe that Flecc mentioned that there is a new manufacturer of batteries for Ezee Quando II. Please update whatever info. there is, since I am facing replacement, even though my battery is only 9months old and still under warranty. How does one know who the manufacturer is? By serial number, color, or??? ps, the reason for replacement is that I need to be able to rely on getting up a particular hill, and soon I will have absolute conclusion whether the old battery can handle this new hill. If it can't, then I will ask the dealer to deal with this situation, which in my opinion, should be in my favor, but I am suspicious of what testing of capacity left will reveal/be used against me. ps, any news on the price of the new battery (I am only talking Lithium, Not Nicad.....

[HarryB]

Originally Posted by bersh

I believe that Flecc mentioned that there is a new manufacturer of batteries for Ezee Quando II. Please update whatever info. there is, since I am facing replacement, even though my battery is only 9months old and still under warranty. How does one know who the manufacturer is? By serial number, color, or??? ps, the reason for replacement is that I need to be able to rely on getting up a particular hill, and soon I will have absolute conclusion whether the old battery can handle this new hill. If it can't, then I will ask the dealer to deal with this situation, which in my opinion, should be in my favor, but I am suspicious of what testing of capacity left will reveal/be used against me. ps, any news on the price of the new battery (I am only talking Lithium, Not Nicad.....

If your battery is a 9 month old li-ion, it is the first generation ezee li-ion (Phylion) and is very poor indeed. The better version (still Phylion) came in around Nov 07 and is much better. In fact they say only the battery monitoring system was changed and this may or may not be true but from my experience the battery is much improved. This is the battery you would get as a warranty replacement. One problem is that testing is very difficult. For example my second battery was cutting out on every hill and was tested and found to be 8.5 Ah and therefore ok. I assumed it was the bms that was causing the cutting out once the cells started to age. It didn't matter as it was useless to me.

The latest battery uses Sanyo cells but you are very unlikely to get that as a warranty replacement as it is not like for like (and the replacement Phylion batteries seem fairly robust now). I have never had a cut out in the 7 months I have used mine and in fact shows no signs of losing capacity (my two previous batteries started to age after 2 months and were useless between 5 and 6 months old.

PS the price of the new sanyo celled battery seems to be about £350 which considering the quality of the cells is not bad.

[john]

I ordered a 10Ah 36V battery from Yesa.

After an initial delay (due to bad weather in China I am told) it was sent from Hong Kong on Friday and arrived this morning (Monday)! I wasn't asked for any duty

I'll report later how I get on with it.

[john]

As it arrived...