LiFePO4's on eBay

[ururk]

This auction seems like a good deal:

http://cgi.ebay.com/36v10ah-LiFePO4-battery-scooter-electric-bike-bicycle_W0QQitemZ290239913885QQihZ019QQcategoryZ11332QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Cost-wise, it is about the same as a Ping battery (Ping sent me an estimate). However... I'm not too sure if this particular type of pack is better/worse than what Ping produces.

Any thoughts? I don't know how many cells make up a Ping pack, but I have to imagine that as the cell count increases, the efficiency of the battery pack decreases.

Thanks!

John

 

[Pete]

Ping currently uses 5Ah cells that seem to be happy up to about 1.5C. WRT cell count, If the picture is correct then the Ping packs actually have a lower cell count . Although you do need to come up with some sort of protection as the cells are foil pouch type cells.

I hear a rumour that Ping is looking at using 4Ah, 3 to 5C cells in packs of 12 to 24Ah.
There is also rumblings of hard cased cells being tested as we speak and also BMS's that will be approved for connection in series and parallel. This is just bits I have picked up from emails with Ping, so for now this is purely rumour and I don't know what the timeline looks like.

So if you are not in a hurry, it might pay to wait for a bit and see what develops.

 

[pwbset]

This is just bits I have picked up from emails with Ping

Yeah, ditto. Looking forward to Ping-Series etc. I have to admit though that I'm becoming a huge fan of emoli spinel manganese like in the Milwaukee packs. I punish these packs each morning climbing 1,600ft in 3.5 miles at 35-40+wh/mi and they keep coming back for more and charge back up from fully drained in 45-50 minutes happy as clams. Loving these batts!

 

[olaf-lampe]

I bought 4 single cells as samples from this seller and I was positively surprised to find valence saphion cells in the envelope!
I'll test them this weekend...

-Olaf

 

[Link]

Valence? What!?

 

[ping]

Hi all,

Let me clarify something about our cells here. All our prismatic cells can discharge at 2C continuously and have 1500 lifecycles. 1000 lifecycle is for the whole battery pack. When cells are combined to be a battery pack, the pack's lifecycles cannot be same as single cells because of balance reason.

BTW, for the 18650 cells you mentioned, there're a lot of this kind of cells in Chinese market. Anyone want them, I will give you a fair price. We can also provide free welding service if you want. But we won't provide warranty for battery pack made of this cell. The cell has 2C continuous discharge rate and 4C peak, rated 1400mah, actually 1300+. Olaf, you could verify it this weekend.

Ping

 

[olaf-lampe]

Hi all,


BTW, for the 18650 cells you mentioned, there're a lot of this kind of cells in Chinese market.
Ping

And there is a lot of crap cells in china too. Just reminded my abf-cell test that proofed a 1100mAh cell is more like 600mAh! So I try to buy samples first...

But with your reputation, you sure will not sell unverified cells.

-Olaf

 

[Pete]

5Ah cells that seem to be happy up to about 1.5C.

I probably should have clarified that statement. I personally prefer to run my ping pack at not more than 1.5C it just 'feels' happier at that. I don't really have a scientific explanation apart from lithiums are way too expensive to flog them to death for no reason and being able to watch voltage sag in the Cycle Analyist in 0.1 volt steps makes things feel a lot worse than they really are.

The BMS on my 24v20A pack has a cutoff set at 35A, so I can't draw more than 1.75C anyway. I am very happy with having a conservative BMS, it makes the battery very idiot resistant. (there is no such thing as idiot proof )

 

[Johnbear]

There are always a few unknown lifepo4 sellers on e-bay cropping up, has anyone bought any?

 

[Pete]

Like anything on fleabayit is a calculated risk. You really need to do your research on the seller and also try and find people who are using the sellers batteries and see how they have turned out in reality.

Having said that, there are a lot of budget concious people on this forum who are now running on batteries bought from Ping. Either on auction via ebay or by emailing him direct.

Not saying there aren't other good sellers however Ping has a known good product that he backs up with good service.

 

[olaf-lampe]

There are always a few unknown lifepo4 sellers on e-bay cropping up, has anyone bought any?

Did you see this blackbox battery with a BMS on top? The same picture is used from 3 sellers in China, Israel and Australia.
...and they even use the same pic for different sizes of batteries :lol:

I bet this box was empty when the pic was taken...
Olaf

 

[dogman dan]

If anybody is flogging his Ping battery it's me, and it seems to be doing just fine. Climbing a huge hill in over 100f heat, I'm real glad I don't have a cycleanalyst! I'd freak if I saw what it really took to get me up that hill. Despite a bad crash and bashing over a lot of wicked wheel bending bumps daily, the Ping has really held up well unlike some from other builders. No broken connections for me so far. Stays perfectly balanced too. Unless you have too much money, I'd run some sla's till Ping is back to normal shipping.

 

[olaf-lampe]

What do you mean with "normal shipping" ? He's shipping for free now!


Olaf

 

[Pete]

I reckon that would be an ebay only thing. If you contact him direct I _suspect_ you will be paying normal shipping. But with the way the Ebay listings have been sky rocketing, it would probably be cheaper to contact Ping direct and pay the postage

 

[Anonymous]

.

 

[olaf-lampe]

I did some testing with the 4 cells I ordered from ebay:

1. When they arrived Voltage was 3.3V on each cell, so I decided to make a 4s pack of it. Charged and discharged with 700mA . Result was 880mAh only. One cell was around 2.6V while the others where over 3V. Hmmmmm

2. Disassembled the one "bad" cell and cycled it separately with 1.4A. 1.3Ah was the result. I repeated it once with the same result.

3. Charged and discharged the 3 remaining cells together with 0.7A. Result was 1.3Ah. Again one cell was way below the others. But I'm sure I've picked out the right cell. So I charged each cell of the 3 individually and discharged them again with 0.7A. Same result: 1.3Ah and the same cell is lower than the others.

I did no more testing yet and the results so far are not very promissing. But of course this short test is not representative at all.
Perhaps with a balancer they would work better. Unfortunately I had no connector for that. Probably next weekend.

It seems there are cells of different age mixed together and all of them seemed to have lost at least 0.1Ah just lying around on the shelf.
Soldering several of these cells parallel is very risky when the capacity varies so much.

-Olaf

 

[dogman dan]

I meant normal, being able to ship at all, both for his outgoing product, and for getting cells to his assemblers. From what I saw posted, one poor guy had his battery shipped back to Ping several times, and Ping was saying that he had trouble getting anything from the factory till after the olympics. Since the ebay customers are bidding up to $200 more than his asking price, good for him to ship those ones free. Waiting also makes sense if he does provide a better BMS this fall.

 

[ping]

From what I saw posted, one poor guy had his battery shipped back to Ping several times, and Ping was saying that he had trouble getting anything from the factory till after the olympics.

Hi Dogman,

Could you please tell me where you saw the post? So far, we have met only one replacement case. The guy is from Australia. We did have shipping problems when we received his 36v15ah pack. But finally, last month, we shipped the replacement to him via UPS Hong Kong when we solved the shipping problems.

Hi Olaf,

I recongised the 18650 cells from the first sight on ebay. We know almost all the LiFePO4 cells made in China.

Ping

 

[dogman dan]

I don't recall exactly where, but maybe on the volts forum, I didn't know if it was a replacement, I thought it was just the same battery that wouldn't go through to him . I'll try to hunt it down. It was one of the last ones that were ordered before shipping got wierd. Sorry if I sound like I'm slamming your buisness I didn't mean it like that at all. I highly recomend your product to those not trying for a 45 mph bike.

 

[dogman dan]

Ping, the post I was refering to was from Pete on the Endless sphere, duct tape ebay lifpo4's 2, on june 12th in the battery section. Before the shipping situation got messy I was telling everybody to buy from you, I hope to resume that soon. My battery has sure taken a licking and kept on ticking. Let us know when to send the stampede of buyers your way.

 

[swbluto]

I have also seen the opposite, where the auction cost is almost all shipping, that way they can avoid large ebay final value fees.

This is true. It helped me acquire 4 1-watt LED flashlights for 1 dollar using eBay's "10 dollars off shipping" coupon. 8)

I've found identical flashlights in the store near the check-out selling for 5 dollars each, so even the "evil practices" can be awesome sometimes.

 

[ping]

Hi dogman,

It's ok. Sorry for making you misunderstand me. I was just curious about the case you mentioned and not complaining. I just wanted to know if there's customer unsatisfied with us and solve the problems.

Thanks,

Ping

 

[dogman dan]

Ping, we just want to know when to send the stampede of buisness your way. Lots of folks out there want one of your batteries.