12Ah 3.3V LiFePO4 cells on ebay

[GGoodrum]

Oh I like this. Like what I did on the chopper forks - 12 a123 stick in compression. (see http://endless-sphere.com/forums/viewtopic.php?f=6&t=4160). But I don't see a spring on the main central compression rod (rod compresses bats but rod is in tension). Just add a spring (to accommodate cell thermal expansion/contraction) and that baby is a winner! Very nice work. And all set up for balancing too. Cool!

Actually, there are springs on each plate, and on the botom of the LVC board, on the top of the stack, so there can be thermal expansion, although in a 4p/9.2Ah configuration the cells just don't get even warm with the 30-50A loads they typically see on my setups.

-I like your chopper setup. Very clever.

-- Gary

 

[olaf-lampe]

I found these aussie-cells on ebay just before reading this thread. I asked the guy if there's actually a protection circuit in each cell. ( that's what he claimed in his ad )

They feature reverse polarity protection, short circuit protection, overload protection, over voltage protection and over temperature protection. They also feature auto cut-off and will switch off automatically at the end of charging when the battery pack has received a full charge.

So it cuts off, when the weakest cell is fully charged, with no chance of balancing the other ones...
For me another reason to not_buy them.

-Olaf

 

[safe]

The new solderless kit I did for a123 packs, listed here, will work for these as well.

Those look pretty good.

Solderless seems to have caught on... (a good thing because I'm thinking of trying it soon) I guess as a "theory" it's now pretty much accepted as being a viable truth. Good to know. (no more having to argue that the concept works)

However (as mentioned above) for LiFePO4 that are more sensitive to low voltage conditions you probably need to spend the extra money for the full scale individual cell balancers and LVC. NiMh and NiCads are the ones to use with the solderless tubes not LiFePO4 or Li ion. Seems that some RC people do it because they don't care if one of their four cells go bad... actually... you could just replace the "runts" as you go because the same cell is going to be the problem each time. If you sequentially rotated the weak cell out it should make the idea workable. Not for Li ion though.

When you buy your cells buy some spares... :wink:

 

[dogman dan]

I was also appalled by the sales pitch. I was scared to send my money to china untill several forums told me I could trust Ping. This cell would be really interesting if i had a larger bike. If the supply is steady a guy could risk his money a little bit at a time, instead of plunging in for a whole pack at once so that could be real good for a lot of folks. Still need a good bms if you buy these or else have to hassle with a lot of monitoring. I like it that somebody saw the niche for high power bikes and scooters. The duct tape cells really aren't what a motorcycle converter needs at all.

 

[flip_normal]

I found these aussie-cells on ebay just before reading this thread. I asked the guy if there's actually a protection circuit in each cell. ( that's what he claimed in his ad )

They feature reverse polarity protection, short circuit protection, overload protection, over voltage protection and over temperature protection. They also feature auto cut-off and will switch off automatically at the end of charging when the battery pack has received a full charge.

So it cuts off, when the weakest cell is fully charged, with no chance of balancing the other ones...

The ebay seller doesn't claim that there is a protection circuit in each cell. It's chargers that's being talked about in that part of the ad;

These chargers are top quality with cases made from powder coated steel and are pretty well "idiot proof" in their operation. They feature reverse polarity protection, short circuit protection, overload protection, over voltage protection and over temperature protection. They also feature auto cut-off and will switch off automatically at the end of charging when the battery pack has received a full charge.

 

[Jeremy Harris]

The Aussie seller has sent me a lengthy email explaining the source of these cells and his experience with other Chinese vendors. I apologise unreservedly for my error in confusing the "Peoples Republic of China" with the "Republic of China". He seems genuine enough, and took the time to explain the background to these cells. They are from the same factory as the LifeBatt cells, BMI, and are purportedly of the same, or better, quality. He has had some cells tested by ZEVA (the guy that did the independent Headway cells test) and they performed as he claims.

I am sure he'd do better to modify his advertising pitch though, as we all know that there are some very good Chinese suppliers, like Ping, Thundersky and Headway. There are undoubtedly some dodgy Chinese sellers as well, as some here have already found out, but tarring all Chinese vedors with the same brush doesn't sit comfortably with me.

I'm sure these cells will sell on their own merits if they are a good as they are claimed to be. In my experience, the seller of a good product doesn't need to bad-mouth other products or vendors to succeed, as good value and performance will ensure that.

Jeremy

 

[Miles]

Thanks for passing on the info, Jeremy.

I agree with you about the negative sales pitch.

Miles