Battery Vendor Advice

[ShreddinPB]

Hi guys.. I bought 3 of these batteries..
http://www.ebay.com/itm/120997463225?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
I liked the size and Mah ratting and the cost was decent. Also he is in CA so it made shipping fast. They had no BMS so I opened up one of them to see what I needed to get as far as a BMS. He has them listed as 12V 10Ah batteries. The batteries inside are lfp26650-c3 which if looked up are 3000mah batteries, not 3300mah. So I emailed him to see what we could do and he told me the batteries are miss marked and they are 3300mah.
So I decided to learn how to use my hyperion 1420i hooked up to my computer to graph the battery!

I first charged it to make sure it was fully charged.. it was done in minutes so it just took a surface charge.
I then Discharged it at 2A, it took 4:20:51 as you can see in this image, so isnt that approximately 8.42 amp hour? So just under 9?


I then charged it up at 1A, which took 9:01, again, basically 9Ah right?


Here is a picture of the cell itself


This guy is trying to swindle me isnt he?

 

[eva-michael]

I think no vendor will mark a wrong capacity because they are selling by how much per ah than how much per cell. Don't they already mark 3000Mah?
But note: there are also some 26650 LiFePO4 cell which is 3.3Ah. I will suggest you to discuss with your supplier and ask them to provide you an answer against your evidence. Otherwise, they are 3mah. This is the way to solve the best issue.

 

[ShreddinPB]

Thanks for your reply.
The numbers dont lie according to the graphs tho right?
Or if you have a 10Ah battery can you only normally get 8.5 from it?

 

[Tommy L]

I've tested my LiFePO4 cells in a 4s4p 12.8v nominal 9.2ah configuration and they provide slightly more than the
9.2ah while discharging them

Tommy L sends...

 

[ShreddinPB]

I've tested my LiFePO4 cells in a 4s4p 12.8v nominal 9.2ah configuration and they provide slightly more than the
9.2ah while discharging them

Tommy L sends...

Ok then, I am asking him to take them back, if not, pay pal reversal here I come!

 

[Jason27]

Nooooo.. not eBay batteries!! It's all junk. Just read the threads on this forum.

 

[ShreddinPB]

Nooooo.. not eBay batteries!! It's all junk. Just read the threads on this forum.

yeah.. was an impulse buy for burning man needed some more energy for the light show on my trike
I liked the cell size cause it would fit in my faux gas tank.. no more for me.

 

[wesnewell]

Can't tell much from those charts. And mine always charges with more amps than I select when charging. Your 1420i charger keeps track of capacity during charge. Push the down arrow during or at end of charge to see the mah put into the battery. Before holding the enter button down. You can actually watch the mah rise during charge. That should be an accurate reading. This feature probably works on discharging too, but I've never used it for that. Let me check it.....Yes, it does.

 

[eva-michael]

Thanks for your reply.
The numbers dont lie according to the graphs tho right?
Or if you have a 10Ah battery can you only normally get 8.5 from it?

We measure capacity of headway LiFePO4 cell and battery pack by 1C discharge. For 10Ah cell, they will be 10ah or more than 10Ah. For not high current discharge, it should be 10ah or a little more than 10ah.
The way we are doing is, we discharge the battery pack and measure the capacity before shipment. They do have 10Ah if they are 10Ah cell(generally 10ah cells are a bit more than 10ah).

Nooooo.. not eBay batteries!! It's all junk. Just read the threads on this forum.

There are really some low quality cells in the market which are not QC pass cells. They are sell by factories in low prices. Just to make up some lose. That's why you can find some battery pack which has a low low price which is even less than you just buy cells.
So choose reputable suppliers will be very important. Especially those who will care ES. They will be notorious very fast if they play trick.......

 

[ShreddinPB]

Thank you both for your advice. He gave me a discount on them, so he took care of that for me.

 

[999zip999]

So more info how much you pay and how much discount. How will you be using them ? if for the operation of your bike how many amp is your controller and what motor ? 6 questions ?

 

[ShreddinPB]

So more info how much you pay and how much discount. How will you be using them ? if for the operation of your bike how many amp is your controller and what motor ? 6 questions ?

I ended up paying $78 per pack.
Its not for the motor on the bike, I have 2 headway packs for that, a 48V 12ah, and a 48V 15ah.
Its for all the electronics. Its a pretty crazy trike. I am going to use one of the packs to run the bikes lights and alarm, I put a motorcycle alarm on it for fun.
The other 2 packs will be to run the sound system. I made a custom box with 2 6.5" two way marine speakers, a 10" marine sub, and 2 2" marine tweaters.

 

[ShreddinPB]

So more info how much you pay and how much discount. How will you be using them ? if for the operation of your bike how many amp is your controller and what motor ? 6 questions ?

I will hopefully have the trike finished up this week, I will post a picture for you when its done

 

[wb9k]

Not sure how those cells are spec'd but it looks to me like you stopped the test too soon. For A123, LVC would be 2.0V/cell under load. You were still a way off from that it seems, though admittedly probably not enough to completely make up the difference. Are you sure your test matched the mfg's capacity test?

 

[ABTsportsline]

I had a similar poor experience with ebay batteries. I had read the "dangers" here going in to the purchase, but the super low price combined with the fact you can't find sub-10ah LiFePO4 batteries anywhere made me pull the trigger (it was a water bottle battery, 6ah).

It is darn near impossible to find 5-6ah 36v & 48v batteries out there (not on ebay or alibaba).