Fried 48v 20ah battery - now what?

[kalpatarutree]

Heres a question I have for people out there: Why the A123 Lithium Ion's so expensive???

I mean: I bought this pack consisting of 288 batteries, all soldered together to make a giant brick of 48v 20ah, with a charger, and a BMS for 450 + 150 Shipping. So essentially they are selling the battery for 450 dollars.

Then I look on Ebay and the A123's of which there are 288 in my pack, sold individually are 10 dollars each??? And the cheapest they get (lot of 100) is 300 dollars? Even in lots of 100, that makes the price $864, just in batteries, to soldier my own brick together - and then I have to buy the BMS + Charger after that.

So how are these battery brick making companies making a profit? There has to be a cheaper bulk source. There has to be some incentive to build a battery from scratch? If I repair my battery, replacing 4 cells, that means it costs me 200 dollars to get the amount of batteries I need. Seems like I could just tear my battery into individual batteries, sell those on ebay in lots of 50 and make the money to buy a new brick, and avoid the soldering work, and order a new 48v 20ah from Hong Kong.

This is ridiculous.

 

[parabellum]

Sure they are real A123 cells? What are those blue cells mixed in?

 

[DAND214]

You need to slow down, and read what others have said and asked.

1 Were the BMS you replaced the same as the original one?
2 was there no name on the battery or charger?
3 have you put the probes on the dead cells? Not the wires at the BMS.
4 Dnmun has a lot of experiance with all types ob BMS and chargers. Listen to what he has to say.
5 Each row of cells are a group that needs to be tested, now that you have it apart. Go right on the tabs to get your reading. Don't do a addition of cell voltage, do each cell then write it down, then the next and so on.

You should update you profile as to where you are located. There my be help right around the corner, you'll never know iuf you don't ask.

Dan

 

[kalpatarutree]

1. Bms is the same as the original, signal lab 2.5
2- name of battery + charger is exactly what Vpower is selling on Ebay, although I purchased it through someone on this forum.
3- probes have been put on the dead cells, and they are dead. Pack has been ripped open and dead cells have been removed.
4 -Listening to Dnmun.
5- Tested all cells, good cells are ranging from 3.3-3.6 in voltage. I now have a perfectly functioning 36v 20ah pack of batteries. From here I either replace fried 4 cells + build back my 48v battery or get a 36v charger + bms and say hello to my downgraded to 36v once was a 48v pack. No biggie magic pie is 24/36/48.

Nice adventure, learning a lot. Before I got into ebikes it was a big mysterious brick that I plugged in to the wall and made my bike go. now it makes a lot more sense to me

 

[kalpatarutree]

The blue cells mixed in a def. a mystery, but they have a slightly bigger Amp hour rating. Each cell row was 18 at 1 ah each, which makes it a 48v 18ah pack. But I ordered a 20ah pack. I think the blue cells give it that extra juice to turn it into a 20ah pack.

I dont think they are "fake" a123 batteries. The print/wrap looks identical to pictures on line. Would they really go through the effort to manufacture "fake" labels, only to be hidden underneath 10 different varying layers of paper, clear tape, duct tape, and hot glue?

 

[999zip999]

Sorry Bro if it's victpower it could b-grade cells or ? You still need to write down and list cell voltage for us and you too.
1. 3.34V
2. 3.45V
Ect.
These are steps to follow to go forward. Yes to make it e.z. ? There will other steps. But first is first. Don't run off buying things yet.

 

[dogman dan]

I have wondered how V power was selling real A123 that cheap. Would sellers in china go to the effort to sell fake A123's?

The world wonders.

 

[dnmun]

when you say dead cells ripped out, what was done?

you had entire channels that were at 0V? how did you remove them?

i find the only way to cut the Vpower packs apart is to open them along the connection between each row like folding open a book and then cut the connecting strap between them with the cells folded away from each other enuff to get the scissors up between them to the connecting strap. if you don't fold it open enuff to get the scissors in between the cells then the scissors will short out to the case when you cut through the connecting strap.

it is possible to use the old BMS you said is dead with the reduced number of channels now too. we would need to see the pictures of that BMS to know how that BMS was already modified. looked like someone had removed the balancing shunt transistor comparator/gate driver. if we know which channels they are on then we can hack that BMS to use on your reduced size battery.

 

[999zip999]

Did you measure at cell level or from the sense wires ? People are asking questions to help you get thru this.

 

[kalpatarutree]

I measured at cell level - 3 rows are completely dead at 0 volts. tried charging them as dogman suggested, and they wont hold a charge, understandably.
Dead cells were ripped out like you describe, dnmun, by cutting the tabs with scissors.
Its all good, i've got a 36v battery and a knowledge of how these things are put together. I might have it be a 36v, or if I get irritated because my bike doesn't feel as powerful as it used to - ill turn it back into a 48v.
None of this was an irritating experience, it was nice learning over the weekend and tearing apart the battery. It was sitting for 4 months anyhow, because I didn't know how to deal with it. Im just happy to have saved 3/4 of the battery. The only thing I found irritating was the price of a123 batteries... I got all excited once I learned how they are put together and want to build batteries -> but the cost of a123 provides zero incentive to do so when you can just order a pre-assembled brick from Hong Kong or China. Spending my time scrapping Lithium Ion power tools and laptop batteries seems a little too vulture like so im not going to seek them out - but if something pops up on craigslist or something, I might jump on it.

I appreciate all the help here. I've always appreciated this forum and it never ceases to amaze me how much I learn when I dive into this stuff, and im very grateful for everyone's input.

 

[dnmun]

it looked like they had removed 4 of those comparators so if they took them off the high end of the BMS you can still use it for a 12S pack. you may end up finding another Vpower pack that is dead with the same width so then you could add them together again to build another bigger pack from the two. up to 18S-24S. and just get another 18-24S BMS and get a charger to go to that voltage.

 

[999zip999]

Be careful as these little yellow cells are very alive and can short and make fire. Be careful. Do not over charge cells 3.6v.

 

[kalpatarutree]

Any idea as to where to find "dead" Vpower packs Dnmun?

Im sure they are out there... I almost was getting ready to let go of mine because I was afraid of taking it apart... Im sure there are loads of people who don't want to get into ebike maitenance/repair that have "dead" scooter / ebike batteries sitting in their garage. Kind of wish I worked at a junkyard or electronics recycling place. Im such a scavenger sometimes.

 

[dnmun]

you can post up a wanted thread, but nobody knows where you live and shipping is the problem for lithium batteries. especially batteries partially disassembled with exposed wiring.