If you have enough laptop batteries...?

11092 Views 11 Replies 6 Participants Last post by bgoner, Mar 4, 2011

bgoner

Discussion Starter · Mar 2, 2011 (Edited)

Ok, that might be really too much but was wondering if you could build a battery pack from laptop/mobile phone lithium batteries. Would it be able to be managed properly or too much hussle/problems?

Is there a part here in the forum for Tricks'n'Tips from the scrape yard. I mean there is so much trashing. For example you could easily get a charger made from there. I found almost brand new batteries, etc. I guess there are so much valuable things in our trash and we don't even know it.

Making yourself independable should be at any cost(as low as possible)

and asap.

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Picasso

· #2 · Mar 2, 2011

Yes you can use laptop cells, such as Tesla does. You will have to take apart the packs and re-weld them into a pack that will work for you. To manage a great number of cells such as you would need for a car pack you will find it a hassle yes.

Main cost is tools and time to test cells. Access to a large amount of used battery's is key. Lots of people recycle and use cells from power tools. These tend to allow a higher C rate than a laptop cell.

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bgoner

Discussion Starter · #3 · Mar 3, 2011 (Edited)

One of the big electric car makers announced a few months ago that they figured out a way to cut battery costs by half; they decided to use cell phone batteries. Big huge massively parallel array of actual cell phone batteries.

The logic being that they're already being produced by the hundreds of millions every year, and the economies of scale are already pretty much in full effect. Versus, trying to design and integrate a purpose-built battery, while better, ends up being actually twice the cost.

Whenever there is a burst in demand and not much competition, they rip you off - Capitalism. They are selling almost the same battery but they sell it much more expensively JUST BECAUSE they know that you will be saving millions of $ for gas, oil, filters, all kinds of spare parts for the too much complicated engines, breaks, etc. And because they know it they also know that you will be willing to pay a higher price.

I saw that mobile phone battery - 3.7V 1100mAh can be sold for 0.5$
X100
you get 110Ah Battery at 50$ ...
Compared to a Thundersky 100Ah Battery at approximatelly $140...
Am I calculating something wrong or it could be up to 3times cheaper to go with mobilephone batteries???
These are new batteries

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steven4601

· #4 · Mar 3, 2011

I bet it can be cheaper yes.
But mobile phone batteries all start to 'buckle' after a year or 4. And thats with a mild load like a phone. Lets compare it to a load which would drain them in a hour or less.

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bgoner

Discussion Starter · #5 · Mar 3, 2011

Yes you are right. The idea is to get people start cheaper. Furthermore if you can make them last a year would be great cause by then there would be far superior batteries!

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steven4601

· #6 · Mar 3, 2011

Isn't murphy's law going to kick in when you do that?

Cheap batteries which will stop working in 4 years, or they set your car on fire.
Or the good batteries become too expensive within 4 years?

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rwaudio

· #7 · Mar 3, 2011

I got some of these cells brand new for free:
http://www.onlybatteries.com/showitem.asp?ItemID=15105
I made some battery packs for some of my old power tools, and they definatially don't put out the kind of current the old NiCad's could.

I built a battery for a 14.4v DeWalt drill and I had to use 16 cells, (14.4v and 8.8AH) just to power the drill under load. And under severe loads the batteries overload, get very hot and the drill stops. The stock battery was 2.4AH but could provide much more current. I have a feeling that the reason Tesla uses 6000 of these cells is only partially to get the range they want, I think it's because most of these cells just can't put out large currents they have to use many many more of them to put out the peak power the Tesla is known for in a safe manor. For that dewalt it would probably take 8 more cells (4S6P) for the battery to be able to supply more current than the drill actually draws under severe load.

On the other hand a single cell worked amazingly well for cordless screwdrivers that previously ran on 2 series nicad cells.

Some of the other tools also worked much better, a simple 3S2P pack for some 12v black and decker tools works very well and now I have 12v 4.4AH packs to replace the 12v 1.8H ones and the cells fit in the stock battery case, and are also much much lighter.

I think these cells have their place, but don't expect to be able to build a road going EV without using THOUSANDS of them.

I won't even mention the 300 charge cycle rating vs 3000 for some LiFePO4.

If I didn't get them for free there would be no way I would use them. I would grab some (fake?) A123 cells off ebay instead. Similar to what Dimitri used in his UPS (mentioned in a thread here a few months ago).

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nimblemotors

· #8 · Mar 3, 2011

Use lead acid batteries if you want something cheap that works that will last a few years.

bgoner said:
Yes you are right. The idea is to get people start cheaper. Furthermore if you can make them last a year would be great cause by then there would be far superior batteries!

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bgoner

Discussion Starter · #9 · Mar 3, 2011 (Edited)

Guys I already have some freaking SAFT SBM 112 Nicads which are quite heavy but I guess will do the job.

The thing is that you might create a battery for a bicycle from few laptop batts or even a moto bike, or UPS, or just batt for light when fishing, camping etc. etc. Build cheap effective "container of energy"

, use it and don't just trash it.

I saw you could build a charger from the scrap yard

. Just want to get ideas on making something out of nothing.

300 cycles are little yes. But if you reach 50km that's 15000km which should be enough for 1 year. For 1 year you would have saved thousands of $$$ to get the freakin new stuff

. Furthermore they could get to 500-600 cycles.

If people reach to electric cars easier and faster and cheaper, companies would collapse or start selling EVs at some decent prices

. They would continue blackmailing us with high prices because they can. They play durty - we play durty

really durty like in the trash and skrape yard

I made some battery packs for some of my old power tools, and they definatially don't put out the kind of current the old NiCad's could.

They could be 2C and not the 10C.

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rwaudio

· #10 · Mar 4, 2011

bgoner said:
They could be 2C and not the 10C.

You are absolutely correct, all of the common laptop cells are 2C, because that's all they need to be. There are 5C and 10C cells in that format, but those are the special (expensive) ones and you won't get anything from economy of scale.

So common laptop cells are 2C, what would a cell phone battery be? 2C? 1C? 0.5C?

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MN Driver

· #11 · Mar 4, 2011

If I try to push 1C into one of my cell phone battery(actually a single cell) with my charger, it tops out at 4.2 volts in just a few minutes from after the cell phone shut itself off. At .5C , the battery has a more respectable charge curve. They don't take high discharge currents too well but do it better than they do at charging. I wouldn't pull more than 1C from a cell phone battery if you want it to last, I'd probably stick with enough capacity to where I'm pulling .5C. ...I wouldn't imagine using these in a car, they are cheap cells that only last for 2 or 3 useful years in a cell phone if you discharge it once a day with plenty of data or wifi usage. ...or some phone can barely last a day in the first place not to mention after some degradation with cycles and age. Same goes for laptop cells, they are designed for energy density and form factor, not life.

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bgoner

Discussion Starter · #12 · Mar 4, 2011

Yes you can't make a car, but I guess you could make a battery pack for an electric bicycle. Or I could use it just for energy storage, solar, wind. I bet we could find these batteries a purpose!

The thing I'm doing now just for the fun is attaching an alternator to my home fitness bicycle. Get a battery to it and attach diodes. It would definetelly stimulate me doing more fitness

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