# How about making your own Li-ion battery pack?



## Manntis (May 22, 2008)

DarkStarModz said:


> I was cruising the internet looking for cheaper Li-ion batterys for my ev when a ran into this web site that sells Li-ion cells in all diffrent type's and im pretty sure you could build your own Li-ion pack instead of ordering ones that are pre-made from places like thunder sky. So i was wondering if it would cheaper to order 250 of these 3.6v/60ah cells and assemble the pack myself http://www.alibaba.com/product-gs/52064595/3_7V_60Ah_Polymer_Battery.html, or 1440 of these LifePO4 3.2/10ah cells http://www.headway-cn.en.alibaba.co...20_10Ah_LiFePO4_lithium_ion_battery_cell.html .
> My requirments for my Ev is 144v/300ah pack. Let me know what you guys think about making my own batterys.


possible, yes. Cheaper? It depends what equipment you have to weld them together and what you view your labour to be worth.


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## Whitey_87 (May 30, 2008)

I have the same power requirements for my project. I would be interested in building my own pack also, but what about a BMS and a charging system? I think just connecting the cells would be the easy part.


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## ww321q (Mar 28, 2008)

what was the price per cell ? You can build a pack from a lot of things that you find on the web . The hard part is getting them to sell them to you and then going to the bank to get a loan to pay the price they think they are worth . J.W.


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## Whitey_87 (May 30, 2008)

But after you take out the loan and get the batteries, what would we do for a BMS?


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## DarkStarModz (May 12, 2008)

Yeah as far as welding them together,there are battery welders that you can buy from the same site but for how much i don't know i have to wait until they send me a quote or I'm sure there ways to do it with a regular soldering iron, it really isn't that complicated Ive seen a electric BMW conversion where the guy made his own Li-ion pack out of cells somewhere online ill post a link when i find it again and as far a case i was planning on welding up a aluminum box for the cells since i work at a machine shop/sheet metal shop i could do that for free. Also, as far as the BMS goes one of the company's listed on that sight offers custom BMS setups. Ive emailed the Li-ion Cell company's and requested a quote through there online application the only requirement that they state is there is a minimum quantity order. For the 3.6/60ah cells there's a 10pcs minimum and for the 3.2/10ah cells it is a 1000pc minimum order. Also Ive etched some of my own PCB's so I'm gong to look into how complicated the circuit is on a BMS. Id rather do as much of the work myself and save a bunch of money.


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## ww321q (Mar 28, 2008)

When I rebuild my cordless drill packs I just solder them . They seem ok , J.W.


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## Madmac (Mar 14, 2008)

If you are going to solder make sure you order them with tags. Soldering direct on the case will damage battery. Tags will increase the cost very slightly.
Madmac


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## DarkStarModz (May 12, 2008)

Ok, i found the link to the guy who made his own battery packs with a battery welder wich is pretty much a programable spot welder and if i go that same route assuming i can get one for a decent price i would probably go with the 3.2v/10ah Life4Po cells wich are around 1.5 inch in diameter and around 5 inches long. That way i can also make my battery packs in any form i need to fit into my ev. So check out his BMW conversion its pretty cool. 

Here's the spot welder= http://evdrive.com/Emoto_project/images/Cellweld2.html
and here's what a packs looks like after welding=
http://evdrive.com/Emoto_project/images/Packvoltage.html


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## paker (Jun 20, 2008)

Why is it necessary to weld lithium battery packs? Why not put them into spring loaded holders like a normal battery? Something like this. This is a 3 pack out of my LED flashlight.


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## DarkStarModz (May 12, 2008)

Well the problem with the spring loaded holders is that there are no standard holders for lithium cells since the cells varies greatly in size from one manufacturer to another, you would have to make custom spring loaded holders for about 1500+ cells and that wouldn't be cost effective. For example: 3.2/10ah Life4Po cells are roughly 1.5"in diameter and 5" in length and the biggest standard battery is a "D" size battery and the dimensions are roughly 1.25" in diameter and 2.25" in length. Thanks for the great idea but just not very cost effective.


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## ww321q (Mar 28, 2008)

I can't wait till you get the price on cells and the welder J.W.


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## DarkStarModz (May 12, 2008)

Ok, i found a very nice welder it is a SonoWeld 1600 ultra sonic spot welder which is the best way to weld lithium cells and the best news is that the company rents them out!!! So hopefully its for a reasonable price just waiting for a response to the email i sent them and as far as lithium cells the company's application said that i would receive a quotes within 3 days so i should a have the quotes Wednesday (3 business days I'm assuming but china might be different) for 3 different kinds of lithium cells.

Here's the link to the welder site= http://www.sonobondultrasonics.com/welders-bonders-metals.asp?sID=sonoWeld


and here's the PDF link = http://www.sonobondultrasonics.com/pdf/FINAL Lithium-Ion Battery PR.pdf


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## Whitey_87 (May 30, 2008)

DarkStarModz,

Depending on when you plan on ordering and building your pack I may be able to place an order with you if you are interested. I don't know if that would help bring the price down much or not. I think it would be a good idea since we have the same battery requirements.

Are you in the states?


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## Whitey_87 (May 30, 2008)

DarkStarModz said:


> check out his BMW conversion its pretty cool.


Metricmind supplies/makes some very nice components. Very clean conversion.


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## DarkStarModz (May 12, 2008)

Whitey_87

Actually i was thinking of getting a few people in on the buy so we could get a discount I'm not sure on how many will need to be ordered but i will email the company and see what size order is needed to get a discount, i was thinking of going with the 3.2v/10ah Life4Po cells i calculated i would need at least 1440 of them to create 48-3.2v/300ah cell packs=144v/300ah total. Also i wouldn't know how to go about getting all the money together and where the shipment would be, i would think you would have to send all the cells to on address and who's address would it be? or who's bank account is going to pay for all of them? would we all meet a certain location to work out all the details? Let me know what you think and maybe we can work something out, hopefully we can get a few people in on it and discuss this via conference call or something. Also to answer your question i do live in Florida near Tampa i just realized i didn't specify my location when i made this account because i can see where other people live on the top of the post but not mine. Also Ive been looking on the metricminds web site for a while because i was very interested in making the same Honda CRX conversion that one guy did. let me know what you think Whitey_87.

I just got the quote for the 3.7V/60Ah Polymer Battery and here's what it was: The 3.7/60ah Polymer Packs are 208USD per pc, and the 3.7/100ah Polymer Battery Packs are 207.50USD per pc i don't know why the higher AH packs are cheaper??? But anyways i emailed them back to see if they offer a discount on a high quantity order. I should hear back from them tomorrow, and I'm still waiting on the quote for the 3.2v/10ah LifePo4 cells, I'm assuming these will be the cheaper route considering the polymer packs are already assembled with tabs and shielding.


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## Whitey_87 (May 30, 2008)

Yeah, I lost a few hours at Metric Minds that I should have spent on work. Like they advertise - High end AC conversions. It seems like a one stop shop, they even have BMS'. I did not get too far into the BMS section but I think all of their units are set up for AC controllers - correct me if I am wrong.

As far as a group buy, I am not familiar with it as far as the logistics go, I think we can set up some kind of custodial account at a bank or something like that. I am sure there are ways, and there have been group buys before maybe someone can give advice.

What is your time frame? A few weeks, months, '09? Personally I am at least 3 months from being able to purchase.

Maybe we should start another thread to advertise the group buy offer.


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## DarkStarModz (May 12, 2008)

Yeah my time frame is towards the end of 08', and i think it would be a good idea to start another thread because this one will get filled with off topic discussion. Anyways i was surprised to see i had another quote so soon the quote i for the 3.2v/10ah LifePo4 and the price is listed by how many are order. For 100-2,500 cells its 17.50usd per cell,For 2,501-10,000 cells its 16.50usd per cell, and for above 10,000 its 16.00USD per cell. So Im pretty happy i did some calculating and comparing price's between these cell and other pre-built LifePo4 Battery's and here's what i discovered, I went to the EVpower web site wich sell's LifePo4 battery's in different configuration so i picked the best one they offered which is the 12v/36ah LifePo4 Battery at $835 USD per battery, and then i calculated how many of the cells it would take to make the same battery pack and here are the result's= it would take 16 cells to make a 12v/40ah battery pack, so 16x16.50= 264USD per battery pack thats a savings of 571USD!!! of course there's some other expenses included in there price i.e. the case,welding,possible BMS included etc. Let me know what you guys think. Here's the link to EVPower page with the LifePo4 Battery's= http://www.ev-power.com.au/-Lithium-Ion-Batteries-for-Electric-.html


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## Whitey_87 (May 30, 2008)

Good info. In the classifieds there is already a group purchase going on.

so at the 16.50, to get 144V and we would end up with 320Ah, the cost is around 25k for just the cells alone. Pretty steep but hey, you wanna play...you gotta pay.

When I first started looking into pricing Lithium, I thought it would have been somewere around 15k. Obviously you could get an outrageous pack for a huge sum, 50k or more. I had the dillusion that the status quo of Lithium (120-144V) would be in the 'teens.

We'll see how the checkbook feels when we get ready to follow through. Thanks for gathering thos prices.

BTW, what was the cell weight of the individual cells you calculated?


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## DarkStarModz (May 12, 2008)

The Life4Po cells are 300 g = 0.661386 lb OR 10.58 oz per cell, I'm also looking into Li-ion phosphate cells they should be allot cheaper than the Life4Po cells but if not I'm willing too lay down the cash for the Life4Po by the end of the year or early 09'. Maybe they will be a little cheaper by than too. Actually the cost for a 144v/200ah Life4Po pack i calculated at a little under $16,000 and thats at 16.50 a cell if we get the 16.00 per cell discount i will be even cheaper around $15,000. So making them yourself can save alot of money.


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## DarkStarModz (May 12, 2008)

ok, i got a the new quote for a high quantity discount, in on the 3.6v/60ah Li-ion polymer packs. They said a order over 1000 of these would bring the cost from $208.USD per pack to $119USD per pack and the 3.6v/100ah Li-ion polymer pack would be from $298USD to $198USD per pack. So a 144v/200ah total pack would be $19,200!! Youch!!!That is a little steap, the Life4Po cells are still cheaper at $16,000 for a 144v/200ah pack.


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## paker (Jun 20, 2008)

DarkStarModz said:


> ok, i got a the new quote for a high quantity discount, in on the 3.6v/60ah Li-ion polymer packs. They said a order over 1000 of these would bring the cost from $208.USD per pack to $119USD per pack and the 3.6v/100ah Li-ion polymer pack would be from $298USD to $198USD per pack. So a 144v/200ah total pack would be $19,200!! Youch!!!That is a little steap, the Life4Po cells are still cheaper at $16,000 for a 144v/200ah pack.


If a 10 year lifespan is possible, and depending on the price of gasoline at the time of the purchase, it could be a deal. I'm reading and hearing that gasoline will probably be $7.00 per gallon in 2 years.


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## Whitey_87 (May 30, 2008)

DarkStar,

Sounds good, lets stay in touch. My plan is to convert with AGM's first so that I can properly gage what size pack I need compared to what the pack of AGM's are giving me. I still need to go through more calculations (like in "build your own electric vehicle"). 

Thanks.


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## JusSumguy (May 19, 2008)

Porsche 914 EV Conversion: Visiting Gary of the OEVA to get a Crimper

Dissecting DeWalt 36V Packs (A123 Systems)

When I contacted A123 about this, they pointed me to this page--> How To Build a Battery Pack from A123 Cells -


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## JusSumguy (May 19, 2008)

*There are other options*










*Main advantages*


Maintenance-free operation
High power/energy ratio
Fast charging
Fully recyclable
More than 2,000 charge/discharge cycles
Low internal resistance
Smaller than conventional batteries
CLICK

---​


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## Whitey_87 (May 30, 2008)

*Re: There are other options*



JusSumguy said:


> *Main advantages*​
> 
> 
> 
> ...


*Nilar announces temporary allocation - Q1 2008* _2008-04-14_Due to overwhelming demand, Nilar is forced to announce a temporary freeze on new orders, and allocation for existing customers 

that's a downer


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## aeroscott (Jan 5, 2008)

*Re: There are other options*



Whitey_87 said:


> *Nilar announces temporary allocation - Q1 2008* _2008-04-14_Due to overwhelming demand, Nilar is forced to announce a temporary freeze on new orders, and allocation for existing customers
> 
> that's a downer


the oil boys needed them a a for a a oil a a exploration yea thats it . lol


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## zelig2 (May 2, 2008)

*Re: There are other options*



JusSumguy said:


> *Main advantages*
> 
> 
> Maintenance-free operation
> ...


Whatever this "Membrane" technology is it isn't better than Lithium stuff right now. The Mass Energy Density is only ~55Wh/kg and it's Volume Energy Density is only ~108Wh/L. LiFePO4 is typically about 2x those numbers


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## Taztech (Dec 5, 2008)

*Re: There are other options*



JusSumguy said:


> *Main advantages*
> 
> 
> Maintenance-free operation
> ...


We may be over looking one major advantage using these cells, quoting from the web site it says...
_"For the EV conversion owner, Nilar Membrane batteries with Smart Switch technology provide freedom from the lead-acid replacement cycle while leveraging the existing charger and controller infrastructure. A drop-in replacement solution for the lead acid packs provides all the benefits of Nilar's NiMH battery with none of the hassles traditionally associated with the chemistry conversion."_. If you needed a 144 V pack and got 42 of these cells (6 in series and 7 parallel) you would have a pack that is only 63 Ah but able to delver 126amps continuous and 315 amps nominal and peak at 630 amps for 10 seconds.
all though they do cost about $250 per cell giving a total price of $10,500 but no BMS or charger to buy. Just plug and play


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## Doctorbass (Dec 12, 2008)

How about making your own GREEN lithium-ion battery pack

Using recycled cells from deffective cordless powertool battery pack!

I built mine (4 x 25.2V 23Ah) ... 

TOTAL COST.. == ZERO $ ==
TOTAL ENERGY: 2.3kWh!

capable of 10C and 5 C continuous

the goal is to remove the deffective cells in each pack and to rebuild a larger oack with the good one.. usually 85% of the cells are still in good state and offer more than 400 cycles (tested)

http://endless-sphere.com/forums/viewtopic.php?f=14&t=5859&p=87720&hilit=+konion+battery+pack#p87720


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## Voltswagen (Nov 13, 2008)

Hey Doc
That was an impressive post. Does the pack have a BMS?
What about LiFePo4? Are they being used yet in power tools?
Wonder what the cost would be to build a 120v pack? I currently
use 15 - 8v Lead Acid batteries to power my Beetle.

Anyway....Impressive!


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## Doctorbass (Dec 12, 2008)

Voltswagen said:


> Hey Doc
> That was an impressive post. Does the pack have a BMS?
> What about LiFePo4? Are they being used yet in power tools?
> Wonder what the cost would be to build a 120v pack? I currently
> ...


I still dont use any BMS anc the cells are well balanced.. these cells dont need any balancer and they are lithium!! I like them cause they can handle 10C and have a very similar discharge curve than LiFePO4 cells.

For sure LiFePO4 cells exist in the powertool.. like the Dewalt XRP18V, the 28 et 36V 2.3Ah pack too.. I had more than 400 cells from partially deffective battery pack =)

The konion i use come from makita pack LXT 18V and they have no balance circuit inside.

instead of Lithium cells, 8V Lead battery are far less complicated to assemble!.. but their efficiency is not as satisfying than Li-Manganese(makita) or LiFePO4.

And the li-manganese (konion) cells in the makita have higher voltage than the LiFePO4 (they have 3.7V nom and the LiFePO4 have 3.3 or 3.2.. so you need less serie group with li-manganese.. and less chance of having priblem in the chain..

I dont sale ant fabricated pack from now.. They need alot of time to assemble!

Doc


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## Technologic (Jul 20, 2008)

DarkStarModz said:


> My requirments for my Ev is 144v/300ah pack. Let me know what you guys think about making my own batterys.


 I would build you a ground up super lightweight EV car for that much money, let alone what you could do yourself.


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