# High Voltage Battery Pack - 240v 50Ah 500A



## Ike (May 16, 2009)

Here is my idea for a very possible EV battery setup. I will cover the chosen cells, BMS, and Charger...Hope this information is helpful to all.

*The goal are to create an working 237.6v 50A LFP battery pack with 12kW, 500Amp discharge rate, and most importantly long life of 2,000 cycles!!! (This should provide 60miles of range for a light weight EV, which is enough for most local commutes and under $20k!).* Of course, you can change things around to get the specification of your own liking, and/or budget.



Here are the main components you'll need to create the battery pack:

*$20k *Green backs (*USD*) –Legal Tender

*330x *3.2v 10Ah M Cells *(LFP-38120P)* -Amazing battery
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=5101

*3x *77v LFP BMS w/ 500Amp relay *(BMS-LF-24)* -This BMS is a standalone system w/ voltage readout, temperature readout, RS232 Port, and others.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4806

*66x *Slave Module *(BMS-LFSM)* -This is needed to provide data to the BMS
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4807

*1x *HV Smart Charger *(CH-400V12A)* –High voltage chargers are hard to come by.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4968


*Part 1: The Cells*

The LFP-38120P have to be one of the best I can find that don't seem to cost a fortune. I tell you what; having a good set of cells is very important for the success of your battery pack. This is the heart of your EV, don't try to cut cost here...you might end up paying much more down the road if you do. This cell are capable of providing 100Amps of discharge rate each, and 150Amp surges for short amount of time (Has already been tested, and discharge graphs can be found by googling). Since the cells are made with the Phosphate chemistry, you can expect 2,000 cycles from it!!! By connecting 5 cells in parallel and 66 modules in series, that comes out to be exactly 211.2v nominal, and 237.6v peak voltage with 50Ah capacity and 500Amp discharge rate. (This is prefect for our custom motor/controller setup, _secret for now_) Best of all, this setup can be achieved possibly under 300LB!

*Pros:*
- Best Cell you can get for the price (less than $40 each)
- High capacity (10Ah per cell)
- High continuous discharge rate (only listed 50A discharge on batteryspace.com, but was tested 100A continuous and 150A surge discharge rate)
- Easy pack built w/ secure screw-on terminals (no tabs nor soldering needed -- can be easily switched out, if cells gone bad)
- Flexible size and shape (easy for fitting in odd spots)
- Sturdy exterior (looks and feels to be durable)
- Light Weight!!! (only 12oz each)

*Cons:*
- Price ($40 per cell is not bad, but when you need 330pcs...you do the math )


*Part 2: The BMS (Battery Management System)*

Even though LFP batteries are stated to be SAFE...An good BMS is a must, if you want to protect your investment. This BMS (BMS-LP-24) will take care of the whole battery pack for you, and it is very nicely priced for what it does. Most, if not all cells do not like to be over-charged, nor over-discharged. If you are not careful, you will kill the cells. This BMS will allow you to check the full status of the battery pack with voltage readout, temperature readout, audible alarm, computer data port (RS232), and it is a complete standalone system. Make sure you pay attention on ordering the correct BMS, there is also a Li-ion/Polymer version of the BMS, which looks to be identical (just programmed for Li-ion/Polymer). The LFP version cost $799.00 with 500Amp relays, were as the Li-ion/Polymer version cost $795.00. The relays on the BMS are removable, which can be upgrade to higher amperage relays if needed (in this case, we don't). You can save some money if you order the BMS without the relays (about $500 I think, check for you self). We will need 3 of these BMS and wire them in series to get the 240v. 70.4v nominal, 79.2v peak per BMS, and 3 of these will equal to 237.6v peak. 22 modules per BMS, the BMS can handle up to 24 modules, but is best to keep them equal all around. Each of the modules are 3.2v 50Ah, which comes to 110 cells per BMS with our setup.

*Part 2a: The Salve Modules (Required for the BMS)*

The slave module doesn’t do much other than to provide a link to the BMS. These things are not cheap ($50each), and we need 66 of these. The slave modules have temperature sensors on them and are to be attached to each battery module. You can find more detailed specs on batteryspace.com

*Pros:*
- Price @ $799ea w/ the relays is not bad
- Standalone battery management specially designed for high voltage battery packs.
- Expendable (Can wire these in Series or parallel, much a like standard battery)
- Flexible (Can be mounted anywhere, doesn’t have to be right on top of the battery…this is good for us, since space and fitment is an issues)
- Small foot print (The BMS is not huge, just right for our needs)
- Very light weight (Always an good thing)
- Computer connection, Audible Alarm, and etc…

*Cons:*
- Not programmable by user (Everything pre-set, good for people whom are not too knowledgably in batteries)
- Expensive Slave Modules
- External 9-32v battery needed to operate the relays (I believe we can run it off the main battery, after the DC-DC converter…which we need the 12v DC for lights & accessories)



*Part 3: The AC Charger*

We have not made our decision on the charger yet, but this (CH-400V12A) Smart Charger from batteryspace.com sounds like it will do the job. Is not easy sourcing all these items and you probably want to give them a call before purchasing. They will help you with loads of information, and great for people whom need parts in a hurry (They always have everything in stock and ready to ship). This charger are able to provide up to 400v, but we only need 240v to fully charge our battery pack. This charge should be able to fully charge our battery pack in about 5 hours, which is not bad. 

*Pros:*
- It’s a Smart charger
- Can be used for higher voltage packs (up to 400v)

*Cons:*
- Price
- Need to be set (No auto detection)


*Final Thoughts:*

There are many aspect of building an EV, but this should take care of the power source. Hope this is help for others whom are planning their EV battery pack. If you have any inputs and comments feel free to share. I possibly have missed lots of details here and there, but feel free to comment.


*Battery** Specs:*

*Peak Voltage: *237.6v _(66series @ 3.6v cut off)_
*Nominal Voltage: *211.2v
*Capacity:* 50Ah_ (12kW)_
*Max Discharge:* 500AmpsContinuous
*Max Charge:* 100Amps Max
*Cycle Life:* >2000
*Operating Temperature: *Discharge: -10 - 60'C, Charge: 0-45'C
*Estimated Total Weight:* 300LB 
*Total Cells: *330qty


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## Showbill (Sep 15, 2020)

Hi everyone I am a little bit confused about this because I’m new in this but if someone can help me with this i will be happy 
I just buy a battery pack from Kia Optima lithium ion polymer one is full with everything 
And the other one I just ave the cells so I would like to use on my car project I am not full of money but if someone of you can help me on what I need to buy for this project I will appreciate , I ave a big DC GE forklift drive motor 13 inches of diameter and 17 inches long and it was rated at 36/48 volts but I give a 8 degrees advance to the brushes so it should be good to receive more voltage ? The car is a Mini Cooper 2010 standard 6 speed and no clutch 
Thank you for your help


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## SHAFILA EBRAHIM (Jul 31, 2021)

Ike said:


> Here is my idea for a very possible EV battery setup. I will cover the chosen cells, BMS, and Charger...Hope this information is helpful to all.
> 
> *The goal are to create an working 237.6v 50A LFP battery pack with 12kW, 500Amp discharge rate, and most importantly long life of 2,000 cycles!!! (This should provide 60miles of range for a light weight EV, which is enough for most local commutes and under $20k!).* Of course, you can change things around to get the specification of your own liking, and/or budget.
> 
> ...





Ike said:


> Here is my idea for a very possible EV battery setup. I will cover the chosen cells, BMS, and Charger...Hope this information is helpful to all.
> 
> *The goal are to create an working 237.6v 50A LFP battery pack with 12kW, 500Amp discharge rate, and most importantly long life of 2,000 cycles!!! (This should provide 60miles of range for a light weight EV, which is enough for most local commutes and under $20k!).* Of course, you can change things around to get the specification of your own liking, and/or budget.
> 
> ...


Hi 
We have a doubt that, Is here used lithium cell is LIthium -ion or Lifepo4 ? . And which type of cell is used here , prismatic or cylindrical ? and wish to know the reasons for why to choose those type of cells
thanks and regards 
Shafila Ebrahim


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## brian_ (Feb 7, 2017)

The original post is from 12 years ago, so the information is out of date, and the member who posted it is long gone.



SHAFILA EBRAHIM said:


> We have a doubt that, Is here used lithium cell is LIthium -ion or Lifepo4 ?


They are LFP, which means LiFePO4. LFP cells are one type of lithium-ion battery cell.



SHAFILA EBRAHIM said:


> And which type of cell is used here , prismatic or cylindrical ?


If you follow the link provided to the LFP-38120P cell, you can see that it is a cylindrical cell. It has screw terminals on each end - that style of cell is now rarely used. The name includes the size (38120 means 38 mm in diameter and 120 mm long). I'm surprised that the web page for this cell still exists. They're now much cheaper than they were in 2009, but far too expensive compared to other cells available today.


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