Hi , I want to build a 48v battery for my motorised cooler. I apolgise if this has been asked a thousand times already. I did some searching on the forum. I know a lot about internal combustion engines but when it comes to batteries and circuits I know very little. A friend of mine gave me a large lithium battery. I have pulled it apart. I have pulled the individual cells out of it. There are 122 individual cells. They measure 65mm long x 26mm across. And they are holding approx 3.2v My questions are, how do I arrange them to get 48v please? Where do I buy the plastic holders please or do I hot glue them together? And what about using nickel strips spot welded on please? And if the motor I am using is 2000 watts - 48v, will these cells give me enough juice or amps for my requirements please? TIA.
DIY 48V Battery Build?
- Thread starter Kudos_74
- Start date
eee291
100 kW
Are the cells marked? like a model name or something that could help identify what cells they are.
If they aren't complete crap I think that they could handle 2kw.
You need to look at the controller to see how much current the controller will pull,
in order to spec other components like BMS, wiring, nickel thickness, etc. correctly.
48V is usually 13 cells in series or 14 (I've always used 14) if they are a Lithium-ion type
Lifepo4 would be 16 cells in series since they are only 3.65V fully charged per cell as opposed to 4.2V with Li-ion
If they aren't complete crap I think that they could handle 2kw.
You need to look at the controller to see how much current the controller will pull,
in order to spec other components like BMS, wiring, nickel thickness, etc. correctly.
48V is usually 13 cells in series or 14 (I've always used 14) if they are a Lithium-ion type
Lifepo4 would be 16 cells in series since they are only 3.65V fully charged per cell as opposed to 4.2V with Li-ion
If you were to find a data sheet for that model of cell then i could help you determine the answer.
Batteries can have pretty huge variances in their output, capacity, lifespan, thermal tolerance, etc etc.
Also age can affect their performance ( capacity and power output decrease with time and/or with age ).
Batteries can have pretty huge variances in their output, capacity, lifespan, thermal tolerance, etc etc.
Also age can affect their performance ( capacity and power output decrease with time and/or with age ).
From-A-To-B
100 W
I suggest the OP replies with the information others have requested, so we can best help the OP with their project.
But, to put forward some generic maths about cell draw:
2,000W at 48V (13S, li-ion) is 42amps.
The OP has 122 cells available, which may be enough for a 13S9P battery.
42amps/9 cells per group = 4.67 amps per cell
Almost all 18650 cells will handle this load as a peak draw, and many will bear it as a continuous draw.
The battery project seems possible — I recommend the OP responds in this thread and takes advantage of the search function on the forum to learn how to safely assemble a new battery.
But, to put forward some generic maths about cell draw:
2,000W at 48V (13S, li-ion) is 42amps.
The OP has 122 cells available, which may be enough for a 13S9P battery.
42amps/9 cells per group = 4.67 amps per cell
Almost all 18650 cells will handle this load as a peak draw, and many will bear it as a continuous draw.
The battery project seems possible — I recommend the OP responds in this thread and takes advantage of the search function on the forum to learn how to safely assemble a new battery.
If they are lithium Iron Phosphate (LiFePO4), they would be charged to 3.6V (I think?). You would use 16 cells in series to get 48V (16S)
Common 18650 cells (18mm diameter, 65mm long), are Lithium Ion NMC or NCA, which can be longer if charged to 4.1V). For these, you would use 13 cells in series (13S)
Once you find the model number, the rest will be easy to figure out.
Common 18650 cells (18mm diameter, 65mm long), are Lithium Ion NMC or NCA, which can be longer if charged to 4.1V). For these, you would use 13 cells in series (13S)
Once you find the model number, the rest will be easy to figure out.
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Hi Everyone, thankyou for all of your responses and for all of your advice. It has been very helpful. I have measured the cells again I get 26mm across by 65mm long. And odd sized cell I am guessing? I have also cut the green plastic off some of the cells looking for markings. What I can find on a couple of cells are the letters SRHIHE in capitals. I have searched this word and letters and all I can see is that "Shihe is a district of the city of Xinyang, Henan province, China" I will keep on investigating and see what I can come up with. Also as I progress with this project I will be sure to post up some photos to assist others in their builds.
eee291
100 kW
26650 cells are less common than 18650. There are plenty of stores selling holders and nickel strips for this size battery.
From my experience Chinese 26650 cells are more likely to be lifepo4.
You still need a way to determine the chemistry though.
Observing the charge curve would be one method that I would use, but I have a battery tester that can draw the curve on my PC. Maybe the others here have a better approach.
From my experience Chinese 26650 cells are more likely to be lifepo4.
You still need a way to determine the chemistry though.
Observing the charge curve would be one method that I would use, but I have a battery tester that can draw the curve on my PC. Maybe the others here have a better approach.
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