1S2P 48V Battery in a Server Rack Case

Delphinus

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I'm building a battery using a rack server case to put inside a cabinet it will be a 10.75Kw using 32 EVE LF105 in 1S2P configuration with JK BMS, will try to show the steps has I progress.

I have one doubt that would like to know your opinion since this is my first and I never installed a similar BMS.

I plan to put the battery inside a closet of my office, do I need to ventilate because of heat from BMS or cells?

This is the first test to see if they fit, I would prefer 2 rows but case is 10mm shorter.

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I will compress cells with 5mm blue steel, 10mm aluminium or steel is too expensive and 10mm steel like EVE recommend in my case that uses 4 rows would weight 18,68Kg :)

Because of weight battery will be assemble in final location and won't be moved but since this is a rack case all panels can be removed except the one of the bottom that support the weight of the cells.
 

Delphinus

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"I plan to put the battery inside a closet of my office, do I need to ventilate because of heat from BMS or cells?"

Can someone help me with this question? Max load will be 0.5C
 

Delphinus

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Bus bars are ready a bit overkill 20x3mm but I had to buy a full bar so went with this to use the remain in next project.

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The best way I found to de-burr the holes was with a center drill, just a light touch using a drill press.

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Delphinus

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Ready for first discharge, wires are a mess because I have to disassemble cells before move battery to final destination so no point in fix it.

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JoeHam

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"I plan to put the battery inside a closet of my office, do I need to ventilate because of heat from BMS or cells?"

Can someone help me with this question? Max load will be 0.5C

Heat is unlikely to be an issue at that C rate but I would monitor it at first to confirm.

A simple small fan with a vent above or in the top of the closet door should easily solve any unlikely problems though.
 

Delphinus

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Heat is unlikely to be an issue at that C rate but I would monitor it at first to confirm.

A simple small fan with a vent above or in the top of the closet door should easily solve any unlikely problems though.
Thanks for the replay, this my first build and I didn't know what happen regarding temperature, I don't want to drill an hole for the fan because closet is Sequoia but inverter is in the attic and I have to drill the concrete for the cables so will drill a bigger to try to vent by convection, it doesn't work will put a fan to help.

Closet will have a fire extinguisher and sensors.
 

Delphinus

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210Ah, have an 30A electronic load, done the math but forgot the voltage, it won't take a few hours to discharge but 37H30 and housekeeper tomorrow will need laundry room clean to work :unsure:

Discharge at 5.6A but BMS report 5.3A, I disconnect balance to see if any 2P deviate from the others.

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Delphinus

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First discharge to know the real capacity, the real value is a bit higher than the displayed since 1/3 of discharge was made without calibrate A in the BMS.

Made it in 2 steps until 3V cell and 2.5V balancer off.

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Delphinus

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Battery is done, since the second BMS arrive I return to the original plan and build 2 to have full redundancy.

Here are the photos without front panel to test temperature, at first I didn't connect correctly the cables got a voltage drop of 0.3V between left and right, last photo have it fixed and now both have same reading.

When I build another probably will use install terminals to fix the the power cable on the outside

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Delphinus

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Very old Enlight EN-8950 with more than 20 years, strong but to use in landscape need to be in a flat surface, in vertical won't have problems since area is smaller, clearance to the top is less than 1cm so for LF105 and similar height strong good case should do.

EN-8950
 

Delphinus

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Heat is unlikely to be an issue at that C rate but I would monitor it at first to confirm.

A simple small fan with a vent above or in the top of the closet door should easily solve any unlikely problems though.
Thanks for your help you are right, have been using the battery for the last 3 weeks and until now only 3-4 degree over ambient temperature with cabinet closed and lids in the box.

Meanwhile decide to run it without front lid because box acts has a faraday cage and reduce Bluetooth range.

Later I will cut a window in the front lid and put a plexiglass sheet to have the box closed.
 
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