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Tim Gu

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  • 1000 W output power limit across the 4 channels, with max current 4 x 15 A.

PSU:

  • Corsair CMPSU-600CX V2 (I believe this is the one we’re using?)

...

  • At +12V, maximum load is 40 A, so this can supply 480 W of power.

    • If we want to charge as fast as possible we will need a convertor rated for 480 W

  • Assuming our boost groundside convertor supplies steps up 12V to 24V, with a power limit of 480 W:

    • If we charge 4 batteries at once, the current will max out at 5 A per channel (each channel is 120 W / 24V)

    • Alternatively we could charge 2 batteries at once with 10 A each.

Supermicro PWS-741P-1R

...

  • DC output: 740W, 12V/61.7A

What convertor to buy?

  • Suggestions from Jerry Tian and Ryan Scomazzon : Charger should be able to charge a 7Ah battery (most of our batteries have less capacity than that) at 1C. This means 7A per battery

    • If charging 4 batteries at once, charger must supply 4 x 7A at 24V = 672 W

COTS options:

  • AliExpress seems to have the most amount of options and is well priced (but might be a bit sketchy?I initially added higher power options here, but based on the maximum PSU load we may not need more than a 480 W convertor

  • Couldn’t really find anything good on Amazon or Facebook Marketplace

Product

Price

Specs

Ratings

Notes/

Features

Datasheet

Notes

Szwengao WG-12S2420M

image-20250121-024436.pngImage Modified

50.36

(AliExpress)

24V 20A

0-480 W

  • High efficiency: 96.6% (@12Vin, 25℃)

  • Non-isolated between input and output

  • 100% full stable current output

  • Support -30 °C environment

  • 100% full load burn-in test

  • OT, OL, LV protections

  • Waterproof level IP67

https://proa2427b-pic7.websiteonline.cn/upload/WG-12S2420M.pdf

  • Not enough power if we want to charge 4 batteries at once

Szwengao WG-12S2430M

image-20250121-024128.pngImage Modified

77.99 (AliExpress)

24V 30A

0-720 W

  • High efficiency: 95.6% (@ 12Vin, 25℃)

  • Non-isolated between input and output

  • 100% full stable current output

  • Support -30 °C environment

  • 100% full load burn-in test

  • OT, OL, LV protections

  • Waterproof level IP67

https://proa2427b-pic7.websiteonline.cn/upload/WG-12S2430M.pdf

  • Load is 672W, at 95% efficiency this convertor would have to handle ~707 W input power

    • Theoretically possible but it would be operating near its limit, would leave very little headroom

Szwengao WG-

12S2450M

12S2440M

image-20250121-023738.pngImage Modified
134

100.68 (AliExpress)

24V

50A

40A

0-

1200

960 W

  • High efficiency: 97.8% (@24Vin, 25℃)

  • Non-isolated between input and output

  • 100% full stable current output

  • Support -30 °C environment

  • 100% full load burn-in test

  • OT, OL, LV protections

  • Waterproof level IP67

proa2427b-pic7.websiteonline.cn/upload/WG-

12S2450M.pdf

12S2440M.pdf

  • More expensive than the 720W option

  • Load is 672W, at 97% efficiency this convertor would have to handle ~693 W input power

  • If charging 4 7Ah batteries at 1C, this convertor would be operating at 693W/960W = 72% capacity, leaving plenty of headroom