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  1. #1
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    BIG power supplies are cooking...

    Alright, guys, I am looking into building very powerful and very cheap supplies. I currently have two dell 700 watt 2850 server power supplies (no internal pots for voltage ) and I am looking at building myself a 120 amp 12 volt power supply out of them. Now, these are originally run with redundancy in the servers, so I want to run them in parallel. They have a +12v current share which I am fairly certain is the communications between the two supplies to equalize the load for redundancy. So, if I connect each of the psu's +12v share to each other they should share the load (based on the name) and connected in parallel should give me 120 amps (psu's are heavily underrated in the server world) To connect them I am planning on using the 2 12awg outputs each psu has and connect them to a power distribution block. (buss bar) I am thinking that stainless steel bolts, washers ring terminals and nuts should be enough to transfer the current. I use this method for speaker terminals in high powered car audio (15,000 watts on the subwoofers) So, 1200-1500 (theoretical) watts shouldn't be a problem. Now, is my plan bone-headed or am I thinking clearly (finals are awful) because, I am hoping to be able to power all of my friends chargers, or all of my local track from one system instead of having those 16 awg ungrounded 20 year old extension cords that they use. Any input is gladly accepted, along with negative feedback.



    I would recommend getting HEAVY duty input wires for the power supplies. My dad works for ATT's datacenters and grabbed 2 unused 15 amp 240volt server cords for me. I have heard of computer cables melting and shorting out when used with smaller supplies.
    I reject your reality and substitute my own!

  2. #2
    RC Champion
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    It's maybe best to find out what is getting charged before making the supply.
    5 people charging 2s batteries would be suitable for 12V with X amount of amps.
    5 people charging 3s batteries would be more suited to 24V with X amount of amps.
    The more current current going through the cables the hotter things get.
    Guide books aren't part of the packaging.

  3. #3
    Marshal ksb51rl's Avatar
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    The PS for the PowerEdge 2850 is rated at 10.1A input. For ONE unit almost any power cord would suffice. For 20A input (two PS) a cord with at least 16awg or preferably 14awg conductors would be better to use.
    Alt-248 on the number pad =

  4. #4
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    As of right now, most of them are charging 2s and 3s, while I am charging 5s. I would love to be able to have 24v for myself, but I have the 106b+ which can't do high voltage. It somehow boosts the voltage with more amps. (small field mouse on a wheel connected to an alternator would be my guess...) so, 12v it is. Some of my friends still have the small 50 watt limited chargers regardless of how much I complain. I have looked at this again and my thinking is correct, they will supply identical amperage and voltage to the source. I am going out to home depot for the hardware and a new case in a few minutes, hope to have this done pretty soon.
    I reject your reality and substitute my own!

  5. #5
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    I somehow got a piece of wire or solder in the supply and it will run for a minute, but shuts down after 5 seconds. So, I have gutted one of the cases and am turning it into a discharger with the monster fan and several heatsinks with LM317t voltage regulators as the load. I will look into building another monster in the future, but for now 60 amps will suffice.
    I reject your reality and substitute my own!

  6. #6
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    I would talk to Jimmy Nuetron and see if he has any ideas he is pretty slick with this stuff...
    Let's Go Steelers!!!... KCCO

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