ATX power supply for charging

[bundydeity]

I'm wanting to mod an ATX power supply for charging my packs at home. I currently have the PL8 and was using the e-fuel power supply, however having problems with the power supply. my backup is using a marine battery however this is not as convenient.

I've been given an 18A 420w total ATX power supply, I want to mod this to replace my e-fuel. most of the videos and info is instructions for adding posts, or banana plugs etc - however all I want to do is replace the bundle of cables with an EC5 connector and a switch if need be to signal on/off
can someone help me configure this? from the link below it seems to me all I need to do is solder 3 or 4 of the +12V wires (yellow) to positive terminal on the EC5 and 3-4 of the common (black) wires to negative on the EC5
will this pull the full 420w though? or do I need to use all of the yellow wires (there is 13 or 14 of them in the bundle)

at the moment most of my charging is single packs 3s 2200mah packs at 3c - (6.6amps), smaller 2S packs and less often my 6S 5000mah at 3c (15amps)

if I don't reach the full 15A its no big issue. 10A I'd be happy enough, but 15A would be better. any suggestions for the on/off signal, or the 5v draw other than an automotive light? maybe I can hook up a spare servo for 5v draw? looking for a really simple solution...

http://www.marcee.org/Articles/PCPowerSupply.htm

[Larry227]

I know if it doesn't come on when you plug it in you need to jump a black wire to the green one. I believe it only has to be momentary. It's been a long time since I used an atx supply. They never lasted long for me. Better off getting a used server power supply.

https://www.helifreak.com/showthread...power+supplies

[19trax95]

I don't think that supply is going to cut it unless your charging smaller 3s or less packs.

Don't forget that if your charging say a 6s pack, and only inputting 12 volts to the charger, your current draw will be twice (higher actually since the charger isn't 100% efficient.

For example. When I charged my 5000mah 6s off a 12v supply, I charged at 5 amps. But my charger was pulling around 11-12 amps if not a but more from the power supply.

[Slyster]

www.feathermerchantrc.com

[Xrayted]

Originally Posted by bundydeity

I'm wanting to mod an ATX power supply for charging my packs at home. I currently have the PL8 and was using the e-fuel power supply, however having problems with the power supply. my backup is using a marine battery however this is not as convenient.

I've been given an 18A 420w total ATX power supply, I want to mod this to replace my e-fuel. most of the videos and info is instructions for adding posts, or banana plugs etc - however all I want to do is replace the bundle of cables with an EC5 connector and a switch if need be to signal on/off
can someone help me configure this? from the link below it seems to me all I need to do is solder 3 or 4 of the +12V wires (yellow) to positive terminal on the EC5 and 3-4 of the common (black) wires to negative on the EC5
will this pull the full 420w though? or do I need to use all of the yellow wires (there is 13 or 14 of them in the bundle)

at the moment most of my charging is single packs 3s 2200mah packs at 3c - (6.6amps), smaller 2S packs and less often my 6S 5000mah at 3c (15amps)

if I don't reach the full 15A its no big issue. 10A I'd be happy enough, but 15A would be better. any suggestions for the on/off signal, or the 5v draw other than an automotive light? maybe I can hook up a spare servo for 5v draw? looking for a really simple solution...

http://www.marcee.org/Articles/PCPowerSupply.htm

Its simple to calculate what the max values will be for your setup. The system will be limited by the max watts or amps, whichever limit gets hit first.

Amps X Volts = watts, so in your case a 2200 mAh 3S pack is 12.6V X 6.6A(3C) = 83 watts, so well within your 420 watt limit. The 6S 5000 mAh pack would need 378 watts at 3C which would be cutting it close since there are always losses and you never really get the full 420 watts, but would allow for a 10% loss and still be good.

The other limiting factor is Amps which is Watts/Volts so 420/12.6V = 33 amps, so well within your 6.6A needed for the 3S packs, however the 6S pack would be 420/25.2 =16.6A max, so once again cutting it close after any losses are taken into consideration, but within a 10% loss limit.

Bottom line, its a marginal setup but should get very close to what you state you want it to do for the 6S packs, but will have no issues at all for the 3S packs.

[whitehedr]

ATX power supplies provide power at several different voltage and current levels. The total wattage spec for your supply will be devised amongst these different voltages. Older supplies had more power allotted to the 5 volt rail while newer supplies have more power allowed to the 12 volt rail.

While surplus ATX supplies are plentiful and cheap so are surplus server supplies. The server supplies are definately better for what you want to do and there is a huge amount of info on what needs to be done to get them up and running. RCGroups has a great thread on the use of server supplies.


http://www.rcgroups.com/forums/showthread.php?t=1005309

http://www.rcgroups.com/forums/showthread.php?t=1292514

This is the supply that I bought. I have two of them connected in series. They are superb supplies, very powerful and quiet. They are also easy to modify to allow the series connection. I got two of them for what this one is selling for. Bargains are out there. Shop carefully. http://www.ebay.com/itm/HP-DPS-1200F...3D281064382790

[jgiannakas]

Echo the same.
PC power supply won't cut it. They need to be loaded on the 5v rail and they output much less stable current at 12 V compared to server power supplies. I've bought myself a pair of HP DPS 600 pb power supplies, used the RCG instructions to float the DC on the second one and hooked them up in series. In under 1h work and with less than £50 ive built a 1100watt power supply that can output up to 48 amps at 24V. For your PL8 I believe you can setup 3 in series for even more current and power (1700 watts!).

Super simple and super cheap. It's not worth even experimenting with the PC power supplies...

How to power it on:
http://www.rcgroups.com/forums/showthread.php?t=2371780

How to convert one of them to run it in series:
http://www.rcgroups.com/forums/showthread.php?t=1581061


http://www.ultimaterc.com/forums/sho...d.php?t=174225

[Creaky Cactus]

I built one a while back from an old discarded PS for no very good reason. It works well. I don't use it since I've got lots of 12V supplies. I even added 4mm banana plug receptacles and managed to put a power switch in the hole where all the wires used to exit.

[Aryemis]

I have one, but it's used for to power a portable fridge now (the small laptop l like PSU's kept dying because it was working 24/7).

I used all the yellow and black wires for the heck of it, but it's probably not needed. I did have to put two 5W ceramic resistors (in series) on the green wire to keep it powered on.
As for the on-off, I just use the integrated AC switch at the back of the PSU.

It's an old no name PSU though, so it did the job for my Accucel-6, but didn't have enough power for my 306B, so that one has a server PSU powering it.