Can I use my PSU as a 12v battery charger?

[TheNiceGuy]

Hi all

I am getting this battery charger:
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=5548
I'll use it for lipos. Instead of buying the extra 12v 5a plug, I was wondering if I could use my extra PSU. The charger comes with alligator clips to run on a car battery. Could I hook these clips up to the PSU 12v output?

Thanks!

 

[BassBomb]

I don't think so... I doubt it will have enough amps

 

[PottedMeat]

Should be fine, you will have to trigger the ATX supply with a wire and may need a load across one of the rails for it to work correctly though.

this site says 10 ohms across the +5V rail should make it stable: http://web2.murraystate.edu/andy.batts/ps/powersupply.htm

 

[Evadman]

I don't think so... I doubt it will have enough amps

:confused; My PWS puts on the 70 amps on the 12v rail. My small 12v charger puts out 2/10/50, though at about 13.8v. According to that site, the charger will pull 50 watts max, or about 4 amps. From a pure amperage standpoint, there will not be a problem. A standard ATX PWS can be forced on by shorting the green and any black wire together. There will generally be issues though as most PWS's need a semblance of balance on the 5v and 3.3v rails though. They will complain (though crappy voltage control I believe) if there is no load on the 3.3 and 5v rails.

The charger will take 11 to 18 volts so 12v is within range. I believe it will work, but a resister (pack) will be needed on the 3.3 and 5v rails. They commonly come as a PWS tester. I have one like this: http://www.mcmelectronics.com/product/TENMA-72-1082-/72-1082

 

[BassBomb]

I thought he was trying to charge his car battery? And most PSU's dont do close to 70A 12V

 

[TheNiceGuy]

Thanks guys.
I only need 6a MAX to the charger. Is there a way to use the PSU without having to buy anything fancy? Would shorting the G/B wires provide at least 6a in output?

I can get a dedicated 12v 5/6a plug with shipping for $20. Just thought I could save some coin and have some fun using my junk.

Forgot to mention - bit disjointed but - I have an old MB I dont use too. How about using that as the resistor that Evadman is mentioning?

 

[Jeff7]

The charger itself might put enough of a load on the power supply to start up properly.

I've got something of a similar charger - a Triton battery charger.
I run it off of a simple 12V power supply. If I turn on the supply without anything attached, it won't power up properly, but if it's turned on with the Triton attached, that's enough to start up the supply normally.

I'd say to hook up the charger to your power supply and give it a shot. I just looked up a cheap 350W power supply at Newegg, and it puts out at least 10A on its 12V line.


Concerning loading the 3.3V and 5V lines, a power supply tester might not be an ideal solution due to heat buildup. The tester I have says specifically that it shouldn't be left connected continuously. This may depend on the specific tester being used; the one I've got uses simple power resistors as a load.
An old motherboard might do the trick just as well though, but I'm not sure what the loading would look like if it's got nothing on it, like a processor or RAM.

 

[TheNiceGuy]

I have cpu and ram if required...

 

[TheNiceGuy]

obviously not an expert. SO do I put the positive clamp on any yellow wire, and the negative on any black wire?

 

[PottedMeat]

obviously not an expert. SO do I put the positive clamp on any yellow wire, and the negative on any black wire?

Yeah, yellow = +12V and black = ground.

As for the load, got any 5V fans? Though you may be able to just go to Radio Shack and pick up a fat 10 Ohm resistor.

like this: http://www.radioshack.com/product/in...ductId=2062291

 

[bobsmith1492]

It won't charge much. Typically you use 13.8V to charge a car battery. It won't hurt anything either, though, unless the battery is dead in which case that is a lot of available current. It could vent some hydrogen from the quick-charging. I'd keep it in an open area so any gas can escape.

 

[Check]

To answer your question, yes you can charge the battery with your power supply.

However, you should not do it.

Battery chargers have a current limit to protect the battery, something your PSU doesn't have. Charging the battery too fast will diminish the lifetime of the battery and cause it to go soft faster (i.e. it won't hold a charge).

If you plug the depleted battery into your PSU, the power supply will rail the battery with as much current as it can until the battery voltage reaches 12V. Once the battery is at 12V the current will drop until the battery is fully charged.

I deal with single cell li-poly batteries at work and we limit the current to 200mA on our power supplies so we don't fuck them up.

 

[TheNiceGuy]

Thanks guys, but I think some of you dont understand my plan. I am using the linked charger to charge batteries, largest is 2200mah. I don't have a 12v 5a power adapter/cord, so thought of the psu. The car battery reference is from the ability of the charger to draw power from a 12v car battery, not viceversa.

 

[EliteRetard]

As long as the charger is smart enough to shut off power to the battery once its done charging, or if you just go unplug it after and hour or two, any old garbage PSU will be perfect...probably dont even need a MOBO hanging off it. Ive got an old 350w no name PSU that came bundled with a case, it was to f-ed up to run a computer, but it works perfect for running a 12v water pump for a few hours. Nothing else hooked up, just the PSU into the wall, a jumper on the green and black wires (paper clip in the ATX 20/24 pin) and the water pump stuck on a 12v rail. I just use the switch on the back of the PSU as the on/off switch for the water pump.

Dunno what everyone else is smoking...

 

[TheNiceGuy]

Is there any danger to my lipo charger?

 

[PottedMeat]

Is there any danger to my lipo charger?

Input Voltage: 11~18v

you'll be fine. unless you hook it up backwards or something.

 

[Throckmorton]

It would be easier to just buy a charger with a built in AC-DC transformer.

 

[Modelworks]

Don't worry about it, you are fine using an ATX supply. I have used them for everything from car audio to powering electroplating. The charger you are using only needs 5-6A at 12VDC. If the supply starts and works okay with just the green and black wire connected you do not need the load on 5volt either. Every supply I have seen in the last couple years already has dummy loads attached to the outputs.

 

[TheNiceGuy]

Thanks guys, appears to work, although have not tried any batteries yet. Needed to connect green/black wire with paperclip.
Is this all safe to be used for a few hours at a time? Can I touch any of the exposed wires (yellow/black, green/black, paperclip) with no risk of shock? Any dangers to be ware of?

It is cool, looks a bit like Frankenstein. I'm using alligator clips on 4 exposed wires (2 yellow together, and 2 black together).

 

[Modelworks]

Is this all safe to be used for a few hours at a time? Can I touch any of the exposed wires (yellow/black, green/black, paperclip) with no risk of shock? Any dangers to be ware of?

You can touch the wires and provided you are not sweaty or wet nothing should happen, but don't get into a habit of doing things like that , try to assume that any exposed wire that is connected to a power source could be lethal.

It is safe to run it as long as needed. The PSU doesn't care what it is powering, it doesn't discriminate

 

[Evadman]

assume that any exposed wire that is connected to a power source could be lethal.

Good advice. If something goes horribly wrong in the PWS, it is possible any output wire could see wall voltage.

 

[TheNiceGuy]

Thanks guys! I actualy charged 2 batteries with it - works awesome! I will tape up all exposed wires. Its amazing it works. I have monkeyd conectors all over the place!
I kept checking all wires, nothing got hot or even warm at full charge power. Only the charge unit did (which it should, its basicaly a big heatsink).

Thanks again!

 

[ModestGamer]

Good advice. If something goes horribly wrong in the PWS, it is possible any output wire could see wall voltage.

its possiable but very unlikely. the diode would likely blow on the decoupling transformer before such a thing would happen.

 

[Modelworks]

its possiable but very unlikely. the diode would likely blow on the decoupling transformer before such a thing would happen.

I'm from the old school where I was taught to never work on anything live with both hands. I still get asked why I keep one hand in my pocket or behind me when working on things. I've worked with voltages that jump several inches to skin so it made me paranoid but in a good way.

The important thing is not to consider how much voltage is on a wire before you touch it. first thought should be , is it connected to something that is generating power, not how much or what kind.

 

[Modelworks]

Thanks guys! I actualy charged 2 batteries with it - works awesome! I will tape up all exposed wires. Its amazing it works. I have monkeyd conectors all over the place!
I kept checking all wires, nothing got hot or even warm at full charge power. Only the charge unit did (which it should, its basicaly a big heatsink).

Thanks again!

I used a PSU to replace about 6 wall adapters . Now instead of having to power router, cordless phone, voip adapter, usb hub, modem, phone charger from a bunch of adapters , I just have the one thing to plug in. I just added plugs that fit the various devices. Most devices are 5 or 12 volt anyway.