wanted: psu with little crossload for 12volt output bench supply, PS powerTek == crap

[davidl340]

I bought this little jewel:

http://images10.newegg.com/NeweggImage/productimage/17-713-001-05.jpg

From newegg for a whole $20!!! it had 5 star review!

OK, I learned my lesson, and a lot about PSU over the last few days. This thing turned out to be a POS.

What I need: a power supply that I can convert to a bench/field 12volt supply to run my large RC airplane battery chargers. I've already figured out I need a certain amount of load on all rails typically to have decent stable voltage. With the above unit, with quite a large load (I forget the exact ceramic resistor I used) I would drop below 10.5 volts at 8amps on the 12 volt rail, and even with a rediculous load, it was not stable.

SO, What do you recommend for an affordable PS that can handle at least 20 amps (preferrably 28) on the 12 volt rail/rails that isn't killed by crossload. PFC is not necc. Since this will be exposed, bling doesn't hurt. The goal here is to have a little fun converting it and stay under the price of a commercial 12volt power supply. Cheaper the better, but not so cheap I'll fry my expensive chargers, and not as cheap build as that crap above.

Here's one:
FSP Group (Fortron Source) AX400-PN
http://www.newegg.com/product/product.asp?item=N82E16817104953

SPARKLE ATX-300PN-B204 ATX 12V 2.0 300W Power Supply
http://www.newegg.com/Product/Product.asp?Item=N82E16817103011
another sparkle
http://www.newegg.com/Product/Product.asp?Item=N82E16817103012

budget silverstone:
http://www.newegg.com/Product/Product.asp?Item=N82E16817163110

[davidhammock200]

Just go to Allied or somewhere & get a bench PSU or a battery charger.

Why are you trying to convert an ATX PSU in to a battery charger? :crazy:

[jonnyGURU]

What I need: a power supply that I can convert to a bench/field 12volt supply to run my large RC airplane battery chargers. I've already figured out I need a certain amount of load on all rails typically to have decent stable voltage. With the above unit, with quite a large load (I forget the exact ceramic resistor I used) I would drop below 10.5 volts at 8amps on the 12 volt rail, and even with a rediculous load, it was not stable.

8A is a pretty hefty load for any PSU without having at least a 2A load on the 3.3V and 5V rails.

Battery chargers are cheap and don't crossload. ;) I'd just get one of those.

[davidl340]

I'm not converting the PSU into a battery charger, I'm converting it to a 12 volt power supply to run electrical equipment. You just can't just buy a car battery charger at walmart to charge these batteries. I need 12 'clean' volts to run the equipment, and have been running it fine with a 135 watt PSU up to it's maximum 12 volt advertised amperage no problem (with a load on 5 volt side).

I could just go buy a bench power supply.
$99 for 25 amps or I could buy a $40 PSU that handles crossload and convert it and have a little fun, people do this all the time in this hobby.
http://www.radioshack.com/product/index.jsp?productId=2103961&cp=&origkw=power+supply&kw=power+supply&parentPage=search


Johny, some of your test are showing only a 4 amp on the 5 volt and 3.3 volt side to keep the voltage above 11.5 and that is at 30 amps on the 12 volt on the particular review I read, (I don't plan on pulling any more than 15 amp to begin with). All I need is above 10.5. I bet if you ran some tests with less amperage on the 3.3 and 5 side you'd keep the 12 above 10.5 volts to run the equipment.

Being the PSU experts, can you recommend a PSU that handle crossload and can put out 25 amps on 12 that is less than $50.

[jonnyGURU]

Back when 135W was the norm, independent voltage regulation was cheap and easy.

Now with higher wattage units, that's not the case. So the higher output the PSU, the less likely it's going to have independent voltage regulation. Never mind a unit for $50 or less.

Meanwell makes some +12V PSU's that a lot of guys I know use to charge RC car batteries. But even those are more than $50. ;)

You get what you pay for.