Cheapest DC-DC converters. 650w for $100 you say?

[lazzer408]

Ok guys. Check this out. I've been playing with a 250w Thermal Take Power Express power supply. What this thing is, is an add-on power supply for a PC computer that fit in a 5.25" CDrom bay and provides 250w @ 12v regulated to power SLI or Crossfire graphics cards. 2 cards. A slot cover plate mounts in the computer to provide a 120v ac-in jack for a boom-box type power cable. This supply is normally activated when the main PSU turns on but if you don't connect the interface cable to the computer psu's atx connector, then it will always be on. It will power up with DC right to the ac input but it's better if you have the ability to open it and put your pack voltage straight to the main filter cap -after- the line rectifier. I've ran HID headlights as low as 48v input on the cap. Normally this cap sees about 150v. That makes 48-150dc input and 12v out but I would de-rate the output with voltages below 100v.

It's also fan cooled and ISOLATED and I've just discovered they make a 450w and 650 watt version!!!

Typical internet prices:

250w (rated 21a max) ~$50
http://www.thermaltake.com/product/P...0130/w0130.asp


450w (rated 30a max) ~$65
http://www.thermaltake.com/product/P...0157/w0157.asp

650w rated 30a max?) ~100 <---- 30a? It's twice as big as the 250 and 450 and takes up 2 bays.
http://www.thermaltake.com/product/P...0158/w0158.asp


This should make you guys very happy!

http://www.amazon.com/s/ref=nb_ss_gw...+power+express

[lazzer408]

I'm tracking down the feedback to try and get 13.8 out of it. This is on the 250w version I have. If anyone would care to donate one of the larger ones I'll figure it out as well and make a nice walkthru for you.

[JRK5150]

Wow! Would this actually work as a DC-DC converter? I was planning to run an alternator off the front of my motor, but this would be more efficient and nearly as cheap! If this works, lazzer408, you are the MAN!

[KiwiEV]

This is good news! Well done on your findings mate! This could save us all a bundle!

[lazzer408]

For my motorcycle, I use it at 12v without any problem. Why do autos still retain a 12v battery? There's no engine to start with it. Why not put the dc-dc on a switch and power it up first?

fwiw the HID heallight ballasts are regulating. It will attempt to draw 55w (or 35w depending on the kit) reguardless of the voltage. LED tail/stop/turn bulbs would be as bright at 12 as 13.8. You wouldn't notice much. But I'll continue to track this down for you guys.

Here's the inside of the Thermaltake 250w. Pardon my mess.

[Twilly]

There is a bunch for sale on E-bay right now, Just got mine...

[John]

Originally Posted by lazzer408

Why do autos still retain a 12v battery? There's no engine to start with it. Why not put the dc-dc on a switch and power it up first?

In a word redundancy. If your DC/DC converter goes belly up you're not going to suddenly go dark. You're lights will still work your vacuum pump will still work and your car will still run.

[lazzer408]

Originally Posted by John

In a word redundancy. If your DC/DC converter goes belly up you're not going to suddenly go dark. You're lights will still work your vacuum pump will still work and your car will still run.

I was thinking that's a good reason to keep the battery. Which is why I'll continue work on the voltage adjustment mods.

What would you guys like the voltage to be? 13.8? 14.2? Let me know that and I'll have this down to "Replace Rx with a x.xk resistor for xx.x volts"

[Twilly]

Doesn't an alternator charge at 14.4V?

[lazzer408]

Originally Posted by Twilly

Doesn't an alternator charge at 14.4V?

About. But that might not be an ideal float voltage. Depends on the battery I guess.