[JRK5150]

Wouldn't the ideal voltage be about 13.9?

[lazzer408]

Originally Posted by JRK5150

Wouldn't the ideal voltage be about 13.9?

Could be. I figured 13.8v because that's what alot of these ham radio etc power supplies are providing. Reguardless. First thing I have to do is find out HOW to adjust it. The sky's the limit once that's figured out. You guys can then adjust these things to whatever you want. =)

[JRK5150]

Hey, if it's easier to do 13.8 vs 13.9 go for it! I don't think anyone could honestly tell the difference without a meter. I just said 13.9 because I think that's the ideal, but I could be wrong. I'm just stoked you found these and shared! There will be one in my ride here soon!

[lazzer408]

Sometimes I regret not making a profit by buying a bunch and sticking my own label on it and selling them to you guys as dc-dc convertors. I feel that way every time I look in my wallet and look up to see my 1/2 built projects everywhere. But on the other hand, I get that warm fuzzy feeling knowing I may have just helped a whole bunch of EV'ers world wide who are trying to save every penny on their own builds. The needs of the many outweigh the needs of the few, or the one. =)

So, if your not helping the comunity what are you doing? I won't be a part of the profit-hungry-price-gouging-customer-raping companies charging 100s of dollars for a simple convertor that's only 50 bucks just because this one is used in another application. They think their the only ones on the planet selling these? See how they stick it to the EV comunity? They just don't want this to be affordable !!

/rant

[lazzer408]

Originally Posted by Lexus

I was reading somewhere ... that the Zilla Controller cost $300 to make ...

I wouldn't doubt it for a second. My argument is more along the lines of "acceptable profit to make a living" vs. "enough profit to fill my 10 garages with exotic cars that I'll never drive while the rest of the world suffers"

I can't wait for China to jump on the controller boat. It sadens me to say that. I wish I could count on an American company to offer me a good product at a good price. :Laughs at the though:

On the Power Express...

It uses a CM6800 Power factor correcting PWM IC. http://pdf.chinaicmart.com/CM6/CM6800.pdf I'm still tracking down the feedback loop. If it's as easy as v-in on pin 15 "Vfb" (voltage feedback) this could be easier then I though. On the other hand it's opto-isolated so there's that circuit to map out to figure out how the output gets back to that pin. I may just try pulling pin-15 lower with a resistor to ground. It's only 1.8v more volts I'm after. The other chip is an LM339 quad comparator. I know for a fact 2 of the comparators are used to drive each of the 2 status LEDs that light when there's a load on either of the "2" outputs. It's really only one 12v rail with 2 shunts to 2 outputs. Just for LEDs? Seems excessive. The other 2 comparators I'm not sure of. One of them might be for the power-on signal handling from the computer's ATX PSU. :shrugs: I should have this figured out by tonight. Dinner time!

[lazzer408]

14.2v close enough?

This is one method of modding a thermaltake power express 250. Solder a 27k ohm resistor across the smt resistor as shown for 14.2v output. 33k will get you 13.7v output (#1). This lowers the voltage on the tx side of the opto isolator. It now takes a higher voltage to produce the signal it's expecting. 14.2v to be exact. This converter has over voltage protection. I'm not sure how far it can be pushed before shutdown. It is also power factor correcting. Please note that you SHOULD NOT apply your pack voltage to the main capasitor!!! To connect your pack voltage, unsolder the bridge rectifier and make your connections to the + and - terminals (#2). Anything between the rectifier and the ac input can be removed if you like. When in operation there could be 400v on the large main cap. This is due to the boost converter used for pfc in this converter.

[lazzer408]

Update:

The 27k is about the best solution I have for now. Any wattage is fine. 1/8w is plenty. I added a pic to show a 1/4w resistor correctly soldered on. I know there is a bridge between the other smt resistors but that's ok because there connected anyways. I'd would have rather done the volt mod at the IC level. That would have probably worked for the 450 and 650 versions as well IF they used the same pwm controller. For now this is fine. Voltage is very stable at 14.2v +/- 0.02v. To power a 55w HID headlamp, it was drawing .62a off a weak 120v pack. It's drooping to about 110v. so 110x.62=68.2watts input for 55 watt output. Not to bad. Just over 80% efficient. It surprisingly ran off 48v as well with closer to 2 amps draw or 96w in for 55w out or ~57% efficient. -yuk- Point is it's stable with seriously varying input voltage.

If anyone wants to send me a 450 or 650 I'll figure it out too.

[Qer]

Originally Posted by lazzer408

Sometimes I regret not making a profit by buying a bunch and sticking my own label on it and selling them to you guys as dc-dc convertors. I feel that way every time I look in my wallet and look up to see my 1/2 built projects everywhere.

The bad thing is that then you'd get all the complaints too, like if it behaves like an ordinary PC-PSU it'll shut down hard if overloaded instead of gracefully step down to limit the current. Now it's "as is" and you can have the fuzzy, warm feeling without complaints or warranty cases.

Good find though. One of those will be perfect, whenever I get to the building stage...

[DVR]

Brilliant idea!!
I must confess tho, that while I'm fairly handy with a soldering iron, and am pretty adept at following instructions like the ones above, I cant follow the tech talk it's like a foreign language

If you do these mods as described here, are you saying that these will do the job of a $300 DC/DC converter?
What would the max output in amps be without stressing the thing?

[favguy]

At the risk of bieng naive, why do we need DC to DC Converters at all? I'll tell you my logic, DC to DC uses power from the main pack and therefore reduces range, range is very important as the range of most EV's is 80 miles at the very most, so with this in mind, is it not better to do as I plan to and have a larger capacity 12v deep discharge battery capable of providing for all expected 12v running load (allowing a sensible factor for diversity) for a period of say 3 hours to a depth of 70%? I've worked out that around 100Ah will do this for mine.

By this time the main pack needs recharging anyway, so the 12v gets charged at the same time as the main pack?

Just my twopence worth...