Zero PWM

[HHO_Control]

Any one use or have a comment on the CCPWM v2.1 made and sold by Zero?

http://alt-nrg.org/store.html

[HHO_Control]

How much do your PWM's sell for? Do you have a web page?

[HHO_Control]

Never mind. I found your page..


How does this EFIE compare to yours? The FS2 Quad Digital EFIE Basic is what I am look to purchase very soon.

http://www.fuelsaver-mpg.com/store/index.php?main_page=product_info&cPath=77&products_id=196

also info here
http://hydrogengarage.com/volo.html

[Philldpapill]

Shane, just curious... How are you able to handle 150A continuous??? The wire you seem to be using looks like 8AWG(?). I mean, you CAN make a PWM to handle that much current, but where are you getting your ratings from? Just because a MOSFET's maximum ratings are 150A, does, by no means, mean you can(or should) get near them. Generally, derating to 1/4 of the stated maximum value(with good heat sinking and dissipation practices), is a bit more safe. I've seen this design before, and I don't doubt that it works at lower currents, but stating the CONTINUOUS rating of 150A doesn't seem correct. I mean, if at the very least, the insulation on your wires would melt off at those power levels.

I'm not trying to bad mouth your product - many people have bought it and I have yet to see a complaint. However, it might be a little better to derate it considerably... It's far better to say a product can 100% reliably work under such-and-such conditions, rather than risk it and over-rate your product just to sell more(and then have some fail dangerously).

Based on the MOSFET specs, it might be better to rate this for 75A continuous, in an open-air surrounding, with 150A surge. That 150A surge being peak currents, and not a sustained surge for more than 1 second... I say this because I'm designing a power supply(not just a PWM), and I know some people that buy a product sometimes say "ahhh they SAY 100A, but I'm sure they just underrated it... Let's try 150A and see how it does!!!". The next thing you know, you've got a lawsuit because some dumba$$ did something stupid and you didn't put enough headroom in for the idiot-effect.

Just my two cents. Again, I don't doubt the design, but some people always try to push stuff beyond what you stated, and it might be better to allow more room in there to compensate.

[Philldpapill]

Just curious, doesn't that capacitor get blazing hot?

[Philldpapill]

No, no, no... Not due to the wire, but from the ESR of the capacitor. If you are dealing with >50A, you are going to have some serious ripple currents. Any inductance from the wires going from the battery/alternator/Load, will only make the ripple currents even higher, causing even higher power dissipation with the capacitor. I mean, it's fine if your cap doesn't reach it's temperature limit, but I'm just curious if it actually gets "hot" to the touch after running for a while.

[Philldpapill]

Yeah, I saw the specs for the same capacitor you have in your pictures. It is "low ESR", but I've been having a similiar problem with my own design, so that's why I was curious. I, however, am using a bunch of 1,000uF caps in parallel on a PCB. It's a little cheaper, and I THINK the total ESR is actually lower by a factor of 10. In addition, there is more surface area in total for power dissipation.