A better alternator delete

[Daox]

I received my output DC-DC buck converter. This thing is rated at 20A and I can see why. The heatsinks on it are quite beefy. The reviews say it doesn't get very warm. That will certainly be put to the test as the Mirage with headlights and heater blowing pull nearly 20A from the battery according to my ammeter in the car. This converter has constant voltage and constant current adjustments.

[UFO]

Originally Posted by Daox

I received my output DC-DC buck converter. This thing is rated at 20A and I can see why. The heatsinks on it are quite beefy. The reviews say it doesn't get very warm. That will certainly be put to the test as the Mirage with headlights and heater blowing pull nearly 20A from the battery according to my ammeter in the car. This converter has constant voltage and constant current adjustments.

Have you checked the conversion efficiency? The heat sink will help, but perhaps it generates less heat due to an efficient design.

[Daox]

That is quite possible. I have not hooked it up yet to try it out. The listing says up to 95% measure at converting 24V to 12V at 20A. However, I am not too trusting of that info.

[Daox]

I was wrong!

I took a closer look at my power usage on the Mirage these past few days. It looks like the single 20A dc-dc output converter may not handle 100% of the load all the time, even at max output. The engine running uses about 6.5A. Turn the headlights on and it jumps to very near 20A (total draw). The fan on low pulls 2-3A and another 3 on full blast. So, I may have to look at a more powerful unit (which I've not been able to find yet) or running two in parallel which I'm not crazy about.

[teoman]

Why not?

More surface area better heat dissipation.

[Piotrsko]

I'm pretty sure that 2 buck converters won't play well together particularly if they aren't isolated outputs. There is a need for impedance and capcitance that will be halved and may fall out of specifications.

[Daox]

I got the hardware for the packs. So, I printed another test. The previous plates were designed for a smaller threaded rod, but this 6-32 was actually a good amount cheaper than the 4-40 rod I had designed it for.





So, new plates were printed up. I assembled things and it went together quite well. Once the threaded rods are in place the assembly is very sturdy.







I am seeing that it'll be difficult to print such a large flat plate on the 3d printer. When you print these pieces, they're warm plastic. As the print continues the plastic cools off which makes it shrink. This shrinking ends up making the print potato chip and peel itself off the table. It'll be interesting to try to get this to print correctly. The test plates came out okay, but did start peeling up which distorted things a little.

[oil pan 4]

Why not run the blower power straight off the battery?
It won't be as strong but it should be enough.
There's also 7 cell lead acid race batteries.
That 7th cell keeps voltage under load close to what you get with a running alternator. But it needs a specific charger.

[teoman]

Put a cardboard box over your printer. That will provide thermal stability to stop warping of the parts.

If you have delamination you may need to up the extrusion temperature.

[mpg_numbers_guy]

Originally Posted by Daox

I was wrong!

I took a closer look at my power usage on the Mirage these past few days. It looks like the single 20A dc-dc output converter may not handle 100% of the load all the time, even at max output. The engine running uses about 6.5A. Turn the headlights on and it jumps to very near 20A (total draw). The fan on low pulls 2-3A and another 3 on full blast. So, I may have to look at a more powerful unit (which I've not been able to find yet) or running two in parallel which I'm not crazy about.

Time to get LED headlights!