Today I’m looking at the DC-DC converter from Thunderstruck motors and EV Parts. I purchased mine from thunderstruck and was only 30 dollars to my door. The unit is pretty small at about 3 in x 3 in x 1.3 in and weighs only (I’ll fill this in later). This converter is rated for 20-60 volts input with 12 volts at 10 amps out. It is a non-isolated converter meaning it doesn’t create a new ground but instead shares the ground with the rest of you scooter. I wanted to use this converter to run two lights on my 36 volt Stealth so I can easy ride at night with out carrying another battery. I plan to have a total of about 50 watts being used but I went ahead and tested this converter to about 80 watts.
Overall the quality of unit’s case is pretty nice. The case is made from cast aluminum and is covered in heat sinking fins. There are two mounting holes, one of mine was not fully drilled out but that’s an easy fix. The wire on this unit is actually of better quality with a fair amount of strands and a softer casing making it much easier to use. Originally it came with a connector but I cut that off. The bottom side of the controller is fully potted, I’m pretty sure it is waterproof which is always nice.
Standby and voltage output
Okay this is what’s important on a DC-DC converter so let get to it. All testing is done with a fully charged 36 volts lead acid battery pack. Yellow wire is output, Black ground, and red input.
So I hooked it all up and the first thing I noticed is this unit has a big capacitor charge up, quite a spark each time it is connected but it not really measurable on my meter when set to max, so it’s fast. The no load current is only 6 ma at something like 38 volts so this could stay on connect to you batteries all the time if you wanted. Output at that time is just under 12 volts at 11.89v.
The chart below is show input voltage, input wattage, output voltage, output amperage, and output wattage:
As you can see the converter does pretty good up to about 6 amps and then realistically from there you’re taking a 20% if not more loss. I didn’t want to really push the converter too hard so 7 amps was my limit, but it is rated for 10 amps. The voltage drop is sort of significant since it started out at under 12 volts and only got lower. If you plan to run something like an inverter or RC car charger you’ll be fine till about 10.5 volt and lights will be fine too they just may be dimmer than you expected. Cars when running are usually at 14.4 volts.
So I recently got an oscilloscope and am still learning how to use it. I recently was comparing my pure sine wave inverter to some junk ones I had laying around and couldn’t believe how crappy the power was coming out of the cheap inverters and it’s no wonder they can burn up certain electronics. So since then I been interested in how clean power is coming out of devices that involve some sort of conversion in power, so naturally I had to look at this DC-DC converter. Below is a picture of the oscilloscope set so that each division (solid line on the screen) is .001 volts. The settings don’t change though out the test. This is with no load:
This looks like regular DC, basically a solid line.
This is with 3 amps. You can see it is rippling about .0008 volts peak to peak . There were several different frequencies running so I couldn’t get the oscilloscope to lock:
I watched the meter as I took it to high currents but didn’t phot graph the results and it really didn’t change much, maybe double to .0016 v at about 6 amps. It seems they have pretty clean power coming out of this unit and I would feel confident hooking up thing like my triton charger and my pure sine wave inverter with out harm. I mean think about rectified (coming from alternator then into rectifier) car power probably isn’t much cleaner if not much dirtier. As of why I’m going to need to use either of these devices on my DC-DC converter is unknown but at least I have the option :-)
Overall for 30 dollars I think this converter is a steal. It handles up to 10 amps output and does it relatively efficiently at lower current levels. Even if you go over 7 amp it still is efficient when compared to most of the converters on Powerstream’s website or at least on par. So pick one up to run you lights and stop carrying more batteries when you have at least ¼ kilowatt hour of power under your feet. Heck if you smoke you probably could run a cigarette lighter.
Oh yah and as usual I don’t have any connection with thunderstruck motors, ev parts, or the Chinese company who name I can’t read. Have fun riding!