48V DC-DC converter

[2manytoyz]

In a previous thread, nobogez42 bought a 48V to 12V converter for his cart. It's only $45, free shipping, no tax. Rated at 25A.

Here's the source: http://www.gpartsinc.com/p-4930-one-...FQKCnQod6GkApQ

I bought one for my cart, and bench tested it a few days ago. It has a very cheap fuse holder, and even cheaper fuses. The fuse crackled, and the converted kept powering up/down. Unlike most fuses, the end caps were not soldered to the wire inside. Consequently, it wasn't making good contact.



Okay, first step, chop off the fuse holder, put a real one on. Powered right up, good output.



Satisfied that it's going to work, I mounted the converter to a 1/4" piece of Lexan, along with a Blue Sea fuse block, and a small 12V muffin fan (type you'd find in a computer power supply). The top tucks under the rolled body seam at the top, and two screws with stand-offs secure the bottom. The yellow control wire is connected to the control wire on the solenoid (and fused at the solenoid). When the key is on, the solenoid is on, which turns on the converter.





The fan is tied to the converter. Converter powers up, the cooling fan quietly keeps it cool. A second fan will be installed on the controller/resistor, to keep it cool when cruising slow in the FL Summer heat.

The converter is connected across the entire battery bank (48V), and is fused at the battery. The wiring was put into split loom, and tie wrapped in various places to keep it away from anything moving and away from the controller & resistor.

The red wire with the black heatshrink is the control wire for the converter.



Overall view of the installation:



Bugs got too thick to continue working on it this evening. In the next few days, I'll put the lights (etc.) onto the converter and look at the output with not only a DVM, but also an oscilloscope to verify the output is a clean DC power. I'll post a follow up on how well it performs.

Pleased with it so far, but not put over about 5 Amps on it...

Edit to add: Those black & red connectors on the top of the fuse block are Anderson PowerPole 30A quick disconnect connectors. Makes it very easy to add/remove hardware.

[Hamnut]

Hi
Looks good. I went to the web site but they didn't give any spec. Do you know the efficency of the unit? Or what is the current draw at no load? I also use Anderson power pole connectors. They are great. Your cart looks just like mine but mine is crean colour.
Thanks Jan

[2manytoyz]

With the converter on, and the fan running, the total current is under 200mA at 35V going into the converter. That's as high as my bench power supply would go, but still in the range of the required voltage for the converter.

Did a little more testing this evening before the rain rolled in.

With the headlights and tail lights on, the total power used by the converter was just under 3A at 48V. The converter maintained a constant supply of 13V.



When the lights were connected directly to one of the 12V batteries, the operating voltage of the lights was slightly less. Not sure if anyone would note the difference visually.



I started grabbing other 12V appliances in the garage and connecting them to the converter. This is a 12V fluorescent light. I also connected a 12V utility water pump. Total current was around 7A being supplied to the converter. Converter was still working fine. I didn't measure the output of the converter, which will be higher due to the lower voltage. I'll post a pic of the converter output current shortly.

The oscope shows the voltage as a nice flat DC source. No noticible ripple or AC component. Quite good for a cheap Chinese product.





More pics info to follow.

[2manytoyz]

Weather eased up for the moment, so backed the cart out of the full garage to test the converter.

This time I put the DC ammeter on the output of the converter since that's really what's being tested. The headlights & tail lights pull a combined 10+ Amps.

I plugged in the 12V fluorescent light used earlier, that added another 3 Amps. I then plugged in a 12V utility pump. Total combined current was over 22 Amps, while still maintaining 13V output:





The highest peak was 22.9 Amps. Close enough to the 25 Amp limit for me. I probably left the lights on (10A) for 1/2 hour while playing in the garage. The converter stayed cool to the touch, but then again, it did have the little muffin fan blowing air on it the entire time.

Time will tell if this converter holds up, but out of the box, works well!

[Hamnut]

Great. Thanks for all your input.
Jan