Today we will be replacing the fan on a Tripp-Lite SMART1500LCDXL UPS / BBU
The fan in question is an ADDA DC Brushless 24V @ 0.26A (Model: AD0824US-A71GL)
The power requirements are definitely odd, and it makes sense that they went with an “industrial grade fan”, many of which are almost always 24V . However, these “industrial” fans tend to be noisy and whiny.
I originally attempted to replace the fan with a 12V 0.07A Noctua 80mm 3-Pin (NON-PWM) using a Buck Converter to step down 24V to 12V @ 3A max …
Unfortunately this did not work, since the Noctua Fan pulled .07A and that was too low for the buck converter, this low power draw caused the Pulse Skipping Mode AKA Low Power Mode/ Dropout Mode to engage.
The fan would not spin up since the power was being cycled On and Off rapidly to the fan IE “Skipping”
I had to go back to the drawing board, and well. On suggestion from @chipt4 . I went with a DC to DC 24V to 12V Converter instead. This had a 2A max, and while bigger than anticipated, it worked perfectly. (I decided to use a cheaper fan, and thus the 80mm Arctic was used instead)
Step 1: Unplug from the wall, and TURN OFF the unit. I did not unplug the batteries, since the unit was OFF, and the fan was not drawing any power in this state.
Step 2: Remove the Top Cover (YMMV depending on the model)
Step 3: 2x wires come off of the UPS/BBU board, RED and BLACK. You will trace these wires to the fan, and then “cut” them close to the fan, removing the fan completely and leaving the wires in place.
Step 4: Strip some plastic sheathing off of the RED and BLACK wires, leave enough to twist and then shrink wrap them with the DC Converter.
Step 5: Take your wonderfully new DC to DC converter and strip the ends of the wires on it as well. (my ends came Tinned already, and I did not want that, so i snipped them down and made them fresh.)
Step 5.1 (Optional): Instead of connecting the fan directly to the Converter, I reused a Fan Header Extension Cable, this lets me pop off the case, and replace the fan easily with any 12V 80mm 3 pin fan (only 2-Pins are used, so it doesnt matter too much) BLACK to BLACK wires and YELLOW to RED wires)
Step 6: Twist/Connect and shrink wrap the DC Converter to the Source Wires on the BBU/UPS
This is a pretty straightforward step. Once this is completed, just plug your fan right up and your ready to rock (I originally was going to use the Noctua shown in the photo, but opted for the Arctic instead)
A silent battery backup unit, with sufficient airflow to cool the equipment inside.