Brulaz
back when i did the Meanwell modification, soldering was much more alien to me than it is now, and I did curse a good amount when trying to desolder and remove the original 1000 Ohm potentiometer, and was fearful of ruining it by lifting the of the traces with too much heat applied for too long.
I have a thread on my Meanwell rsp-500-15
Herehere. All the Pics will be dead though because of Photobucket's money grab.
From memory, My original pot that I removed from the meanwell measured 973 ohms, and with this original potentiometer, the voltage range was 13.23v to 19.23v
The Bourns ten turn 1000 Ohm potentiometer measured 1023 ohms, and with it voltage range increased to 13.12v to 19.23v.
While voltages above 16.2v are pretty much useless, unless I want to hear the screwy31 fizz like a freshly opened soda bottle, I was happy to have a little lower range for if/when i decide to cycle/float a warm a flooded battery.
Recently my friend's sealed flooded battery was discharged to a rested 11.6 volts and when I set voltage to 13.6v, the amperage quickly rose upinto the 35 range, and a few years ago this same battery got very warm quickly when fed more than 20 amps. So I basically did lower the voltage as much as I could to limit amp flow into this particular sealed flooded ca/ca maintenance free battery, and just bumped up voltage to keep about 10 to 15 amps flowing into it every half hour until it was down to sub 0.4 amps at 15 volts and the battery never seemed to warm much above ambient.
I understand that a lower ohm potentiometer will allow for more precise voltage adjustments, but I would not want to lose the original voltage range.
Honestly it is quite easy to dial in voltage to 0.01 of a volt with the 1000 ohm 3600 degree potentiometer.
I also have a bourns 3600 degree potentiometer controlling my alternator's voltage regulator, this one is a 2000 ohm and I find it a bit of a pain to twist the pot 4+ times to go from 13.6 to 14.7 or back. I would prefer a three turn potentiometer for this duty, but a couple more twists is hardly going to make me shake my fist at the sky in frustration. My point being I do not require the precise control of 10 turns for the whole voltage range.
I will defer to mex's expertise, but I am confused why he would recommend a lower ohm potentiometer than what came in installed in the units.
I 'think' a 200 Ohm potentiometer in my meanwell vs the original 1000 OHM, would not allow me to dial in voltages under 16v, and i would be stuck in the ~16.5 to 19.23 range.
973 ohms yielded 13.23 minumum voltage
1023 ohm yielded 13.12 minimum voltage
0 ohms yielded the same maximum 19.23 volts
What would 500 or even 200 ohms yield for minimum voltage?
Color me confused.
Regarding the original fan, yes it is loud. I have employed 2 Noctua fans, known for being well designed and quiet, on the steel lid. One 60Mm to push air in and one 80mm to suck air out. In 75F ambients it takes about 10 minutes at max output before the turbo 40MM original fan will kick on, and at 65F ambients it will not come on at all at max output.
The casing of the meanwell is used as a heatsink. I put rather large finned heatsinks thermoepoxied to the casing adjacent the transistors which generate the heat drilling holes in the heatsink to allow access to the screws which pull the trnasistors tight to the casing. These can get quite hot. I could really add a 60mm fan to each one of these, but in my use with my battery capacity 40 amps will only flow for about 25 minutes maximum, so the loud meanwell fan only needs to be tolerated for a short while.
I cannot hear the Noctua fans with cabinet door closed, and unless it exceeds 32 amps output, the meanwell fan will never come on. with the electrical cabinet door open the Notcua fans are whisper quiet.
Without the Noctua fans the loud Meanwell fan would cycle on and off at just 6 amps IIRC. But with them, and the external heatsinks 32 amps seems to be the figure at which the unit makes much more heat. I have thermopoxied a thermocouple to an internal heatsink. the Meanwells fan comes on at about 104f but does not turn off until it drops to 96f. I;ve yet to see temps on this heatsink exceed 120F, unless I block the flow of the Noctua fans with my hands.
Seeing the lack of arctic silver thermal grease on Mex's part list, I assume his method does not require removing the guts from the casing to access the underside of the circuit board.