The part I just for the life of me don't understand (read that as I'm not sure what value components to install here) is involving D18 and Q7. In my conversations (limited as they were, the tech guys at meanwell are awesome - sales at Meanwell USA isn't even worth bothing with and I was inquiring with regards to 1000 unit purchase, the sales biat** referred me to mouser who had 2 in stock?) with Meanwell tech, he was very hesitant (I think he could get in trouble) but at least informed me the transistor is of type NPN.
Vanquizor wrote:With the concerns about instability with the fan cycling wouldn't the quick and dirty be to just force the fan to run 100% of the time? Would still give predictable output and it can't hurt life cycle to keep things a little cooler.
Suggestions on the best way to accomplish this?
fechter wrote:Part of the problem might be if you're increasing the output voltage too much over stock. It really needs a new transformer wind to push it really far
fechter wrote:Part of the problem might be if you're increasing the output voltage too much over stock. It really needs a new transformer wind to push it really far. A sidestep approach is to simply use two or more supplies in series to get the desired voltage. With two in series, I suspect you could get away with just keeping one stock and mod the current limit on the other one. The one with the lowest limit will do all the limiting anyway. You may actually need to turn down the voltage on one in this case to get what you want.
Hyena wrote:Mike, I picked up some 1k, 2k and 200 ohm 10 turn pots + a handful of 100 and 200 ohm resistors yesterday afternoon to do pretty much the exact thing you just described! I was just going to put the 2k in svr1 to allow the voltage to go a bit lower. What was R25 before you changed it ? Mine is 22k I think. If yours was the same and you've dropped 7k that sounds like a fair bit (assuming your R25 is in series with SVR1) Or is this big drop what's enabling you to go to 63v ? (plus upping the zener under the transformer of course).
As for higher voltage mods, if the transformer is even up to it you'd have to swap out the front caps atleast. Mine are only 63v units so you're running right at the upper limit of what the 48v models can do.fechter wrote:Part of the problem might be if you're increasing the output voltage too much over stock. It really needs a new transformer wind to push it really far
I don't think so Fechter, at least not completely. Mine has all the same symptoms Mike is describing and unmodified it's running at the lower end of its range (42v on a 48v unit)
mwkeefer wrote:Actually... my 48v units come with 100v caps on the output already (sure-electronics)
My unit was different, R25 was 2k I think... I don't remember anymore = )_
I'll look at your PCB pics in the AM and figure out what points to check for impedance... then we can bump the unit either way or just expand the range.
mwkeefer wrote:Dont give up on that supply yet, I have one from my first days testing that does the same thing.... I'll figure it out, meanwhile email meanwell.
EV4LIFE wrote:1.Even if it outputs 20A my battery pack can handle the charge current? (considering the turnigys are rate to 2C charging), or is it too high, or some other reason?
2. (Stupid question but I still need an answer) When charging with these Power Supplies do I need a BMS or something to stop charging when it hits HVC, or can I directly connect the battery pack(no BMS system or anything, just 12S4P) into the power supply and turn the power supply on, and then somehow the power supply turns off when the battery pack tops off at 49.8v (lol, still getting the hang of electronics).
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