Meanwell clone- AD488.3-400W power supply mods

[fechter]

I found this one on eBay for around $22 usd. It's very similar to the Meanwell S-350 but rated for 400W.
http://www.ebay.com/itm/110-220V-to...862040?hash=item5b16a3de98:g:hyEAAOSw4HVWCfUo

Nameplate label (sorry about tearing it up where it covered the screw):





Since I want to use it for charging my 16s A123 pack (or a 14s Li-ion pack), the maximum voltage needs to be around 59v.
With the stock adjustment, I could only get about 52v. By placing a 10k resistor across R40, I'm able to get it over 60v. (warning: the output caps are rated for 63v, so not a good idea to go past this).

This model is pretty crude and does not have a secondary OVP circuit like the Meanwell S-350. This makes tweaking the voltage higher easy, as I don't need to mess with any zener diodes.



Next step is to make the current limit adjustable downward. Stock current limit is around 8.3A, which will be too high to run continuously. By placing a 10k trimmer pot across R35, the current limit can be adjusted. I used a pair of wires to the pot, which is mounted near the voltage adjuster for easy access.



Both mods can be done without removing the board from the frame.

The first time I turned it on, it made a really bad burning smell and I thought something fried in there. I traced it down to the inrush current limiter NTC, which was getting pretty hot, but this is normal. I guess there was some oily, stinky residue on the NTC part that gave off a bad smell. The smell dissipated after a while and the NTC seems to work fine.

While I had the board out, I touched up a bunch of sketchy solder joints and trimmed some excessively long lead wires. I think it will help the reliability quite a bit.

The fan runs continuously but is very quiet compared to my old S-350.

 

[agniusm]

So its sort of manual charger where you have to dial CC at the end of charge cycle?

 

[fechter]

When it starts out, it runs CC (I have it set at 5A) and it stays there until the pack voltage gets close to the CV setting, where it starts to drop. It will eventually drop to near zero at the CV setting if I let it run long enough. I have another circuit that cuts it off at end of charge.

Its just like all the other Meanwell supplies.

The reason for the current adjustment mod is simply to lower it enough so the thing doesn't overheat when running for hours. You could use a fixed resistor.

 

[MrDude_1]

What kind of heatsinking does it use? Or is it just bolted to the case as a heatsink?

 

[fechter]

What kind of heatsinking does it use? Or is it just bolted to the case as a heatsink?

The case is the heatsink. I'll post more pics of the completed unit after my camera gets recharged.

 

[fechter]

Here's the overall with the volt/amp meter attached. It's the same size as a S-350.



Current adjusting pot:

 

[Mammalian04]

Very nice Fechter! I'll be picking one of these up for my Adaptto.

This is what I'll be ordering if I have your instructions correct above:
10k Trimmer Pot

1/4w 10k ohm resistor

Just curious, how did you know what changes to make for the Amperage pot and voltage change? Is this just something that EEs can see when they see a circuit board?

 

[fechter]

Those resistors should work fine.

I've reverse engineered enough of these to know the basic circuit. Most of them use the same KA7500 controller chip. Seems like every model has a slightly different layout so you have to trace the circuit to find the right spots.

 

[Mammalian04]

Thanks Fechter. I suppose if you know what you are looking it it seems more simple!

Thanks again for the help.

 

[DrkAngel]

Nice find and great mod diagnosis.

Just throwing in my 2¢ to bookmark thread.

Ordering a few.
Will test and document for 7s (29.4 x 13.6A), 9s (37.8V x 10A) and 10s (42V x 9.5A) modability

 

[kje]

I found this one on eBay for around $22 usd. It's very similar to the Meanwell S-350 but rated for 400W.
http://www.ebay.com/itm/110-220V-to...862040?hash=item5b16a3de98:g:hyEAAOSw4HVWCfUo

Nameplate label (sorry about tearing it up where it covered the screw):

View attachment 3



Since I want to use it for charging my 16s A123 pack (or a 14s Li-ion pack), the maximum voltage needs to be around 59v.
With the stock adjustment, I could only get about 52v. By placing a 10k resistor across R40, I'm able to get it over 60v. (warning: the output caps are rated for 63v, so not a good idea to go past this).

This model is pretty crude and does not have a secondary OVP circuit like the Meanwell S-350. This makes tweaking the voltage higher easy, as I don't need to mess with any zener diodes.

View attachment 2

Next step is to make the current limit adjustable downward. Stock current limit is around 8.3A, which will be too high to run continuously. By placing a 10k trimmer pot across R35, the current limit can be adjusted. I used a pair of wires to the pot, which is mounted near the voltage adjuster for easy access.

View attachment 1

Both mods can be done without removing the board from the frame.

The first time I turned it on, it made a really bad burning smell and I thought something fried in there. I traced it down to the inrush current limiter NTC, which was getting pretty hot, but this is normal. I guess there was some oily, stinky residue on the NTC part that gave off a bad smell. The smell dissipated after a while and the NTC seems to work fine.

While I had the board out, I touched up a bunch of sketchy solder joints and trimmed some excessively long lead wires. I think it will help the reliability quite a bit.

The fan runs continuously but is very quiet compared to my old S-350.

Can I use this to limit the current? ☺
http://www.ebay.com/itm/251877265728?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[DrkAngel]

The fan runs continuously but is very quiet compared to my old S-350.

I prefer a constant run fan, as opposed to a fan that cycles at some heat thresholds.
Temperature fluctuations cause expansions-contractions that eventually produce failures!

Ideal is a fan circuit that varies speed in response to actual temperature.

 

[fechter]

Can I use this to limit the current? ☺
http://www.ebay.com/itm/251877265728?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Yes, those should work fine.

 

[kje]

Can I use this to limit the current? ☺
http://www.ebay.com/itm/251877265728?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Yes, those should work fine.

Thank you.
How did you find out where to place the 10k trimmer pot so the current limit can be adjusted?

I wonder if I can do the same on my 350w power supply...

 

[izeman]

I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.

 

[MrDude_1]

I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.

What voltage are you trying to hit?

 

[kje]

Yes, those should work fine.

I've taken additional picture (look at the attachment under) of underside of circuit board so R35 function might, possibly, have a chance of being determined?
Does R35 in this power supply controls amp output?

 

[izeman]

I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.

What voltage are you trying to hit?

As low as it gets. I was hoping for 0-60v.

 

[izeman]

.

 

[MrDude_1]

I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.

What voltage are you trying to hit?

As low as it gets. I was hoping for 0-60v.

With this type of circuit, you can only go so low before it has to cut out. There is no way to get it all the way down to near zero without turning it off. Its not a lab power supply.
What do you need a 0-60v supply for? if its a low amperage lab supply, there are plenty of other cheap options. We use supplies like these to bulk charge batteries, so they only need to sweep within a specific voltage range.

 

[fechter]

I wonder if I can do the same on my 350w power supply...

I traced out the circuit and used the datasheet for the controller chip. There's a good chance you can do the same thing with your supply. If you post good pictures of both sides of the board, I might be able to trace it out for you.

I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.

Some of these supplies can only go to about half the rated voltage and some can go to near zero (but will be in discontinuous mode below a point). I need to see both sides of the board to tell which resistor to mess with. In most arrangements, adding resistance in series with the pot will lower the voltage.

 

[Hillhater]

I have one of these clones that was listed as 0-24 volt variable. (350 W, 17 A max)
In practice it actually runs down to about 6 volts before it becomes unstable(and noisy ?) and all the way up to 30 volts, on the standard "V" adjuster.
There is no current adjustment, so I guess it would theoretically try to feed 17amps at 30 volts, but I have never tried loading it up that much.
Oddly, I have not seen any like this lately on sale.?

 

[DrkAngel]

Couple years ago I got a 350-48 that adjusted down to single digits ... forget how far ...
No discernible manufacturer or model number.

Look for items with a multi-turn pot ... and take your chances?

 

[fechter]

The voltage reference for the regulator is 2.5v, so you could theoretically make most of them go this low with a single resistor change. It will not be able to do the full rated current below some higher voltage. The screechy sound happens when it goes discontinuous. This is rough on the output caps. Most of the ones I've tested will be happy down to about half the nominal rated voltage.

 

[kje]

I wonder if I can do the same on my 350w power supply...

I traced out the circuit and used the datasheet for the controller chip. There's a good chance you can do the same thing with your supply. If you post good pictures of both sides of the board, I might be able to trace it out for you.

Here is pictures of both sides of the board. Can you trace it out for me?

Side 1:


Side 2: