CCCV Mod+Review - Meanwell S-350-48 from SureElectronics.net

mwkeefer

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Hello all,

I finally got to crack open the 48v unit and mod it tonight for bulk charging of my 15s packs... I've limited the cutout to 61.8v which is only 4.12v per cell just because I don't have the right Zener Diode on hand.

There is no more time for working on documentation tonight (though I do have pics) so I figured I'd just dump my entire "notes" - even though I may refer to users and people, these are just rough draft of a review on this product and seperate mod thread for all meanwells which I am in the process of writing (about 50% complete). I have only 1 supply available to me to review still the 145w 24v model which I'm looking at as a slow 15s charger (really slow) for me and some others.

Below is a literal, copy and paste from OneNote where I keep all my engineering and R&D notes - they aren't pretty and probably really "train of thought" but there have been so many questions about how to reverse engineer these lately to get a desired output voltage and this "engineering" (I use the term loosely) notes may help people to do just that... in a sane and well thought out mannor (well.... not my notes literally but I do cover all the caveots - I think).

I will update the following when I craft the final review / how-to:

Hope this helps!

-Mike

PS: If this should be somewhere else besides Reviews and Testing (Like rantings of a lunatic) please let me know... I'll gladly remove and repost in a more appropriate category.

----

S-350-48 from SureElectronics.net

Friday, November 13, 2009
6:18 PM

Initial impressions:

Quality piece - it worked better than expected!

Out of box voltage: 47.8v
Out of box range: 38.8 - 58v (almost enough - 4 more volts is all I need for 15s - 62.25v)

Disassembly Notes:

1.) One screw seemed to have threads which were off a bit… I had to use a special screw driver on this one and be very, very careful. Drilling it out would have been the solution if the head had gone bad (or notching with a dremel and using a flat head).

[Voltage Limiter Circuit]

R25: 2k, 5%, 1/8th watt - (red-black-red-gold)
R61: 10k, 5%, 1/4 watt - (brown-black-orange-gold) *Note the 1/4w - first meanwell with this large R61
C35,36,38: 100v330uf - (highest voltage of any meanwell I've seen yet and should handle to 85v fine.)
ZD1: 1N4759 - 62v, 4mA Zener Diode - this will work for 15s without mod @ 4.15v per cell = 62.25v
Shunts: 3x ?? - ** These are the same as in the 24v model but they have been "smashed" with a hammer to raise their effective resistance by narrowing the pathway - interestingly enough, this could be a calibration method used by the manufacturer but my guess is it's the builders attempt at being as frugal as possible… nice part is now we know it's cool to do this = )_

SVR1 - 1k - .6 ohm or 600 milliohms
Replaced with precision SVR1 - 10 turns - 1K, top voltage=58.1v (so range is same but precision - 10 turn is far better… I wonder what going to 5k will result in for range?)


If I test for resistance on the between leg 3 of the pot and the far side of R25 I measure 2.xK with the pot reading milliohms (no resistance) this is the point I get the highest voltage… everything else is lower. This means to increase the top or maximum voltage the supply can achieve I must lower the value of R25 some… how much is the question?

Since I'm flying blind here… lets turn the pot all the way up (down) and test the resistance again: 2.82k max resistance @ 39.1v

Now assuming a linear scale… for a voltage output swing of: 58.1 - 39.1 = 19 volts we have a maximum swing of 2.82 - 1.92 = 0.9 k or 900 milliohms call it 1K for argument sake.

19 / .900 = 21.1111 milli ohms per volt so…

63 - 58.1 = 4.9 * 21.111 = 103.4439 more milli ohms reduction to R25 (Correct me on this if I am wrong or doing the math wrong)

So we are trying to find a resistor of 1.5k actual value (1.6 measured - 100k), time again to turn to my trusty bin of scrap resistors:

Looking for: 1.5k(brown, green, red), 1.2, 1.8k resistors to find the best actual value match (closest to 1.6k)

Changing to a 5K pot (10 turn) will really fix the bottom end range… I will do this once I test the 1.6k upgrade for 63v (roughly)… In my 24v supply tests this change gave me a 6.9v low end (that's range).

Ive changed my mind… for the first test phase run of this "charger" in brick mode… I will set the cutout to 4.1v per cell just to keep a margin of safety coming from the charger so my actual output will be: 61.5v which will still require the mod and even falls within the rated spec of the diode (62v) which I am counting on some tolerance with so I can get to 62.25 without the limiting effect kicking in. There is 0 danger of popping these in no-load testing, only when they are asked to limit and there is current in place will they pop.


Out of circuit the resistor R25 tested to 1.98k - well within tolerance… adjusting the assumption above:

Found a 1.5K which tests out of circuit to: 1.46k, close enough for my needs… just need to set the pot to highest resistance position before power up.

2.35k - 1.41k is my new resistance range… in theory, this will give me far past 62v output voltage range and will limit the low end voltage (I've only shifted the scale by changing just 1 resistor, changing the SVR1 for a 5 or even 10K will extend rather than move the range of voltage).

I preset the variable network to 1.95 K - just a little more resistance than our previous lowest… that will put the voltage on power up around 57-58v and I can adjust up from there gradually while monitoring other components… time for power up:

Starting Voltage (with 1.95k of impedance in the voltage regulator network): 56.5v (@ 1.95k calibrated)

So I nudge it up a bit… 58.1 now passing the delivered range…

59.1v - grinding my teeth (you would be too if you realized im running this PCB on styrofoam board - elmers style).

60v - I could stop here and consider it a successful first test but… nope, lets go.

61.5 the max I need for now… keep going 15 * 4.25 = 63.75

62.2 - 62.3 reached which is 4.15v per cell and meets my actual maximum needs… however, lets push to the max.

Hmmm… interesting 62.5 seems to be the limit - probably the Zener diode protection kicking in so lets dial back to 61.6v cutout (4.1 without balancing seems safe - I have active hvc for this method at cell level.).

Now… I begin to think about modes / gears like the chinese charger manufacturers speak of… just switching between resistors would do this - so why won't they offer an adjustable pot in addition to the gears - sales volume, plain and simple.

So… once the power was removed and the LED died out (caps drained, always wait for this before touching) I measured the impedance of the voltage regulator (I am assuming voltage of 61.55v as it would teeter between 61.5 and 61.6 on my crappy volt meter) to be:

** Another trick I've learned… disconnect and reconnect power without changing pot once you have desired voltage showing on volt meter… make sure it powers up to the same voltage - if not… adjust the circuit and try again.

61.55v (4.1033v per cell) : 1.81K Ohms
61.8v (4.12v per cell): 1.81K (my meter isn't getting any better at measurements than this.).
62.2v (4.1467v per cell): 1.82K Ohms
62.5v (4.1667v per cell): 1.79K Ohms
63v (4.2v per cell): not possible - diode override I believe… there is still adjustment range in the circuit.

So I need to add some diode, not much 5v in series or upgrade to a single 1N4760 (68v, 4ma zener) which would allow full adjustment to 63 and then some (could be dangerous). I think instead I will combine 2 in series for a perfect 64v maximum cutout (true 15s overvoltage protection)… I will need to test the cutoff curve of these to be sure… for now I will live with 62v 4.1333 maximum charge per cell. This should be safe since the supply is not really operating far beyond it's values… I will test a quick "burst" in a moment with the eagle tree and a pack which I have run down to 3.3v per cell (it's out of balance too) but it's a single 5A pack. In theory the current limiter designed in this unit feeds back into the TL494CN and should automatically adjust based on the new voltage limiter impedance to it's factory preset which in the 48v supply is: 48v @ 7.3A or 48 * 7.3 = 350.4 watts so we can expect (hope) to see the limiter keeping the supply current at start of charge 15 * 3.3 = 49.5 : 350.4 / 49.5 = 7.0788 A and when we reach HVC the supply itself should only provide 350.4 / 62 = 5.6516 A (still 1C hence the happyness with 4.13 cutout until I log this properly and see the batteries reduce their consumption as they reach HVC) - otherwise I believe 4.13 is still below the 90% mark and I know these will fast charge until 90% (as seen in the past on other experiments) capacity or so… that should make this safe(ish).

I set the actual supply output voltage to 61.8v to keep it under the Zener Diode rating since I don't feel like replacing it yet (but I should since I have the PCB out of the case and have to reseat the heat sinks in either condition). That keeps the evenly (hopefully) distributed cell voltage at cutout to be 61.8 / 15 = 4.12 v per cell (very safe) and I have cell log 8 connected with an active HVC interface on each of the 3 5S packs in series which I will be test charging.

*** Be sure to power off the unit and repower to recheck the output voltage… the first time I did this on 61.8 it came up at 61.6v - I turned it up, unplugged… waited for v to hit 0 on the DVM and plugged in again to retest… tada 61.8v = )_

So… time to button this supply back up (oh yea… have to measure impedance for reference:
1.81K Ohms = 61.8v calibrated output.

One thing I should note… this is HIGH VOLTAGE technically and not only voids the warranty but could cause all sorts of issues including YOUR DEATH if your not careful or don't know what your doing. To be perfectly honest… I will not run my own supplies with this mod alone… since it's over the 60v mark I have a fear of arching and shorts… so I will line the inner case (below the PCB) with non-conductive material and take other required high voltage precautions. I will post the final spec which should be "safe" but I still don't recommend anyone else follow this thread - it is for edumactational purposes only. If you don't know what your doing with power / ac, then go to an electricican or TV repair shop with a power supply and print out of this thread… he should be qualified and competent to make the modifications needed - can't say he/she will be willing!

Next installment, making sure the current and voltage remain within spec - WITH LOGGING and pretty GRAPHS.
 
Inital charge using bulk method with CV set to 61.8v...

All cells stopped once 4.15 was hit anywhere...
Lowest Cell: 4.129v
Highest Cell: 4.155v
Difference (just after charge, before time to settle): .0026v which isn't bad and if this pack had been broken in a bit more (only had 3 cycles on iCharger as 3P5S balance charge) I think It would be much better within tolerance..

I had taken a freshly 4.15 charged pack and discharged it very slowly over about an hour and a half to 4v flat - I didn't balance then I charged bulk style for 10m to put back the 2500+ mah into the pack.

CellLog8 are still beeping about 2 minutes later so I guess one or more cells didnt' settle below 4.15v cutout I setup... I think I will go run on this pack for a while see how it balances once a load is applied.

This would be much better with properly matched / balanced 2P 15S pack.

Rough results are still = results!

-Mike
 
GGoodrum said:
Looks good. One thing, the website is http://www.sure-electronics.com.

-- Gary

Actually I thought so too........ They abandoned the url with the "-" in favor of http://www.sureelectronics.net/ which I was corrected for in a previous post by Alan from Sure Electronics (nice guy). Apparently this is their "new" easier to remember URL.

-Mike

PS: Just got back from a quick 6 mile trip to Wawa for a snack (yep in the rain) avg spd 32mph - left with previous balance range returned and resting:
High Cell Voltage: 3.774v
Low cell voltage: 3.752v

Final difference: .022 v difference or .02mv?

-Mike
 
Final update for tonight -

I decided to hookup an ammeter finally... trouble in paradise:

@ 3.94v per cell rough (+- .02v per cell) I'm pushing 11A + into the 5AH rated pack - somthing smells funny (not burning up just funny) batteries are okay temp, charger is HOT...

Here is the charge cycle - cell voltages, currents at various times:

@5m into charge - High Cell: 3.95v; Low Cell 3.90v; Current: 11.12 A

@15m into charge - first cells have now hit 4.00v and the current has falled to 9.60A... so it is going to taper, I'll close this post when I finish the charge process... but 11A was scary.

@ 17m into charge: highest cell is 4.03v and current has tapered down to 8.65A...

I have the celllog8 set for 4.15v cutout but since the charger should stop and go to CV mode at 61.8 or so... that will allow for "balancing" of a sort... at minimal currents

@ 19m into charge: high cell: 4.06v low cell: current: 6.75 A

@ 22:40 - High Cell: 4.105v ; Current: 3.8A

@ 24:00 - High Cell: 4.109v ; Current: 2.6A

@ 28:00 - High Cell: 4.127v ; Low Cell: 4.102v Current: 1.76 A

... just waiting for 4.15v beeper or current to drop down to .6 amps for charge / trickle / balance (i think) to complete.

@ 30:00 - High cell: 4.133v ; Low Cell: 4.107v ; Current: 1.25 A

Just 1/2 amp more drop and we should be completed.

@ 35:00 - High Cell: 4.138v ; Low Cell: 4.111v ; Current: .84 A

-- That's just about it... I still don't have 4.15v on any single cell so the .8 A trickle rate is fine...

@ 36m current dropped to .64 A but we still haven't reached 4.15v on any given cell... Going to leave this until current tapers to 0 and see what happens.

Charge should complete when current is at 6% of initial current so 6% of 11A is .66A or 660 milliamps.

Still don't have 4.12v across the board... turned the variable pot up just 1/4 turn - current jumped up to .85A so I will let this fall back down to nothing and call the charge complete.

I really do hope this helps someone...

I should be able to charge a 15S2P pack from empty in less than 2 hours (give or take) with a single S-350-48 with only slight modifications... I do want to limit the maximum current to 10A but that will be tommorows excercise and experiment.

-Mike
 
Awesome Mike!! Thanks for posting this, there is only one thing missing though: PICTURES!! :lol:

Did you ever find out what the burning smell was? Was it just the electronics in the supply heating up? Also, 11 amp charge rate is a lil high for a 5ah pack but it would be fine for a 10ah right?

Thanks for measurements during charge, that is what I was mostly concerned with. 8)
 
etard said:
Awesome Mike!! Thanks for posting this, there is only one thing missing though: PICTURES!! :lol:

All in good time - this is comprehensive and will cover each and every various Meanwell S-350 and S-145 unit in depth (pictures are taken but will need 1-3 hours of editing (cropping, reducing resolution unless someone wants 8mp images for DVM Readings)?

I am also trying to be responsible - at this point, I am not giving step by step and am cautioning everyone to wait until I get all the safety testing done (better I cook a supply I have several of than you burn a supply you have one of.

So... A little Update:

My old DVMs were total SHI* - 10.00 junk, I realized my iCharger 1010B+ must be out of calibration since testing between the various CellLog8 was within .013mv when I manually presented load of about 1A per cell (one cell at a time) until I could get them all into balance (as close as possible)...

Next I went to Radio Shack (mistake, may go to microcenter later for a better one, who needs the PC ineterface) and bought the best unit these guys had in stock: Cat #: 22-812

-Mike

More to come, run to HW store !
 
Time for an update:

Meanwell 48v unit is dead. It just blows fuses no matter what I try... had it running at 61.x volts (just a hair above normal adjustable range of 59v), I have checked for shorts (as it's fairly obvious)... this just began yesterday.

I got an email tonight indicating that my 2 new meanwell 48v (since the first was pushing far too many amps even within the stock range, I am assuming an assembly error) supplies had been delivered - not to my house they werent. Sadly I wasn't watching for this delivery (didn't even know it was coming today) but according to UPS it should be on my front porch - obviously it's not and not in my entire neighborhood though I only found out about the delivery tonight at 9pm and it was supposedly left at 11:28AM (*I was not only home but right next to the front door with the patio screen door open from 10AM - 2PM) but I guess the UPS guy must have been new and left it at the wrong place (we don't have things stolen from here - I get stuff this way all the time, nothing has ever been "stolen" just mis-delivered).

With that setback and a handful of 24v supplies still here for review (I was going to use 3 combined for 62v @ 15.5A to charge up a 10A pack) but... there is no need... 2 with nothing more than an additional 5v zener in series will acheive 62.25v (4.15v per cell) and it's peak current was 20A in my first test tonight. I didn't upgrade (should) the caps for better than 36v since really I think I am pushing the full 60 through the outputs but honestly I'm not sure...

Since this thing seems to want to peak at 2C of my pack (I was actually testing charging a 5AH pack at 4C-3C) 10AH capacity or 20A peaks... I will assume each of the 3 shunts is worth 6.6A so.. I am connecting a DPDT relay rated for 220 @ 10A (the fuses in these are 220 8A so this should suffice). I will be clipping a shunt and wiring it to this DPDT so when I engage it, it will reduce the shunt resistance and bring the peak currents back into the 20A range... meanwhile, normal operating max will be 12A - since each supply is putting out 31.11v that means 13A in normal mode (10AH pack should be fine with this... I can fine tune if needed).

This will be my "home" charger for my 15S 10-20AH packs - although for a well balanced pack, charging at just over 1C should not be an issue - 2C even (methods charges at 3C with no issues to speak of).

There it is... I've been really busy with everything and now it seems my 15S portable charger (a single modified 48v unit providing 62.25v) will have to wait until UPS gets their poop together or I order yet another pair of 48v units. = ( - If my math is correct, these 350s will actually handle 400w so long as they are limited at 400w (out of the box) - for the 15S single brick charger it will be capable of 6.5A roughly and I expect < 2hr 10AH charge times, which is fine for a portable charger.

-Mike
 
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