Meanwell NES Schematic..almost complete

[neptronix]

I already did that. Previously, i had a switch on the fan mod, so that i could turn it on and off while i was trying to do the shunt mod. It didn't make any difference in current ( like it did with the old meanwells ). It didn't make any difference in screeching at various degrees of shunt adjustment either.

[NeilP]

That is a bugger.
At least it is easy to go back to original, easy to bridge that cut on the track

[bobale]

It didn't make any difference in screeching at various degrees of shunt adjustment either.

Bugger indeed.

[NeilP]

I am thinking maybe a multi turn pot may work better
Just wondering if the system swings a big and takes a while to settle down, also maybe needing only small resistance change to adjust current
A single turn pot, not being so precise makes control difficult, small resistance changes from a multi turn pot may give better results

[neptronix]

It was a 10K, 15 turn pot actually, i bought it thinking of that sensitivity issue.

There seemed to be basically a threshold with no real middle ground.. either 12-some amps, or 17-some amps. Kinda weird. That was within a range of maybe 5 turns.

You know. If anyone here wants it.. it still functions. And i haven't mangled it too bad. Throw me an offer. I need $ to go towards something greater.

[NeilP]

Oh, well, if you already have multi turn then it really is now one for Cor.

I'd take it if we were closer, but I have gone over to the BMS alloy shell chargers now. so much less hassle, a ready to go plug and play solution for higher volts.

Just wait for Cor to chime in now with suggestions

[fechter]

One of my Mini Limiter boards would probably work with it.

[neptronix]

One of my Mini Limiter boards would probably work with it.

$15 plus shipping and you have a test unit to find out. lol. I'm done screwing with it.

[shawn_1976]

I know this is an old post. But back in april I had bought a couple of the NES power supplies not know that the board would be different inside. After frying a couple I think we got it figured out. We have moded about 12 so far since then. Everything seem to be fine. They get used daily with no problems. If anyone is still looking to do this let me know.

[NeilP]

Don't be so cryptic, just tell us what you did, am keen to know the mod you used

[VANDY]

Shawn asked me to explain.

The mod was based off of the "SP" mod of the same version. Based on the schematic, thanks "NeilP", I was able to find the similar voltage divider. Off of Q1 and Q2 R1k and R36K make the voltage divider to the Isense pin of the PWM module. Unfortunately they have designed the circuit so that the R2 is a 36k ohm surface mount resistor, so this makes copying the mod for the "SP" not possible since it requires installing a potentiometer at or in parallel with "R2". IMO it is ideal to adjust R2 since you do not run into the problem of being able to over current the power supply by accident. In order to prevent this Ive found that you can include a series resistor with the pot in order to set a maximum current limit and still be able to trim to 0A. So in this case I've had to mod "R1" of the voltage divider to increase the value instead of decrease it. Also this is an easy to access 1K ohm resistor; marked as R55 on a genuine meanwell board(see pic).

photo(1).JPG (40.35 KiB) Viewed 352 times

Just to be clear you replace R55 with a pot greater than 25k ohm, include a resistor of at least 15kohm to create a max. current limit if you are worried about over current; since we have modded "R1" and not "R2"

[NeilP]

Ok thanks.

i do not have a NES or SP here now, and probably am not looking at getting one again at the moment, as I have no need at the moment.

I know I am not going to get any time at the moment to look at this, as I have no need to, and to be honest, it is of no need to me at the moment, but for the sake of completeness, any chance you could produce a sketch or schematic of the mod..again , not for me, but for anyone in the future that may want to also carry out this mod.

I used PCB Express for the schematic, and I could send you the file for you to add the mod to if you had the time

Interested to see how this mod differs to how Cor did his mod

Cheers for the help in this,

Neil

[VANDY]

I am not sure how the other mod is intended to work...I wasn't willing to try it based on the discussion and posted results. Also I didnt quite understand it.

Modding the shunt is always a last resort IMO because it is too imprecise/unreliable.

This mod differs in that its a simple single resistor mod, you cant mess it up....tested and works from 0 - 9A at 50V and 100V. It is indicated on the schematic by the black box and the resistor has been relabeled as R55.

[NeilP]

Ah nice one ,. ,cheers, am sure that is going to be very much appreciated by many other members,..and only your second post too.

Modding the shunt is always a last resort IMO because it is too imprecise/unreliable.

TOTALLY AGREE, shunts mods..ugg. I know I can be fairly ham fisted in some things I do, but shunt mods leave me cold

[potatorage]

So what is necessary to modify a SP series power supply?

[VANDY]

There is a thread about this guy who blows up meanwell's like they are candy...search for "sp-320-48 meanwell mod" of something like that. No sense re-posting what has already been done. I believe the mod involves swapping "R33" with a 1k Ohm pot...haven't modded one since last year. This mod requires turning the pot to 0 Ohms, I believe, in order to limit current and is more intuitive....aka easier not to blow up when testing the limit.

[liveforphysics]

There is a thread about this guy who blows up meanwell's like they are candy...search for "sp-320-48 meanwell mod" of something like that. No sense re-posting what has already been done. I believe the mod involves swapping "R33" with a 1k Ohm pot...haven't modded one since last year. This mod requires turning the pot to 0 Ohms, I believe, in order to limit current and is more intuitive....aka easier not to blow up when testing the limit.

Right on Vandy!

Welcome to ES, and thank you for your help!

[VANDY]

hahaha was that too obvious? I wasn't sure about the etiquette on ball busting... lol

I've been reading the forums for a few years, that's how I met the guys in Pickering. They finally convinced me to post, just to explain the charger mod, since it seemed that the solution was not posted yet. I use this power supply for testing motors, controllers, discharge circuits etc. Ive tried to take out 50A with the power supply current limit set at 8A, with no problems.

If anyone needs genuine meanwell with mod. let Steveo or I know...otherwise the mod is available for all eyes to see.

[NeilP]

I am not sure how the other mod is intended to work...I wasn't willing to try it based on the discussion and posted results. Also I didnt quite understand it.

Modding the shunt is always a last resort IMO because it is too imprecise/unreliable.

This mod differs in that its a simple single resistor mod, you cant mess it up....tested and works from 0 - 9A at 50V and 100V. It is indicated on the schematic by the black box and the resistor has been relabeled as R55.

NES 350-48 01 .bmp

Hey Vandy

Did you ever work out an exact figure for R55 to drop the current to a figure below max..say 6.5 to 7 amps? Have just ordered a new NES and was thinking to save the hassle of a pot, I might just fire in a single new resistor, knock out the 1K R55 and replace it with a ???

Cheers

Neil

[NeilP]

OK, well a few findings and mods I have done to mine

I used a fixed resistor at R55, to bring the current down to a fixed amount...I would have to rip it apart again to check the value, but seem to think it was about 36kΩ gave me about 6.5 amps.

I also took a 12 volt feed off the regulator that feeds the fan, to power an external voltmeter.

I also bridged the Collector/Emitter of the transistor that switches the fan on/off..so the fan now runs constantly.

Also fitted an early version Fechter CC/CV board, wiring the board control output wire direct to the OVP point.

have uploaded two pictures here. the one that displays at 800 pixels. and also the full size image if you want to see it full size

Mod done

Fan-and-12-volt-mod-done-.gif (240.17 KiB) Viewed 406 times

[johnamon]

Thanks to everybody's help, not least NeilP who supplied the very clear photographs my first lipo's are now bulk charging

I replaced R55 with a 50k multi-turn potentiometer to control current, and performed the fan always on mod.

I have installed an arduino voltage / current monitor which will turn the charger off when the pack voltage reaches 49.8v (cell voltage of 4.15V if all cells are equal). Here is a photo of the Mean Well / Arduino hybrid about 30mins after I set the cells balanced to 3.8V to charge....




The grey box with the red light on it, located to the right of the fan, is a Solid State Relay which is used to allow the Arduino to shut down the charger.

Anyway, I couldn't have gotten this far without the help of NeilP and the other members which have taken their own time to post such useful information.

Please forgive the rat's nest of wires, my next part of the project is to tidy them up!

Thanks

John

[NeilP]

Nice work
just wondering if you could cause the arduino unit to feed into the OVP ( over volt protection ) point on the board, just off to one side near the meanwell green LED.

This is the point that Fechters CC/CV board taps in to. The CC/CV board pulls the voltage (up ? down?) and controls the current of the meanwell and acts as a system shut down too.

Would need to wait for someone that understands the exact mode of operation of the CC/Cv board to chip in, but if you could get the arduino unit to perform the same job, then that may give a more flexible control of the Meanwell.

[johnamon]

Hey Vandy

Did you ever work out an exact figure for R55 to drop the current to a figure below max..say 6.5 to 7 amps? Have just ordered a new NES and was thinking to save the hassle of a pot, I might just fire in a single new resistor, knock out the 1K R55 and replace it with a ???

Cheers

Neil

Hi Neil,

From my first few bulk charges it appears that the R55 mod works as a current limiter but not a constant current selector. I previously charged my pack cells from a slightly discharged voltage of around 3.9v to 4.15v and adjusted the R55 potentiometer to allow approximately 5.5amps of current. As the pack charged the current applied decreased, as I expected from reading other's experiences with Mean Wells. After a 10mile bike ride, last night I charged the pack's cells from around 3.8V - upon starting the charge I noted the current being delivered was around 7amps - a little too high for the charger to continuously ouput! I altered the resistance to further reduce the current being applied.

From further charge cycles, it appears that as the voltage of the battery pack reduces, the current which the Mean Well will supply increases for any given R55 value. Therefore a single R55 value will not provide a constant current during pack charging.

The simple solution is to fully deplete your pack, then attach the charger and set the desired maximum current via the R55 potentiometer. The problem with this simple solution is that as the current the Mean Well outputs drops away as your pack voltage increases - even though the charge is not nearing completion. The ideal solution (for me) would be to have a microcontroller variable resistor such as this to allow me to vary R55's value throughout the charge based on the pack voltage.

Cheers

John

[NeilP]

Ah yes, I found this too. charge current really drops off ...so the search for the elusive current mod continues...or use a Fechter CC/CV board

[amigafan2003]

FWIW - I've been running one of my NES-350-48's without any mods at all to charge a 12s pack (49.8v cut off). It show a peak current of 390 watts.

It's clocked nearly 150hrs of charge time so far. Maybe the NES's don't actually need a current limiting mod?