S-350-48

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MeanWell S-350-48

S-350-48.JPG

Specs:

  • Mean Well S-350-48
  • 350w max continuous output
  • 48V - adjustable from 41V - 56V
  • 7.3A max continuous output@48V -
  • 48V x 7.3A = 350W
  • Thermal regulated fan
  • [S-350 Factory Specs]

Problem:

  • Rated at 7.3A, but will surge-sustain much higher, burning components

Solution:

  • Restrict the amp output -
  • The "R33" resister is the key to regulating amperage.

S-350-48 2.jpg

  • For testing purposes, I soldered 2 wires of a 2s balance plug to the ends of the R33 resister.
  • Then plugged a multi-turn 2K Pot (potentiometer) into the balance connector.
  • Then I lowered the voltage to minimum and applied "load".
  • Removing and measuring the pot's ohms at each 1/2 amp mark.
  • (Pot must be removed to measure! "In circuit" it is laid parallel with 2 other resisters.)

Restricting Current (Amps):

  • 9.1A = (OEM resister only) .350K = 350ohm
  • Add resistor in parallel with R33
  • 7.9A = 2.000K = 2000ohm
  • 7.5A = 1.432K = 1432 ohm
  • 7.3A = 1.200K = 1200 ohm
  • 7.0A = 1.000K = 1000 ohm
  • 6.5A = .775K = 775 ohm
  • 6.0A = .580K = 580 ohm
  • 5.5A = .458K = 458 ohm
  • 5.0A = .368K = 368 ohm
  • 4.5A = .288K = 288 ohm
  • 4.0A = .225K = 225 ohm
  • 3.5A = .180K = 180 ohm
  • 3.0A = .132K = 132 ohm
  • 2.5A = .098K = 98 ohm
  • 2.0A = .065K = 65 ohm
  • 1.5A = .038K = 38 ohm
  • 1.0A = .013K = 13 ohm

Wider Amp adjustment:

  • Disconnect, or remove R33.
  • Replace with adjustable "pot"
  • Amps ........ Ohms
  • 1A ... from ... 12.5 ohms
  • 2A ... from ... 55 ohms
  • 3A ... from ... 96 ohms
  • 4A ... from ... 137 ohms
  • 5A ... from ... 180 ohms
  • 6A ... from ... 218 ohms
  • 7A ... from ... 260 ohms
  • 8A ... from ... 302 ohms
  • Above values extrapolated using a parallel resistor calculator - reasonably accurate!
  • 9.1A ... from ... 350 ohms
  • 10A .. from .. ? ohms
  • 11A .. from .. ? ohms
  • 12A .. from .. ? ohms
  • 13A .. from .. ? ohms
  • 14A .. from ..  ? ohms
  • 15A .. from ..  ? ohms
  • 16A .. from ..  ? ohms
  • 17A .. from ..  ? ohms
  • 18A .. from ..  ? ohms
  • 19A .. from ..  ? ohms
  • 20A .. from ..  ? ohms
  • etc.
  • Need lower voltage high drain rig to determine higher amps.
    • Not precise ... used analog amp meter.

Widening the voltage range:

  • By changing the value of the Voltage pot, I was able to lower the output range substantially.
  • 1K = 38.3 - 56.7V (oem)
  • 2K = 29.8 - 56.7V
  • 5K =  ? - 56.7V (<20V - 56.7V estimated)
  • 10K = ? - 56.7V
  • 20K = ? - 56.7V
  • 100K = ? - 56.7V
  • As I will demonstrate later, there can be great advantages to lower voltages.
  • Lowering voltage below ~ 50% of rated voltage results in a fault condition - requires a on\off cycle to recover

Note! The higher value pots (100K etc) only allow a very "coarse" adjustment at the high voltage end. Harder to fine adjust.

Lowering Voltage

  • Lowering voltage could take advantage of higher amperage.
  • Without removing components, amperage is regulated below 9.1Amps.
  • R33 has a measured resistance of 350 ohms.

Component View

2006 - 06 - 20

S-350-48 1.JPG

Raising Voltage?

Raising Voltage: R25 Mod

  • R25 Mod
  • The voltage adjustment pot (SVR1)limits voltage adjustment between 39V - 56V. It is possible to adjust voltage lower, but not higher, using a "larger" than 1K pot.
  • However, the SVR1 pot is "in series" with the R25 resister.
  • Altering the value of the R25 will shift the entire voltage range higher or lower
  • Secondary voltage regulation seems to be regulated by component ZD1, (Zener Diode #1), reputably a ?V value component.
  • ZD1 is reputedly beneath the major transformer - above the center screw.
  • This model has 63V caps ... a fairly strict limitation!

350 Watt!

  • To be safe and effective, amperage should be adjusted as voltage is altered.
  • Volts x Amps = Watts
  • Watts should equal, or be slightly below, 350 watts.


  • 63V x 5.55A = 350w
  • 62V x 5.64A = 350w
  • 61V x 5.73A = 350w
  • 60V x 5.83A = 350w
  • 59V x 5.93A = 350w
  • 58V x 6.03A = 350W
  • 57V x 6.14A = 350w
  • 56V x 6.25A = 350w
  • 55V x 6.36A = 350w
  • 54V x 6.48A = 350w
  • 53V x 6.60A = 350w
  • 52V x 6.73A = 350w
  • 51V x 6.86A = 350w
  • 50V x 7.00A = 350w
  • 49V x 7.14A = 350w
  • 48V x 7.30A = 350W
  • 47V x 7.44A = 350w
  • 46V x 7.60A = 350w
  • 45V x 7.77A = 350w
  • 44V x 7.95A = 350w
  • 43V x 8.13A = 350w
  • 42V x 8.33A = 350w
  • 41V x 8.53A = 350w
  • 40V x 8.75A = 350w
  • 39V x 8.97A = 350w
  • 38V x 9.21A = 350w
  • 37V x 9.45A = 350w
  • 36V x 9.72A = 350w
  • 35V x 10.00A = 350w
  • 34V x 10.29A = 350w
  • 33V x 10.60A = 350w
  • 32V x 10.93A = 350w
  • 31V x 11.29A = 350w
  • 30V x 11.66A = 350w
  • 29V x 12.06A = 350w
  • 28V x 12.5A = 350w
  • 27V x 12.96A = 350w
  • 26V x 13.46A = 350w
  • 25V x 14.00A = 350w
  • 24V x 14.58A = 350w
  • 23V x 15.21A = 350w
  • 20V x 17.50A = 350w
  • 15V x 23.33A = 350w
  • 10V x 35.00A = 350w
  • 5V x 70.00A = 350w
  • Yeah ... I'm gonna try pushing everything to the limits ... and then a little further!

(Will test to confirm)


Fan Mod

The S-350 Series incorporates a thermally regulated fan.

  • Problem - Sadly? Fan only switches on at an uncomfortably warm temperature.

When used as a charger, operating temperature is at a consistent high. Logically, a fan cycling will produce temperature variations.

  • Temperature variations produce damaging thermal expansion and contraction.
  • Solution - Modding the fan circuit for continuous operation.
  • Method 1. Jumper, or add switch to the Q5 transistor, connect the 2 legs farthest from the fan connector. (will add picture after tested and confirmed)
  • Method 2. Disconnect-cut the negative-black fan wire and connect it to the DC negative.
  • Method 3. Cut into the fan neg leg and bridge to dc neg through a resister and possibly a diode. This would induce a slower-quieter continuous fan and still enable full fan speed if temperature rises sufficiently.

In Series


  • "In series" is when the negative of one power supply is run through the positive of another - combining their voltages.

Important!

  • When run in "series" the DC "negative" must be isolated from the 110AC neutral ("negative") ... on all but the primary unit!. Otherwise, the DC positive from the primary unit will "short" through the AC negative on the secondary unit.

The negatives are usually connected through the "ground".

  • It appears the S-350 series is ready for "in series" with no mods!

AC neg to DC neg shows no "continuity". This, preliminarily, indicates as being safe for "in series" use with no further modification necessary.

Theoretically safe but not confirmed by actual circuit use. Use caution! Use low value fuse between units for 1st test?

--Drkangel 12:43, 3 November 2013 (EDT)