I have a SU3000 that works from AC power and inverter will start if you remove power, but it wont start up from battery power.

Originally I didn't have batteries to test it so I used a couple of small power supplies in series to produce the 48V it requires to operate. They were only a 1 amp supply or so but it worked.

Now with nothing plugged in, it draws a lot more amperage on startup from battery and instantly goes to overload..
When using the power supplies I originally used to start it up, it draws too much power from them and they shut down, and it doesn't get a chance to do anything but beep once and the lights blink once.


So obviously the unit is using more power than before and not just a software issue.


I am thinking it may have a bad mosfet. Cant remove them until I get my hot air station. Does this seem like a reasonable place to start troubleshooting? Maybe the mosfets were damaged from using the power supply to power the unit?

Thanks in advance for any advice

On 07/03/18 03:06, wrote:
I have a SU3000 that works from AC power and inverter will start if you remove power, but it wont start up from battery power.

Originally I didn't have batteries to test it so I used a couple of small power supplies in series to produce the 48V it requires to operate. They were only a 1 amp supply or so but it worked.

Now with nothing plugged in, it draws a lot more amperage on startup from battery and instantly goes to overload..
When using the power supplies I originally used to start it up, it draws too much power from them and they shut down, and it doesn't get a chance to do anything but beep once and the lights blink once.


So obviously the unit is using more power than before and not just a software issue.


I am thinking it may have a bad mosfet. Cant remove them until I get my hot air station. Does this seem like a reasonable place to start troubleshooting? Maybe the mosfets were damaged from using the power supply to power the unit?

Thanks in advance for any advice


You could put an ohmmeter from drain to source and from gate to source,
and see if any of them are shorted or have blown gates.

If your power supplies overshoot badly after a large load transient, you
could have had a transient overvoltage. Doesn't take much energy to
blow a gate.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Tue, 3 Jul 2018 00:06:33 -0700 (PDT), wrote:

I have a SU3000 that works from AC power and inverter will start if you remove power, but it wont start up from battery power.

Originally I didn't have batteries to test it so I used a couple of small power supplies in series to produce the 48V it requires to operate. They were only a 1 amp supply or so but it worked.

Now with nothing plugged in, it draws a lot more amperage on startup from battery and instantly goes to overload..
When using the power supplies I originally used to start it up, it draws too much power from them and they shut down, and it doesn't get a chance to do anything but beep once and the lights blink once.


So obviously the unit is using more power than before and not just a software issue.


I am thinking it may have a bad mosfet. Cant remove them until I get my hot air station. Does this seem like a reasonable place to start troubleshooting? Maybe the mosfets were damaged from using the power supply to power the unit?

Thanks in advance for any advice

In the APC SmartUPS, some of these run the switching power supply
section full time, whether on AC or battery. On AC, the voltage from
the switching section is slightly below the input AC voltage, so the
load draws most of its power from the AC line. Of course, they are
phase locked. When the AC line voltage disappears, the switching
power supply section takes over running the load with zero switching
time. I'm not sure if the SU3000 SmartUPS works this way but it's
worth checking.

A schematic should be useful:
https://elektrotanya.com/apc_smart-ups_su2200_3000.pdf/download.html
(175K)

Offhand, I would guess(tm) that you blew something up with your 48V
power supply. The SU2200/3000RM uses a pile of 4ea 12V 18AH AGM
batteries. I believe that they are wired 2 in series and 2 in
parallel for a total of 24VDC, not 48VDC. You probably blew up the
electronics with the overvoltage.

If it draws lots of current from the battery section, the fets are the
likely culprit. However, as I vaguely recall, the SU2200/3000 series
has 4 strings of 8 FET's in parallel. It's not going to be much fun
finding the one FET out of 32 that is blown. I built a crude current
probe using a Hall effect device at the end that is useful for finding
which device is sucking the most current.

Most of the value and cost of a UPS are in the batteries. In this
case, a set of batteries is about $130 plus shipping. At the local
recycler, such large UPS's without batteries are plentiful because the
price of a new or refurbished UPS is only a little more than the cost
of decent batteries. Incidentally, beware of junk batteries and look
at the weight of the battery for a clue as to how much lead is inside.
I have my own collection of UPS's with dead batteries.

https://excessups.ca/refurbished-ups-systems/apc-ups-refurbished/apc-smart-ups-rackmount-refurbished

Good luck.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/3/2018 9:43 AM, Jeff Liebermann wrote:
I built a crude current
probe using a Hall effect device at the end that is useful for finding
which device is sucking the most current.

I've been considering doing that.
Can you share details about which parts you used?
What kind of sensitivity can you get?

Thanks, mike

On Tuesday, July 3, 2018 at 12:43:13 PM UTC-4, Jeff Liebermann wrote:
On Tue, 3 Jul 2018 00:06:33 -0700 (PDT), wrote:

I have a SU3000 that works from AC power and inverter will start if you remove power, but it wont start up from battery power.

Originally I didn't have batteries to test it so I used a couple of small power supplies in series to produce the 48V it requires to operate. They were only a 1 amp supply or so but it worked.

Now with nothing plugged in, it draws a lot more amperage on startup from battery and instantly goes to overload..
When using the power supplies I originally used to start it up, it draws too much power from them and they shut down, and it doesn't get a chance to do anything but beep once and the lights blink once.


So obviously the unit is using more power than before and not just a software issue.


I am thinking it may have a bad mosfet. Cant remove them until I get my hot air station. Does this seem like a reasonable place to start troubleshooting? Maybe the mosfets were damaged from using the power supply to power the unit?

Thanks in advance for any advice

In the APC SmartUPS, some of these run the switching power supply
section full time, whether on AC or battery. On AC, the voltage from
the switching section is slightly below the input AC voltage, so the
load draws most of its power from the AC line. Of course, they are
phase locked. When the AC line voltage disappears, the switching
power supply section takes over running the load with zero switching
time. I'm not sure if the SU3000 SmartUPS works this way but it's
worth checking.

A schematic should be useful:
https://elektrotanya.com/apc_smart-ups_su2200_3000.pdf/download.html
(175K)

Offhand, I would guess(tm) that you blew something up with your 48V
power supply. The SU2200/3000RM uses a pile of 4ea 12V 18AH AGM
batteries. I believe that they are wired 2 in series and 2 in
parallel for a total of 24VDC, not 48VDC. You probably blew up the
electronics with the overvoltage.

If it draws lots of current from the battery section, the fets are the
likely culprit. However, as I vaguely recall, the SU2200/3000 series
has 4 strings of 8 FET's in parallel. It's not going to be much fun
finding the one FET out of 32 that is blown. I built a crude current
probe using a Hall effect device at the end that is useful for finding
which device is sucking the most current.

Most of the value and cost of a UPS are in the batteries. In this
case, a set of batteries is about $130 plus shipping. At the local
recycler, such large UPS's without batteries are plentiful because the
price of a new or refurbished UPS is only a little more than the cost
of decent batteries. Incidentally, beware of junk batteries and look
at the weight of the battery for a clue as to how much lead is inside.
I have my own collection of UPS's with dead batteries.

https://excessups.ca/refurbished-ups-systems/apc-ups-refurbished/apc-smart-ups-rackmount-refurbished

Good luck.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Everyone thanks for the advice. It is for sure a 48V unit,(batteries were wired as such and it puts out 48v charge current) but the SMPS power supply may have overshot that a bit under load.

My Hakko 936 doesn't quite have enough thermal mass to desolder the FETs
(even with the giant chisel tip I put on it) because of the huge double sided traces.

Getting a new hot air rework station this week and that should be able to do the job without cooking the components. I had one before but didnt make it with me on the last move.

Strictly speaking the unit works as a UPS as it is, but I can't use it as an off grid inverter because it won't start off batteries only.

I will check back in after I get the FETs out and check them.

On Wed, 4 Jul 2018 15:41:52 -0700 (PDT), Michael
wrote:


It is for sure a 48V unit,(batteries were wired as such and
it puts out 48v charge current) but the SMPS power supply
may have overshot that a bit under load.

Look on the top of the first page of the schematic. It says +24v and
is connected to the diodes after the AC power transformer. The
external battery connectors J5 and J9 traces to a collection of power
relays (RY3, RY4) that are labelled as 24V coils. The 4th drawing
"Main Circuit BD" also shows +24V. While most of the electronics runs
on +12V, I found no evidence of anything labeled +48V. Either the
schematic is the wrong unit, there might be a different between "3000"
and "SU3000RM", or your batteries were wired incorrectly.

Digging deeper, the SU3000RM uses two 24V RBC11 battery cartridges:
http://www.batteryspec.com/cgi-bin/cart.cgi?action=link&product=152
that are wired like this:
https://www.vps-ups.co.uk/rbc11.html
The connectors go to J5 and J9 which connect the two connectors in
parallel for 24V, not 48V.

My Hakko 936 doesn't quite have enough thermal mass to desolder the FETs
(even with the giant chisel tip I put on it) because of the huge
double sided traces.
Getting a new hot air rework station this week and that should be
able to do the job without cooking the components. I had one before
but didnt make it with me on the last move.

Anything attached to a heat sink is going to be a problem removing
with a hot air desoldering station. I suggest a big chisel tip and a
solder sucker.

Strictly speaking the unit works as a UPS as it is, but I can't
use it as an off grid inverter because it won't start off batteries only.
I will check back in after I get the FETs out and check them.

Do you still have the old batteries? If so, can you test the SU3000RM
with the batteries installed and see if it survives the initial self
test? During this test, the UPS runs on battery for a few seconds. If
the batteries are dead, it will so indicate with the front panel
lights. It might be a good quick check of the inverter section.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 03 Jul 2018 12:36:23 -0700, mike wrote:

On 7/3/2018 9:43 AM, Jeff Liebermann wrote:
I built a crude current
probe using a Hall effect device at the end that is useful for finding
which device is sucking the most current.

I've been considering doing that.
Can you share details about which parts you used?
What kind of sensitivity can you get?
Thanks, mike

I tried to find the one I built but couldn't. So, I do it from
memory.

The "probe" is a wooden coffee stirring rod that I stole from the
local coffee shop. Stuck onto the end was a linear Hall effect device
in a TO-92 package. As I recall, it was a TI DRV5053:
http://www.ti.com/product/DRV5053
http://www.ti.com/product/DRV5053/datasheet
http://www.ti.com/lit/ds/symlink/drv5053.pdf
It comes in several sensitivity ranges. Methinks it was EA or +45
volts/Tesla. That's not very sensitive, but more on that later.

The schematic was very simple. See 8.2.2. on the data sheet or:
http://www.ti.com/product/DRV5053/datasheet/application-and-implementation#SLIS1534512
The output went to crude x1000 LM358 DC amplifier and then to my TEK
2247A scope on the lowest 2mv/div scale.

The reason I threw this together was that I was trying to fix a
no-name Chinese solar inverter that had about 32 IGBT devices in
parallel in 4 strings. One device was probably shorted, but I
couldn't tell by probing. I also couldn't run it long enough to check
which device got warm. Checking the gates showed nothing useful. So,
my last resort was to try and measure the collector current without
breaking any wires. Looking for a switching waveform on the collector
would have been so easy, except that some protection circuit turned
off the drive oscillator because of the high current. I tried an
inductive pickup, but it just picked up junk from the adjacent working
devices.

I had just enough exposed collector lead accessible to sense a
magnetic field. I had a sample DRV5053 device, so I quickly threw it
together on the wooden stick and looked for some indication of a
magnetic field. After some tinkering, I could just barely see the
current on the scope. Walking it down the line, I found that 3
devices had shorted. I removed the shorted device but did not
initially replace them. It worked. I then made a guess as to some
potential replacements, actually found some in my pile, and proclaimed
the inverter to be repaired (until some better parts arrived in the
mail). Note that this repair was done from start to finish in about
an hour.

The key here was that it was only going to work with fairly high
currents. Judging by my automotive magnetic field ammeter, the
inverter was sucking about 30A with the blown devices which was
probably distributed as 10A per device. So, how much sensitivity will
it take to get a 1 division (2mv) change on the scope? Plugging into
a handy Ampere's Law calculator at:
https://getcalc.com/physics-amperes-law-calculator.htm
for 10A at 2mm radius (my guess), I get a 4x10^-8 Tesla field. The
Hall effect device has a sensitivity of -90V/T for an output change of
a fabulous:
4x10^-8T * 45V/T = 1.8 uV
with a gain of x1000, that becomes 1.2mv, which I could just barely
see under the noise and garbage on the scope.

So, you're welcome to build such a device, but I don't think it will
be a troubleshooters dream current probe, that can measure DC currents
without breaking the line. You might want to look into IMC
(integrated magnetic concentrator) type Hall effect structures. By
grabbing more of the magnetic field and concentrating it into the tiny
Hall effect chip area, it produces a higher reading and therefore a
higher sensitivity. The problem is that the pickup toroid or core
needs to go around the wire, which defeats the basic purpose of the
no-contact current probe. However, I suspect that some kind of probe
can be contrived with will sense more of the magnetic field than the
tiny chip, which will help with the sensitivity problem.
"Measuring Current with IMC Hall Effect Technology"
https://www.sensorsmag.com/components/measuring-current-imc-hall-effect-technology


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/4/2018 7:20 PM, Jeff Liebermann wrote:
On Tue, 03 Jul 2018 12:36:23 -0700, mike wrote:

On 7/3/2018 9:43 AM, Jeff Liebermann wrote:
I built a crude current
probe using a Hall effect device at the end that is useful for finding
which device is sucking the most current.

I've been considering doing that.
Can you share details about which parts you used?
What kind of sensitivity can you get?
Thanks, mike

I tried to find the one I built but couldn't. So, I do it from
memory.

The "probe" is a wooden coffee stirring rod that I stole from the
local coffee shop. Stuck onto the end was a linear Hall effect device
in a TO-92 package. As I recall, it was a TI DRV5053:
http://www.ti.com/product/DRV5053
http://www.ti.com/product/DRV5053/datasheet
http://www.ti.com/lit/ds/symlink/drv5053.pdf
It comes in several sensitivity ranges. Methinks it was EA or +45
volts/Tesla. That's not very sensitive, but more on that later.

The schematic was very simple. See 8.2.2. on the data sheet or:
http://www.ti.com/product/DRV5053/datasheet/application-and-implementation#SLIS1534512
The output went to crude x1000 LM358 DC amplifier and then to my TEK
2247A scope on the lowest 2mv/div scale.

The reason I threw this together was that I was trying to fix a
no-name Chinese solar inverter that had about 32 IGBT devices in
parallel in 4 strings. One device was probably shorted, but I
couldn't tell by probing. I also couldn't run it long enough to check
which device got warm. Checking the gates showed nothing useful. So,
my last resort was to try and measure the collector current without
breaking any wires. Looking for a switching waveform on the collector
would have been so easy, except that some protection circuit turned
off the drive oscillator because of the high current. I tried an
inductive pickup, but it just picked up junk from the adjacent working
devices.

I had just enough exposed collector lead accessible to sense a
magnetic field. I had a sample DRV5053 device, so I quickly threw it
together on the wooden stick and looked for some indication of a
magnetic field. After some tinkering, I could just barely see the
current on the scope. Walking it down the line, I found that 3
devices had shorted. I removed the shorted device but did not
initially replace them. It worked. I then made a guess as to some
potential replacements, actually found some in my pile, and proclaimed
the inverter to be repaired (until some better parts arrived in the
mail). Note that this repair was done from start to finish in about
an hour.

The key here was that it was only going to work with fairly high
currents. Judging by my automotive magnetic field ammeter, the
inverter was sucking about 30A with the blown devices which was
probably distributed as 10A per device. So, how much sensitivity will
it take to get a 1 division (2mv) change on the scope? Plugging into
a handy Ampere's Law calculator at:
https://getcalc.com/physics-amperes-law-calculator.htm
for 10A at 2mm radius (my guess), I get a 4x10^-8 Tesla field. The
Hall effect device has a sensitivity of -90V/T for an output change of
a fabulous:
4x10^-8T * 45V/T = 1.8 uV
with a gain of x1000, that becomes 1.2mv, which I could just barely
see under the noise and garbage on the scope.

So, you're welcome to build such a device, but I don't think it will
be a troubleshooters dream current probe, that can measure DC currents
without breaking the line. You might want to look into IMC
(integrated magnetic concentrator) type Hall effect structures. By
grabbing more of the magnetic field and concentrating it into the tiny
Hall effect chip area, it produces a higher reading and therefore a
higher sensitivity. The problem is that the pickup toroid or core
needs to go around the wire, which defeats the basic purpose of the
no-contact current probe. However, I suspect that some kind of probe
can be contrived with will sense more of the magnetic field than the
tiny chip, which will help with the sensitivity problem.
"Measuring Current with IMC Hall Effect Technology"
https://www.sensorsmag.com/components/measuring-current-imc-hall-effect-technology


Thanks,
Looks like that's not gonna be worth the trouble for me. Too little
sensitivity.
I had some success with AC fields using the tiniest torroid core
I could find. I cut a slot in the core and wound it full of tiny wire.
Took about a dozen tries to cut a slot without breaking the core...good
times...
In your case, proximity to other strong fields would be an issue.

For stuff that's actually shorted, I've had great success using the
HP current tracer and pulser. I can stick the pulse on a trace and
tell which direction the current is going. Also useful finding
bad caps.