[RE-wrenches] Magnum MS 4448 AE issues

Sun Dec 23 10:15:18 PST 2012

I would try to see if you could get Skystream to widen their low voltage and low frequency trip points as far as possible.
If this has already been done then an inverter change may be needed.

Assuming the battery can support it....
The Sunny Island is much better than Magnum and Outback FX in terms of stability on surges.
It has a very fast control loop and can really grunt it out for big loads.
My 5048's can do 12kW for 3 s (each) and close to 200 Amps for 60 ms (they do sag voltage and frequency a bit to support this high a surge).
As I recall the DC side current limit is 400 Amps.

Best Regards,

John Berdner
General Manager, North America

3347 Gateway Boulevard, Fremont CA 94538 USA  (*Please note of our new address.)
T: 510.498.3201 ext 747
M: 530.277.4894

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Ray Walters
Sent: Sunday, December 23, 2012 10:03 AM
To: Howie at CatamountSolar.com; RE-wrenches
Subject: Re: [RE-wrenches] Magnum MS 4448 AE issues

I've seen those dips in output voltage from almost all off grid
inverters under load.   They either dip the voltage or worse (like an
old Trace SW5548) just shut off. Outback for instance just has a constant 50 amp output for 5 sec, and lets the voltage dip a bunch on surges.  The idea is to to run them like a generator, which also dips voltage on surges.

2nd,  I know he didn't measure much volt drop on the DC side, but I've had poor results with Rolls batteries under load.
3rd, I didn't know the Sky stream was recommended for off grid,  I thought it was grid tie only.  I could see the Sky stream shutting off every time a large load came on.  It probably would not work very well on generator power either.
One fix would be to have separate inverters, to isolate the Sky stream from the surge loads.
The only inverter I haven't tried is the Sunny Island, but I would imagine it would have a voltage dip on surge too.
Perhaps some capacitance might help too?

Ray Walters
Solarray, Inc.

  On 12/23/2012 8:45 AM, Howie Michaelson wrote:
> Hi All,
>
> I am trying to help my brother-in-law figure out if he can continue
> using his Magnum MS 4448 AE in his now off-grid home in Nova Scotia
> which we installed about 3 years ago as at the time a battery backup
> inverter.  I would preface the following with the information that he
> is a very knowledgeable/hands on physicist (chair of the Physics
> department at Dalhousie U. in Halifax, as well as an intrepid sailor
> having sailed all over the world in 2 different sailboats he built
> himself).  I mention this to explain that he is very capable and
> understands the inner workings of his equipment much better than most wrenches I know (and certainly me).
>
> About a year ago he installed a SkyStream 3.7 to add to the roughly 3
> kW of solar on an FM80, and then a short time later disconnected
> himself from the grid.  He immediately started having problems with
> the Skystream regularly disconnecting from his system and shutting
> down, then reconnecting and cycling off again, were as there hadn't
> been a problem while grid-tied.  After much investigation and
> conversation with SW WindPower tech support and some software patches
> from them, things improved somewhat.  But the regular disconnections continued.
>
> Since then he has spent a great deal of time on the phone with
> Magnum's tech support but they have not been able to answer his more
> technical questions.  The best they've offered is to have him send the
> inverter in, but of course that is now not practical.
>
> The basic problem seems to be the voltage regulation during loading
> and unloading of the inverter (even with medium sized loads). He tried
> to get an internal wiring diagram and/or service manual from Magnum with no luck.
>   He has not been able to get through to any engineers that would be
> able to answer his more technical questions.  He is trying to figure
> out if there are any internal set points that he can adjust or
> components that can use tweaking. He has looked at the wave form with
> a scope and would like to see if there are changes that he can make to
> the electronics to allow for better regulation.
>
> Here is what he has written me:
>
> "Here is my report on the Magnum MS4448AE observing the AC output with
> a Fluke 189, measuring the max and min values in slow mode (not it's
> fast mode which would look at spikes for short times):
>
> I have checked several water heater elements running on 240 V (they
> are between 2000 and 2500 Watts - immersion heaters). When switching
> any one of them on, the voltage drops from around 240V to 197 V on
> average, sometimes going as low as 170 V. These are serious drops, the
> lights dim drastically and the radio may cut out for .5 s or so!
> Switching the thermal heaters off again raise the output voltage to
> 271 V sometimes reaching 282 V.
>
> The battery bank during those test were at 53 V at the DC input side
> of the inverter, measured at the inverter. The voltage drop for the DC
> was around 1 V DC. The battery bank is a 800 AH (Rolls S530) with 2/0
> copper cables 5 - 6 ft inverter cables.
>
> We had great wind yesterday and I had to switch to the hock up the
> diversion load to 240 V so it would draw 2.5 kW.  Needless to say it
> stalled the windmill each time my outback kicked on the diversion
> load. I had to leave  the windmill off during the day. When I run the
> heating element on 120 V (and therefore 625 W) it works beautiful if
> the wind isn't too strong. Obviously the inverter handles 625 W quite well!"
>
> He is also thinking about replacing the inverter with a newer split
> phase inverter (an XW or a Radian).  If anyone has an opinion about
> which might work for him, I'd appreciate any feedback.  I am not a fan
> of Xantrex, although I know some on the list really like the XW. If
> anyone has any ideas of either a fix or someone we can get through to
> at Magnum, that would be a great help.
>
> Thanks,
> Howie

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