[RE-wrenches] Magnum MS 4448 AE issues

[bob ellison]

Voltage drop with Magnum inverters has been an issue as it has with many
other off grid inverters.
That said, I doubt that you will ever get a Skystream to function correctly
off grid. You might get it to play nice if you hook it up to an Exeltec
inverter and have the inverter feed nothing else so it gets power separated
from the main system. Adding another string of batteries might help smooth
things out also, that would give it a larger sink to draw from and feed
into. The Rolls batteries have really dense plates and don't respond really
fast to changes.
A 2nd set of 2/0 cables wired to the opposite side of the battery bank might
help, unless you have them wired to buss bars or switch to 4.0 cables.

Just some random thoughts.

Merry Christmas everyone,
Bob Ellison     

-----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 1:03 PM
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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