Mobitronic MS-50A Switching Supply Problem in 200 Series Cruiser

Submitted: Tuesday, Nov 12, 2013 at 06:24
ThreadID: 105086 Views:4925 Replies:5 FollowUps:6
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Mate has a 200 series diesel Cruiser with a 220v outlet plug in the rear at 100w. He has a Waeco CF50 with an external switching supply MS-50A which powers the fridge.

The problem is when he plugs the Mobitronics in to the 220v outlet in the vehicle there is no audible click to show it is turned on and working, hence does not power the fridge. However, when he plugs the Mobitronics into a GPO in the shed it works. We plugged my CF50 with its built in inverter into the 220V outlet in the vehicle and it worked.

Any clues as to what is going on?

Technical details of the MS-50A are;

AC input 100 - 240v AC 50/60Hz 3A
DC output 27VDC 6A 150W
DC Battery input 12/24 VDC 12A/6A
DC Battery output 12/24 VDC 12A/6A

Many thanks in advance.

Jeff

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Reply By: Member - Boobook - Tuesday, Nov 12, 2013 at 06:42

Tuesday, Nov 12, 2013 at 06:42
The power supply is rated at 720W ( 240v x 3 A), the poor old power supply in the vehicle is under rated at only 100W, and is cutting out or blown a fuse.

Why not use 12V?
AnswerID: 521281

Follow Up By: Member - Boobook - Tuesday, Nov 12, 2013 at 06:43

Tuesday, Nov 12, 2013 at 06:43
Oops for clarity, the Waeco fridge Power supply is 720W and the 240V vehicle power supply is only 100W.
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FollowupID: 801984

Follow Up By: Member - Phil G (SA) - Tuesday, Nov 12, 2013 at 17:02

Tuesday, Nov 12, 2013 at 17:02
Also, the Landcruiser 240V 100W outlet in the rear only works when the engine is running.
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FollowupID: 802006

Reply By: mildew - Tuesday, Nov 12, 2013 at 06:48

Tuesday, Nov 12, 2013 at 06:48
Thanks for the quick reply Boobook. Problem is there should be an audible click when the Mobitronics starts even without the fridge plugged in under load and I would have thought 100W (0.45 amps) would have been enough for this.
AnswerID: 521282

Reply By: Sand Man (SA) - Tuesday, Nov 12, 2013 at 07:41

Tuesday, Nov 12, 2013 at 07:41
Looking at the Mobiltronic MPS-50A specs, (if this is what your mate has) it would appear it has 2 inputs, so may be not a 12v/240v inverter but a 240v/12v converter.
If 240v supply is not available it will switch to "house battery" (12v) supply.
So it would have two separate inputs.
One 240Vac input when plugged into "house supply" via the 240v inlet.
One 12Vdc input when switched to "battery" supply.

Have you checked the output from the MPS-50A?
Maybe an inline fuse from the 12 volt circuit has blown.

It would appear a strange choice to have installed in a vehicle though.
A simple 12Vdc supply, preferably from a separate (dual) battery supplyto which the fridge can be plugged into, would give a much better solution.

Just as an aside, Waeco have withdrawn these units from sale, due to several problems experienced.




Bill


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AnswerID: 521283

Reply By: Ross M - Tuesday, Nov 12, 2013 at 09:25

Tuesday, Nov 12, 2013 at 09:25
It seems you have a 220v outlet which would be a switchmode power supply, to power a switchmode power supply (the Mobitronic unit) to power the fridge.

If it is that way everyone would ask WHY?

The 12v of the vehicle will power it in a direct manner 12v to 12v plug is best.

If the 220v ac unit ISN"T a FULL SINE WAVE then it is putting out a the crappy "modified square wave", strangely often called modified sine wave.
It is a wave above 0 and below 0 but not sine at all in shape, so a modified square wave it is.
That means there are funny shaped pulses in the power delivery and if Mobitronic unit want to see a reasonable clean power delivery ie SINE WAVE LIKE to it, then it may just not begin switching at all. Hence no CLICK even if it isn't connected to the fridge load.

That could be why it doesn't work.
AnswerID: 521288

Follow Up By: oldtrack123 - Tuesday, Nov 12, 2013 at 16:04

Tuesday, Nov 12, 2013 at 16:04
Hi
As others have said
It makes no sense to convert 12v to 240v the convert it back again to 12V when the fridge can be run DIRECT from 12V
Each step involves effieciency losses just a waste of available power


PeterQ
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FollowupID: 802003

Follow Up By: mildew - Tuesday, Nov 12, 2013 at 18:19

Tuesday, Nov 12, 2013 at 18:19
Thanks for the info guys. I'll pass this on to my mate. He was a sparky before he retired so will understand better than me.
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FollowupID: 802011

Follow Up By: Ross M - Tuesday, Nov 12, 2013 at 21:07

Tuesday, Nov 12, 2013 at 21:07
You mean to say, we are trying to advise a sparky who should know better than us anyway.
I can't imagine why a sparky would be having the problem and would be aware of using the gear in the best, most efficient manner anyway.

Something is amiss.
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FollowupID: 802022

Follow Up By: oldtrack123 - Tuesday, Nov 12, 2013 at 21:51

Tuesday, Nov 12, 2013 at 21:51
Hi
Well, there are SPARKIES & sparkies
Some work in very limited fields ,with little experience outside of their field
Some even forget the basics from lack of use!

PeterQ
0
FollowupID: 802027

Reply By: ABR - SIDEWINDER - Tuesday, Nov 12, 2013 at 21:53

Tuesday, Nov 12, 2013 at 21:53
The modified sine wave inverter can't run the MS50.

Here is a picture or the tiny Toyota inverter.



As already mentioned it is far more efficient to run the fridge on 12V DC.

Regards

Derek from ABR
AnswerID: 521329

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