Prowatt inverter problem

[jerryat]

Hi all you electronic technophobes,

I need some help with a problem that occured suddenly with my Statpower Prowatt 250i 12vdc to 240vac inverter that we use to charge/run our computers/mobiles etc. /forums/images/graemlins/frown.gif

It's worked beautifully for the last 8 years or so then, last night, when we switched it on, it only produced 116Vac i.e. effectively half power.

Batteries were at 12.7vdc (open circuit) so no problem there. We changed to our old 150watt Prowatt and that was fine (though 'noisy' on the computer) so it looks as if the 250 is ill. /forums/images/graemlins/frown.gif

Anybody come across this before and, if so, is it user repairable and how do you get into the damned 'box'. i've replaced the 'reverse polarity protection' diodes on the 150 a couple of times over the years, but not opened up this one yet.

Very grateful for any advice.

 

[tugboat]

I inherited the same unit with my boat, though I haven't tried it yet. In case you don't have the manual I've found mine and looked in the troubleshooting section. Under LOW OUTPUT VOLTAGE it gives 3 poss causes and remedies. I'm a technonumpty myself so treat any of my suggestions with caution!

Using average reading voltmeter ....... Use true RMS reading meter.(see below)

Inverter is overloaded ..................... Reduce load to 225 watts maximum to
maintain regulation.

Power source voltage below 11volts .... Keep power source above 11 volts to
maintain regulation.

Might be worth checking battery voltage under load in case of a duff cell.

There is a section in the manual about the output waveform and use of voltmeters to check. If you like I can post that. Won't do it now in case you have the manual and already know this stuff.

 

[sarabande]

Before dissecting it, is there, by chance, an output switch which changes from 110 to 240 ?

 

[Anonymous]

High resistance connections on the input side would cause this problem. Check all the 12V wiring right through to the unit's terminals, check all contacts are tight and clean. Check the fuse - fuses can get tired and high resistance and fuse holders can go high resistance. These sorts of contact problems are common on boats where we get high humidity and salt around.

I'm puzzled why you've needed to change your diodes in the 150W inverter. What have you been doing with it? Is it wired direct from 12V to the thing you are using (e.g. TV) or is it wired into the boat's supply? I smell a rat /forums/images/graemlins/smile.gif

 

[jerryat]

Hi tugboat,

I think I've got the manual somewhere on the boat (just lifted out today so no time to look) so I'll have a good look through it if it's there. If not, I'll come back to you if I need further info.

It certain wasn't overloaded as there wasn't 240volts even with nothing connected. The service battery bank is 420amps and it's fully charged (actually 12.72 when I tried the unit) so I doubt low voltage is the cause.

Many thanks for the input, and I'll ask you post the waveform/voltmeters if I can't find the manual.

 

[jerryat]

Hi sarabande,

That's a good idea and was the first thing I looked for, in case I'd missed it over the years. But no, unfortunately is only 240volt.

Thanks for the input.

 

[jerryat]

Hi Lemain,

Nice to hear from you again. You make a couple of good points that I'll try and check out tomorrow.
Certainly the fuse-holder (for example) is the original one I fitted, so may well now be a bit tired, though it looks fine. I've changed the odd fuse over the years I've had the unit, but will try a new one just in case.
The wiring is only 450mm long from the batteries to the unit and is in perfect condition so far as I can tell i.e. bright shiney- no sign of corrosion - so I suspect that's not the problem.

Regarding the 150 diodes. Prowatt (at least in those days) didn't put an easily replaceable reverse polarity fuse in their units, and maybe still don't, so if. like me, one inadvertently plugged in the (then) Spanish two-pin plug I'd fitted to the unit the wrong way, it was a £25.00 'return to manufacturer' job.
Since removing the end covers and changing the 5p diode was dead easy, that's what I did! /forums/images/graemlins/smile.gif

Yes, I know I should have got a fool-proof plug but, like many, I just never seemed to get round to it!!! /forums/images/graemlins/crazy.gif

Thanks for your ideas, and I'll post the results of my efforts as soon as I get the rotten thing back in action, in case it helps someone else.

 

[Anonymous]

Hi Jerry, nice to see you again - hadn't noticed you around for a while? If there is a plug in series with the 250W one, do check that as well.

 

[Stoaty]

I would treat myself to a new one if it's not easily fixed. They are not as expensive as they used to be.

Look HERE