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Convert a 24v inver...
 
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Convert a 24v inverter to 12v?

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(@glenn-s)
Eminent Member
Joined: 3 years ago
Posts: 23
Topic starter  

Ok, so here's the thing. I have a 24v 3500w hf inverter. It was a warranty replacement that took way too long to get here, so in the meantime I bought my U-power LF inverter which is what I currently use. When my replacement hf inverter finally arrived, it was too late, so it currently still sits in the box.

Anyway, my buddy sent me his 12v 3000w inverter to repair. As I opened his inverter, I realized it was identical in every way to my 24v 3500w inverter. I even used my old one for some parts to repair his.

Now, my gf's Reliable just shit the bed on me when I hooked it up this year(fets blew out the moment I turned it on, no load).

So while I'm fighting with them to get a replacement, I remembered my inverter.

Since his 3000 was identical to my 3500, and rated at a lower wattage (3000), could I possibly modify my 24v to a 12? I know you can with the GS and probably PJ ones with some work. Is it as simple as turning a pot down in my case? Normally I know you'd want to maybe beef up the wiring, but like I said, its 12v counterpart there was exactly the same internally, and I really examined the bitch too because I was really surprised to see that.

Anyway, is it doable at all?

 

Thanks!


   
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(@dickson)
Noble Member
Joined: 3 years ago
Posts: 1043
 

Anyway, is it doable at all?

NO .      


   
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(@sid-genetry-solar)
Member Admin
Joined: 3 years ago
Posts: 2869
 
Posted by: @glenn-s
Ok, so here's the thing. I have a 24v 3500w hf inverter. It was a warranty replacement that took way too long to get here, so in the meantime I bought my U-power LF inverter which is what I currently use. When my replacement hf inverter finally arrived, it was too late, so it currently still sits in the box.

Well, only if you don't mind rebuilding the entire thing.  Otherwise...ESPECIALLY with an HF inverter.......no, it's not feasibly possible.

 

Posted by: @glenn-s
Is it as simple as turning a pot down in my case?

Not a chance. 

On a PJ LF inverter, you'd need to replace the transformer, and reposition a bunch of jumpers.

On an HF inverter (which you said these are)...you would need to replace ALL of the boost converter transformers with the proper spec ones.  (99% guarantee that they're custom spec, not an off-the-shelf option.)  As you're aware, going from 24v to 12v DOUBLES the amperage from ~160A to ~320A.  If the transformers aren't wound differently to handle this (i.e. twice the primary thickness), they're going to melt down.

Check the part number on the transformers (if any!)  They'll be different.


   
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(@robertm)
Estimable Member
Joined: 2 years ago
Posts: 205
 
3 hours ago, Glenn S said:

Ok, so here's the thing. I have a 24v 3500w hf inverter. It was a warranty replacement that took way too long to get here, so in the meantime I bought my U-power LF inverter which is what I currently use. When my replacement hf inverter finally arrived, it was too late, so it currently still sits in the box.

Anyway, my buddy sent me his 12v 3000w inverter to repair. As I opened his inverter, I realized it was identical in every way to my 24v 3500w inverter. I even used my old one for some parts to repair his.

Now, my gf's Reliable just shit the bed on me when I hooked it up this year(fets blew out the moment I turned it on, no load).

So while I'm fighting with them to get a replacement, I remembered my inverter.

Since his 3000 was identical to my 3500, and rated at a lower wattage (3000), could I possibly modify my 24v to a 12? I know you can with the GS and probably PJ ones with some work. Is it as simple as turning a pot down in my case? Normally I know you'd want to maybe beef up the wiring, but like I said, its 12v counterpart there was exactly the same internally, and I really examined the bitch too because I was really surprised to see that.

Anyway, is it doable at all?

 

Thanks!

Could you convert her system to 24V? 


   
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(@sid-genetry-solar)
Member Admin
Joined: 3 years ago
Posts: 2869
 
52 minutes ago, RobertM said:

Could you convert her system to 24V? 

Same gauntlet....you'll need to replace the transformers (and likely the boost FETs, if they aren't rated to 40-60v).

And that's not even changing the UVP/OVP setpoints to make it work even after doing all the parts replacements.  It's anyone's wild guess as to how the voltage limits are implemented--that's entirely dependent on the inverter manufacturer design.  There's a lot more innovation in Chinese HF inverters than in LF inverters--meaning that the methodologies can be considerably different from manufacturer to manufacturer.


   
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(@robertm)
Estimable Member
Joined: 2 years ago
Posts: 205
 
1 hour ago, Sid Genetry Solar said:

Same gauntlet....you'll need to replace the transformers (and likely the boost FETs, if they aren't rated to 40-60v).

And that's not even changing the UVP/OVP setpoints to make it work even after doing all the parts replacements.  It's anyone's wild guess as to how the voltage limits are implemented--that's entirely dependent on the inverter manufacturer design.  There's a lot more innovation in Chinese HF inverters than in LF inverters--meaning that the methodologies can be considerably different from manufacturer to manufacturer.

No, I meant putting the panels and batteries in series, and maybe buying a new controller. 


   
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(@glenn-s)
Eminent Member
Joined: 3 years ago
Posts: 23
Topic starter  
7 hours ago, RobertM said:

No, I meant putting the panels and batteries in series, and maybe buying a new controller. 

Not really. I've converted my own to 24v, and use a buck converter for my 12v systems. But she's quite shaded where she is so I ran everything in parallel to keep her current as high as I could.

Plus she only has 4 batteries and not great ones at that so I'd lose too much capacity going 24v in her case.

 

It's really not a huge deal. I just had this inverter kicking around so I thought I'd ask. Thanks for all the info guys.


   
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(@sid-genetry-solar)
Member Admin
Joined: 3 years ago
Posts: 2869
 
Posted by: @glenn-s
But she's quite shaded where she is so I ran everything in parallel to keep her current as high as I could.

Umm....watts are what comprise power, not amps.  And if you rewired the batteries from 4P (4 parallel) to 2S 2P (2 series strings of 2 parallel), you haven't lost any capacity.  It's simply arranged differently. 

Same with the panels...as long as you have sufficient headroom voltage for charging, it's watts that matters, not amps. 

Yes, current will be halved at the higher voltage--but just as 12v * 100A = 1,200W, so does 24v * 50A = 1,200W.  Better, since amperage is the bane of efficiency....the reduced losses in the wiring and converters (basically, everything!) will result in you actually ending up with MORE power (albeit a very small amount!) in your system.

 

Just my 2 cents.


   
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(@glenn-s)
Eminent Member
Joined: 3 years ago
Posts: 23
Topic starter  

Well, yes, you're not wrong. And this is why I run my own system at 24v.

The problem lies in the shade though. Wired in parallel, if one panel becomes shaded, I lose a large chunk of that panel. But the others keep going. Wired in series, I lose almost all of it in the same situation.

The output of a panel, as I was demonstrating to her, to show the importance of being able to move the panels around her camp site, went from 5amps down to 3 just by covering a single cell with my hand. But the other panels were unaffected. In series, you lose everything after that shaded feel. Not just one panel.

 


   
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(@aquaticslive)
Reputable Member
Joined: 3 years ago
Posts: 247
 

Sorry your in the the situation of trying to get an inverter rolling.  I have my 12V setup in an ambulance so I know the pains.  On the solar side of things one trick possibly for the future is making a combiner box with options to change the wiring.  When I am in a sunny area I setup all the panels in series that runs it at 80v I get max wattage that way.  When I camp in a shady area I swap them over to 40v mode it gives me a little better wattage in the shady areas.  I am sure stationary setups could benefit from some actual power testing with different configurations for winter and summer  Trusting what you read or others tell you only goes so far try everything yourself and learning new tricks is fun.  Good luck out there.


   
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