Inverter while charging?

[JayGuevara]

Guys, this inverter I’m looking says it can’t be connected whilst replenishing the batttery.

Does that mean it can’t be on if the solar is charging the battery?

Seems odd. Is this unit junk?

I’ve been using the 300 watt version for 3 years trouble free but not whilst charging which is why I looked at the same brand for a larger one.

https://www.streetwizeaccessories.com/files//6e247293-31d7-4ff3-b9ab-aab000a6aba2/SWINV1500%20Manual%202019.pdf

 

[tictag]

Tbh, I just wouldn't consider buying a Modified Sine Wave inverter these days - you're just asking for trouble.

 

[JayGuevara]

No good for a fridge then?

 

[tictag]

MSW makes everything inefficient and, in the case of motors (compressors), can cause them to overheat and potentially fail completely. They waste power, get hot and cause RF interference. They should be consigned to history, just like PWM charge controllers.

 

[JayGuevara]

I get it. Can you recommend a good PSW around 1000w that wont break the bank?

 

[MichaelK]

Refrigerators typically have large surge currents while starting, which can overwhelm smaller inverters. You can determine exactly how much power the frig draws on startup with a clamp-meter the measures "inrush current". They tend to be more high-end on the meter scale of things, but you can find a functional one for about 60-80$US. I have this one, and it works well.

UNI-T UT216C 600A Digital Clamp Meters NCV LCD Test ACDC Auto Range Multimeters 747045037461 | eBay

Specifications Range UT216C. AC current (A) 600A ±(2.5%+5). DC current (A) 600A ±(2.5%+5). Jaw opening 　 30mm. Analog bar graph. VFC, low pass filter. Display count 　 6000. Auto range 　 √.

www.ebay.com

In terms of starting the frig, I'd suggest going a bit higher, say 1500W. This Samlex unit might be the right choice to start your frig.

Samlex PST-1500-12 Pure Sine Wave Inverter - RES Supply

Free Shipping! Samlex PST-1500-12 Pure Sine Wave Inverter, PST Series, 1500W, 12VDC, 120VAC, 200A, 60Hz, UL Listed, FCC Compliant

ressupply.com

Note that it is sine-wave, so it should produce power clean enough for a refrigerator compressor. In any case, let the numbers you determine guide your purchase choice.

 

[gnubie]

I'm in the 'pure-sine' camp but I do have a 12v MSW inverter, Powertech, something like this (seller of that is amazingly optimistic with the price!) and surprisingly it will start my Fisher & Paykel E411T fridge without complaint. That model controls the compressor with a microcontroller rather than a simple thermostat so the compressor is never short cycled, ie started with a large pressure imbalance across it so that helps. I would only use this to run the fridge as a last resort for all the reasons already stated.

Inverter fridges run the compressor with DC so in that regard don't care about the mains waveform but their mains input filtering still will. My LG inverter fridge's mains filter buzzes audibly and gets warm trying to smooth out the MSW. If the inverter fridge uses active power factor correction it may not start at all from MSW.

'Pure sine' is definitely the way to go.

 

[tictag]

Can you recommend a good PSW around 1000w that wont break the bank?

Will has a few component recommendations on his website, a place to start at least. Growatt seem to be receiving some praise on here (no personal experience). Samlex is oft quoted as a tier-1 product manufacturer, and I can personally recommend Victron Energy based on my own experience - about $300 for 800W and $400 for 1,200W on amazon.

 

[Ampster]

Inverter fridges run the compressor with DC

Can you explain that in more detail. I have heard them described as digital inverter refrigerators but never with a reference to DC. I understand that to drive a compressor at a variable speed, one would need to take the 50 or 60 Hz, rectify it to DC to invert it back to variable frequency AC to run the compressor at different speeds. Is that what you mean?