Replacing Internal Fuse on LV2424

[heirloom hamlet]

Has anyone ever replaced or does anyone have knowledge if it is possible to replace the internal inverter fuse in an LV2424?
For some time, I have felt like the unit cannot take the load it once could.
It is currently not being pushed to or beyond what it was designed to do, yet it does a thermal stoppage routinely on relatively light loads. I'm wondering if pushing a heavier load in the past (right at it's 2400w limit) could have impacted the endurance of it's internal inverter fuse.
Is that possible, can fuses degrade and lose their umph while remaining someone operational?

 

[heirloom hamlet]

Nevermind, as for the How-to part of my question. MPP sent me this:

 

[BiduleOhm]

It's very very unlikely (impossible?) for fuses to fail that way. Electronic components however can.

 

[heirloom hamlet]

It's very very unlikely (impossible?) for fuses to fail that way. Electronic components however can.

Like which? Would they continue to operate normally under some loads and not others? Because thats what's happening.

 

[BiduleOhm]

Given what you said I would say it's more likely on the power side than the control side. Electrolytic capacitors are a good suspect as they are heavily affected by heat and have a finite lifetime. Mosfets would be the second probable suspect. But without more infos and tests we can't say.

Also is the problem on the inverter or the SCC (or both)?

 

[heirloom hamlet]

Given what you said I would say it's more likely on the power side than the control side. Electrolytic capacitors are a good suspect as they are heavily affected by heat and have a finite lifetime. Mosfets would be the second probable suspect. But without more infos and tests we can't say.

Also is the problem on the inverter or the SCC (or both)?

On the inverter side.

 

[BiduleOhm]

Ok, first thing I would do is some load tests to know at which load it cuts out and how close it is to the specs.

 

[heirloom hamlet]

Okay, I'll do that today. Thanks for your expertise and input.

 

[tictag]

100% agree with @BiduleOhm, no way a fuse is causing this. A fuse is only just about smarter than a rock, it either conducts electricity or it blows up. There is no middle ground. And that's why they're so cheap

A poorly specified or some other material failure in one or more of the unit's power FETs or similar, that's different thing; they heat up, temperature sensor trips the inverter offline.

I would not recommend swapping out FETs if the unit is still under warranty but, as @BiduleOhm suggests, if you can provide evidence that your unit is not performing per its datasheet, then you could claim on the warranty. It's easy and cheap to do this, simply get yourself one of these:



...and video yourself testing a device that causes the LV2424 to fail (yes, I did say video, they always ask for video...)

p.s. If you have a thermal camera, you can usually spot failing components.

Edit: added postscript

 

[heirloom hamlet]

100% agree with @BiduleOhm, no way a fuse is causing this. A fuse is only just about smarter than a rock, it either conducts electricity or it blows up. There is no middle ground. And that's why they're so cheap

A poorly specified or some other material failure in a FET or similar, that's different thing; they heat up, temperature sensor trips the inverter offline.

I would not recommend swapping out FETs if the unit is still under warranty but, as @BiduleOhm suggests, if you can provide evidence that your unit is not performing per its datasheet, then you could claim on the warranty. It's easy and cheap to do this, simply get yourself one of these:

View attachment 20443

...and video yourself testing a device that causes the LV2424 to fail (yes, I did say video, they always ask for video...)

p.s. If you have a thermal camera, you can usually spot failing components.

Edit: added postscript

Thank you. I did some troubleshooting today, including doing the same tests on a second LV2424.

They behaved the same.

I don't have a thermal camera, but I took detailed notes on the wattage meter device, I have one of those.

It went this way:

Speaker, Fans:
252w
Hi 350w
2.15a
119v

Speaker, Fans, Vac:
1384w
Hi 1391w
12a
117.1v

Speaker, Fans, Vac, Saw (No Cutting):
1740w
Hi 1769w
15.83a
116.4v

Speaker, Fans, Vac, Saw (Ripping 2x4 1' long for, 5 to 10 sec then shutdown):
1800w
Hi 2245w
20.8a (Startup peak...18.8 continuous)
115.8v

These units is a 2.4kw inverter. Does it look from these figures that they should be able to do this and are failing. Or is it simply what they are capable of and the rated numbers just aren't legitimate?

 

[gnubie]

The fans, vac and saw probably all have poor power factors being mostly AC motor loads. Effectively they look like higher draw loads to the inverter. Check your power meter for the power factor and post the value if you can see it.

The manual for the 2424LV doesn't provide a kVA rating for the inverter, only watts and while it does mention power factor it's hard to tell to what that applies.

 

[heirloom hamlet]

The fans, vac and saw probably all have poor power factors being mostly AC motor loads. Effectively they look like higher draw loads to the inverter. Check your power meter for the power factor and post the value if you can see it.

I don't know what the power factor is.

 

[gnubie]

Basically it refers to how close your load is to being a purely resistive load like a bar heater where current draw is in step with the voltage coming from the inverter. The worse the power factor the more the current being drawn gets out of step with the voltage being supplied. It doesn't really matter that you understand how it works, just that it's an issue that might be causing your problem. Some watt meters can report the power factor. Check yours to see if it does, and if so post the value.

Here's a wikipedia article on power factor if you want to see what it's all about

 

[BiduleOhm]

Yep, ideally you want to test with resistive loads (heaters are nice for that), I should have precised that before, sorry.

1.8 kW for 2.4 rated would be a PF of 0.75 which is plausible given your loads (mainly motors).

 

[tictag]

Check whether your power meter has the option of showing both Real and Apparent power, use whichever is the bigger number! If it doesn't then, as already mentioned, tell us the power factor under your biggest load. If it doesn't show power factor, try to use a purely resistive load e.g. space heater, heat gun, hairdryer etc.

I don't have an intuitive understanding of how power factor effects an inverter but if what @BiduleOhm is saying is true, it might be that you're just maxing it out.

 

[heirloom hamlet]

Yep, ideally you want to test with resistive loads (heaters are nice for that), I should have precised that before, sorry.

1.8 kW for 2.4 rated would be a PF of 0.75 which is plausible given your loads (mainly motors).

The meter does show the Power Factor, and I thank you for teaching me about it. But it looks like I have to read it while running the test. I'll do it again in the morning.
It has never shutdown like that unless operating that saw/vac combo. I don't know if you are familiar with Festool or not, but they were strictly a European brand until ten or fifteen years ago, which of course operated on 240v power supply. They motified their motors and designed a 120v version of as many of their tools as they could and came to the states. But as I learn more about electricity and in particular our US design, it seems they really designed a tool combo that doesn't mesh well with our style electricity. Even with a dedicated 20a breaker it's pushing that 80% 1920w threshold we hold to.