How to test a used inverter to know it works good

Only way to test it is to see it functioning normally on a working vehicle, unless of course you're an electrical engineer nerd and can go through the whole system testing each component.

But odds are, the problem with the Gen2 you're working is that it's giving error codes for a bad inverter even though the problem exists elsewhere in the hybrid system, usually the hybrid battery pack. As in all of us who have worked on Gen2 Prius often for 4 or 5 years have one of those inverters on our parts rack because we bought a used one thinking it was the problem and it turned out being a problem elsewhere.

I'm so certain the problem in your 2007 is not the inverter that I'll bet you the inverter on my parts rack if it really is. As in it's yours for free, as long as you cover cost of shipping if your car really needs it. Of course 2007 had an inverter upgrade mid year, so date of manufacture of your 2007 has to be July or later of 2007 for my spare inverter to be compatible.

 

Those hybrid synergy drive inverters from whatever it is 01 to 09 are built with Hitachi parts and are built like tanks Open up a Gen 3 or 4 and look at it everything got smaller less precious metal just like anything else practically and I would agree The likelihood of it being your inverter is so slim it's almost ridiculous but maybe you've exhausted everything else maybe you're looking at tec stream And you can tell it's not outputting I don't know but it's extremely rare I've got tons of these inverters around here none of them are bad No one's ever called or asked for one and they cost nothing in the junkyard because they're almost never sold I guess and I can't imagine anybody buying them new but I learned something new everyday with this car stuff with folks.

 

In another thread, it's possible lunarkingdom recently put ten times the working voltage (five thousand volts) into his inverter. No telling yet if it survived that or not, but this may be a little different from your typical "I've got some codes and wonder if it's my inverter" situation.

 

It just bolts up but won't be missing a chunk and won't be pinched into the some weld into the firewall or what have you but I don't know how they pushed it up against the firewall and did all that damage so when you put the new one on is it going to be sitting up against the firewall too It sounds like somebody's really articulated something in your engine bay

 

I didn't know a magometer would put any volts through a system but then again we learn something new everyday I thought a megger. Red on a display or a digital readout mega ohms.

 

Well sure, but how did you think any ohmmeter worked?

You find something's resistance in ohms by putting some voltage V across it, measuring how many amps A then flow, and dividing V by A to get ohms.

The ohmmeter in your typical multimeter uses just a few volts (the spec for mine is 1.3 volts maximum). So using my multimeter to measure a 40 MΩ (the highest resistance it can read), the 1.3 volts will make 0.0000000325 amps flow, and the multimeter will divide 1.3 volts by 0.0000000325 amps and say "that's a 40 MΩ resistor you've got there".

But a megohmmeter for insulation testing has to be built for resistances where millions of ohms would be the low end, and readings can go into the billions. it can't do that with just a volt or two; the current would be too tiny for the instrument to practically measure. Also, it might be looking for degraded insulation that really only shows up above some voltage.

So a megger doesn't just use some low voltage to test with. It usually lets you select among voltages sometimes as low as 50 or 100 volts, usually includes 500 and 1000 volt settings, and some will have settings for 2500, 5000, 10000, 15000 volts or even higher.

Those voltages are no joke, which is why not to treat a megohmmeter like you would your everyday multimeter.

On a Prius, there'd not be much point using a setting above 500 or 1000 volts. Gen 1 Prius used 274 volts at the motors, Gen 2 boosted that to 500, and Gen 3 up to 650. Testing for insulation flaws up to roughly twice that, the 500 volt setting for a Gen 1 or maybe the 1000 volt setting for a Gen 2 or 3, could be reasonable, but not so much going above that. If your fancy higher-voltage megger tells you the insulation starts to fail at some voltage above 1000, well, the Prius doesn't ever hit that voltage anyway.

And you'd have to be careful what parts in a Prius you want to expose to those kinds of test voltages anyway, especially voltages many times higher than designed. Things like wires and motor windings can usually take it (up to some reasonable point); electronics, transistors, and microchips, not so much.

The megohmmeter doesn't always produce the exact voltage you select on the dial. At lower resistances that would cause insanely high currents to flow and take crazy amounts of power. So the meter produces a voltage that tops out at the voltage you selected, as long as the resistance you're measuring is high enough. At lower resistances, the test voltage drops. For my megger, which has 100, 250, 500, and 1000 volt settings, that looks like this. For all the settings, it pretty much reaches 100% of the selected voltage, by a resistance of 10 MΩ or above.

 

Inside edge of driver side door is date of manufacture... As long as its July 2007 or later a 2008 will work. But if its before July then it might not be compatible because they upgraded starting in July 2007. Then again we've yet to have someone to verify that by trying it. That's just what the data base all the auto wreckers use for parts compatibility.

 

Good thing posters on here make sure to scatter vehicle history through multiple threads so it's harder to keep track of everything. Makes us better at guessing.

More to the point, my parts rack isn't big enough for an inverter that's likely never gonna get used. :-(