Ran inverter but keeps tripping breaker.

If it's tripping the 100amp then the output from the inverter has to be over 1000 watts or you have a problem with the rectifiers in the inverter.
Do you have the breaker mounted close to the batteries?
Find a car stereo place and get a block fuse holder and a few different amp fuses. With 4ga wire I wouldn't go over 150amp.

 

160 would be 2000 watts at 12 volts roughly. Google watts to amps it will give you calculators to use.
If you have over 10ft of wire from batteries to inverter I would go with a single 2ga wire.

 

Check your connections first. Even though they are new, a plug soldered connection should not have you drawing that many amps.

This is presuming you DID make proper connections.

 

I have an 1800 watt inverter with a 700 watt microwave, plus a dorm size fridge/freezer. That fridge might be a monster or the compressor is kicking in when the microwave is on. Try unplugging the fridge while using the microwave.

 

Almost positive it's exactly what lovesthedrive posted earlier. The "Surge watts" are tripping the inverter. And if your batteries are on the fritz, it's compounding the problem. Can you post what the name is and model # for the microwave?

 

The specs are showing 1050W peak for the microwave. You have to take a couple of things into consideration here. Startup loads vs Continuous loads (Which will always, or should be less)

With everything plugged in, (Printer, Laptop, fridge and then, kicking on the microwave) you're outrunning the limits of your overall setup. Not to mention what you've got left in the battery bank,

The basics - make sure your fuse is as close as possible to the battery connection. Slow blows are considered the better ones. If you're going to bump it up, try going with a 150a.

What would I do? Increase your wire size to either 2AWG or 0AWG and keep the length as short as possible. 3 and a half feet - 5. Are they cheap? No, but they'll help reduce the possibility of further problems. The shorter, the better. The "4 wire setup" you've got is a recipe for problems. Keep the wires to 1 Red, 1 Black - 2 total. Change the hookup to to a soldered end with lugs, and ditch the clamps. (See Post# 15)

Standard inverters are also infamous for not being able to handle hi surge load demands. A good Pure Sine Wave Inverter with a 2000w rating often times (Depending on the brand) has double the load capacity for startup loads. Modified Sine waves are better than the standard inverter, just not as bullet proof or quiet hummmm wise, as a Pure Sine Wave Inverter.

Finally, get your batteries load tested. There's a right way and and lots of wrong ways to do it. One battery out of spec or failing can throw the other 3 off.

Hope this helps.