I have 5000W inverter & hooked up to my battery power supply.display is saying "l up" .i think it means lock up.i was wondering how to unlock.

? I'm at a lost on why you need 8 battery's for 96 volts? make it 9 and you have 108 in volts?
not my problem, You hook up positive from bat 1 to Neg on battery 2 pos on battery 2 to neg on battery 3, and keep going till you only have 1 positive and i negative and when those are used you will have 96 volts,. OR you could just use the inverter and 1 battery for 110 volts?

You may not have adequate input voltage. And unless you are hooking up to a forklift battery, the battery will not have adequate current delivery capability for any more than a few seconds at full power of the inverter.

1200 Watts is 100 Amps. 1500 Watts is in the neighborhood of 130 Amps.

Let us look at the math. 1250 watts at 120 volts is w=va Watts equals volts times amps. Or in this case 1250 divided by 120 volts = 10.41 amps. But what is the 12 volt side capable of drawing. 1250 watts divided by 12 volts. 104.10 amps. This is more than what the average cigarette lighter or power port can provide. So, yes you need to connect directly to the battery, you can use a relay rated for 100 A in between the inverter and battery to control the power to the inverter. I would use a good #2 copper welding cable for the power leads. Now, if you are not planning on using the whole 1250 watts, then you can use a #4 welding cable (it is very flexible) for power leads.
JOE

A 5000 wat inverter is very large. Your alternator could not supply it alone without the batteries. The moderate to low usage is the key. Calculate the wattage of the load you want to connect. Depending on what else you're doing with the truck, lights, heater, air condition etc, you could probably draw somewhere between 1,0000-1500 watts on that alternator. Rember even if your alternator is rated for 150amps (large alt) it is not a 100% duty cycle. Alternators are usually around 50% duty cycle, so figure about 75amps continuous, or around 900 watts. That's considerably less than your 5,000 watt inverter. Buy a generator.

a very thick one,,,like a baby battery lead on your car,,,its a very bad idear to have it so far away from the battery point, you would be far better off finding a closer place to put it as the volts drop off would have a big drop in out put on the inverter,,,also thats one big mother of a fridge to use 3000 watts????
you need a small power station to run it,,and if it do use 3000 watts your inverter is far to small to do the job, read the out put plate on the inverter,,it says 3000 watts max? not all the time,,,,thats about 2000 watts realy running contently and the whire to feed the inverter will need to carry about 30 amps so your car battery is say 90 amp hours plus the volts drop off, you would be lucky to have the inverter running for 3-4 hours before your battery go's is very flat on you!

carry an extra altenator just in case for your truck

Thirty amp should be fine.

You should use 2 red and 2 black cables, Install the inverter as close to the batteries as possible and use minimum #4ga cables #2 are better. Keep the cables as short as possible. You will need also connectors, like the ones on the truck's battery cables, attach these to both ends of each cable and crimp VERY well, connect all 4 cables to the inverter first, then the red cables at the positive battery terminals (if 4 batteries use one on each end) then the black cables to the negative posts the same way.

The amp meter on this unit measures the battery current. So if you have an 8 amp load at 120 vac you will draw more than 80 amps at 12 volts and 40 amps at 24 volts. While this may not explain the 180 amps that you are seeing -- it's possible that the dryer is drawing more than 8 amps.

The inverter power supply logic board has probably goe out. You can get it here or have it fixed.
http://www.lcdrepair.us/e176FPf-inverter-power-logic.html