how long do u have b4 battery dies if not idling with power inverter?

anything over 300 needs a direct hookup. Ive had one of those walmart 400 watt cig lighter ones. it only had maybe 250 watts total because it couldnt power my laptop charger. As soon as i bought a direct battery 400 watt it powered my laptop fine.

 

The Kenworth I run in has a connection for a fridge and a built in switch for it in the dash up front. It'll run the fridge on its own as long as possible, but if the battery gets too low it will kill the juice to the fridge and the rest of the sleeper to make sure it can still fire up the engine.

I still use a 12v Coleman, but I've debated looking into an actual fridge for it instead.

 

i have a 2550 inverter, a dorm fridge that is always kicking on and off, used to be i could not go 5 hours till the alarm went off. now i have new batt's. and i am able to sleep thru the night once again. i recently got a window A/C that i used over this last weekend for 5 hours /no truck idle / till it got cool enough to turn off.

 

The best thing to do is buy an inexpensive voltage monitor that plugs into your cigarette lighter socket, they have them at Walmart in the car battery department.

Then you can monitor your voltage, the lower you let it go without starting the truck, the shorter the life span of your batteries. You'd be surprised just how fast you can destroy a whole truck battery bank, inverters used regularly should really be used with deep-cycle batteries. I wouldn't let it get below about 11 volts, which is really lower than you're supposed to let it go, but screw it, you really don't want to wait until the inverter shuts off. Most of them shut down at 10.6 volts, but like I said if you do that often, your batteries will not be long for this world.

Another consideration is your alternator. Most of them are rated at 6000 RPM'S, and are about 2.5 times overdriven, meaning if your truck idles at say 600 rpm's, your alternator will be spinning at about 1500 rpm's, so you are not getting anywhere near the full output of the alternator to recharge your batteries unless you are rolling down the road as opposed to idling.

Sears makes a nice 400 watt "Die Hard" inverter that has digital readout for both wattage being used, and battery voltage.