How big is your inverter? I carry a 75w for my travels and leave a 120w in the Deer Slayer.

 

I put the odessey 1200 in my car and have not had a problem runnning my computer now. I leave it on all night and the 300 w inverter and my ryobi 12 volt charger and even in the really cold temps it has not failed me.

 

I went with an Optima as I was using my car stereo during the day and it would die. Went with the Optima and it is 100 times better than the stock battery. hinsonsupercars.com for $120 shipped.

 

My guess would be that the inverter is larger than needed, inverters are not very efficient and draw much more power than they put out. The solar panel will not even come close to keeping up with an inverter, unless it's one of those small ones.