I have owned my truck for 2 years and it has always started very slow as if the battery was not powerful enough. Yesterday was a very cold day in Ohio and my truck finally did not start. I took the old battery out had it tested and indeed it was bad but was the correct size battery for my Avalanche. I replaced the battery with a brand new optimus battery with 730 CA which cost me $160 dollars. Even after the new battery is starts very slow. This morning I had enough power to unlock my doors but not to start. I tried to jump my truck but did not have any luck. I put the brand new battery on a charger and it was down to 75% charge. Do you think I have an electrical problem or a starter problem?