I have a single XS Power D3100 battery up for sale. The battery will NOT fit under the hood of the Envoy without modifying a lot for space however I used it in the rear of my truck to support the sound system I used to have. It works great and has a resting voltage at 12.65v after sitting for a week and a half without being charged. Looking to sell it for $250 shipped to the cont. U.S. Shipping alone will be a big bear for this battery as it's very heavy.