Because I'm drinking the EarthX coolaide, and because I'm a lazy ass, I recently replaced my AntiGravity Battery with two EarthX Jump Packs (one for each plane).
http://earthxbatteries.com/shop/earthx-jump-pack

For the lazy ass part I can't be bothered with actually going to the trouble of attaching alligator clips to the battery terminals when I need to either charge or jump start a battery so I also purchased two 48" Long Quick Connect Charging/Jump Start Cables w/SAE Connectors which I attached to the battery terminals.
http://earthxbatteries.com/shop/48-inch-long-quick-connect-chargingjump-start

This allows me to hook up either the aforementioned EarthX Jump Pack or the Optimate Lithium Battery Charger with BMS Reset.
http://earthxbatteries.com/shop/optimate-lithium-battery-charger-lifepo4 (they didn't offer the 9 amp charger at the time).

The only problem I've had with the EarthX batteries is on the SQ2 after the plane has sat for a couple of months. But on my other plane, after sitting for even longer, I don't have any problems. I swapped batteries and the problem remained with the SQ2 so I'm suspecting a small battery drain which is being investigated.

I ordered the EarthX jump starter package today and she was able to give me the Pac NW discount, which was totally worth it.

Rod