There’s a relatively recent addition to the battery technology mix using Lithium-Iron-Phosphate chemistry, sometimes listed as LiFePo4 in marketing literature.  The benefits are weight & size, shelf life, and safety.  The two recent iterations of the Celestron PowerTank use such a battery and the Explore Scientific power bank might as well.  The downside, because there’s always a downside, is cost.  I priced a 100 amp-hour LiFePo4 deep cycle for solar applications and the price was over $1,100.00.  Even with all the benefits and 15 pound weight, I couldn’t justify the cost compared to my 100 amp hour, high-maintenance, 50 pound, Group 31 deep cycle AGM battery.

The price will come down on LiFePo4 batteries, so they’re something to keep on your radar.

-Steve