I would second that suggestion, Lithium battery. Specifically I would recommend a LiFePO4, LFP, battery. They have the safest chemistry out of the common Lithium battery types, light and reasonably high energy density. One other advantage to LFP batteries is the terminal voltage. At full charge they are around 13.3 or so VDC, a very good match to most mobile equipment that expects 13.8 VDC. The battery has a very flat voltage verses discharge curve so when the terminal voltage drops to 12.8 VDC the battery is almost completely discharged, like around 80 to 90 percent of the rated capacity is used. Don't try this with a lead acid battery. I've also found they have a very low self discharge rate. You can charge them up and let them sit for months and the terminal voltage hardly drops. For an Ecom application this would be an advantage. I've wreck enough Gel-Cell lead-acid batteries over the years I won't buy them anymore if the equipment can use the LFP type. Lead acid batteries don't like sitting around unless they have a trickle charger attached and don't let them sit around at less than full change, they will sulfate the plates. Neither of these conditions hurt LFP batteries. As a matter of fact one recommendation for long term storage of LFP batteries is to discharge them to around 50-80 percent of capacity, they can stay that way for months to a year or more this way without damage. While LFP batteries are much more expensive than the common lead acid type once you ruin a few lead acid batteries you'll get sick of replacing them and the cost adds up. I've had good luck with the following company for LFP batteries. https://www.bioennopower.com/collections/12v-series-lifepo4-batteries If you want to use a solar panel to recharge the battery a small MPPT controller designed specifically for LFP batteries is required. I have several from this company. https://sunforgellc.com/genasun/ I have a couple of the GV5 charge controllers, a good match for a 50 watt solar panel. For solar panels I got some from this company. https://www.renogy.com/products/solar-panels/ I have a couple of their 50 watt mono and 1 of their 30 watt mono panels. The build quality is good and they do guarantee them. On solar panels from my experience don't expect to get more than around 70 to 75 percent of the panel rating, which is derived under lab conditions, which you won't get in the field.