If a vehicle won't start now it sure won't later, I know a few tricks to keep them ready to roll. I keep the little solar chargers on our two spare vehicles over time, clocks, radios, charging system drain, or just sitting will drain a battery, the charger eliminates this problem. If a battery is not a sealed unit, I drop a teaspoon of epsom salts in each cell once a year, then hook a trickle charger to it for two days, this helps keep the plates clean and drops the bad junk to the bottom of the cells. I have replaced the acid, in a weak battery after doing this, then used the battery for some time, instead of buying a new one. It doesn't always save a buying a battery, but it's worth a try. I keep two 50 cal ammo cans in each auto, stocked with battery cable ends, tire plugging kit, enough wrenches to change battery cables, two complete valve stems to fit the auto, fuses, some pliers, screwdrivers, small hammer, 12 feet of wire, some hose clamps, enough heater hose to by pass the heater core, a test light, roll of black tape and a few wiring connectors. I also keep a 12 volt air compressor in each auto, and a tow strap. If I am traveling, I carry two gallons of 50/50 antifreeze water mixed. In the diesels I carry two sets of fuel filters, and a gallon jug of fuel to fill the filters with, I rotate the fuel into the tank every three months. In my shop, I have enough oil and air filters to service my two diesels twice and I keep engine oil, trans fluid, gear oil and antifreeze to service my autos and tractors when needed.