The massive Golems are nearly impervious to harm. Thanks to the New Golem Army, the nascent Dutch Republic's castles and forts are now safe from harm. The century-long external threat has been finally and permanently put to rest, as the bones of our enemies are bleaching in the sun by our castle's walls.
A decision has been recently made in the Staten-Generaal council that defense is to give way to offense. We will no longer be content to defend ourselves in our high castles, leaving the enemy to roam free, but instead, we will march out and take the fight to them, and bring them down for good.
This brings up obvious problems. The strings of wind- and river-mills on our mighty rivers and polders are currently providing the power elektrik to galvanize our Golem troops.
The question now is how do we handle this out in the field, far away from the castles and the galvanic stations? A young apprentice has suggested that given the frequent storms that batter the lands of our neighbors, we could power our army from the lightning strikes themselves. Would that be plausible with our rough copper wiring? How much energy could we harness from these bolts?
Assume that golem insides are a black box, we don't care about that. Would capturing lightning be plausible with early renaissance technology? If so, how could it work and how much energy could we get?
For the sake of argument and specificity, let's assume that a fully charged golem can operate for 5-7 days on normal stress level, and for 1/2 day in intense combat. Before you ask, I didn't get the chance to run a voltampermeter by the golems, so I don't know their full capacity.
If lightning is deemed unfeasible, I'm willing to hear suggestions for alternative ways of charging up in field operations conditions.