I used cast-off AGM batteries as well. Portable X-ray machines use a bunch and they have a mandatory replacement of 24-36 months. The ones I got were 29Ah each and I used a bank of 10 for 290Ah of capacity. 100 watt panel and a charge controller are used in the second garage. I have 3 strings of LED's that light it all up. Under normal conditions the panel put out around 4A and the lights draw about 5A.