I got a this Schumacher Battery charger this week at a pawn shop for $10
Hooked it up to my 87 Carrera today, too early to make any opinions, but one the battery clamps are stronger and heaver made than any charger I have had in my life !! Will know tomorrow if it has brought my 10yr old Interstate Battery back to full charge. Surprising my old battery still works well, only going dead if I didn't drive it evey two weeks. So I would keep it running 1/2 a hour to heat the oil up and charge the battery.
Schumacher SEM-1562A Battery Maintainer and Charger - Walmart.com
I wanted a Battery Tender brand, but for $10 dollars I couldn't say NO !!
