6.2L Trickle Charger?
 

Hey everyone, I have a k5 blazer with the 6.2 diesel, it has 2 batteries but only one good one, and it it doesnt start on the first two tries, it doesnt have enough juice to start. I dont have enough money for another battery, but trickle chargers dont seem to be too expensive. Has anyone hooked one up to come on with the block heater? That's what im looking to do. Preferably a float charger than turns off when the batteries are full. Any tips or tricks on how to do this? Thanks guys!