I bought these to properly charge the Renogy 50AH lithium home battery on my Volkswagen Euro Camper Van while driving the van. I've done quite a bit of 12v wiring on both our boat and RV, but it was almost embarrassing. The product is too big and the instructions look more like a cartoon than real instructions. This is an absolutely horrible product and a quality company like Renogy (I have a Renogy solar panel, controller and lithium battery) should be ashamed of this piece of junk. I could never get this thing to work and warned everyone to stay away from this huge useless box.