Note that 0.000863 A is 0.863 mA. Given that you appeared to measure 4.83 mA, something is far more wrong than you state in your post.
You really need two meters here so that you can measure both voltage and current at the same time without swapping leads around and twisting the range selector.
You should test a single resistor. Measure the voltage and current at the same time and calculate the resistance. (Make sure to measure the voltage across just the resistor so the ammeter doesn't interfere with the reading.) Then take the resistance out of circuit and measure the resistance using the resistance range on a meter. Check that they match.
After that, try to repeat your experiment, taking great care over every detail.
Also, be careful with that big ass lead acid battery. One false move and you will let the magic smoke out of everything in the vicinity, start a fire and burn yourself all in one go.