Battery sparks when bilge pump wire are connected?

[youngsalty]

I have one battery on board. When I connect the bilge wires directly to the battery, sparks fly. The first time small amount of spark, then to many sparks to leave connected. I do have my engine connected and a small panel of electrical items running off this battery. The bilge pump was completely submerged. Would a short in the pump cause this, is there too many electrical items hooked to the battery? I had the battery switch set to off before using the bilge pump. Suppose I might test it on my lawn mower battery to see if it's the boats battery's setup. Open for any advice or wisdom.

[transmitterdan]

There should be a fuse or circuit breaker in the + lead of the bilge pump. If you don't have that tell us what kind of bilge pump and that may give an idea what size fuse to use. Most likely 10A or 15A will do.

Did the bilge pump run when you connected the wires? If it ran then most likely there is no short. Bilge pumps can draw a few amps when running so sparks are to be expected. But heed the advice about a proper fuse. If there is a short and no fuse or circuit breaker then the wires could start a fire in a hard to reach place.

[youngsalty]

The bilge pump did run when connected to the battery. These sparks where leaving dimples on the negative terminal. I am going to look for the fuse on the positive and the type of bilge pump it is. Thank you for quick help.

[transmitterdan]

Also, find out the size of wire used for the bilge pump. Undersized wires are fairly common.