We get lots of questions regarding battery terminal repair on electric golf carts. Often, the need to repair the terminal is due to a melted post, or other scenario that does not allow the power wires to be secured to the terminal. Rather than replace an otherwise good battery, we’ve gotten creative over the years and have learn how to easily handle this battery terminal repair.
All deep cycle lead acid batteries used in golf cart and other electric vehicles have both a positive and negative post on top of the battery where power connections can be made. Battery terminal repair can be daunting but is usually not that difficult. This is fairly well applicable across the board to 6V, 8V, and 12V deep cycle lead acid batteries. The “post” generally consists of a bolt pointing skyward which has been cast inside a lead terminal sticking out of the top of the battery. Often, the bolt portion of this post melts down due to heat and breaks off. The number one cause of this issue is due to loose or corroded connections. No matter how tight you get your connections, they will eventually loosen due to the expansion and contraction which occurs through use. This looseness or corrosion causes resistance and a byproduct of electrical resistance is heat, which leads to melting.
Often beside the connection portion of the post is a nice flat pad of lead which connects down into the battery plates. Our best battery terminal repair to fix melted posts is to drill down into this flat pad of lead. First you need to locate a lag bolt approximately ¾” long, measured from the bottom of the bolt head to the tip of the point. Then locate a drill bit which is approximately, the thickness of the core of the lag bolt. DO NOT use a bit which is as large as the threads. You want the hole to be slightly too small to allow the thread to bite into the lead and hold fast. Get your drill out and disconnected both the positive and negative leads to the battery while performing this battery terminal repair to be safe. See example of lag screw and appropriately sized drill bit for this battery terminal repair.
SLOWLY, drill into the flat lead pad next to the battery post. Lead is a soft material and it will almost instantly fill up the grooves in your bit. Approximately, every 1/8” in depth you drill, you must remove the bit and clean out the lead. Failure to do so will clog the bit and break it off in the lead. If that happens, your chances of successful battery terminal repair are finished. Once you’ve drilled a ¾” deep hole into the lead pad, you are ready to complete the repair.
Place your lag screw through the ring end hole of your battery cable first. Then, with an appropriately sized socket, slowly turn the screw clockwise down into the lead pad. If there is excessive resistance, you may not have drilled a large enough pilot hole and you may need to enlarge it. Be very careful once you get to the point where the screw is going to bottom out. You want to snug the screw up well without over tightening it. If you over tighten, the lead is such a soft material, you may likely strip out the pilot hole and the screw will become loose again. If this happens, you must go to a slightly larger lag screw size and try again. Once completed, your repair should resemble something to close to what is shown below. Always spray the terminal with a protectant when completed, and don’t forget to reconnect your power connections.
This battery terminal repair procedure can often save a lot of money to get you up and running quickly in a pinch without replacing the battery. It has proved handy many times during field repairs and house calls.
By Michael Williams