How to Clean Battery Terminals
Cleaning car battery terminals can prevent connection issues which will cause a car not to start. Remove automotive battery corrosion with tips from an automotive service excellence (ASE)-certified master auto technician in this free video on automotive maintenance.
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I'm Dave Erb from Dave's Ultimate Automotive in Austin, Texas. We're going to be talking about servicing or cleaning your battery terminals. This seems like a fairly simple venture but can cause you major headaches if not done properly. The first thing we want to talk about is getting ready to service the battery terminals. In today's cars you have a lot of computers. You have radios with memory, you have security radios that will lock themselves out if you disconnect battery power because it thinks they're being stolen. So the first step I would do before I service or disconnect a battery is I would purchase one of these and basically it is a lighter type receptacle or a 12 volt source that you've seen that you plug your phone into and a 9 volt battery and this would plug into the outlet in your dash that is hot all the time with the key off in other words it has voltage all the time to it with the key off. In other words it is probably the one you use to keep your phone charged, something of that nature so you want to make sure that it has constant power. You plug this in and what that does is keep power to the memory on the radio as well as the memory on the radio so that when you are done you don't have problems with the computer and you have to relearn idle or being locked out of your radio and having to learn what the code is so that you can then get back in your radio. So that would be the first step. The second step is you are dealing with a battery which has sulfuric acid in it. The reason you need it to clean the terminals is that over time there is corrosion because that sulfuric acid vapor will collect on the battery terminals, cause corrosion and cause a connection issue which can cause you to have a no start. That happens over a long period of time so what you want to do is monitor your battery terminals. Make sure that build up doesn't get bad and head it off before it becomes bad. Because you are dealing with acid you want to always wear eye protection. Now when disconnecting a battery I'm going to keep this off so I can talk, the very first thing you want to do is disconnect the negative terminal, not the positive terminal. The negative terminal will be noted by the negative sign on the battery. Positive will be a plus sign. The reason you want to disconnect the negative battery terminal first is if your wrench touches anywhere on the body of the car and you are doing a positive first then you would arc or cause a short and you could burn yourself as well as do damage to the car. So you always want to do negative terminal off first, negative terminal on last. In this case we have an 8 millimeter wrench that we would loosen the negative battery terminal. Give it a wiggle, take it off and you want to set that to the side. Make sure you tuck it somewhere where it is not going to flap back over and make contact while you are working with something else. You would then disconnect the positive and if this had a lot of corrosion on there I would be wearing my eye protection right now. Get it loose and just give it a little back and forth wiggle to get it off. A lot of tool stores or parts houses will sell a battery terminal cleaning tool that you can use to make it easier if you would like. I use a wire brush and I use a screwdriver. There are also many products on the market that if they are extremely corroded that you would use a product that would saturate the corrosion, let it sit for five or ten minutes, and it would help break it down and make it easier to clean. What you are trying to do is make sure that the connection between the two metals, the terminal and the battery are good so what you want to do is go in and clean the battery of all its corrosion, terminals as well. You want to go in and then scrape the inside of the terminals to get a good clean surface area as well as on the battery itself. I use the side of a screwdriver and just scrape it all the way around to get new fresh metal. Like I said you can buy a tool especially for that that has an inside and an outside where you can clean the terminals and clean the terminals and you might have a side post battery. You might want to make sure that you get both sides of that plate and just get them nice and clean, whatever you use. Whether it be a metal brush or a screwdriver, or maybe a little knife or the tool. The object is to get the terminal surfaces clean, both inner and outer. A lot of places will sell a pad that goes underneath the terminals that helps keep this from happening and keeps that connection good in the future and you have got your black for negative, your red for positive and you can apply those as well if you'd like. At that point if you've got everything nice and clean you would put your positive back on first, snug it down and make sure that the post comes above the terminal head, tighten it down. Once again your positive goes on first and negative back on last, nice and snug. Put your negative back on, snug it down. There is also coatings out on the market that you could use to then treat the terminals with to help the corrosion from happening again. You might want to consider getting your battery checked while you are doing this or your charging system checked. Sometimes problems with those systems can cause this corrosion to become worse if the battery is getting weak and expelling a lot of gases, those kind of things. But that's how you clean and service your terminals.