{"id":278,"date":"2010-01-16T01:00:17","date_gmt":"2010-01-16T09:00:17","guid":{"rendered":"http:\/\/www.todayifoundout.com\/?p=278"},"modified":"2016-08-04T00:43:48","modified_gmt":"2016-08-04T07:43:48","slug":"how-to-test-a-car-alternator","status":"publish","type":"post","link":"http:\/\/www.todayifoundout.com\/index.php\/2010\/01\/how-to-test-a-car-alternator\/","title":{"rendered":"How to Test a Car Alternator"},"content":{"rendered":"<div class=\"pf-content\"><p><a href=\"http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/funny-pictures-pony-mechanic.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-279\" title=\"Pony for a mechanic\" src=\"http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/funny-pictures-pony-mechanic-e1263615472847.png\" alt=\"Pony for a mechanic\" width=\"310\" height=\"207\" \/><\/a><a href='http:\/\/www.todayifoundout.com' title='Interesting Facts'>Today I found out<\/a> how to test a car alternator.<\/p>\n<p>Equipment needed: <a rel=\"nofollow\" href=\"https:\/\/www.amazon.com\/s\/ref=as_li_ss_tl?url=search-alias=aps&amp;field-keywords=multimeter&amp;linkCode=ll2&amp;tag=vicastingcom-20&amp;linkId=1b6050313b539a56883d6cd259582cbe\">multi-meter<\/a><\/p>\n<p>With the engine on:<\/p>\n<ul>\n<li>Step 1: Open your hood and so you have clear access to the car battery.\u00a0 Locate your alternator and check to be sure the alternator belt isn\u2019t loose.<\/li>\n<li>Step 2: Turn your multi-meter to the 20 V setting.<\/li>\n<li>Step 3: Start the engine.\u00a0\u00a0 At this point, check to make sure the alternator pulley \/ belt is spinning properly without slipping.<\/li>\n<li>Step 4:\u00a0 There are two ways to test the voltage coming from the alternator.\u00a0 If you have easy access to the alternator without getting your body parts \/ clothing \/ etc tangled in the spinning pulley\u2019s, then place the positive multi-meter probe (red) and touch it to the red terminal connector coming out of the alternator.\u00a0 Now take the negative (black) multi-meter probe and touch it to some metal part of your car frame (like a bolt head nearby or even the negative terminal on the car battery).\u00a0 Don\u2019t ground to the alternator itself.\u00a0 That would be potentially bad.\u00a0 You should now be getting a reading on your multi-meter display.\u00a0 If you don\u2019t have good access to your alternator, then you can simple test the alternator by touching the positive multi-meter probe to the positive terminal on your battery and likewise the negative probe to the negative terminal on your battery.<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/alternator-testing.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-48455\" src=\"http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/alternator-testing-340x227.png\" alt=\"Testing an Alternator\" width=\"340\" height=\"227\" srcset=\"http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/alternator-testing-340x227.png 340w, http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/alternator-testing-768x513.png 768w, http:\/\/www.todayifoundout.com\/wp-content\/uploads\/2010\/01\/alternator-testing-640x427.png 640w\" sizes=\"auto, (max-width: 340px) 100vw, 340px\" \/><\/a>If the alternator is working well, your multi-meter should read somewhere in the vicinity of 14 volts (typically 13.8-14.2).\u00a0 If it is reading excessively higher than 14 volts (greater than 15 volts) it is possible that the voltage regulator on your alternator is faulty or going bad.\u00a0 If it is reading lower than 13-14 volts, there are a number of possibilities as to the reason.\u00a0 First, it is possible that your engine idle speed is too low for the alternator to put out sufficient voltage\/power.\u00a0\u00a0 Try revving up the engine to 2000 RPM or higher and take a reading.\u00a0 If the voltage is still too low, check to be sure all the connectors on your alternator are tight and that the alternator belt is not slipping and is spinning on the pulley correctly.\u00a0 If it is still not putting out sufficient power, then the alternator\u2019s voltage regulator could be bad or the alternator itself may need replaced.<\/p>\n<p>A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery.\u00a0 If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery.\u00a0\u00a0\u00a0 When a battery is near fully charged the alternator will cease to put out sufficient voltage to charge the battery and the reading you will get from the battery probing method will simply be the voltage coming from the battery itself.\u00a0 In this case, you can simply leave your lights on with the car off for ten or fifteen minutes to drain your battery a little bit.<\/p>\n<p>It can also be helpful to test at the battery terminals with the engine off and then turn the car on and test again at the terminals.\u00a0 If your battery is more or less fully charged, it should read at around 12-13 volts with the car off.\u00a0 If you\u2019ve run your car for a long time and while the car is running the voltage reading is in the 13-14 volt range, but then you shut the car off and the battery voltage instantly drops to well below 12 volts (10 volts or under; 9 volts or under in freezing weather conditions), it is likely that your battery needs maintenance or replaced.<\/p>\n<p>If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (<a href=\"https:\/\/itunes.apple.com\/us\/podcast\/the-brainfoodshow\/id1350586459\" rel=\"nofollow\" target=\"_blank\">iTunes<\/a>, <a href=\"https:\/\/open.spotify.com\/show\/36xpXQMPVXhWJzMoCHPJKd\" target=\"_blank\">Spotify<\/a>, <a href=\"https:\/\/playmusic.app.goo.gl\/?ibi=com.google.PlayMusic&#038;isi=691797987&#038;ius=googleplaymusic&#038;apn=com.google.android.music&#038;link=https:\/\/play.google.com\/music\/m\/Insimdi4g6puyyr4qbt6tup5b6m?t%3DThe_BrainFood_Show%26pcampaignid%3DMKT-na-all-co-pr-mu-pod-16\" rel=\"nofollow\" target=\"_blank\">Google Play Music<\/a>, <a href=\"http:\/\/www.todayifoundout.com\/index.php\/feed\/brainfood\/\" target=\"_blank\">Feed<\/a>), as well as:<\/p>\n<ul>\n<li><a href=\"http:\/\/www.todayifoundout.com\/index.php\/2010\/02\/how-to-drastically-increase-the-life-of-your-shaver-razor-blade-cartridges-or-disposable-razors\/\" target=\"_blank\">How to Drastically Increase the Life of Your Shaver Blades<\/a><\/li>\n<li><a href=\"http:\/\/www.todayifoundout.com\/index.php\/2010\/06\/how-to-hack-an-alarm-clock\/\" target=\"_blank\">How to Hack an Alarm Clock<\/a><\/li>\n<li><a href=\"http:\/\/www.todayifoundout.com\/index.php\/2010\/01\/how-to-make-a-ridiculously-cheap-analog-pressure-sensor\/\" target=\"_blank\">How to Make a Ridiculously Cheap Analog Pressure Sensor<\/a><\/li>\n<\/ul>\n<span class=\"collapseomatic \" id=\"id69eb6fb01871a\"  tabindex=\"0\" title=\"Expand for References:\"    >Expand for References:<\/span><div id=\"target-id69eb6fb01871a\" class=\"collapseomatic_content \">\n<ul>\n<li><a title=\"How to test a car alternator\" href=\"http:\/\/www.ehow.com\/how_2283281_test-car-alternator-power.html\" target=\"_blank\">How to test a car alternator for power<\/a><\/li>\n<li><a title=\"How to test a car alternator\" href=\"http:\/\/www.2carpros.com\/how_to\/how_to_test_alternator.htm\" target=\"_blank\">How to test a car alternator<\/a><\/li>\n<li><a title=\"How to tell if your car alternator is bad\" href=\"http:\/\/knol.google.com\/k\/how-to-tell-if-your-car-alternator-is-bad#\" target=\"_blank\">How to tell if your car alternator is bad<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p><a href='http:\/\/www.todayifoundout.com' title='Interesting Facts'>Today I found out<\/a> how to test a car alternator. Equipment needed: multi-meter With the engine on: Step 1: Open your hood and so you have clear access to the car battery.\u00a0 Locate your alternator and check to be sure the alternator belt isn\u2019t loose. Step 2: Turn your multi-meter to the 20 V setting. Step 3: Start the engine.\u00a0\u00a0 [&#8230;]<\/p>\n","protected":false},"author":2,"featured_media":48455,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,11],"tags":[78,82,81,79,80],"class_list":["post-278","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-today-i-found-out","category-miscellaneous","tag-alternator","tag-automotive","tag-battery","tag-car","tag-testing-alternator"],"_links":{"self":[{"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/posts\/278","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/comments?post=278"}],"version-history":[{"count":12,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/posts\/278\/revisions"}],"predecessor-version":[{"id":48457,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/posts\/278\/revisions\/48457"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/media\/48455"}],"wp:attachment":[{"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/media?parent=278"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/categories?post=278"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.todayifoundout.com\/index.php\/wp-json\/wp\/v2\/tags?post=278"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}