{"id":1222,"date":"2017-03-26T11:15:25","date_gmt":"2017-03-26T18:15:25","guid":{"rendered":"http:\/\/198.171.78.101\/wordpress\/?p=1222"},"modified":"2017-03-26T11:13:58","modified_gmt":"2017-03-26T18:13:58","slug":"i-love-classes-that-make-you-think-part-ii","status":"publish","type":"post","link":"https:\/\/www.tradewindssailing.com\/wordpress\/general\/i-love-classes-that-make-you-think-part-ii\/","title":{"rendered":"I Love Classes That Make You Think! Part II"},"content":{"rendered":"<p>We left the previous installment of<strong> I Love Classes That Make You Think!<\/strong> wondering how long one needs to run the motor\u00a0in order to recharge batteries that have been in use while at anchor.\u00a0 That actually brings up a whole other topic.\u00a0 Calculating electrical consumption, battery capacities, and battery charging.\u00a0 Sadly, I&#8217;m not enough of an expert to turn this into a true technical discussion, so this tip includes a few assumptions and is more of a layperson&#8217;s guide to battery usage and charging while at anchor and on charter.<\/p>\n<p>Personally, I believe the first things you need to know are how many batteries, what are their sizes, and how is the system set up.\u00a0 The only way to get this information\u00a0on a charter is to ask the charter company.\u00a0 Then, double check what you have been told.\u00a0 In Part I, we ended the tip while on a 42&#8242; Catalina during a two week charter in the Sea of Cortez.\u00a0 Let&#8217;s continue that discussion and see if we can approximate how long per day to run the motor in order to charge batteries back to a usable state.<\/p>\n<p>A pretty common set up on this boat is three batteries.\u00a0 Two set up as two separate\u00a0house banks, and one as the starter and windlass bank.\u00a0 Because the starter\/windlass battery isn&#8217;t used much and should charge back up pretty quickly we won&#8217;t worry about it.\u00a0 The house bank(s) on the other hand are well used while at anchor.\u00a0 Every boat potentially has different batteries.\u00a0 In this case lets assume there are two Group 8D AGM batteries rated at 225 amp hours, giving a total of 450 amps of capacity.\u00a0 Unfortunately, you should never go below 50% of maximum charge, so you have about 225 amp available to you.\u00a0 We have a starting point.\u00a0 Now for consumption.<\/p>\n<p>Here are some common devices and their consumption requirements while at anchor for 24 hours:<\/p>\n<ul>\n<li>Anchor light &#8230; 0.8 Amps &#8230; 12 hours per day\u00a0&#8230; 9.6 Daily amp-hours<\/li>\n<li>Cabin Fan (two of them) &#8230; 0.2 Amps each &#8230; 6 hours each per day &#8230; 2.4 amp-hours<\/li>\n<li>Cabin Light (three) &#8230; 2.1 Amps each &#8230; 4 hours each per day &#8230; 25.2 amp hours<\/li>\n<li>Fresh water pump &#8230; 6 Amps &#8230; 5 min per\u00a0day &#8230; .5 amp-hours<\/li>\n<li>Refrigerator &#8230; 5 Amps &#8230; 12 hours per day &#8230; 60 amp-hours<\/li>\n<li>Music player &#8230; 1 Amp &#8230; 6 hours per day &#8230; 6 amp-hours<\/li>\n<li>Monitoring a SSB &#8230; 2.5 Amps &#8230; 1 hour per day &#8230; 2.5 amp-hours<\/li>\n<\/ul>\n<p>This a pretty much a bare minimum while sitting at anchor, and so far we are at 106.2 amp-hours.\u00a0 Let&#8217;s assume you do some sailing during the day.\u00a0 You only run the motor for a few minutes to get out of the anchorage and back, sailing for 6 hours.<\/p>\n<ul>\n<li>Depth sounder &#8230; 0.2 Amps &#8230;\u00a06 hours per day\u00a0&#8230; 1.2 Daily amp-hours<\/li>\n<li>GPS &#8230; 0.5 Amps &#8230;\u00a06 hours per day\u00a0&#8230; 3 Daily amp-hours<\/li>\n<li>Chart Plotter &#8230;\u00a01 Amps &#8230;\u00a06 hours per day\u00a0&#8230; 6 Daily amp-hours<\/li>\n<li>Radar &#8230; 4 Amps &#8230;\u00a06 hours per day\u00a0&#8230;\u00a024 Daily amp-hours<\/li>\n<li>Speed sensor &#8230; 0.1 Amps &#8230;\u00a06 hours per day\u00a0&#8230; 0.6 Daily amp-hours<\/li>\n<li>Wind indicator &#8230; 0.8 Amps &#8230;\u00a06 hours per day\u00a0&#8230; 4.8 Daily amp-hours<\/li>\n<\/ul>\n<p>This is another 39.6 amp-hours, making our total so far 145.8.<\/p>\n<p>Now let&#8217;s add in a few luxury items.<\/p>\n<ul>\n<li>TV\u00a0&#8230;\u00a03.5 Amps &#8230;\u00a02 hours per day\u00a0&#8230;\u00a07 Daily amp-hours<\/li>\n<li>Electric Head\u00a0&#8230; 40 Amps &#8230;\u00a0.3 hours per day\u00a0&#8230; 12 Daily amp-hours<\/li>\n<li>Microwave\u00a0&#8230; 100 Amps &#8230;\u00a06 minutes per day\u00a0&#8230;\u00a010 Daily amp-hours<\/li>\n<li>Cell Phone\u00a0&#8230; 2 Amps &#8230;\u00a04 hours per day\u00a0&#8230; 8 Daily amp-hours<\/li>\n<\/ul>\n<p>Another 37 amp-hours, for a total of 182.8 amp-hours consumed over a 24 hour period.\u00a0 This is well within our usable 225 Amp battery capacity!<\/p>\n<p>Now all we have to do is charge the battery back up.\u00a0 Based on our scenario, you are at about a little over\u00a050% charge.\u00a0 If you have an alternator rated at 120 Amp, that is the most output\u00a0you are going to get.\u00a0 With an alternator the\u00a0maximum output is only achieved when the alternator is turning about 4,000 to 6,000 PPM.\u00a0 If you are idling the motor at 700 RPM, the alternator is probably turning about 1,400 RPM, so you aren&#8217;t getting the full 120 amps.\u00a0 At idle you might only be getting 40 to 80 Amps output from the alternator.\u00a0 Let&#8217;s assume 60 amps.\u00a0 You will get that output until the battery is about 75% charged.\u00a0 After using 182.0 Amps of 450 total, it you will need to &#8220;add&#8221; back about 70 Amps to get to 75%.\u00a0 Charging at\u00a060 Amps, 70 minutes will get you there.\u00a0 Now for the challenge.\u00a0 At 75% capacity, the regulator is going to choke back the flow to the battery to the point it will take about 3 more hours to reach a full charge.\u00a0 I think we have an answer.\u00a0 To replace the 182 Amps used over 24 hours is going to require about\u00a04 hours of charging.<\/p>\n<p>Looking back to Part I.\u00a0 Remember to add\u00a04 hours of engine time to your fuel calculations.\u00a0 At .55 GPH, that&#8217;s\u00a02.2\u00a0gallons of fuel per day.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>We left the previous installment of I Love Classes That Make You Think! wondering how long one needs to run the motor\u00a0in order to recharge batteries that have been in use while at anchor.\u00a0 That actually brings up a whole &hellip; <a href=\"https:\/\/www.tradewindssailing.com\/wordpress\/general\/i-love-classes-that-make-you-think-part-ii\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":14,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[4],"tags":[],"class_list":["post-1222","post","type-post","status-publish","format-standard","hentry","category-general"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts\/1222","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/users\/14"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/comments?post=1222"}],"version-history":[{"count":3,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts\/1222\/revisions"}],"predecessor-version":[{"id":1225,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts\/1222\/revisions\/1225"}],"wp:attachment":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/media?parent=1222"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/categories?post=1222"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/tags?post=1222"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}