[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-568798-105":3,"detail-sidebar-cat-1-en-105":80,"doc-detail-568798-en":126},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":73,"head_meta":75,"extra_data":77,"updated_unix":79},105,"en","parasitic-current-draw-batteries-and-battery-tenders","Parasitic Current Draw - Batteries and Battery Tenders","","Explains parasitic current draw in modern cars, why it exists, typical normal ranges (about 10–30 mA, sometimes up to 50 mA), and what it means for battery life. Gives guidance on how long a parked car can remain unattended based on measured parasitic draw and battery capacity/charge state. Provides a practical method to measure current using an ammeter while avoiding circuit interruptions that can wake car computers and skew results.",{"@graph":14,"@context":72},[15,34,55],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/template/","Template",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/template/general/","General",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/template/parasitic-current-draw-batteries-and-battery-tenders/568798/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/parasitic-current-draw-batteries-and-battery-tenders/568798.png","ImageObject",442,249,{"name":42,"@type":43},"Melati","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-21","2026-10-13",true,{"@type":52,"interactionType":53,"userInteractionCount":33},"InteractionCounter",{"@type":54},"ViewAction",{"@type":56,"mainEntity":57},"FAQPage",[58,64,68],{"name":59,"@type":60,"acceptedAnswer":61},"What causes parasitic current draw in modern cars?","Question",{"text":62,"@type":63},"Constant current is required to maintain settings and functions such as the radio, anti-theft system, internal car computer memory, and RF lock/unlock modules, which continuously draw some power.","Answer",{"name":65,"@type":60,"acceptedAnswer":66},"What is considered normal parasitic current draw for modern cars?",{"text":67,"@type":63},"Most modern cars show parasitic current draw between 10 mA and 30 mA, and it could be as high as 50 mA. Significantly higher than that likely indicates a problem.",{"name":69,"@type":60,"acceptedAnswer":70},"How do you measure parasitic current draw without waking the car’s computer?",{"text":71,"@type":63},"Use an ammeter setup that maintains circuit continuity so moving probes or changing meter ranges does not open the circuit. Wait 15–20 minutes for the computer to sleep, then disconnect the jumper while keeping the ammeter probes connected before taking readings.","https://schema.org",{"og:url":32,"og:type":74,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":76,"canonical":32},"index,follow",{"doc_id":78,"site_id":7},568798,1792501369,{"code":4,"msg":81,"data":82},"success",[83,88,93,98,103,108,113,118,123],{"id":84,"doc_module":22,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},11,"Presentations",90,"presentations",{"id":89,"doc_module":22,"doc_module_name":25,"category_name":90,"show_sort_weight":91,"slug":92},12,"Resumes",80,"resumes",{"id":94,"doc_module":22,"doc_module_name":25,"category_name":95,"show_sort_weight":96,"slug":97},14,"Invoices",70,"invoices",{"id":99,"doc_module":22,"doc_module_name":25,"category_name":100,"show_sort_weight":101,"slug":102},15,"Posters",60,"posters",{"id":104,"doc_module":22,"doc_module_name":25,"category_name":105,"show_sort_weight":106,"slug":107},16,"Social Media",50,"social-media",{"id":109,"doc_module":22,"doc_module_name":25,"category_name":110,"show_sort_weight":111,"slug":112},17,"Forms",40,"forms",{"id":114,"doc_module":22,"doc_module_name":25,"category_name":115,"show_sort_weight":116,"slug":117},18,"Letters",30,"letters",{"id":119,"doc_module":22,"doc_module_name":25,"category_name":120,"show_sort_weight":121,"slug":122},21,"Paper Templates",5,"papers-templates",{"id":124,"doc_module":22,"doc_module_name":25,"category_name":29,"show_sort_weight":4,"slug":125},158,"general-158",{"code":4,"msg":81,"data":127},{"doc_id":78,"user_id":128,"nickname":42,"user_avatar":129,"doc_module":22,"category_id":124,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":130,"file_id":131,"file_url":132,"file_type":133,"file_size":134,"view_count":33,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":84,"language":135,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":136,"faqs":137,"seo_title":138,"seo_description":12,"update_tm":139,"read_time":33},962085570644,"https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d","Parasitic Current Draw, Batteries and Battery Tenders  \nThis paper is written as a result of my personal research on three related topics. Opinions expressed here are my own – based on this research as well as personal experience.–Steve Bisel, Forza Componenti, Scottsdale, Arizona  \nParasitic Current Draw  \nWhat is Parasitic Current Draw?  \nParasitic current draw occurs on virtually every modern car. Why? Because constant current is required to maintain settings on your radio, the car’s anti-theft system, internal memory of car computers, the RF module to lock/unlock your car and many other potential electrical devices.  \nWhat is Normal Parasitic Current Draw for Modern Cars?  \nMost modern cars have a parasitic current draw of between 10mA to 30mA. But it could be as high as 50mA. If it is much more than that, it is likely something is wrong. The more devices requiring constant power, the higher the draw. Luxury cars typically have higher draw than econo boxes.  \nHow Long Can I Leave my Car Unattended before the Parasitic Current Draw Drains my Battery?  \nThe amount of time you can leave your car off and not have the battery drain so low that you cannot start the car depends on two things:  \n1. What is the parasitic current draw of your car's various electronics on the battery?  \n2. What is the capacity and charge state of your battery?  \nWhy Should I Care?  \nDetermining the parasitic current draw on your car is probably more of curiosity factor – until you have a problem with battery life. For the more anal among us, you may want to determine a baseline for the parasitic current draw so you have something to compare to in the future. It is important if you need to diagnose future battery life problems. It is also good to know to help you with battery and battery tender selections. The procedure should take less than an hour.  \nHow Can I Determine the Parasitic Current Draw on my Car?  \nTo understand normal parasitic current draw, you need an ammeter. Unfortunately, the methodology for getting the measurement is not as straightforward as you may think. I have seen advice telling the user to merely disconnect the negative side of the battery and then connect your ammeter in series with the negative terminal of the battery and the battery cable. Then, with the ignition off, measure the current that is being drawn. That method works fine on older cars, but on modern computer-controlled cars, the procedure is more involved. The problem is that you must measure the battery drain AFTER the computer goes to sleep (so to speak) . After turning off the ignition, many manufacturers have at least one computer (maybe more) that can draw as much as 3 amps for up to 20 minutes. When the car’s computer does finally go to sleep, the current draw will drop to a low steady state. After the computer(s) goes to sleep, anything that creates an open circuit (e.g., disconnecting the battery) may wake the computer for another 20 minutes.  \nThe problem is to insert an ammeter into the circuit without breaking the circuit. For example, if you have your ammeter connected in series to measure current draw and you move the probe connection or switch the scale knob on the ammeter, this action may open the circuit which then will wake the computer. Some multi-meters do not have auto ranging capability and even the simple act of selecting a different scale on the meter will open the circuit as the internal switch on the meter is typically a break-before-make type switch – meaning that it breaks one connection before contacting the other one. The illustration below is a good depiction of the difference between a make-before-break switch and break-before-make switch.  \nThat momentary break in the circuit is enough to wake up the computer. And, if the resulting current draw exceeds the range on your ammeter, it may blow the fuse on the meter.  \nThe following procedure is written for use with a multi-meter that does not have auto ranging capability for measuring","cbCaiiDDUFNpUUwf","https://ap.wps.com/l/cbCaiiDDUFNpUUwf","pdf",1051334,"English","# Parasitic Current Draw\n## What is Parasitic Current Draw?\n## What is Normal Parasitic Current Draw for Modern Cars?\n## How Long Can I Leave my Car Unattended?\n## Why Should I Care?\n## How Can I Determine the Parasitic Current Draw on my Car?\n### Measuring without waking the computers\n### Connection procedure with selectable-range multi-meter","[{\"question\":\"What causes parasitic current draw in modern cars?\",\"answer\":\"Constant current is required to maintain settings and functions such as the radio, anti-theft system, internal car computer memory, and RF lock/unlock modules, which continuously draw some power.\"},{\"question\":\"What is considered normal parasitic current draw for modern cars?\",\"answer\":\"Most modern cars show parasitic current draw between 10 mA and 30 mA, and it could be as high as 50 mA. Significantly higher than that likely indicates a problem.\"},{\"question\":\"How do you measure parasitic current draw without waking the car’s computer?\",\"answer\":\"Use an ammeter setup that maintains circuit continuity so moving probes or changing meter ranges does not open the circuit. Wait 15–20 minutes for the computer to sleep, then disconnect the jumper while keeping the ammeter probes connected before taking readings.\"}]","Parasitic Current Draw - Batteries and Battery Tenders | PDF",1791872401]