In my last post I built a multiple AA battery tester but it used the 5V as a voltage reference which wasn’t ideal and was giving readings that were good but could be better. I modified the code to use the 1.1V internal reference of the Mega328 MCU to calculate the actual 5V supply voltage and this has proved to be much better. Voltages measured by the Arduino are now within 10mV when compared with a calibrated DVM.<\/p>\n
As far as the battery tester goes this will produce a more accurate mAh rating and a couple of tests show that battery capacity is now within 100mAh instead of the 250mAh as it was before. These measurements were taken at the load resistors as the battery holders and wiring produced a voltage drop between 30 and 110mV which at 550mA load current is fairly acceptable. If you wish to build this project please refer to my previous post<\/a> as all the build details are in there. I will also put the latest firmware download on the project post as well.<\/p>\n Issues to resolve – spurious voltages displayed when no battery present. Does not affect operation but will look into resolving this.<\/p>\n","protected":false},"excerpt":{"rendered":" In my last post I built a multiple AA battery tester but it used the 5V as a voltage reference which wasn’t ideal and was giving readings that were good but could be better. I modified the code to use the 1.1V internal reference of the Mega328 MCU to calculate the actual 5V supply voltage […]<\/p>\n","protected":false},"author":179,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"NIMH battery tester - firmware version 2. Now with improved voltage reading accuracy. - Adrian's electronics blog","description":"In my last post I built a multiple AA battery tester but it used the 5V as a voltage reference which wasn't ideal and was giving readings that were good but cou"},"footnotes":""},"categories":[5],"tags":[],"class_list":["post-251","post","type-post","status-publish","format-standard","hentry","category-projects"],"_links":{"self":[{"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/posts\/251","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/users\/179"}],"replies":[{"embeddable":true,"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=251"}],"version-history":[{"count":4,"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/posts\/251\/revisions"}],"predecessor-version":[{"id":257,"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/posts\/251\/revisions\/257"}],"wp:attachment":[{"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=251"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=251"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.adrian-smith31.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=251"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}