An intelligently managed battery<\/h4>\n
The USB battery gives me a USB chargeable device and integrated power management, you can’t overcharge these or run them flat, and as someone who has just trashed a LiPo battery by leaving it connected overnight and flattening it, I appreciate that thought. Until I find out that<\/p>\n
iSmart is too darn smart<\/h4>\n
and decides my device isn’t drawing enough power and pulls the plug after a couple of minutes. Damn. My GPS draws a hefty 50-60mA, depending on whether the unbelievably bright LED the Chinese makers decided to fit is on or not.<\/p>\n
<\/p>\n so we aren’t talking about some micropower application. There is much discussion and complexity associated with providing a smart-ish but dumb (in not having a microcontroller) USB charging socket, which involves connecting resistors to the data lines<\/a> of the output socket, but there’s not so much on what do I have to look like to draw power from a smart battery. Maxim have quite a bit more on what a charger looks for<\/a>, and I tried their trick of putting a couple of 27k (must be >24k) resistors to ground, with no success.<\/p>\n So it’s probably back to the simplicity of four NiMH AAs and a 500mA fuse. At 1800mAh I’m good for 30 hours runtime. Which stinks for a general purpose GPS but is good enough for me.<\/p>\n The new Raspberry Pis (Raspberry Pi 2 Model B+ v1.1 in my case) with the new switching regulators drop power significantly when you do sudo halt<\/strong> to power down. This works a treat with the Ravpower which pulls the plug entirely and depowers everything, includig the static LED, all you need to do to restart would be to bump the power supply – a NC relay in the 5V line pulsed for half a second would restart it and only draw relay power for half a second. I’ve only tested this by pulling out the USB connector and plugging it back in, but earlier models of the Pi at least don’t have anything on the data pins<\/a> of the power socket, these are floating. There are no obvious switches in the Ravpower USB sockets to reset the outputs.<\/p>\n The Pi2 ModelB+ draws 230mA and up<\/a>, which is enough to keep the iSmart outputs active, it seems.<\/p>\n","protected":false},"excerpt":{"rendered":" I have one of these Ravpower iSmart USB batteries, and it works a treat when used as the manufacturer intended\u00a0 – to power a mobile phone or an iPod (4th gen touch in my case). No complaints whatsoever. I constructed a remote GPS module with MAX232 RS232 chip, and all this wants to run off … Continue reading “A Ravpower USB iSmart battery doesn’t like low loads”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":2572,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_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":[57,10],"tags":[],"class_list":["post-2571","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-electronics","category-raspberry-pi"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.richardmudhar.com\/blog\/wp-content\/uploads\/2015\/12\/1512_ravpower_PC082977.jpg?fit=1024%2C519&ssl=1","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5aOO7-Ft","jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/posts\/2571","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/comments?post=2571"}],"version-history":[{"count":7,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/posts\/2571\/revisions"}],"predecessor-version":[{"id":2609,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/posts\/2571\/revisions\/2609"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/media\/2572"}],"wp:attachment":[{"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/media?parent=2571"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/categories?post=2571"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.richardmudhar.com\/blog\/wp-json\/wp\/v2\/tags?post=2571"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"a](\"https:\/\/i0.wp.com\/www.richardmudhar.com\/blog\/wp-content\/uploads\/2015\/12\/1512_draw_PC082979-550x413.jpg?resize=550%2C413\")
<\/a>ISmart is well suited for a Raspberry Pi<\/h4>\n