<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>hinkley</author><text>You are confusing yourself and everybody else. The 10A your outlet provides is at 120 volts.  The lithium battery in your phone is a little under 4 volts, so multiply all your numbers by 30.&lt;p&gt;Also. An Anker USB charger can do 2.4 amps max per port, at 5V, not 0.9A. I don&amp;#x27;t believe any modern smart phone only accepts .9A.  But a USB-C port can negotiate a higher voltage too.  That&amp;#x27;s how you have 40W USB-C chargers powering laptops a year ago, and higher now.  The new MacBook is pulling 87W over USB-C.</text><parent_chain><item><author>gus_massa</author><text>The size of the battery varies from phone to phone, but let&amp;#x27;s choose 3000mAh as a typical value so the battery is enough for a full day.&lt;p&gt;If you want to charge it in &amp;quot;seconds&amp;quot;, let&amp;#x27;s use 60 seconds as an upper bound.&lt;p&gt;So if the charger has a 100% efficiency, then it has to provide 3000mAh&amp;#x2F;60sec = 3000mAh * 3600 sec&amp;#x2F;h &amp;#x2F; 60sec = 180000mA = 18A.&lt;p&gt;An USB can provide between 0.1A and 0.9A. For comparison, a typical plug in a home can provide 10A. So to charge the phone you will need some big connector, not a tiny microUSB like connector.&lt;p&gt;But it&amp;#x27;s worse. From the article:&lt;p&gt;&amp;gt; &lt;i&gt;&amp;quot;If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn&amp;#x27;t need to charge it again for over a week,&amp;quot; said Nitin Choudhary, a postdoctoral associate who conducted much of the research published recently in the academic journal ACS Nano.&lt;/i&gt;&lt;p&gt;To recharge the phone once a week, I guess you will need a 20000mAH battery, and a few seconds is something like 5, so the connector must survive to 1000A, that is a ridiculous current.</text></item></parent_chain></comment><story><title>Supercapacitors Batteries charges in seconds without degrading</title><url>http://today.ucf.edu/phone-charges-seconds-ucf-scientists-bring-closer-reality/</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>puetzk</author><text>You could also charge at something higher than 5V, to keep the current manageable. Something like 1.8A&amp;#x2F;50V would deliver 90W, same as 18A&amp;#x2F;5V, still be within most of the safety guidelines, and allow a pretty similar connector bulk to microUSBr.&lt;p&gt;Or looking at what&amp;#x27;s already popular, USB-C connectors already spec do 3A@5V while handling data, or in PD mode (re-purposing pins) can do 5A@20V (100W).&lt;p&gt;So the first case of a charge 3000mAh in a minute doesn&amp;#x27;t seem completely ludicrous, though it&amp;#x27;s going to be challenging to make everything efficient enough the heat isn&amp;#x27;t prohibitive.</text><parent_chain><item><author>gus_massa</author><text>The size of the battery varies from phone to phone, but let&amp;#x27;s choose 3000mAh as a typical value so the battery is enough for a full day.&lt;p&gt;If you want to charge it in &amp;quot;seconds&amp;quot;, let&amp;#x27;s use 60 seconds as an upper bound.&lt;p&gt;So if the charger has a 100% efficiency, then it has to provide 3000mAh&amp;#x2F;60sec = 3000mAh * 3600 sec&amp;#x2F;h &amp;#x2F; 60sec = 180000mA = 18A.&lt;p&gt;An USB can provide between 0.1A and 0.9A. For comparison, a typical plug in a home can provide 10A. So to charge the phone you will need some big connector, not a tiny microUSB like connector.&lt;p&gt;But it&amp;#x27;s worse. From the article:&lt;p&gt;&amp;gt; &lt;i&gt;&amp;quot;If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn&amp;#x27;t need to charge it again for over a week,&amp;quot; said Nitin Choudhary, a postdoctoral associate who conducted much of the research published recently in the academic journal ACS Nano.&lt;/i&gt;&lt;p&gt;To recharge the phone once a week, I guess you will need a 20000mAH battery, and a few seconds is something like 5, so the connector must survive to 1000A, that is a ridiculous current.</text></item></parent_chain></comment><story><title>Supercapacitors Batteries charges in seconds without degrading</title><url>http://today.ucf.edu/phone-charges-seconds-ucf-scientists-bring-closer-reality/</url></story>