Hi Guys, I'm new here, I have searched the forum and general internet already, I am trying to find out how these modern automotive 12v battery testers actually test the battery, for example you input the SAE rating of the battery and after a few seconds it responds with battery voltage, internal resistance, actual capacity and charge level. How does it actually test this as the leads are not thick enough to put the battery under a high load. I am still trying to find out and will post here if I find anything. I would like to replicate something like this with an arduino to get an understanding of what is going on. Any input would be appreciated.