<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div></div><div><br></div><div><br></div><div>In order to keep this email small, I have put all the files for this project in my public Dropbox folder - <a href="https://www.dropbox.com/sh/9qdzturvffr66do/AAAv0D0bogqsjLA9GiF5-DD6a">here</a> I have included the output for two runs - three AAA NiMH (~700mAH) batteries and a single cell LiPo (2000mAH) pack. In each case, the measured capacity from the test rig matched the expected capacity of the cells. </div><div><br></div><div>Here is what I learned:</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>1) Buck is where it is at - at least under a 165mA load. 95% of the run down was in the buck or pass through modes. Adding the ability to “boost” added only about 5% to the rundown test.</div><div> 2) It seems the biggest advantage of these buck boost converters is that they have no “drop out” voltage. Neither of these packs would have worked at all with a converter with a 1V drop out like the 7803</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>3) The current demand on the battery supply spikes dramatically once the converter switches over to “boost” and the efficiency of the converter drops like a rock.</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>4) That <a href="https://www.sparkfun.com/products/8483">SparkFun LiPo pack</a> delivers a lot of juice in a small package - almost three times longer on the rundown in a package that is much smaller than three AA cells. </div><div><br></div><div>So, my question is whether this is an interesting project or nothing more than a noobie - me - “discovering” the information that is already in the data sheet. My plan was to try some different battery packs and some different DC DC converter designs in order to better understand what the best combination may be for my projects but can I get this information using already published information? </div><div><br></div><div>If this is something that could be of general interest, I was thinking about building a simple PCB board so I am not tying up one of my breadboards What do you think?</div><div><br></div><div>My next step is to take Jim’s advice and test my actual circuit with amore realistic load and a big capacitor instead of a battery to see the relative performance under a more realistic and modest load. </div></body></html>