[Completed Project/Video] 9v battery using boost regulators, supercapacitors - Page 1
Forum section: electronics / projects

author: mariush
author_rank: Super Contributor
timestamp: August 22, 2013, 07:14:33 pm
content: This was a project that I wanted to do for a long time but kept delaying or working on other things. So I decided to push myself into finalizing it by making a video tutorial out of it. (Yeah, that worked out great, it took me about 2 weeks to record and edit it but it's done)Below you have a series of 4 videos that go through planning, building, testing etc a 9v battery replacement using supercapacitors.I've used aLT1037boost regulator IC and a 25F 2.7v supercapacitor to keep my Uni-T UT61E powered logging voltage readings for more than 1 hours and 10 minutes, after charging the supercapacitor within 1 minute. With 100% surface mounted components it's possible to do even better.If you watch the videos, I hope you won't be bothered too much by my accent and diction - English is not my native language. I will appreciate any feedback you may have.Also, I consider myself somewhat of a beginner, so there may be some mistakes or terms not used quite properly or I may have made some incorrect assumptions in the videos... hope those won't stop you from watching the videos and pointing these things out to me and learn something out of it.Tutorial "page" :http://www.helpedia.com/pages/Designing_and_building_a_9v_battery_replacement_using_supercapacitorsPart 100:10 Introduction03:10 9v battery types, discharge rates18:30 Why are 9v batteries used in digital multimeters?23:00 Why supercapacitors?26:30 Benefits & trade-offsPart 2 shows how to select a boost switching regulator that would be most suitable for creating such battery replacement, one that would be able to take out as much energy from the surpercapacitors, generating the higher voltage digital multimeters expect, with a reasonably good efficiency.00:10 Selecting a DC-DC boost switching regulator06:00 Things to look for when deciding on a DC-DC boost switching regulator14:00 LT1037 datasheet and application circuit24:00 Adapting datasheet application circuit for the 9v battery footprint28:00 Simulating the circuit using LTSpice IVIn Part 3, the circuit is actually built. After a brief presentation of the components needed for the circuit, changes to the planned circuit are explained, circuit is finalized, mistakes are detected and corrected and everything is ready to be tested using a home-made constant current load.00:10 Components used to build the circuit08:50 Building the circuit16:40 Correcting mistakes19:30 Testing the circuit using a constant current loadPart 4 goes through selecting a linear regulator suitable for charging the supercapacitor at a safe maximum current, and building such regulator from scratch.After the custom charger is built and tested, some suggestions for improving and refining the built battery design are made and conclusions are drawn.00:10 Selecting a suitable linear regulator IC, options for limiting charging current14:50 Presenting and testing built custom charger20:20 Problems experienced, changes made to planned design, suggestions and improvement suggestions26:45 Conclusions

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 23, 2013, 10:22:59 pm
content: I haven't had a chance to watch your videos yet but I'm curious: did you get the device down to the same size as a 9V battery? Can you actually fit it in a 9V battery compartment? If so then that's pretty cool. Either way it's a good idea.

author: mariush
author_rank: Super Contributor
timestamp: August 23, 2013, 10:48:29 pm
content: Yes, I did... kinda.I managed to put it inside the battery compartment and partially screw the back on, but not fully closed ... with a bit of filing down of the two vertical pcbs, it would be possible to fully close the case. It was good enough to make reliable connection to the battery terminals (if I wanted i could have soldered two wires directly but it worked as designed)With a slightly smaller supercapacitor in diameter and trimming the vertical boards, it would fit just fine.When I have more time, I plan to make a fully surface mount version using Diptrace or Kicad and build some boards. No trimpot (thinking of using just a jumper to switch between let's say 5.8v and 7v, for those multimeters that have a higher low battery voltage threshold), no electrolytic capacitor, just ceramic capacitors and resistors, so would fit 2 smaller supercapacitors with no problems at all.