TechIO 0 Posted October 31, 2014 Share Posted October 31, 2014 Hello , i finished my project and now i want do work the MSP430 G2553 standalone (without the Launchpad). It works with 3 ultra bright LEDs and are stored under the case of a lamp box with plexiglass. What kind of batteries would you recommend me to hold those 3,3V for the longest time? Or just tell me how you are driving your MSP430 standalone? Thanks ! Quote Link to post Share on other sites
Fred 453 Posted October 31, 2014 Share Posted October 31, 2014 I've had a MSP430F2013 running from 2xAA for over 3 years. No regulator or anything needed. The G2533 supply voltage range is 1.8 to 3.6V so don't obsess that it needs exactly 3.3V. The LEDs will likely require more voltage so perhaps best to have a separate supply. I've driven LEDs (not as bright) and a MSP430 by using 3xAA (4.5V) for the LEDs and tapping the 3V supply voltage for the MSP430 from just two of them. Quote Link to post Share on other sites
roadrunner84 466 Posted October 31, 2014 Share Posted October 31, 2014 How about using 3xAA NiMH cells? They should add up to 3.6 volts, maybe add a little resistor just in case. Quote Link to post Share on other sites
Fred 453 Posted October 31, 2014 Share Posted October 31, 2014 Any suitable cell(s) should do if you can keep it in that range. If you're running at high clock speeds, communicating with external devices, etc. then getting a nice 3.3V might be important. I suppose my point is that for something like driving LEDs then you might as well keep it simple. Of course if the ultrabright LEDs need to run for a while and need mains power, then a regulator would make more sense. The best solution is probably dictated by other parts of your project rather than the MSP430. Quote Link to post Share on other sites
zeke 693 Posted October 31, 2014 Share Posted October 31, 2014 I am a super fan of LiFePO4 cells. Here are two examples: 18650 size and 26650 size. Li-ION cells are more common but require a protection circuit to prevent them from blowing up. Here are some examples: 14500 (AA) size, 18650 size. You can also get LiPoly Packs. There are numerous options here. Which battery you need will depend on the power consumption over time of your LEDs, what charger you have and what box you're stuffing them into. You should start your calculations by doing a current consumption over time budget. That will make it obvious what type of battery you need. spirilis 1 Quote Link to post Share on other sites
dubnet 238 Posted October 31, 2014 Share Posted October 31, 2014 @zeke I like the data sheet on the LiFePO4 cells....you can abuse the daylight out of them with, to quote the datasheet, "no explosion, no fire". I really like the idea of incorporating batteries in projects that will tolerate my mistakes without causing harm. In your experience, other than the approximately 30% reduction in power density over the Li-Ion cells, are there any other major differences between them? Quote Link to post Share on other sites
spirilis 1,265 Posted October 31, 2014 Share Posted October 31, 2014 LiFePO4 are used a lot in EVs correct? I went to an EV meetup a few years back and everyone was talking about them in the DIY crowds. Sent from my Galaxy Note II with Tapatalk 4 Quote Link to post Share on other sites
zeke 693 Posted October 31, 2014 Share Posted October 31, 2014 @zeke I like the data sheet on the LiFePO4 cells....you can abuse the daylight out of them with, to quote the datasheet, "no explosion, no fire". I really like the idea of incorporating batteries in projects that will tolerate my mistakes without causing harm. In your experience, other than the approximately 30% reduction in power density over the Li-Ion cells, are there any other major differences between them? Yes, you can hammer a nail through the center of a LiFePO4 cell and no explosion occurs. It just ignores you. The first thing that I recall is its operation temperature range. Below -20'C, the cell will stop working. The charge carrier medium inside the cell freezes up and shrinks the effective area that can transport charge. It turns into an ever decreasing hour glass shape. At -20'C, the diameter of the waist of the hour glass shape approaches zero units of length. That disconnects the anode and the cathode resulting in no current flow. It also explains why the battery will charge almost instantly at, say, -15'C. There is very little volume being charged up because there is very little volume that is unfrozen. As the temperature rises back up, the innards of the battery thaw and that hour glass shape of effective internal region balloons back out to a cylinder shape. About charging, the LiFePO4 can be charged violently quick and the cell takes the abuse without trouble. I've hooked a 26650 cell to a bench supply set to 3.65 Volts and pushed ~1.5 Amps (0.5 * C where C=3300mAh). I made sure to watch the cell to make sure it didn't get hot (bad cell condition). The other detail that I recall is about the protection circuit. I remember it being optional with the LiFePO4 battery. It's NOT optional on a Li-Poly or Li-ION chemistry battery. It must be installed or bad things WILL happen. I watched the Tesla car documentary and they showed the guts of their battery pack. It was full of 26650 cylindrical cells. They did not indicate the chemistry of that battery but I do believe that they are LiFePO4. They bought a battery factory that I was trying to do business with two years ago. That is a good thing by the way. With Tesla owning a battery factory and a solar panel factory, the future of off grid power is bright and full of hope. Elon Musk is going to do well in my opinion. By the way, I designed a solar harvesting LiFePO4 battery charger a while back. I can create a stand alone module with that technology. Would anyone here be interested in that for their projects? dubnet, tripwire and spirilis 3 Quote Link to post Share on other sites
zeke 693 Posted November 2, 2014 Share Posted November 2, 2014 I just remembered two more important super awesome things about LiFePO4 batteries: charge cycle life and high temperature operation. The charge cycle life for LiFePO4 is around 2000 charge cycles. To contrast, a regular Li-ION or LiPoly battery (like in your iPhone) has a life of about 400 charge cycles. So let me ask you, how long is the AppleCare warranty on an iPhone? Two years you say? I bet I could charge my iPhone 400 times just after the warranty runs out. No wonder my iPhone 4s barely lasts one day now. Conspiracy I tell you! And the other point... high temperature operation. The LiFePO4 battery loves working at high temps. In fact, due to chemistry, it has a higher capacity at higher temperatures. About 10% I am told. dubnet 1 Quote Link to post Share on other sites
SixSixSevenSeven 23 Posted November 2, 2014 Share Posted November 2, 2014 How about using 3xAA NiMH cells? They should add up to 3.6 volts, maybe add a little resistor just in case. Fully charged they are usually higher than the 1.2v nominal. Measured one at 1.45 from charger. Quote Link to post Share on other sites
RFEE 1 Posted November 6, 2014 Share Posted November 6, 2014 If you want it to last as long as possible, you should use a buck regulator like http://www.ti.com/product/tps62736 so the voltage regulator inside the MCU doesn't burn up excess voltage. If the current draw of the MCU at 3.6 and 1.8 is the same, then there's a regulator in there, thus running it at 1.8 will make it last the longest. tripwire 1 Quote Link to post Share on other sites
roadrunner84 466 Posted November 6, 2014 Share Posted November 6, 2014 If you want it to last as long as possible, you should use a buck regulator like http://www.ti.com/product/tps62736 so the voltage regulator inside the MCU doesn't burn up excess voltage. If the current draw of the MCU at 3.6 and 1.8 is the same, then there's a regulator in there, thus running it at 1.8 will make it last the longest. It is possible to have a software defined (or ESI) buck regulator inside the msp430,you'll need a kickstart to get it working though. Quote Link to post Share on other sites
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