1 2 Previous Next 21 Replies Latest reply on Mar 25, 2014 7:34 AM by Clayton Hofrock

    Battery Pack w Galileo

    JamesBond

      Hi Guys,

       

      I have a battery pack running on 4 rechargeable AA batteries clocking in at a stable 4.66v and 1.05amps. When I connect the battery pack to the board via the 2.1mm jack (stripped from original power source) the led right next to the sd led begins flashing incessantly. Does anybody know what's going on and how to fix it? Thanks so much!

       

      EDIT: Just to confirm, this is the led labeled "NC" and it repeatedly flashes at a very high rate. Is the voltage inadequate? Please help- I don't know what to do. Thank you!

        • 1. Re: Battery Pack w Galileo
          AlexanderMerz

          You really need to provide 5V, also 1A isn't enough. I was able to boot the Galileo sucessfully with 5V/2.2A, but this works only with nothing attached except a wlan card or ethernet.

          • 2. Re: Battery Pack w Galileo
            Len

            My retail Galileo came with a 5 V 2A power supply. If I were to use a battery, I would probably use SBEC, (switching battery elimination circuit) that provided three amps ( because that is a common size). You can run batteries up to 26V into one and it outputs five volts three amps. I have a Turnigy 5 amp SBEC on another project fed with 12volts from three A123 cells. It is a debug setup so it doesn't run for long. The advantage of the switcher instead of a linear circuit is the linear would dump (or attempt to dump) the 7volts difference as heat and the switcher is much more efficient stepping the voltage down. In this case the switcher would run more than twice as long as a linear voltage regulator.

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            • 3. Re: Battery Pack w Galileo
              JamesBond

              Thanks, Len. However, wouldn't the SBEC overload the Galileo since it outputs 5 amps instead of three which is the Galileo's maximum? Thanks for your help!

              • 4. Re: Battery Pack w Galileo
                flummer

                James,

                 

                It doesn't work that way with ampere.

                 

                Volts is the electrical potential, and you have to use a PSU (Power Supply Unit) that outputs the desired voltage, but the amps rating on a PSU is a max value of how many amps the PSU can supply, not how many the board will get.

                 

                The load (in this case the Galileo board) decides on how many amps it will pull out of the PSU. In base configuration without any shields or Mini PCIe cards installed, it's about 550mA that the board uses at 5V. If you have it do a lot, it will likely go up, and the same is true if you add shields that uses a lot of power.

                 

                The BEC circuit is just a PSU that uses a battery as power source instead of plugging into a wall outlet.

                 

                Hope it helps!

                 

                /Thomas

                • 5. Re: Battery Pack w Galileo
                  Mikal.Hart

                  If I wanted to operate a Galileo for some time on battery power, could I make a circuit with, say, 4 D batteries (nominal 6V) regulated down to 5V with a regulator that can supply 3A?  This is what I have in mind: http://www.pololu.com/product/2177.

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                  • 6. Re: Battery Pack w Galileo
                    flummer

                    Hi Mikal,

                     

                    Yes, you would be able to run the Galileo board using the step down regulator from Pololu and 4 D cell batteries in series.

                     

                    If you use alkaline D cells (LR20) you will be able to run the board for maybe something like 24 hours, of course depending on battery brand, since the capacity varies a bit between them.

                     

                    The math behind this is 12000 mAh / 550 mA ~ 24 h

                     

                    The 12000 mAh is the capacity of the D cell and since they are connected in series, only the voltage is multiplied to 6 V, not the capacity. You might win a little bit in the down conversion to 5 V, but that won't be much... and the voltage might drop too much on the batteries before they are fully used which will shorten the time.

                     

                    /Thomas

                    • 7. Re: Battery Pack w Galileo
                      AlexanderMerz

                      It did a real world test some weeks ago. A 7200mAh battery on a Galileo with a Wlan card and running from the SD card.

                      I connected to the Galileo via WLAN to my computer, ssh'ed to Galileo and started "top", then I waited.

                       

                      The battery was flat after 4h:30min exactly.

                      • 8. Re: Battery Pack w Galileo
                        flummer

                        Hi Alexander,

                         

                        That sounds a bit short, but the reason is probably to be found in a combination of:

                        • additional use from the wifi card (if it uses about 1 A, that could explain it alone)
                        • that the battery pack has a discharge curve that is going down slowly, and gets too low before it's empty
                        • or that the battery doesn't fully have the listed capacity

                         

                        What kind of battery was it and what was the voltage of the pack?

                         

                        How did you adjust the voltage to the 5 V the Galileo board needs?

                         

                        /Thomas

                        • 9. Re: Battery Pack w Galileo
                          AlexanderMerz

                          I used a portable battery charger, usually used to charge mobile phones or mp3 players. It has a 5V/2,2A USB port and I made a USB-to-powerjack adapter.

                          • 10. Re: Battery Pack w Galileo
                            flummer

                            Hi Alexander,

                             

                            OK, there could be somewhat of an overhead in that electronics, and the capacity rating is probably a bit optimistic ;-)

                             

                            /Thomas

                            • 11. Re: Battery Pack w Galileo
                              JamesBond

                              In addition, the Turnigy BEC that you provided said that it was Li-po, but the a123 cells I think are Lithium-ion. Are they the same? Also, are you aware of rechargable (by DC) batteries that are compatible with the SBEC that you mentioned? Thanks.

                              • 12. Re: Battery Pack w Galileo
                                flummer

                                Hi James,

                                 

                                LiPo and A123 are similar, but not the exact same chemistry. Most of these BEC's can operate with a voltage range on the input side and the voltage of these Lithium based batteries are in the same range (nominal cell voltage usually between 3.2 V and 3.8 V).

                                 

                                The tricky thing is the protection circuit in the BEC... if it expects a LiPo (nominal 3.7 V), it thinks that an A123 (nominal ~3.3) is almost empty, so some configuration might be needed to protect the batteries and not have it shut off too early. Lithium based batteries does NOT like to be run all the way down and likely won't come up with full capacity ever again if they are drained fully.

                                 

                                All lithium batteries should be charged with a special charger and if used in packs, also balanced to make sure single cells doesn't die prematurely.

                                 

                                A123 is a bit more durable, as is the very similar LiFePO4, but charging with a simple DC current isn't good.

                                 

                                NiMH like the Sanyo Eneloop AA batteries are a bit more robust, but the power to weight ratio isn't as good, but they can transform overcharge into heat, so as long as you charge them slowly, the charging is simpler.

                                 

                                If you only use a single LiPo cell of about 3.7 V, there are single chip solutions to managing the charge and use scenarios, e.g. charging from USB, but the voltage needs to be stepped up to 5 V to be used on the Galileo, and that's a bit more tricky than down. But circuits for that can be found on e-bay, etc.

                                 

                                /Thomas

                                • 13. Re: Battery Pack w Galileo
                                  JamesBond

                                  Ok, thanks for the information. However, is there a battery that is rechargeable by DC current (from a solar panel) but can still be used with a BEC to provide a stable 5v and 3+amps? My idea is to create a system such that the solar panel charges the battery which could be used to power the board in the case of low sunlight. Is that possible? Thanks for all your help!

                                   

                                  EDIT: Specifically is there a SBEC that uses NiMH or similar? Thx

                                  • 14. Re: Battery Pack w Galileo
                                    flummer

                                    Hi James,

                                     

                                    Sounds like an interesting project... I would really like to hear how it goes. With a cellular connection, it could allow for some nice remote projects.

                                     

                                    Maybe something like http://www.adafruit.com/products/390 for the solar charging... It's for LiPo and only 1S, so you will need a step-up system in addition. I haven't tried it, but the stuff from Adafruit is usually pretty good.

                                     

                                    As I remember, most SBEC can be used with NiMH, but you will need 6+ cells to get a high enough voltage on the input side.

                                     

                                    /Thomas

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