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I am building a college project for a national level competition. In my project (which is similar to a drone), I am trying to charge the lithium-ion battery pack quickly.

I am using a 10000mAh Li-ion battery pack but would like to feed as much current into so as to charge 50% of the battery in under 10 minutes.

Most of the battery packs that I came across usually accept 2-3A input current.

I am using a DC-DC converter to increase the current but would it be feasible?

And how can I achieve such quick charging? Can Tesla's supercharging technology (that's used to charge up entire vehicle in 40-50 minutes) be somehow applied to charge up Lithium ion batteries in a model drone?

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  • \$\begingroup\$ If you haven't done this before, you have a lot to learn. So buy one then understand how it works completely. \$\endgroup\$ – Sunnyskyguy EE75 Feb 6 '18 at 16:12
  • \$\begingroup\$ Be aware that fast-charging stresses batteries and reduces their service life. That probably won't be an issue on the contest day, but it might be a good reason to install new batteries just prior to the contest day. \$\endgroup\$ – Solomon Slow Feb 6 '18 at 16:21
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    \$\begingroup\$ Re, "using a DC-DC converter to increase the current." Increasing the current is not what is not what DC-DC converters do. A DC-DC converter is a power supply. Power supplies generally either provide a set, constant voltage up to some current limit, or else they provide a set, constant current up to some voltage limit. I don't know how to charge lithium batteries specifically, but for some battery technologies, a smart charger will go through a sequence of different current and/or voltage modes, while monitoring voltage, current, and maybe also battery temperature. \$\endgroup\$ – Solomon Slow Feb 6 '18 at 16:32
  • \$\begingroup\$ yeah i am using the DC - DC converter at a voltage limit. i'll be maximising current from my dc generator (consant output) . \$\endgroup\$ – user177195 Feb 8 '18 at 11:38
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If you want 50% charge in 10 minutes, you are charging at 3C which is pretty ambitious (30A charge current for that battery). The internal resistance of most RC flight batteries is low enough to do this, but you are going to have to carefully monitor the temperature of the battery pack; probably with multiple temperature sensors.

You will also have to monitor the internal resistance of the battery pack during the charge cycle (measure the pack voltage and charge current, use ohm's law to get the internal resistance). If you see the internal resistance go down significantly during the charge cycle or you see the temperature go up, stop the charge cycle immediately.

Building a 30A switching converter that operates stably in CC/CV regulation is also a significant technical challenge. If you don't have significant experience with switching power supply design the odds of success are not great for a student project like this.

In any case, this is something you will not want to operate indoors (ever) and charging the battery in an environment where you just expect a battery fire is highly recommended.

Charging at 3C will also require active monitoring of the voltage of each cell individually and balancing during or after the charge cycle. Minor differences in cell capacity/impedance will be exacerbated by the aggressive charge rate.

You will also have to wait for the battery to cool between the discharge (flight) cycle and the charge cycle. You will probably also have to wait for the battery to cool between charge and flight (and this will pretty much render the 10 minute charge cycle as useless). The Tesla batteries (AFAIK) use water cooling to deal with this.

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  • \$\begingroup\$ well, that many complications in monitoring just the battery pack would result in my loss on the contest day . I can use liquid cooling to cool the batteries but that would defeat my purpose. One thing i didn't mention in my question is i'm planning to charge these batteries in mid air . So that apparatus for all the monitoring and cooling has to be on the drone itself . Is there a simpler method to achieve this ? \$\endgroup\$ – user177195 Feb 8 '18 at 11:33
  • \$\begingroup\$ Fast Charging in the air like that will probably be impossible for a project like this. You will have to have significant active cooling for the battery pack and the weight penalty will be unacceptable. \$\endgroup\$ – Dean Franks Feb 8 '18 at 17:35
  • \$\begingroup\$ yeah . i figured. weight is one of the factors i'm most concerned about. i just need help in charging batteries as quickly as possible . The best i can do right now is implement the quick charging technology available in the market(mobile) right now but that is just too slow for my idea. \$\endgroup\$ – user177195 Feb 10 '18 at 8:40

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