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Author Topic: LithPoly Charger, and parallel batteries  (Read 1442 times)
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Monterey CA
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http://www.adafruit.com/index.php?main_page=product_info&cPath=44&products_id=280

Would it be safe to put 2 batteries in parallel with this charger? Would it but like charing one? I would be using 2 of the Sparkfun 6Ah batteries which is made of up 3 2Ah batteries.

Thanks
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The easy answer is no, you always need to have one charger per defined group of cells, otherwise you run the risk of destroying the cells, your house and possibly you. This is because of the issue where if a single cell drops below a certain charge, it will never charge again, and by leaving this on the charger with a good cell, the charger detects the good cell and thinks that its fine to keep charging it. This charging will either do nothing or it will set the cell off in a violent combustion which will leave you at minimum quite shocked.
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Monterey CA
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Yea that wouldn't be good.

What about 2 chargers and then tie the outputs together?

Or 1 charger/battery for arduino/sensors and another set for the motor controller/motors.

 I don't know if all this will fit on the dfrobot 4wd platform, but I am having problems with being able to draw enough power for full speed and using the dfrobot wifi shield draws a lot of power, more then that sparkfun one, which I might have to switch to. In the mean time using an xbee.
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Manchester (England England)
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Quote
What about 2 chargers and then tie the outputs together?
Sorry no.

Quote
Or 1 charger/battery for arduino/sensors and another set for the motor controller/motors.
Better - that would work.
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Monterey CA
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Thanks, I might able to cram in another battery/charger/step-up lol. Maybe my GF can come up with something creative. I rather not have to buy another Wifi shield.

At least I can do testing and see if that helps. Maybe connect the USB to power the board and let the existing battery do the motors/controller.
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The problem you have here seems to be what R/C enthusiasts have had for years, they solve it by having a small lipo for the control circuitry (5v) and then a complete 7.2 or higher lipo system powering only the motors and simply join the ground leads to ensure all the controllers work. In this way no matter the state of the motor battery, the arduino will work fine.
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Monterey CA
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Thanks that sounds like a plan. So I connect the ground anywhere right?
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Anywhere really, but for simplicitys sake, you might want to just link the negative battery terminals.
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