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USB/DC Lithium Polymer Batter Charger 5-12v
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USB/DC Lithium Polymer Batter Charger 5-12v

by BVILLAN on Thu Sep 09, 2010 8:43 pm

I wanted to know if there is anyway to modify the USB/DC Lithum Polymer battery charger 5-12v in order to charge two 3.7v lithium batteries for a total of 7.4v, and if so how?


Thanks
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Re: USB/DC Lithium Polymer Batter Charger 5-12v

by adafruit on Thu Sep 09, 2010 9:48 pm

The charger isnt meant to charge two batteries at once
we are going to have a version soon that is for charging 2cell batteries (7.4-8.2V) but we suggest using a real 7.4v battery that is matched correctly rather than DIY'ing your own since that will be safer and also get you better performance :)

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Re: USB/DC Lithium Polymer Batter Charger 5-12v

by pstemari on Fri Sep 10, 2010 11:51 am

Is the charger going to have a balance input?
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Re: USB/DC Lithium Polymer Batter Charger 5-12v

by adafruit on Fri Sep 10, 2010 1:19 pm

no, you want to have the balancer on the batteries.

not sure how many ways we can say it but its much better to get a battery pack that is prematched and has a proper circuitry on it than to DIY your own. really! getting premade packs is about the same price too! :)

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Re: USB/DC Lithium Polymer Batter Charger 5-12v

by pstemari on Sat Sep 11, 2010 1:59 am

Most of the RC packs I've seen have a JST connector for balancing and the chargers make provision for it, e.g. http://www3.towerhobbies.com/cgi-bin/wti0093p?&C=ANC, http://www3.towerhobbies.com/cgi-bin/wt ... &C=CGE&P=7, and http://www3.towerhobbies.com/cgi-bin/wt ... &C=PKH&P=7.
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Re: USB/DC Lithium Polymer Batter Charger 5-12v

by adafruit on Sat Sep 11, 2010 1:02 pm

we like camcorder batteries. they are easy to get at any electronics store, and are prebalanced.

RC packs are a very specialized product, for RC people. RC people need extra-light batteries and often skip the protection circuitry to avoid having the batteries cut off. they also skip the balancer circuit to keep the packs lighter and because they dont particularly care if they damage the batteries if it means the RC device survives.

adafruit does not sell or specialize in RC products and doesn't have nearly anything that would be good for RC use. if you want to make RC projects we suggest shopping at an exclusively RC shop such as towerhobbies, since pretty much everything is custom designed in the RC world

If you are not working on an RC project then RC products need to be used with care for the above reasons

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Re: USB/DC Lithium Polymer Batter Charger 5-12v

by pstemari on Sun Sep 12, 2010 3:06 am

Fair enough. I'll give the camcorder battery packs a look. I would have thought any of the consumer electronics stuff would be ill-stated for use outside the specific device they were designed for.
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