Charging and using Lithium

[batterynoob]

Hi guys, I needed a 14.8v battery pack but was working in a confined space for a product that I am working on so I had to buy two separate Tenergy 7.4v battery packs. My logic is that I can just connect the batteries in a series, to double the voltage and be good to go. But for the project, I want to be able to use the batteries and have them charge simultaneously, like a selfphone or gameboy or any other electronic made in the last 10 years.

My problem is that it seems to easy to simply connect one of the + to the other - to create the series and then use then connect the other + and - to the device to power it...and then im assuming connect the charging plug at the point that the positive and ground of the batteries meet the pos and gnd of the device? I am trying to learn electrical engineering and I understand path of least resistance, but would that really ensure that the voltage coming from the charger goes to the batteries and not the device? and then how would it work if batteries were pushing current one way to a device, and then had an alternating current pushing the other way...i think i just hurt my brain...Am I just overthinking this? any help would be greatly appreciated?


P.S there may just be a PCB out there somewhere accomplishes what I am trying to do and I just have to attach the batteries to that...idk...

 

[itsmoked]

Over thinking and not over thinking..

Yes, hooked in series as described will provide 14.8V.

Yes, there is no major reason they won't all charge up just the same as any typical series pack of batteries does.

If these are Lithium batteries you need to take all the standard precautions. You should have a correctly sized/rated fuse included.

Your charger will need to be a correctly designed charger for the correct battery chemistry made for charging a 14.8V pack.

No board I'm aware of though you could look at dealextreme as they might have something with all the weirdness they have. [URL unfurl="true"]http://www.dx.com/[/url]


Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Generally, Li batteries of this type should have a Li-specific charger that has a balancing capability that allows the charger to optimally and separately charge each 3.7V segment

TTFN
faq731-376

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