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Old Oct 30, 2010, 07:51 PM
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I Need To Make An Extended Battery Pack

The battery in the device is a 3.7v 1340mAH Poly Lithium Ion.
I need to make or buy a 6600mAH battery. Trouble is I have seen one before with no specs on it. It looks to be 6 AA sized batteries laid flat with shrink wrap.


So When I google it up I see a bunch of 4 AA batteries. Does it sound possible for the 6-pack to be only 3.7 volts?

Whats a guy to do or who can he call?
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Old Oct 30, 2010, 08:11 PM
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6 cells in parallel will still have the same voltage as one cell, so yes it is possible. 6 cells in series would have 6 times the voltage.
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Old Oct 30, 2010, 08:14 PM
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Thanks, I'll show you exactly what I need in the link below. Except I want the battery with molex connector only. I do need a charger for it though. Can a guy get this cheaper?

$149.99! Sheesh.

LINK
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Old Oct 30, 2010, 08:49 PM
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Old Oct 30, 2010, 09:24 PM
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Take two of these and solder in parallel for 3.7v 6000mah.

http://cgi.ebay.ca/4-x-18650-UltraFi...item3efe7f8137

or you could use 3 for 9000mah.
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Old Oct 30, 2010, 11:11 PM
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Thanks guys.

Well I am totally noobish in this area and need you help and so far so good, thanks.

So by the pics in this post you can see why I need the molex connector. I believe it is a molex, correct me if I'm wrong please.

I cannot do the soldering so I need a vendor or board members services if that's a possibility. As you can see the people selling the battery are reaming us out pretty good.

I need a pack the physical size as pictured to attached to the block in the pic. If I can get a setup with more capacity that's even better.

Can you put me onto a custom builder? Will the cost be better than the 149.00 listed for the kit? Thanks again.

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Old Oct 31, 2010, 08:08 AM
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Quote:
Originally Posted by Druss View Post
Take two of these and solder in parallel for 3.7v 6000mah.
http://cgi.ebay.ca/4-x-18650-UltraFi...item3efe7f8137
Or you could use 3 for 9000mah.
So in saying take two of them you mean a total of 8 cells in parallel?
And how about an OCP unit. Can you show me one that would apply.

Are these batteries the same size diameter wise as normal AA batteries? When I lay AA batteries in my case only 7 fit loosely. But the battery pack in my post pics fits snugly.

I would love to gather the parts and have a tech assemble it.
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Old Oct 31, 2010, 09:59 AM
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How about the performance difference in the same application between a lipo and a lion as in pictured below.
Still pricey but I have not spoken with a custom builder yet either. I have emails sent to them and may call on monday.

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Old Oct 31, 2010, 01:03 PM
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The differences between lipo and li-ion are that the lipo is lighter and slightly more powerful (higher C rating) neither of which I think is a consideration for your application.

The lipos big negative is that the packs are a bit finicky, they need to be treated properly or you can damage them... in some cases they will catch fire if mishandled (remember all the laptops that were overheating and catching on fire 2-3 years ago?).

I'm afraid at this point I'm not sure what we can do in terms of helping you any further without a lot more information.

What is the application? What are the EXACT dimensions you need the battery to be?

The cells I linked might be too large for your application... I don't know.

As for batteries and how they work... whenever you put cells in series you add the voltages together but the capacity remains the same. When you put cells in parallel you add the capacity and the voltage remains the same... you can also mix the two together in order to get what you want.

For instance, if you have 4 cells which are 3.7v and 3000mah and put them all in series then you get a 14.8v 3000mah battery pack (4P). If you put them all in parallel you get a 3.7v 12000mah battery pack (4S). If you put them in 2 sets of series which are in parallel then you get a 7.4v 6000mah battery pack (2S2P). The notations in brackets are pretty self explanatory where "S" stands for series and "P" stands for parallel and the numbers in front tell you how many cells.
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Old Oct 31, 2010, 02:34 PM
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Thanks,

The battery will be used in a fleet tracking GPS that will operate when it senses movement.
The company that we purchase from is marking up the batteries by at least 100%.
The size you see in the pic is just right and max would be 2.5" x 4.5" or 63.5mm X114.3mm. Thickness would be the size of a AA battery.

So with a protection circuit what do you think price wise I would have in parts?

And I take it Lipo is less tolerant to heat?

Thank You
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