Lithium Polymer Batteries -- How to wire and what to buy.

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collinE
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by collinE » Tue Jan 26, 2010 4:45 pm

What if you wanted to wire together two battery packs of similar voltage, but different combined Ah? I assume that as long as their protection circuit does it's job, it doesn't matter if one cuts out before the other. Am I correct?
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by snowpenguin » Tue Jan 26, 2010 5:35 pm

I'm pretty sure you're not, I think they have to be the same cell from the same pack/new, they have to hae the same amount of use on them or else charging is messed up etc.

But like a 4000 mAh cell and a 6000 mAh cell wouldn't work I think.

I think.

Ya, they'd be outputting different voltages based on their level of charge, which would be different, so everything could get pretty screwed up.
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by limpport » Tue Jan 26, 2010 9:28 pm

It is dangerous, and should not be attempted.

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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by Kyo » Wed Jan 27, 2010 3:27 am

don't mix batteries. it's just not a good idea.

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TheGeneral
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by TheGeneral » Wed Mar 03, 2010 4:51 pm

what if i took two 3.7v batteries at 4700mah, connected them in parallel and then wired them up to the pcb in a series as if it were a regular 3.7 volt pack but with double capacity. would it work?

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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by hailrazer » Wed Mar 03, 2010 6:07 pm

TheGeneral wrote:what if i took two 3.7v batteries at 4700mah, connected them in parallel and then wired them up to the pcb in a series as if it were a regular 3.7 volt pack but with double capacity. would it work?
I think that would be fine but you would need a higher Amp Pcb like this one :
http://www.batteryspace.com/pcbfor74vli ... artup.aspx" onclick="window.open(this.href);return false;
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TheGeneral
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by TheGeneral » Wed Mar 03, 2010 6:53 pm

so if i were trying to attain 12a i would just use a pcb that could handle it?

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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by hailrazer » Wed Mar 03, 2010 7:08 pm

http://www.batteryspace.com/pcmwithequi ... 0-265.aspx" onclick="window.open(this.href);return false;
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by TheGeneral » Thu Mar 04, 2010 5:55 am

ok, thanks

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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by windwaker » Tue Mar 23, 2010 7:33 pm

how would you wire a charger to be inside a portable or the wire to one?

EDIT:and would 3 of these power a gcp for two hours or would i need 4

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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by Talakoski » Thu Apr 08, 2010 1:01 pm

hailrazer wrote:Lithium Polymer batteries are the newest and currently one of the best choices for batteries in a portable. They are smaller than other batteries, don't develop a "memory" , and last through more charges/discharges than other types of batteries.

But working with Lithium Polymer batteries can be dangerous and precautions must be observed. Be very careful with polarity when hooking up Li-Po's. Also ALWAYS use a protection circuit (PCB) and a Lithium charger that is appropriate for the number of Li-Po's you will be using.

Lithium Polymer batteries come as single 3.7v cells. These cells can be packed together to get 7.4v , 11.1v, 14.8v , etc Li-Po Packs.
When using a 7.4v pack you will want a 7.4v Pcb and a 7.4v charger. Ditto on the rest.

The following diagrams will be based on wiring the 3.7v cells in series to add their voltages together to get the required voltages we need. Batteries wired in series are wired like so :

Image

This is the typical battery most of us use because it has a relatively high capacity for a very small size and cheap price:
http://www.batteryspace.com/highpowerpo ... arate.aspx" onclick="window.open(this.href);return false;
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Here is an example on how to wire the different sets of Li-Po packs you might be using :

7.4v pack. (Two 3.7v Li-Po's)
Image

For the Pcb you will need the following :
http://www.batteryspace.com/pcbfor74vli ... limit.aspx" onclick="window.open(this.href);return false;

For the charger you will need the following:
http://www.batteryspace.com/smartcharge ... isted.aspx" onclick="window.open(this.href);return false;

11.1v pack (Three 3.7v Li-Po's) :
Image

For the Pcb you will need the following :
http://www.batteryspace.com/pcbfor111vl ... ocket.aspx" onclick="window.open(this.href);return false;

For the charger you will need the following:
http://www.batteryspace.com/smartcharge ... isted.aspx" onclick="window.open(this.href);return false;

14.8v pack (Four 3.7v Li-Po's) :

Image

For the Pcb you will need the following :
http://www.batteryspace.com/pcbfor148vl ... ocket.aspx" onclick="window.open(this.href);return false;

For the charger you will need the following:
http://www.batteryspace.com/smartcharge ... isted.aspx" onclick="window.open(this.href);return false;
So I will need 2 of these for my project?

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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by hailrazer » Thu Apr 08, 2010 1:27 pm

Talakoski wrote: So I will need 2 of these for my project?
Yes 2 of them.

And please go back and edit your post and remove the quote to my entire post. It's a huge waste of space.
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by Hifeno » Mon Apr 26, 2010 6:08 pm

Is it possible to wire 3 3.7v 4300mah together to get 11.1v and 12900mah and if so how and what kind of charger and circuit

Also I have them connected right now to output 11.1v 4300mah and when I plugged in the charger to them it only took 30 or 45 min for the indicator light on the charger to say they were charged. Is that normal?
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by Black Six » Tue Apr 27, 2010 8:00 am

Hifeno wrote:Is it possible to wire 3 3.7v 4300mah together to get 11.1v and 12900mah and if so how and what kind of charger and circuit

Also I have them connected right now to output 11.1v 4300mah and when I plugged in the charger to them it only took 30 or 45 min for the indicator light on the charger to say they were charged. Is that normal?
If you have three batteries, you can get either 11.1 V and 4300 mAh or 3.7 V and 12900 mAh. To get both you'd need nine batteries.
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Re: Lithium Polymer Batteries -- How to wire and what to buy.

Post by Schmeman » Wed May 05, 2010 9:23 pm

I have two 3.7V 5700mAh batteries with protection circuits already installed in them. I want to wire them in a series in order to obtain 7.4V. Does it matter if they have two protection circuits? Can I follow the directions on the first diagram on page one and expect the results to be the same? I apologize if these seem like silly questions but I am highly inexperienced. Thanks for your help.
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