How to make a 18650 unprotected cells battery pack

[Synergic]

Hi there;
I have 8 unprotected 18650 cells (1800mAh) from a laptop battery.
I want to make a 14.8V 3600mAh battery pack,i mean 4 cells in series in paralell with another 4 cells in series.
How can i do that? I have found protection pcbs for 4 cells pack,but i dont know how to conect the other 14.8 battery pack in paralell...

Thanks.

 

[geek4christ]

Here's a really nice site that might help you out: http://scriptasylum.com/rc_speed/_lipo.html

It even shows balancer hookups if you desire such a thing.

Also, there is a standard notation for pack building that makes it much easier to communicate your desired configuration. It goes something like this

XsYp

Where X is the number of cells in series and determines the pack voltage, and Y is the number of those series "sticks" that are wired in parallel. So that would make your pack a 4s2p configuration.

 

[Sabrewolf]

Hi there;
I have 8 unprotected 18650 cells (1800mAh) from a laptop battery.
I want to make a 14.8V 3600mAh battery pack,i mean 4 cells in series in paralell with another 4 cells in series.
How can i do that? I have found protection pcbs for 4 cells pack,but i dont know how to conect the other 14.8 battery pack in paralell...

Thanks.

Do you allready have an 18650 charger that will work with
non-protected batteries? ie, will it shutoff at 4.2v?

If so, Charge all of your batteries to make them all of
an equal voltage. Then you can build your pack, as
you have just balanced them beforehand, and dont have
to worry too much about one cell in parallel overloading
another.

One tip that is VERY important,
DO NOT Solder directly to the battery!!
You can use the existing tabs on the laptop
batteries to solder too. Even if they are a little
short, you still have the heat isolated from the
battery when you solder the cell together.

If you dont have the tabs on them anymore,
then you could have someone put them on for
you. Or, you can do it yourself with a Special
tab machine, or a simple do-it-yerself setup.
But i can't stress it enough to NOT solder directly
to the battery casing.

When you build your pack (After initial charging),
you solder 2 cells in parallel, and then solder
the 4 seperate 2-cell packs in series to give you
the needed 14.8v. Make sure you solder the 3
seperate balance wires to your batteries in series
for the protection boards.

Try here for the PCB's
http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=711
and order one with a battery meter plug
and board to show your remaining capacity,
as shown here, in my sales thread for my
mag light customs for an explanation:
http://www.candlepowerforums.com/vb/showthread.php?t=206766

Try to get a PCB with a built-in Pack-Balancing option.
They cost a little more, but they will make the
batteries last a little longer lifewise.
Also, check with your current requirements too.

Have Fun
Robert M.

 

[Synergic]

Thanks!

So i only need 1 protection pcb?
Want kind of charger will i need?
And where can i find a tool to put on the tabs?

Thanks

 

[Sabrewolf]

Thanks!

So i only need 1 protection pcb?
Want kind of charger will i need?
And where can i find a tool to put on the tabs?

Thanks

First i need to know what the highest current drain you will
be using this pack with. As far as the tab machine, i havent
seen the website in awhile. But it might be more worth your
while to order new batteries with the tabs allready installed.
How old are the ones you have?
We will start from there :thumbsup:

Robert M.

 

[Synergic]

Well,i think they have about 7 years.Maybe they are too old?

Abot the current drain,around 3A.

Thanks.

 

[Sabrewolf]

Well,i think they have about 7 years.Maybe they are too old?

Abot the current drain,around 3A.

Thanks.

Yeah, don't bother using them... Too old..
As for a board, use this one:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3206

And this battery meter:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4479

And These Batteries:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1404

Don't forget to get the "Tabs" option for $.25 per battery.
And that way, you don't have to worry about a battery
tab machine.

Robert M.

 

[Synergic]

Thanks very much mate ;-)

Btw, how can i test my old batteries?

 

[Sabrewolf]

Thanks very much mate ;-)

Btw, how can i test my old batteries?

You would need a MAHA 800 series or equivalent
battery charger/tester. But at that age, i would
not even bother..

 

[Synergic]

I have a C808M, but they are only for Nimh or Nicad.

 

[Synergic]

Hi!

Is there another alternative to Batteryspace? Shipping cost is really too high...

Thanks.