Extermal Battery Pack.

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david_halliday
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Posts: 84
Joined: Wed Apr 01, 2009 3:13 pm

Extermal Battery Pack.

Post by david_halliday »

OK, tonight's project was to work out what makes the external battery pack tick.

So using brute force I opened up one of them up.

Once open I discovered that there are two screws hidden under the labels that would allow the pack to be opened without destroying it. Here is probably the place to mention that,  lithium is toxic so take care not to damage any cells.

My pack comprised of 4 3.7V Panasonic Lithium Ion Prismatic Cells wired as follow:

    -VE       -VE     +VE      +VE
  +-----+ +-----+ +-----+ +-----+
   |       |  |       |  |       |  |       |
   | C1  |  | C2  |  | C3 |  |  C4 |
   |       |  |       |  |       |  |       |
  +-----+ +-----+ +-----+ +-----+
    +VE       +VE     -VE     -VE

C1 and C2 -Ve terminals are wired together and connected to the -VE terminal on the controller board. C3 and C4 +VE terminals are wired together and connected to the +VE terminal of the controller board. Now all the bottom terminals are all wired together and wired to the UM connection.

This works as follows C1 and C2 are wired in parallel to make a single larger 3.7V Cell and C3 and C4 are wired to make a second large cell. Now the two 'larger' cells are wired in series to make a single 7.4V cell.

With this knowledge it should be possible to make your own replacement pack. It looks like the cells are Panasonic ones similar to these.

http://www.panasonic.com/industrial/bat ... 03450A.pdf and can be had for $13 each here:

http://www.sabahoceanic.com/epages/saba ... s/14058004

Dave.

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Last edited by david_halliday on Tue May 12, 2009 1:09 am, edited 1 time in total.
david_halliday
Developer
Developer
Posts: 84
Joined: Wed Apr 01, 2009 3:13 pm

Re: Extermal Battery Pack.

Post by david_halliday »

I got thinking this morning before ordering some bare cells, what if there is some charge counter stored on the board so I did a little more digging.

One of the IC's on the board is S8232U which is a battery control logic

http://datasheet.sii-ic.com/en/battery_ ... 8232_E.pdf

The second IC was marked SA D2017A while I could not find this I could find FTD2017A here:

http://www.datasheetcatalog.org/datashe ... clie3y.pdf

Which just looks like a logic switch.

Maybe Foxx our resident HW expert can shed more light on this but to me it looks like the charging circuit is fairly simple and does not contain a charge record. (Unless it is in the S8232)

Dave.
hardwarej
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Posts: 15
Joined: Sun Feb 07, 2010 8:07 am

Re: Extermal Battery Pack.

Post by hardwarej »

Hi dave,

i would like to build a battery for the webdt366 that lasts 12 hours.
now i would like to connect this battery to the secondary battery output on the device.(3 pins) because i want to charge it from the webdt
i checked the voltage on the webdt battery connector and found 6.5 v between the first and second pin , 3.05 V between the second pin and third and 9.6 v between first and third (SEE FIGURE)
can you tell me what does this mean and how i can plug an external battery to it
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Last edited by Anonymous on Tue Feb 23, 2010 3:04 am, edited 1 time in total.
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