Searching \ for 'OT determining amount of cells' in subject line. ()
Help us get a faster server
FAQ page: techref.massmind.org/techref/index.htm?key=determining+amount
Search entire site for: 'OT determining amount of cells'.

Truncated match.
'OT determining amount of cells'
1999\07\02@112437 by

I have seen battery chargers that determine the amount of cells in a
battery pack and then charge acordingly. The chargers is mp controlled,
but I haven't opened it up to see it if it is a PIC.
The battery packs are made up of 1.2V Nicad cells. But if the cells are
discharged, it is not just a case of measuring the voltage.

Anybody knows how?
Quentin

>The battery packs are made up of 1.2V Nicad cells. But if the cells are
>discharged, it is not just a case of measuring the voltage.

Sure, Quentin.

The basic chemistry determines voltage.  A NiCd with no load on it, unless
_very_ dead, will register around 1.2V.  All they do is a no-load volt test.

Some of the smarter units will apply a small charging current to it for a
short duration, then measure the pack to determine cell count before
starting charge.

Even smarter ones will continuously monitor cell voltage.

Note that a fully-peak-charged NiCd can exceed 1.2V by quite a bit, so as
the cell count gets above 7 cells, these chargers become less accurate as
charge approaches full.

The real issue though is that they charge with the correct current.  NiCd
cells like constant current charging, not constant voltage (like lead-acid
cells).

Andy

==================================================================
Andy Kunz               Life is what we do to prepare for Eternity
------------------------------------------------------------------
andyrc-hydros.com      http://www.rc-hydros.com     - Race Boats
==================================================================

Quentin wrote:
>
> I have seen battery chargers that determine the amount of cells in a
> battery pack and then charge acordingly. The chargers is mp controlled,
> but I haven't opened it up to see it if it is a PIC.
> The battery packs are made up of 1.2V Nicad cells. But if the cells are
> discharged, it is not just a case of measuring the voltage.
>
> Anybody knows how?

I'd look ate the rate at which the voltage climbs at a constant
current. NiCd's voltages climb very quickly. You should be able
to identify the curve without too much problem.

--
Friendly Regards           /"\
\ /
Tjaart van der Walt         X ASCII RIBBON CAMPAIGN
tjaartcellpt.co.za / \ AGAINST HTML MAIL
|--------------------------------------------------|
|  GSM Technology for Positioning and Telematics   |
|  Cellpoint Systems SA    http://www.cellpt.com   |
|    http://www.wasp.co.za/~tjaart/index.html      |
| WGS84 -26.0124 +28.1129  Voice +27 (0)11 2545100 |
|--------------------------------------------------|

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...