Re: NiMH cell voltage

On Sep 16, 7:13 am, ransley <Mark_Rans...@xxxxxxxxx> wrote:
On Sep 16, 2:47 am, Ron Hunter <rphun...@xxxxxxxxxxx> wrote:





ransley wrote:
On Sep 14, 11:21 pm, ASAAR <cau...@xxxxxx> wrote:
On Sun, 14 Sep 2008 20:32:27 -0700 (PDT), ransley wrote:
ransley <Mark_Rans...@xxxxxxxxx> wrote:
My sanyo Eneloops are fully charged at 1.5v and wont run my camera at
1.29v My Sony came with Nimh, Get new batteries or charger.
nimh batteries do not put out 1.5v.
Right, go buy a new V meter and some Eneloops and a good charger. I
just got done charging 3 sets. And I supose you think a cars lead acid
battery is charged at 12v. Nimh-Nicad are basicly dead at 1.2v
  Totally wrong, as a quick glance at NiMH manufacturer's data
sheets will show.  Eneloops have the same voltage characteristics as
standard NiMH batteries.  This is from one of Energizer's old NiMH
AA engineering data sheets :

Designation: ANSI-1.2H2
Battery Voltage: 1.2 Volts
Average Capacity: 1850 mAh (to 1.0 volts)
(Based on 370 mA (0.2C) discharge rate)
 and this is from Duracell's Tech Bulletin :

5.1 General Characteristics
The discharge characteristics of the nickel-metal
hydride cell are very similar to those of the nickelcadmium
cell. The charged open circuit voltage of both
systems ranges from 1.25 to 1.35 volts per cell. On
discharge, the nominal voltage is 1.2 volts per cell and
the typical end voltage is 1.0 volt per cell.
http://www.duracell.com/oem/rechargeable/Nickel/nickel_metal_tech.asp

I just read a few spec sheets showing 1.35-1.4 being a stablised full
charge of Nimh, My sony charger peaked it out at 1.5 and today on 2
different meter I am showing 1.38-1.4v on Eneloop cells, at 1.2v they
are basicly discharged and wont even power up my camera at 1.29v,
These are nearly the same voltage patterns as I have seen from Nicads..
Eneloops do take 1.5v to peak on my 2 sony Nimh chargers.

I have never seen a battery that will put out more voltage than the
chemical action allows, and for NiMH, that is about 1.24-1.3 volts.  The
1.3 volt reading is a no-load condition on a battery fresh out of the
charger, and should be considered 'transient'.  A discharged NiMH would
measure about 1.0 to 1.1 volt.  I suspect you have a meter inaccuracy,
and please send the URL for those 1.39-1.4 voltage numbers.- Hide quoted text -

- Show quoted text -

1.35 - 1.4v  a cell unloaded is most easily found at Wikipedia, I
peaked out of the sony charger at 1.5v, within a day it showed 1.4.
After a few shots 1.38. So what I just saw at Wikipedia shows I am
inline with specs. My Nicads are about the same in full v charge even
on my manualy done charging, peaking by just reading voltage drop, for
my RC toys. An auto lead acid battery is nearly discharged at 12v, so
are AA rechargeables.- Hide quoted text -

- Show quoted text -

www.batteryuniversity.com on page BU11 has interesting info on
charging NiMh. Is it possible the chargers some people use are not up
to the job. What I see is my voltages are correct within 0.2v on my
meters.
.

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