Re: NiMH cell voltage

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.
.

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