9V NIMH - discharge cutoff voltage?

[lee321987]

I just bought some 9.6V (8-cells) NIMH batteries, and a charger.
I'm trying to figure out what I should set the cutoff voltage to be when designing circuits.

It's universally accepted that cutoff for a single NIMH cell should be 0.9V-1.0V, but what about a battery?
I asked a guy where I bought the batteries and he said, for these 9.6V batteries I should use 8V (1.0V per cell) as a cutoff, but I'm thinking that is too close to risking one cell hitting zero volts and getting reverse-polarized.

These batteries aren't cheap.
I'm thinking about using 8.8V (1.1V per cell) as a cutoff.
What do you think?

 

[kak111]

Here are some datasheets of NiMH batteries,
you can check yourself.

I suggest for 8 cell NiMH , do not go under 1.0V / cell.

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[lee321987]

I read your links.
I guess I'll go with 1.0V / cell for cutoff voltage.
Thanks a lot.

 

[serbattery]

The cut off voltage is 7.0V, Please see below details on NIMH 9V from SERui Battery Technology CO.,LTD

NIMH 9V 280mAh Rechargeable BatteryNominal voltage: 9V
Nominal capacity: 280mAh
NiMH battery features twice the capacity
Wide operational temperature range from -10 to 50C

1. APPLICATION

This specification applies to the NiMH 9V battery

Model : 170H7D (280mAh)

2. CELL AND TYPE

2.1 Cell :Sealed Ni-MH Button Cell

2.2 Type :Button type

2.3 Size type : 8.4V



3. RATINGS

3.1 Nominal voltage : 8.4V

3.2 Nominal capacity : 170mAh/0.2CmA

3.3 Typical weight : 39g

3.4 Standard charge : 17mA×14hours

3.5 Rapid charge : 32mA×6hours

Trickle current : 4.8mA

3.6 Discharge cut-off voltage: 7.0V

3.7 Temperature range for operation (Humidity: Max.85%)

Standard charge 0~+45°C

Rapid charge +10~+45°C

Trickle charge 0~+45°C

Discharge -10~+45°C

3.8 Temperature range for storage (Humidity: Max.85%)

Within 2 years -20~+35°C

Within 6 months -20~+45°C

Within a month -20~+45°C

Within a week -20~+55°C

4. ASSEMBLY & DIMENSIONS

Per attached drawing

5. PERFORMANCE

5.1 TEST CONDITIONS

The test is carried out with new batteries (within a month after delivery)

ambient conditions

Temperature: +25±5°C

Humidity: 60±20%

Note 1

Standard charge : 17mA×14hours

Standard discharge : 0.2C to 7.0V
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