Factors Affecting Battery Life on Shearwater Dive Computers
The factors that affect battery life on the Shearwater Perdix and Petrel dive computers are, in order of most to least significant:
- Battery Type
- Display Brightness
The most significant factor affecting run time is battery type. Lithium batteries tend to have the highest capacities. Further, primary (non-rechargeable) batteries tend to offer longer run times than secondary (rechargeable) batteries.
For most users, the standard AA alkaline batteries offer a good balance of performance and cost. The major disadvantage of alkaline batteries is that can they leak corrosive fluids, especially when fully discharged. Do not store your computer with alkaline batteries installed for more than 1 or 2 months.
Battery life in Table 1 is for medium brightness at room temperature.
|Battery Type||Perdix||Petrel 2||Cost (USD)|
|130 hours||100 hours||$7.00|
|Energizer Ultimate Lithium
|70 hours||50 hours||$3.00|
|1.5V Alkaline (e.g. Duracell Coppertop)||50 hours||35 hours||$0.75|
|50 hours||35 hours||$35.00
(2 batteries + charger)
|NiMH Rechargeable 1.2V||40 hours||30 hours||$20.00
(2 batteries + charger)
|Carbon Zinc 1.5V
|20 hours||15 hours||$0.50|
Table 1: Runtime for Various Battery Types
Ensure your battery type setting is correct when you change batteries. A common mistake is to use the 1.5V Alkaline setting with 1.5V Photo Lithium (Energizer Ultimate Lithium) batteries, or vice-versa. If the setting is wrong, warning levels will occur at the wrong times, leading to shorter than expected life or batteries dying without warning.
The display is the major consumer of power in the Perdix and Petrel. The total Perdix system power consumption for various brightness settings is shown in Table 2.
|Brightness Setting||Power Consumption||Current at 3.3V|
|Turned off||0.07 mW||0.02 mA|
|Cave||30 mW||9 mA|
|High||66 mW||20 mA|
Table 2: Perdix Power Consumption at Various Brightness Settings
The “Auto” brightness setting uses measured ambient light conditions to optimize battery life and readability. In bright sunny conditions, the screen brightness is increased to compete with the sunlight glare. In dark conditions the brightness is reduced to maximize battery life.
Longest battery life is about 250 hours using a Saft LS14500 at cave brightness. Cave brightness is a new feature introduced in firmware version 33, created specifically for cave divers with a further reduced brightness.
Measured alkaline battery voltage when discharged in a Perdix is shown in Figure 1.
Figure 1: Alkaline Battery Discharge in Perdix at Various Brightness Levels
The model of dive computer impacts battery life. The Perdix, being a newer model, is about 30% more efficient than the Petrel 2. Table 1 above shows a comparison at medium brightness. The Predator has similar battery life to the Petrel 2, but note that the Predator can only use the Saft LS14500 type battery.
In general, batteries perform better in warm conditions than in cold conditions.
For example, alkaline batteries have about 75% of their capacity at 0°C as compared to at room temperature (22°C). This drops to about 25% at -20°C. NiMH performance is similar to alkaline.
Cold water divers should choose a lithium battery such as the Energizer Ultimate Lithium or Saft LS14500, as these have the best cold weather performance. Lithium batteries retain 95% of their capacity at 0°C and 75% at -20°C.
Upcoming Dive Shows
Shearwater Research will be at the following dive shows:
DEMA SHOW 2019 (Orlando)
Read More / Nov 13-16 Booth No. 2537
Read More / Nov 23-24 24
DRT HONG KONG 2019
Read More / Dec 13-15 Booth No. 232
2020 Diving Festival Tokyo
Read More / Feb 1, 2020 - Feb 2, 2020
2020 Underwater Intervention
Read More / Feb 4, 2020 - Feb 6, 2020 306
2020 Boston Sea Rover
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2020 Beneath the Sea
Read More / Mar 27, 2020 - Mar 29, 2020 738
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2020 Adex Singapore
Read More / Apr 17, 2020 - Apr 19, 2020 Booth P10
2020 DRT Shanghai
Read More / Apr 24, 2020 - Apr 26, 2020
Read More / Apr 25, 2020 - Apr 26, 2020 41
2020 Scuba Show Long Beach
Read More / May 30, 2020 - May 31, 2020 720
Read More / Jun 12, 2020 - Jun 14, 2020 406