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
- Model
- Temperature
Battery Type
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) |
|---|---|---|---|
| Saft LS14500 3.6V Lithium | 130 hours | 100 hours | $7.00 |
| Energizer Ultimate Lithium 1.5V Lithium | 70 hours | 50 hours | $3.00 |
| 1.5V Alkaline (e.g. Duracell Coppertop) | 50 hours | 35 hours | $0.75 |
| Li-Ion 14500 Rechargeable 3.7V | 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 (not recommended) | 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.
Display Brightness
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 |
| Low | 40 mW | 12mA |
| Med | 53 mW | 16mA |
| 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
Model
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.
Temperature
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.
Tyler, this is great news, easy to understand and apply to my diving, the Energizer Lithium look to be the best, another benefit to the longer life is fewer replacements, which means the seal on the battery compartment is less likely to pick up a stray hair and leak.
Hi Chauncey, I am glad you found it helpful. The Energizer Ultimate Lithium batteries are a good choice. Pricing is highly variable, but I can often find them for a great price when on sale. Their package claims “8X the life” or something, but this only applies to high-drain uses. For a low-drain use like ours, about 40% more life is available compared to Alkalines. The great thing is that they don’t leak when discharged.
Remember to set the “Battery Type” setting to “1.5V Photo Lithium” when using the Energizer Lithium batteries. If you don’t then the warnings will be all wrong. If left at “1.5V Alkaline” you will not get a low battery warning until the battery very quickly dies. If the other way around (using Alkaline but set to Lithium), you will get the warning way too early. This can be seen from the voltage graph showing very different discharge curves, that I have uploaded here:
https://app.box.com/s/jxixb4q9g7ctvtaplueqjlyb6qewkyn1
Best regards,
Tyler
I have had the Energizer Ultimate Lithium leak in my computer. The battery went flat and the computer turned off, then 2 weeks later when I opened it up the battery had leaked.
You are missing a couple of serious battery drains – the “Wow” factor, and the “Toy” factor.
The Wow factor is when someone shows off his or her computer and all the features and logs to everyone they meet.
The Toy factor is when one plays with all the settings and runs all the dive programs. 😀
Hey, this is serious engineering stuff. Only serious replies! 🙂
Thanks for the great info. Have you tried any of the above test on the Nerd ?
Thanks,
Colin.
Hi Colin,
The NERD is about the same as the Petrel, maybe very slightly higher draw for the NERD. The NERD at medium brightness draws about 22mA at 3.3V (73mW).
The NERD display backlight doesn’t draw much current, so the brightness setting isn’t as big as a factor. About 20mA at low brightness to 25mA at high brightness.
Best regards,
Tyler
Excellent information Tyler!
Predator is not really in stock but still very popular and for those a color settings of the display will affect the battery life a little bit because of OLED pixels combination more consuming versus plain RGB colors, I guess.
Thanks a lot!
Hi Ol, You are right. For the Predator with its OLED screen, the current draw depends on what is displayed. At 3.3V on medium brightness, the draw is normally about 20mA. But if displaying three 3 O2 sensors, and all are red (low or high PPO2), and red and yellow warnings are flashing, it could peak as high as 35mA.
The title colour also has a bit of an impact as well, but it is minor. The green OLED is more efficient so green titles use a bit less power than cyan or blue. Blue is the lowest efficiency, but the difference is only about a 5% impact on battery life when comparing blue titles to green.
Best regards,
Tyler
Good afternoon!
I want to become one of your dealers in Russia.
I understand that in Russia there are already your some representatives.
Russia rather big country and therefore I want to develop your brand for territories of Russia.
I am an instructor of CMAS, TDI and I can intelligibly explain to people with what Shearwater differs from other underwater computers. And on how many his advantages in front of other computers are big.
At present I form the website and is ready to consider your wishes for more successful placement of production of Shearwater.
Hello Dimitrii
Please send your enquiry to our info@shearwater.com email address. Someone will reply to you from there.
How about “LiFePO4” rechargeable batteries? The AA size LiFePO4 battery is typically 3.2V
Hi YQ, I have not personally tried the LiFePO4 battery type. For looking at the specifications, it should work fine if you can get a 14500 size. One issue is that there is not a “Battery Type” setting for this chemistry, so a proper gauge and warning levels will not be available. I would try the “3.6V Saft” battery type setting when using the LiFePO4, and see if it gives reasonable results.
Hi Tyler,
I had read your topic and all the infos, thx for that.
I have a little question cause I must change my battery inside my Petrel : The cost/hour between SAFT and Energizer Li is the same and it’s not really important, but what are the differences between both in quality. The Petrel can be used with 3,6 or 1,5, but what’s the best choice ?
Thanks for all
Hello, what can I do after fully discharging my computer Teric? it didn’t work for about 5 months. Thanks.
Hi There, sorry to hear that you are having issues with your Teric, please send an email to info@shearwater.com with your Teric’s serial number. Our Customer Care member will be happy to assist you. Thank you and have a great day.
Hello: I’m afraid of battery leakage in my brand new Perdix AI and transmitter.
1) Is there any problem in leaving both Perdix AI and transmitter without battery for a long time?
2) Does Perdix lose data if I leave it without the battery for a long time?
3) Is there any risk in opening and closing battery compartment frequently?
4) I’m turning on my Perdix once a week and checking the battery level. At which level should I change the battery?
I’m asking that because I haven’t had a chance to use my Perdix AI for the first time, as I purchased it in march/2020 and due to coronavirus pandemic, I’m not diving.
Thank you very much. Kind regards.
Hello Alexandre,
1) If you are storing your Perdix-AI and Transmitter for a long period of time we recommend taking the battery out to prevent any possible corrosion.
2) Your computer will preserve your dive log and settings even if it is without battery for a while.
3) We recommend opening the battery compartment as little as possible, as this increases the risk of contaminating the o-rings.
4) You only need to change the battery once it reaches the red battery indicator on the display
If you have any more questions please send us an email to info@shearwater.com and we’ll get back to you right away.
Thank you and have a great day
Hi
what is your recommendation for Sherwater HUD concerning Battery type?
Hi, could you please confirm if this is a DiveCAN rebreather? As not all re-breathers are the same, I would advise checking the user manual for your unit or contact the re-breather manufacturer. It’s usually a Saft battery though.
Best,
Trisha
what about battery for the sherwater HUD?
do you give the same suggestions?
Hey! Was wondering if there is any inherent risk of a rechargeable 14500 battery with protection circuitry (it’s slightly longer than SAFT or AA battery) with regards to closing of the battery compartment.
Thank you in advance!
Thank you for your response! Is there a clear indication that the compartment is fully closed?
Kind regards,
Sergej
When I run the rechargeable 14500 on my Perdix 2 the orange and red warnings come on like around 3.6v ( after around 15 dives, auto brightness and vibration on, AI on). The battery seems less than half discharged. The battery gauge is set on rechargeable 3.6v lithium. Is this normal?
Hi Justin. I’m very sorry for the delay in reply. Could you please email us at info@shearwater.com with a photo of the battery you are using so we can help you further from there?
Thank you,
Trisha
The battery compartment is closed once the circuit is closed and the computer turns on. Does not have to be screwed in tight.
The battery in question is the Vapcell L10 INR14500 1050mAh 3.78Wh which was rated quite highly. Warning signs come on around 3.6v. What voltage will normally trigger the orange and red warnings on the Perdix 2 using 3.7v 14500 rechargeables?
Hi Shearwater,
Would it be possible to offer a discussion of the battery problems that have been encountered with the Teric?
I bought my 1st Teric in May 2019 and have had 3 replacements due to poor and deteriorating battery performance. Charging recommendations and any other guidance would also be appreciated.
The service I have received from Dive-Tronix and from you has always been absolutely exemplary. The Teric is a perfect computer for me.
Appreciatively,
‘
Craig
thank you for the article
My Perdix AI is 13 months old. I fitted a lithium 1.5V earlier this year. After the firmware updated this year the battery time on and date fitted info was not preserved and are currently reporting as unknown :(. I am currently on a dive trip doing three 60 minute dives a day. Past two days I have see seen voltage start at around 1.48 to 1.5V , battery bar 80 to 90% and drop to around 1.46V by end of last dive today with the battery symbol turning orange and battery bar is showing maybe 60%. A few hours later the orange is gone and the battery bar is back at maybe 70 to 80% although it soon drops a bit back to 1.46V if I look at logs . But the orange is gone?? In your article the orange phase seems very short before it turns red in the figure. The voltage still seems high to be seeing an orange warning. I am wondering how much life my battery really has left and whether to change it now as my trip has 4 days left. The dive log shows 50 dives total since new including dives on the original alkaline. It seems early to be changing the lithium 1.5V cell. I don’t believe the lithium has had more than 30 hours of use. It is frustrating the firmware update did not preserve my battery life info. My brightness is set to auto. Any advice?