Shearwater Battery Question

[GregSaiz]

I had a strange experience with my Shearwater Petrel on Saturday. At about an hour and fifty minutes into my dive in 52F water, my shearwater started flashing a low battery warning. A few minutes later, it reset underwater and seemingly started a new dive. The battery was replaced just a few weeks earlier and had only been used for a couple of dives. I'm willing to chalk up the poor battery performance to user error: it is possible the Alkaline battery used wasn't "fresh".

The really disturbing part is the shearwater dive log shows no record of ANY dive on Saturday. Even with a battery loss, you'd think the log would be written for the last recorded depth/time prior to battery loss. I'm going to send a note to Shearwater to see what they recommend. Anyone had similar experiences?

On a related note, I've ordered SAFT batteries as the lifespan of Alkaline batteries in the Petrel is pretty short.

 

[decidedlyodd]

Although the manual doesn't actively discourage the use of alkalines for cold water, it does specifically recommend 1.5V photo lithium and 3.7V rechargeable Li-ion batteries for colder conditions. I've had decent luck with the 1.2V NiMH Eneloop rechargeables, but I already own a ton for my strobes for underwater photography. I try to switch the battery out for a fresh one before it gets to the low battery warning, but they don't last terribly long and the NiMH's don't have a gradual battery remaining meter (only full, low and dead).

I'm considering ordering a pair of the rechargeable 3.7V Li-ion batteries, just so I can have a better battery discharge gauge and longer time between switching.

 

[GregSaiz]

Thanks Odd, I hadn't noticed that recommendation or if I did, it went out the window after watching Shearwater's "what battery" video on youtube. I found this FAQ to be helpful too: Petrel FAQ | More Info on The Petrel Trimix Dive Computers

 

[Divin'Papaw]

I too have noticed short battery life on alkaline batteries in cold water. I also hadn't noticed the battery recommendation for cold water. Thanks for pointing that out! I think I'll switch to photo lithium since the majority of my diving is cold water.

 

[Peter69_56]

How cold is cold? I haven't experienced any of these issues, coldest is about 12C/54F

 

[Divin'Papaw]

The FAQ talks about 46F and below. The majority of my diving since getting my Petrel has been between 32 and 45. So by cold they mean seriously COLD!!

 

[GregSaiz]

Shearwater responded to my support request. They want me to return my unit for testing to ensure it isn't defective. They also indicated they are making some changes in an upcoming firmware release to better handle dive logging if an unexpected shutdown occurs.

Regarding how cold is cold, some of my recent dives in Carmel have registered 46-48 so that could be running the alkaline battery down faster. Wish I would have read the cold water batter recommendations prior to ordering a set of four Saft's!

 

[Divin'Papaw]

I bought the unit last Nov and I'm on my second alkaline now. My first ran down quite quickly. However, between last Nov and this Mar, I was diving in water between 32.3 F on the low side and 42 F tops. Not surprising now that I've read the Shearwater battery recommendations that the first battery didn't last very long.

 

[Peter69_56]

I'm a crazy diver but not that crazy to dive 46F or less in a semi dry. 50C is about as cold as I will go so I guess the battery wont be an issue.

 

[GregSaiz]

Update: From logs, it looks like my battery was last changed on 3/9/13 and I've logged about 22 hours of diving since then. Several were training dives where the computer was on for long periods during surface debriefs. I'm going to assume about 25 hours on a normal alkaline battery. I'm going to use a SAFT battery and closely monitor voltages in the logs for the next series of dives.

By the way, Shearwater support has been excellent!