Petrel One Battery Issue

[Capt Jim Wyatt]

I started a cave dive yesterday with my Petrel 1 with the battery icon showing 50%. I did not look at the voltage. I had an Energizer Ultimate Lithium battery in it, and the computer was set for that battery.

Moments after getting into the water the computer went blank. Would not restart. Got it home and replaced the battery and it works just fine now.

Seems odd the battery icon showed 50% & died within a few minutes.

Anyone else experienced this issue?

Luckily I had my Perdix AI on also. it worked just fine so we could make the dive.

 

[Searcaigh]

I've rarely used non-SAFT batteries in my Petrel 2, but never had issues with them.

Perhaps it was a dodgy Energizer battery?

Do you still have the battery? Perhaps it can be tested somehow ?

 

[davehicks]

It's not a good idea to start a dive with a less that full battery. The metering of power levels does not work a predictably as could be hope with some types of batteries. The drop off from warning to zero can be very rapid. Was the the warning not there 1 day before or had it been some time since it was last checked?

Factors Affecting Battery Life on Shearwater Dive Computers - Shearwater Research

 

[tbone1004]

Lithium has a very flat discharge curve so the computers really struggle with them. Use eneloop rechargeable nimh batteries or get a couple 14500s and recharge them with your backup lights.

 

[Capt Jim Wyatt]

OK. But I have been using Shearwater computers for about 10 years, sometimes Saft, sometimes NiMh, sometimes alkaline and sometimes lithium. I have a Predator, a Petrel and a Perdix with over 600 dives on them and never saw this happen before.

I have a bunch of NiMh 3100 mAh & 1500 mAh rechargeable batteries I used in my handheld GPS and I will give them a go....

 

[davehicks]

OK. But I have been using Shearwater computers for about 10 years, sometimes Saft, sometimes NiMh, sometimes alkaline and sometimes lithium. I have a Predator, a Petrel and a Perdix with over 600 dives on them and never saw this happen before.

The Predator with SAFT cells was complete wacky and unpredictable with it's warnings. They would flip on an off at random. When ever I got a warning I just replaced them.

I've been using the Energizer Lithium cells with my Petrel 2 units for a few years now with good results. The battery meter is more rational now and once it's drops it stays that way. But I change the cell as soon as I see a warning. Always carry a spare AA in case it happens at an inconvenient time like you experienced.

 

[Capt Jim Wyatt]

Is there any alternative to Saft batteries in a Predator?

 

[tbone1004]

Is there any alternative to Saft batteries in a Predator?

14500s work fine. Been using one on my meg for 5 ish years now. They also work in the petrel and Perdix and I just charge them with my backup light batteries.
I do second changing them as soon as you see a warning though but with the rechargeables it is a lot less annoying

 

[Capt Jim Wyatt]

14500s work fine.

Cool....

 

[kelemvor]

Energizer recommends devices combine voltage and battery ir measurements to effectively estimate remaining capacity. Clearly shear-water is only using voltage as they struggle with estimating capacity on lithium primary cells. Probably because it would require a suitable capacitor to run the DC for a few hundred milliseconds while a measurement is taken and there isn't room for that.

Here's the data sheet where Energizer describes discharge curves, temperature effects, and capacity measurement techniques. https://data.energizer.com/pdfs/lithiuml91l92_appman.pdf