when is it time to replace a SAFT battery?

[davehicks]

I use the 14500 LiON rechargeables in my Petrels, but didn't know the work in the Predator. Is that supported?

The great thing with the petrel is it will take nearly any AA sized battery.

 

[michael-fisch]

I usually buy the SAFT LS14500s in quantities of 10 through Amazon pretty cheaply. Since I have 4 Shearwaters, that lasts me about 15-18 months.

Michael

 

[tbone1004]

I use the 14500 LiON rechargeables in my Petrels, but didn't know the work in the Predator. Is that supported?

The great thing with the petrel is it will take nearly any AA sized battery.

yes, a couple threads about it on here, but I've been using them for 2 years in my meg. The Predator just needs the higher voltage and the chemistry is similar with the two batteries, one just has about a third of the capacity because it's rechargeable. Long term cost though is much cheaper for the 14500's

 

[flymolo]

@Shearwater what's the min voltage for a saft in a perdix computer?

 

[davehicks]

yes, a couple threads about it on here, but I've been using them for 2 years in my meg. The Predator just needs the higher voltage and the chemistry is similar with the two batteries, one just has about a third of the capacity because it's rechargeable. Long term cost though is much cheaper for the 14500's

Frequent battery changes on the Predator are a pain since it wipes tissue saturation data and memory. One Saft was usually good for a full 7--10 day dive trip, maybe not a rechargeable?

 

[tbone1004]

@davehicks Mine was usually good for about that long, roughly 20 hours of bottom time. Obviously a problem if you had to change mid-trip, but I never had to. If you have the second battery ready I have had about 70% chance success of swapping it quick enough and not having it lose data with the computer off.

 

[Shearwater]

We've discussed with the engineers. They warned me that SAFT batteries don't tend to have much of a sloped discharge ramp. They tend to keep a somewhat steady voltage and then they die. The Predator has a similar battery life to the Petrel 2.

@flymolo and @rjack321 you can read more about the expected battery life for our computers here: Factors Affecting Battery Life on Shearwater Dive Computers - Shearwater Research

 

[rjack321]

We've discussed with the engineers. They warned me that SAFT batteries don't tend to have much of a sloped discharge ramp. They tend to keep a somewhat steady voltage and then they die. The Predator has a similar battery life to the Petrel 2.

@flymolo and @rjack321 you can read more about the expected battery life for our computers here: Factors Affecting Battery Life on Shearwater Dive Computers - Shearwater Research

I'm familiar with the discharge curves on lithium batteries. I guess I was hoping for a recommended replacement voltage. I understand given the chemistry that maybe that's not possible

 

[rjack321]

Frequent battery changes on the Predator are a pain since it wipes tissue saturation data and memory. One Saft was usually good for a full 7--10 day dive trip, maybe not a rechargeable?

I'm getting way more life out of mine. I probably have 50hrs on the current one in there.

 

[Shearwater]

I'm familiar with the discharge curves on lithium batteries. I guess I was hoping for a recommended replacement voltage. I understand given the chemistry that maybe that's not possible

I'm hesitant to put in a recommended voltage, specially when it could be used for the primary ppO2 monitoring. I had a SAFT die on me while on a long dive in a 5 C (41 F) cold lake. I was able to finish the dive manually on a NERD 2 monitor. The point being that even following the 3.3 V min on my checklist I still had an event. External factors like temperature affect batteries. Divers will have to keep these into consideration.

To further complicate matters, every now and then you encounter counterfeit SAFTs or used SAFTs sold as new. Mere voltage checking may not be enough to detect these substandard batteries. It is best to load test them like @Dsix36 mentions.

..Many of us have built small load testers that we test each Saft prior to installation. this seems to have sorted my issues entirely. I just built one for my girlfriend a few weeks back when she began to have the same issue.

As posted above, 3.3v is the recommended minimum voltage to begin a dive. 3.0v is the minimum when load testing.