Computers and backups - looking for pearls of wisdom from the more experienced

[Belzelbub]

My batteries come from a place I can rely on to be buying the real thing, not some no name eBay or Amazon reseller.

Unless you watched the batteries being made, and followed every logistical stop on their way to you, then you can’t.

For many years, I was responsible for counterfeit component mitigation. One sure way to point out someone who had no clue what they were doing was if they were to tell you that they could ensure that they were 100% safe from counterfeits impacting their supply chain.

The dive was over an hour in 6C water. I can only guess at the draw of a Perdix but this page is vaguely interesting. https://www.saftbatteries.com/energizing-iot/impact-temperature-your-iot-application’s-power-consumption/

Yeah, without a doubt, the cold water will definitely consume more, but I wouldn’t think that 1 hour in that cold water would be enough to consume a good portion of a fresh battery. You are complaining about battery predictability, and using batteries that aren’t compatible with the “Fuel Gauge” feature. Using a battery that is compatible will help with predictability.

Also, on the Shearwater site, they note that SAFTs are not compatible with the “Fuel Gauge” and are also very susceptible to temperature. SAFTs do last long, but if you can’t predict when they will be dead, is it worth it?

 

[tursiops]

Also, on the Shearwater site, they note that SAFTs are not compatible with the “Fuel Gauge”

Exactly my point in post #91.

 

[Wibble]

Also, on the Shearwater site, they note that SAFTs are not compatible with the “Fuel Gauge” and are also very susceptible to temperature. SAFTs do last long, but if you can’t predict when they will be dead, is it worth it?

What's the old adage... If it's important, bring two.

Especially important for monitoring PPO2 on a rebreather -- need a second computer to display this.

 

[KenGordon]

Unless you watched the batteries being made, and followed every logistical stop on their way to you, then you can’t.

For many years, I was responsible for counterfeit component mitigation. One sure way to point out someone who had no clue what they were doing was if they were to tell you that they could ensure that they were 100% safe from counterfeits impacting their supply chain.

Yeah, without a doubt, the cold water will definitely consume more, but I wouldn’t think that 1 hour in that cold water would be enough to consume a good portion of a fresh battery. You are complaining about battery predictability, and using batteries that aren’t compatible with the “Fuel Gauge” feature. Using a battery that is compatible will help with predictability.

Also, on the Shearwater site, they note that SAFTs are not compatible with the “Fuel Gauge” and are also very susceptible to temperature. SAFTs do last long, but if you can’t predict when they will be dead, is it worth it?

It is not a fresh battery, it has had some use. My point is that the Perdix is actually not better than a Teric, Peregrine or Eon Steel with respect to power. It might not be Shearwater’s fault completely (although perhaps never letting the level go up to full once it has shown near empty might be a plan) but replaceable batteries just have a different set of compromises.

Today there seemed (n=2) to be correlation between turning on the AI transmitter (by turning on the gas) and the battery level dropping, it even gave me a low battery interrupt warning. When I look it claims the battery is at 3.48v.

I buy my batteries from the the UK Shearwater importer. There is no more respectable place to buy them. It is run by a proper engineer who has been responsible for a number of entertaining rebreather bits and pieces. He fully understands that he is selling batteries to people who might have to spend hours manually running unit to get back to the surface should a battery fail. Both ways of knowing the ppO2 rely of these SAFT batteries and if there was a batch that failed all at once it could kill someone.

To be clear if the Petrel controller complained about a battery it would get a fresh one immediately. The Perdix is just one of two OC computers I was using this weekend and if it had failed it would have just been a teaching point about why you want two computers.

Hi, rjack. For the Petrel 2 controller I dive with, I use 3.3 V as my minimum. I'll ask the engineers about the Predator on Monday. Is it for a KISS monitor?

Cheers

A quick scan of the (Nitrox rec) manual didn’t confirm your assertion that the battery indicator doesn’t support SAFT. There is an article about SAFT batteries bought on Amazon which did not work and failed with a load.

I’ll probably stick with this suspect battery until I am next doing a CCR dive, just to see how it behaves. Maybe if I end up in the sea it will be warm enough to work or maybe the computer is in an iffy state. It also seems confused about how long it is since the battery was changed.

 

[ATJ]

The dive was over an hour in 6C water.

The only times I've had the battery in my Perdix nearly die on me were on dives longer than 2 hours (but 16ºC water).

There was no hint of a battery problem before the dive. During the dive the yellow low battery indicator came up and on my safety stop it went red.

I use rechargeable 14500 Li-ion batteries.

 

[ATJ]

Today there seemed (n=2) to be correlation between turning on the AI transmitter (by turning on the gas) and the battery level dropping, it even gave me a low battery interrupt warning. When I look it claims the battery is at 3.48v.

That's the opposite of what you'd expect.

The Perdix is a simple receiver, listening for the broadcast from the transmitter.

It was posted with information from Shearwater that the Perdix uses slightly more battery power when it doesn't receive a signal from the transmitter because it is polling more often. If this is the case, once it receives the broadcast it should be polling less often and so using less power.

 

[tursiops]

A quick scan of the (Nitrox rec) manual didn’t confirm your assertion that the battery indicator doesn’t support SAFT.

The manuals -- excepts below -- say that SAFT is supported, but not recommended. Only 1.5V Photo Lithium is recommended. The older Petrel manual also said that 1.5V Alkalines were recommended.

Page 79, Perdix Operating Manual DocRev A

Page 64, Petrel SA 1/2 and EXT

 

[tursiops]

I use 14500 batteries.

What kind of 14500? That's a size, not a type.

 

[ATJ]

What kind of 14500? That's a size, not a type.

Rechargeable 14500 Li-ion. I've updated my post.

 

[Belzelbub]

A quick scan of the (Nitrox rec) manual didn’t confirm your assertion that the battery indicator doesn’t support SAFT. There is an article about SAFT batteries bought on Amazon which did not work and failed with a load.

Below is what is posted under the FAQ section for batteries at Shearwater’s site under Perdix AI. Only the 14500 Li-Ion rechargeables are indicated as compatible with Fuel Gauge.

Short Answer:​

While almost any kind of AA sized battery works with your Shearwater Perdix, the standard 3.7V Li-Ion battery (the type found in stores around the world) works best.

Long Answer:​

There are numerous types of AA sized batteries that will work in your Shearwater Perdix, read below for more details.

Saft​

The Saft 3.6V LS14500 battery (used by the Shearwater Predator) is also a good choice, primarily because it has the longest usable life (130 hours on medium brightness). However they are:
A) Expensive
B) Hard to find
C) Sensitive to temperature and storage conditions
In addition they are incompatible with the new “Fuel Gauge” feature so only three levels are given: Full, Low (Yellow) and Critical (Red).

Li-Ion - Rechargeable​

The 3.7V Li-Ion 14500 battery is a good choice that can be purchased online. The AW brand is recommended and typically high quality. The brands Trustfire and Ultrafire can be good, but seem to come from a wider variety of sources and many users report getting duds. The Li-Ion batteries give about 40 hours per charge and are compatible with the new “Fuel Gauge” feature. Note that these batteries are actually about 4.2V when fully charged. Some brands of Li-Ion rechargeable include a protection circuit that extends the battery significantly beyond the 14500 standard 50mm. The Perdix is confirmed to work with batteries up to 52mm in length. Longer batteries may not allow the battery compartment to fully seal. Do not dive with a battery that prevents the battery cap from screwing all the way down.

NiMH - Rechargeable​

The 1.2V NiMH battery can also be used. These are commonly used in photo flashes and digital cameras, and can be purchased in most electronics stores. About 35 hours per charge can be expected. We recommend using the low self-discharge models typically labeled as “pre-charged”, “ready charged”, “stay charged” etc. and have capacities around 2000mAh. The older style high self-discharge batteries have higher capacities (around 2800mAh) but are not recommended. They will work, but will go dead in a few weeks just sitting on the shelf. Also, all NiMH batteries are incompatible with the new “Fuel Gauge” feature so only three levels are given: Full, Low (Yellow) and Critical (Red). If you have these batteries already from your photo flash, feel free to use them. However we do not recommend buying them for the Perdix as better choices are available.

Photo Lithium 1.5V​

These are the best choice for cold water divers. Sold as the Energizer brand Advanced Lithium and Ultimate Lithium batteries. The 1.5V Photo Lithium batteries offer almost double the run time in a Perdix when compared to an alkaline battery. However they can cost about 4X as much as an Alkaline. They are a good choice if you want longer run time than alkaline batteries provide or if diving in waters colder than 8 degrees Celsius (46 degrees Fahrenheit) . They can be found in most department stores or electronics stores and also in many drug stores.

Zinc-Carbon 1.5V​

1.5V Zinc-Carbon batteries are el-cheapo batteries commonly found in dollar stores. Although they work, they only provide about 10 to 15 hours and so are not recommended. However if they are all you can get on a tropical island somewhere, feel free to use them. Set the Perdix battery type to “1.5V Alkaline” when using zinc-carbon batteries.