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

[KenGordon]

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.

So the short answer to the point is that AA batteries are better than a built in rechargeable one but only when they are rechargeable and not fakes?

One of the disadvantages of these computers with big colour screens is that you have to worry about battery life. The SAFT mitigates that somewhat. I don’t like opening battery compartments on expensive computers, especially on boats.

 

[KenGordon]

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.

Do you have a link?

BTW there is a difference between power over time and instantaneous draw. I can imagine there being extra work as the receiver establishes the channel. Of course n is too low to really conclude anything.

 

[tursiops]

LOL. You are bound and determined to use the SAFT, whether Shearwater thinks it is a good idea or not.
Just use a non-SAFT lithium, rechargeable, 3.7V, and you'll get 40h of diving. That's probably enough for any boat trip. Charge it before the trip, put it in before the trip, carry one spare just in case. Then you won't have to post on SB anymore about how your SAFT crashed in the middle of a trip.

 

[ATJ]

Do you have a link?

No. I think it was @scubadada that posted it.

However here FAQ and Support | Shearwater Dive Computers
they say

AI will not affect the battery life of the Perdix AI when it is turned off. If the Perdix AI has AI enabled, power usage when on will increase by a small amount (roughly 10%, but this will vary) with one transmitter and a little more with two transmitters. If a transmitter is not being used, it is recommended that it be disabled (does not need to be unpaired) in the Perdix AI system menu.

but this is just having it on and receiving.

BTW there is a difference between power over time and instantaneous draw. I can imagine there being extra work as the receiver establishes the channel. Of course n is too low to really conclude anything.

There's no channel to establish as such. It just listens at the same frequency.

 

[Blackcrusader]

One of the disadvantages of these computers with big colour screens is that you have to worry about battery life.

I've never worried about the battery life for my Perdix. I simply look at the fuel gauge for voltage and when I get to yellow I replace the battery. I always carry spare fully charged batteries as I also keep fully charged AA batteries for my torch.. Certainly I don't know of any dive torch that has a 40 hour battery life. I get 3 day dives on my torch but would change batteries for the night dive. Extra batteries are cheap to buy and charge up before diving or after a days diving.

 

[scubadada]

Do you have a link?

BTW there is a difference between power over time and instantaneous draw. I can imagine there being extra work as the receiver establishes the channel. Of course n is too low to really conclude anything.

The information I previously posted was from my Teric. Applies to dive mode

 

[poseident]

It’s a good idea to have a backup computer on any big trip but it lives in your save-a-dive kit with your o-rings and wrenches, it doesn’t normally get wet.

Jonn, I'd recommend you to always dive both computers on a big trip. If you're switching to a fresh computer after any significant amount of diving on a multi-day trip your NDLs are going to be off, maybe dangerously so.....

 

[dmaziuk]

It's also the Backup 101: if you never test your backup, it'll be dead when you need it.

 

[AKPDB]

+1 on the vote for Peregrine as backup to your Perdix. That's what I use as backup for my Teric.

 

[boulderjohn]

Jonn, I'd recommend you to always dive both computers on a big trip. If you're switching to a fresh computer after any significant amount of diving on a multi-day trip your NDLs are going to be off, maybe dangerously so.....

I Fully agree; in fact, I cannot understand why you would not want to have your backup with you on every dive. If it is truly to be used as a backup, a backup stored above water won't be much good to you during a dive in which the primary fails or on the dive after a primary failure.