Garmin Descent MK2

[waterone]

I get about a 6-7 days use out of the watch. That is either recording activities for 3 to 4 days or diving 3 or more times a week.


The transmitter battery seems to last decent for me so far..unless it is stuck on the new battery level for the last 30 dives and 20 or so pool sessions.

 

[scubadada]

Seems like really crappy battery life from the Garmin CR 123A battery compared to the PPS CR2. I easily get more than 200 dives. I have never gotten a low battery signal, change it when I change the battery in my Oceanic VT3

 

[dmaziuk]

Well if does both radio and ultrasound, that's twice the juice already. I wouldn't be surprised if ultrasonic emitter eats more volts than the radio that everyone else uses, too.

 

[stiebs]

Well if does both radio and ultrasound, that's twice the juice already. I wouldn't be surprised if ultrasonic emitter eats more volts than the radio that everyone else uses, too.

Umm.. just.. no..

The transmitter uses ultra-low power ANT to communicate with the Descent before being submerged. After being submerged, the ANT transmitter is turned off, and sonar is enabled. There is only one transmitter enabled at a time, so no - not twice the juice.

And electronic devices don't "eat volts". They "eat amps". If you're unable to understand what roles voltage and current each play in an electronic device, I don't think you qualify to have an opinion on this..

 

[ATJ]

Seems like really crappy battery life from the Garmin CR 123A battery compared to the PPS CR2. I easily get more than 200 dives. I have never gotten a low battery signal, change it when I change the battery in my Oceanic VT3

I reckon I get 400-500 dives out of the CR2 in my PPS transmitters. They last way longer than the specs.

 

[waterone]

Garmin states 100 dives or more. Mines on its way since it still rates as new.

Apparently when it says low battery it means less than 20 hours left.

And electronic devices don't "eat volts". They "eat amps". If you're unable to understand what roles voltage and current each play in an electronic device, I don't think you qualify to have an opinion on this..

It really isn't hard to grasp what was meant, that simply the sonar probably has a higher draw than radio. You know what, I bet he is on to something..

Personally if I cared about how much power it consumed I'd look at volts and amps so I could get the watts.

 

[stiebs]

It really isn't hard to grasp what was meant, that simply the sonar probably has a higher draw than radio. You know what, I bet he is on to something..

Personally if I cared about how much power it consumed I'd look at volts and amps so I could get the watts.

Oh, I grasped exactly what he had meant to say. But the way it was said is exactly comparable to a newspaper article referring to a scuba diver's oxygen tank. It broadcasts that the person saying it has no real grasp of the underlying concepts of which they're talking about, and therefore they are voicing no more than an uneducated opinion.

As far as sonar vs RF transmitter power - they both generate a signal of sufficient power to transmit to the receiver. I haven't looked at the specifications for any transmitters, but there is just as much likelihood of the sonar being *more* efficient than RF. Radio does not travel well through water, whereas sound does. So to achieve a similar signal distance through water, more power is required for an RF transmission than for a sonar transmission.

 

[ATJ]

Here are some interesting data.

PPS Transmitters (used by Oceanic, Shearwater, etc.) use CR2 batteries. These are 3V with a typical capacity of 800mAh (e.g. Energizer). They are rated for around 300 hours of use (although I get way more than double that).

The Garmin T1 transmitters use CR123A batteries. These are also 3V but typical capacity is around 1500mAh (e.g. Energizer). They are rated for up to 100 hours of use.

This to me suggests that there is a much greater load from the sonar as the batteries have almost twice the capacity but last less than a third as long.

 

[dmaziuk]

... but we'll never let those pesky facts spoil @stiebses story ...

(So garmin transmitter has the wet sensor too, to turn the radio off and u/s on? Talk about multiple points of failure...)

 

[ATJ]

(So garmin transmitter has the wet sensor too, to turn the radio off and u/s on? Talk about multiple points of failure...)

Interesting... I have seen quite a few reports of people with T1 transmitters reporting it connects fine above water but doesn't work below. Other reports of the reverse, works underwater but won't connect above. Garmin have replaced the transmitters in each instance.

A bad batch or a point of failure?