Garmin Descent T1 transmitter battery life

[ChrisMBC]

Hi all,

I finally received my T1 transmitter a few weeks ago, and I've put ~8 hours on it since then. Last dive, I started getting low-battery warnings on my watch. I see from the Garmin website that it's an easy replacement of a CR123A battery, but I'm not wild about the idea that I'm going to be replacing the battery once a month.

Have any other owners experienced this? I talked to my LDS and they offered to send it back to Garmin, but with the supply chain at the moment and the fact I just got this, I don't really want to part with it if there's nothing 'wrong' with it.

 

[stiebs]

The transmitter goes into a sleep mode when there is no tank pressure. If you leave your tank value open whilst not using it, that will leave the transmitter in normal transmit mode and drain battery.

Do you have it set to low or high transmit power? Would be an idea to set it to low transmit power and only switch to high if there are connection problems.

I've put about 2hrs of dives on mine so far. Am also curious to see how long it lasts.

 

[ChrisMBC]

The transmitter goes into a sleep mode when there is no tank pressure. If you leave your tank value open whilst not using it, that will leave the transmitter in normal transmit mode and drain battery.

Do you have it set to low or high transmit power? Would be an idea to set it to low transmit power and only switch to high if there are connection problems.

I've put about 2hrs of dives on mine so far. Am also curious to see how long it lasts.

I have it set up with the auto/default power, whatever that is. Don't have any issues with it losing signal. I'm shore diving and have to tear down my gear to fit it in my car so it's never pressurized for longer than the dive time, plus about 30 minutes. If it's a persistent problem, maybe I'll put it on a short HP hose (which I'm inclined to do anyway) and set the transmit power to low...

 

[landshark_IPA]

I have the Garmin descent Mk2i. The manual says that the transmitter battery should last 100 hours. This would be roughly 100 dives depending on pressurized hose time per dive (referring to the need to depressurize so the transmitter goes in to low power state).

I have only ~35 dives over the past 6 months with this system and am on my 3rd battery. Not knowing how long a transmitter will last when the watch says “low”, I swap batteries as soon as they report Low. On the third swap, which I just did prior to googling battery life for this transmitter and finding this post, I decided to actually test the battery voltage with my multi-meter…. It was 3.2v for a battery rated at 3v. For perspective, a brand new battery was testing at the exact same voltage.

This tells me that the Garmin is either being extremely conservative with battery capacity estimation, there is a flaw in the code and someone messed up their decimal places, or the measure of capacity at depth at temperature is more complicated than just reading the voltage. I’m inclined to think it’s a software calculation issue and intend on seeing just how long (cumulative dive time) a battery will last in low state in the safety of our shallow (36ft max) quarry with my always present SPG backup at the ready.

I have always been taught that batteries over their rated voltage are good. Batteries near their rated voltage are weak and they should be replaced as soon as the voltage falls .10 below the rated voltage.

Eg a 9v: you “should” replace at ~9v give/take .05v. You “must” replace at 8.9v and anything less than that may not function.

Regardless, I got an Amazon 12 pack of these things, always check my reported battery level by the watch before a trip and carry a fresh spare at all times. Two if going on an extended trip like say a week long dive vaca or live aboard. I just haven’t had it long enough to have a number of dives/battery that I’m confident in.

BTW, my transmitter settings are default.

 

[ACHiPo]

I just got one and am wondering if I should pull the battery when storing? No information on how long a battery should last in “low power mode”. Any updates would be appreciated.

 

[Alastor]

Just my two cents: measuring batteries voltage while there is no load can lead to erroneous values. I often realized that as soon as the load is draining current, the voltage drops well below the open circuit value. This is especially true with lithium battery. I don't own a Garmin transmitter, but if it is draining more current than others transmitter, the nominal battery duration can be easily overestimated.
If someone would check, should be easy to perform electrical measurement (voltage/current) in a dry environment.

 

[waterone]

I have the Garmin descent Mk2i. The manual says that the transmitter battery should last 100 hours. This would be roughly 100 dives depending on pressurized hose time per dive (referring to the need to depressurize so the transmitter goes in to low power state).

I have only ~35 dives over the past 6 months with this system and am on my 3rd battery. Not knowing how long a transmitter will last when the watch says “low”, I swap batteries as soon as they report Low. On the third swap, which I just did prior to googling battery life for this transmitter and finding this post, I decided to actually test the battery voltage with my multi-meter…. It was 3.2v for a battery rated at 3v. For perspective, a brand new battery was testing at the exact same voltage.

35 dives and 3 batteries is insane! I have a couple hundred dives and you are somewhere near me. Maybe its time to give Garmin a call.

I just got one and am wondering if I should pull the battery when storing? No information on how long a battery should last in “low power mode”. Any updates would be appreciated.

I always leave mine in and I do get somewhere around 100 hours with good batteries. I always depressurize my 1st stage after setup (if Im on a boat ride) and right after I exit the water. I have also dove well after I had a low battery warning..

Just my two cents: measuring batteries voltage while there is no load can lead to erroneous values. I often realized that as soon as the load is draining current, the voltage drops well below the open circuit value. This is especially true with lithium battery

While some voltage sag is normal, large voltage sag happens more often with batteries that have a larger draw than they can handle. Though at the same time some lithium batteries can handle much more than 20c and can handle the rated draws all the way down to LVC.

The cr123a is normally about 1500mAh and since the T1 lasts 100 hours that would be around 15mA draw. I would guess that it should not have much if any voltage sag with its minimal power draw

 

[ACHiPo]

I always leave mine in and I do get somewhere around 100 hours with good batteries. I always depressurize my 1st stage after setup (if Im on a boat ride) and right after I exit the water. I have also dove well after I had a low battery warning..

Thanks. This really helps. It was not clear whether the "up to 100 hours" spec referred to. It's good to know that it's pressurized time.

 

[Manatee Diver]

8 hours is a bit low, but shorter battery life compared to other transmitter has been a common compliant.

 

[waterone]

8 hours is a bit low, but shorter battery life compared to other transmitter has been a common compliant.

8 hours a bit low, that's funny! IMO it needs to be sent in to be looked at if it only last that long.

The tx does have a shorter life but closer to half of the of other common tx's and it also does things others cant. The watch also has an insane battery life with all the fixings compared to any other dive watch. So IMO not much to be complained about if it works per spec, it's give and take