How many of you have had a dive computer fail?

[kelemvor]

I'm surprised how many people are admitting to dead battery problems! Why wouldn't you treat the computer like the rest of your gear with regards to maintenance? You can buy a whole pile of batteries for the cost of one thumbed dive.

I did have a uwatec luna get to about that 75% mark after just 25 dives. Way too few for that kind of drain so the LDS replaced the battery under warranty. They swapped the O-ring while it was open. I've got at least 100 since then on it and it still shows full. That's in line with the battery life expectations the dealer set for me. Faulty battery originally, I guess.

Don't have enough bottom time on my new petrel's to make a worthwhile statement on their reliability.

 

[mk706]

I had a Predator battery fail. It had less than two hours in it, and was changed the day prior. It showed good. Goes to prove why it's not good to stockpile batteries as they degrade over time. I had had that battery over a year as my spare.


Pred is now my B/U computer to a Petrel. Lithium AAs are great and so far last very long.


Sent from my iPhone using Tapatalk

 

[dsr30]

Thanks for all the input guys, keep it coming.

Mk, how old was the battery? Lithiums usually have a pretty long shelf life. I'd like to get a Petrel too, besides being an awesome dive comp, I really like the battery flexibility.

 

[The Laconic]

I had a suunto gecko display odd depths during a dive, LDS sent it in and suunto replaced it with a zoop.

Similar experience here. It didn't happen during a dive, but it sure did fail spectacularly. Apparently it was the pressure sensor. (Props to Suunto, by the way, for paying for shipping both ways and diagnosing the problem at no charge.)

 

[drbill]

I'm surprised how many people are admitting to dead battery problems! Why wouldn't you treat the computer like the rest of your gear with regards to maintenance? You can buy a whole pile of batteries for the cost of one thumbed dive.

In my four battery failure incidents, the following held. First one, remaining battery life indicator said 38% and manual said you could still do a few dives at 0%. Not the case. Second time my fault for not changing the battery before a trip. Third time no indication of low battery before failure. Fourth time, new battery failed the day after it was installed.

 

[KeithG]

I'm surprised how many people are admitting to dead battery problems! Why wouldn't you treat the computer like the rest of your gear with regards to maintenance? You can buy a whole pile of batteries for the cost of one thumbed dive.

I did have a uwatec luna get to about that 75% mark after just 25 dives. Way too few for that kind of drain so the LDS replaced the battery under warranty. They swapped the O-ring while it was open. I've got at least 100 since then on it and it still shows full. That's in line with the battery life expectations the dealer set for me. Faulty battery originally, I guess.

Don't have enough bottom time on my new petrel's to make a worthwhile statement on their reliability.

Could be related to the accuracy of the battery level indicators? And then trying to interpret what that really means in real life?

My old Sherwood simply had a "low battery" indicator. Does that mean it will now fail next dive? Since I was doing repetitive diving, I did not want to replace the battery mid week. So I over maintained the computer and put new batteries in it every dive trip. I discovered by trial and error (once it became my backup computer) that there was still a whole week of live aboard diving capacity left on it once the low battery indicator appeared. Great news. With this knowledge I never experienced a battery failure with that computer while in water.

On the other hand, I have had Uwatecs that failed with over 50% battery level remaining. Surprise! Seems like the battery level indicator was not so useful in this case.

 

[GrumpyOldGuy]

Battery technology has been developed to give us a nice flat power curve over time. Below I have a sample of a pretty good battery. In use, the voltage remains stable (usable) over most of its life. This is overall a good thing. It has one bad side effect, the voltage does not vary in a nice linear manner and trying to characterize the actual voltage to how much energy left is more difficult than with old battery technology were voltage dropped in a more linear manner.

Also note the different curves based on temperature. That adds more error to the calculation. So it is pretty easy to understand while top side (nice and warm) you may appear to have a 1/2 full battery and 30 minutes later in cold water, the thing is near zero. If you do a search on battery discharge curves, the variation is astounding between manufacturers and types. The computer may be somewhat calibrated to one type and manufacturer, you switch batter types and it works, but the gauge is now off.

The result is the stupid battery meters cannot be relied on for an accurate measurement, only a very general indication.

 

[kr2y5]

So my question is how many of you have had a dive comp failure while diving?

At some point, my Suunto Zoop started misbehaving in a bizarre manner, which I initially attributed to a hardware failure. For the most part, it would selectively forget things: that I just set it to Nitrox some 10 minutes ago (and it would go back to air right before I enter the water), or that I just made a dive (the dive profile would just disappear, even though it was still there right after the dive). On at least one occasion, it was slow to activate after entering water, so the depths it was showing throughout the dive were several feet shallower. Of course, I quickly started carrying a backup, and only continued to carry the malfunctioning computer out of curiosity, to see what other weird symptoms it was going to exhibit. Oddly enough, besides those symptoms mentioned above, it appeared to behave quite normally, and the display was just as easy to read as it ever was, and if I did not already know that something was wrong, I would have had no idea that this computer cannot be trusted. Before the next trip, I asked the LDS to replace the battery, and all the symptoms appear to have gone away. The moral of the story is that under certain circumstances (e.g., when the battery voltage gets low), the computer may not only shutdown, but more disturbingly, it may appear to continue to function correctly, but misbehave in subtle ways...

 

[victorzamora]

Also note the different curves based on temperature. That adds more error to the calculation.

Sorry, but it's NOT showing different temperature curves. Those are "C" ratings (hence the Amp figure in parenthesis). C-ratings are one terminology for discharge. Amperes is another. Comparing C-ratings is good for packs of similar chemistry but different capacity. For example, high-performance LiPo packs are currently capable of discharging at 65C constantly. They used to max out at about 40C as of just a few years ago. Burst discharges are now allowable up to 130C or so. 130C is WAY less current if you have a 220mAh battery than if you had a 20Ah battery. 1C is the Ah rating of a pack per hour....so in theory a pack would go from full charge to full discharge in one hour at 1C, that's why different capacities have such drastically different Amps at different C ratings, and that's why C-ratings are so crucial to comparing pack performance.

---------- Post added June 21st, 2014 at 10:28 AM ----------

Your point, however, is 100% valid. We can't use simple voltage readings anymore. As electronics get more advanced, they require increasingly stable input voltages. One easy way of doing this is ensuring the flattest input voltage from the original source...in this case, the battery. Cell phones are awful at calculating actual capacity until they get REALLY low, because that's where the curve gets sensitive.

 

[GrumpyOldGuy]

Sorry, but it's NOT showing different temperature curves.

You are correct, I misread the chart. However, the temperature does affect the battery, which is why you have to be a bit more careful in cold water diving than warm. I jumped the gun though when I assumed the C on the graph was temp. There are 2 rules of posting I sometimes violate to my detriment. 1) Never post after drinking a beer. 2) Never post before drinking coffee.

Guilty as charged.