Are replaceable batteries in a dive computer better than rechargeable?

[icthyophile]

I am looking for my first dive computer, and every one that I found (minus the mares matrix) seemed to have replaceable batteries instead of rechargeable. Are replaceable batteries in a dive computer better than rechargeable? I'm not talking about how long the battery life lasts, just if there's some great difference between the two. Also, it would be helpful, if there is no big difference, if someone could tell me of other rechargeable dive computers. Thank you!!!!

 

[GrumpyOldGuy]

My DC needs a battery about every 60-70 dives. Most dive computers are low current and do fine on silver oxide batteries, just like your watch but bigger. As long as the batteries are "user replaceable" it is not an issue. There were (and maybe still are) some computers with factory replaceable batteries (not so good).

 

[beaverdivers]

The battery needs to be replaced maybe every year or two. Replacement batteries make more sense.

 

[pasley]

No, Yes, it depends on which you prefer and the power requirements of the computer.
Standard batteries in a dive computer tend to last a year or more (I replace mine ever few years and average about 100+ dives or about 75+ hours bottom time a year on average. So they last a very long time. If you get user replacable batteries they are swaped out in minutes. Factory replaced batteries, well that could take a few weeks.

Rechargable batteries will need to be recharged on frequent basis (rechargable batteries tend to loose a portion of their charge every day) like say every day of diving. Some of the new color display computers like say Liquidvision use a lot of battery and their rechargable battery I am told (no personal experience) is good for about 6 hours.

So at the end of the day is it a question of how much battery does your dive computer use and will you be able to charge a rechargable dive computer on your travels?

For my needs, user replacable works. If you want color displays and all that the high end dive computers bring, with their higher power requirements, then maybe a rechargable makes more sense. It is essentially a Ford or Chevy question, which is better. The answer is the one you like.

 

[icthyophile]

Thanks everyone!!!!!!! You were a lot of help!

 

[RonR]

It depends on the power requirements of the computer. Older segment based LCD displays use very little power, so watch type batteries can work well and last a long time. I'm one of the designers of the Atomic Cobalt: Cobalt Guide: Home
And we use rechargeable batteries, as the power requirements of the color OLED display are higher than coin cells could supply, and we also have a bit more processing going on, which takes power. We get about 40-60 hours of actual display-on diving time on a fully charged battery, or about six months of standby power. Recharging from a full discharge takes about two hours, and can be done through a wall charger or through USB, including solar or auto chargers. It's nowhere near to requiring a charge every dive day- closer to every dive week- though there are some computers using color TFT displays that probably do use batteries that fast.

The internal discharge on modern Li-Ion batteries is quite low, but the computer "wakes up" to sample ambient air pressure every few minutes, and that takes some power. All batteries, including rechargeable, wear out eventually and will need to be replaced, for Li-Ion that is typically about 5-700 charge/ discharge cycles, or many years of diving.

One plus is that rechargeable batteries are a bit more eco friendly, as they have fewer toxics and are not thrown away as often. Also, in our case anyway, you can recharge without opening up the case of the computer. On the negative side, rechargeable batteries will be more expensive initially, as the batteries themselves cost more and, if they can be charged in situ, there needs to be charging circuitry in the computer.

IF the computer and the power supply are appropriately matched, there is no inherent advantage to one or the other, it's weighing ease of use and availability vs. cost. I expect more and more dive computers will come with rechargeable batteries as technology improves and they become more sophisticated, just as has been the case with other electronics.

Ron