Question Cobalt 2 Flaky Battery Behavior

[Av8nAz]

My wife and I both have Cobalt 2 dive computers (which we love). I don't recall when we originally purchased them, it was shortly after they were introduced (a friend recommended them, and told us to be sure to get the Cobalt 2).

Since our last big trip, the battery on my wife's computer has been draining more quickly. I used to be able to get by with putting them on the charger once every couple of months, but hers has been draining faster, so I've upped the charge ritual to monthly. Mine holds the charge, but it was replaced a few years back (maybe 2017 or 2018) after it locked up a couple of times at safety stops. I should note that when I do this cycle, the same charger is used for both. My wife's goes on the charger first, and then mine because hers might be pretty low when I get them out.

I've looked for a battery, but the shop told me parts are unavailable, and of course Atomic no longer sells them. (Although they do still have firmware downloads).

I've been assuming I'd need a new battery, but this charging cycle was odd. When I first checked it, it powered up but said the battery was 0%. Got it on the charger. Within perhaps an hour, it said 99%. (It hasn't gone above 98% or 99% for quite some time). Unplugged it, put it to sleep, then about 10 minutes later checked it. Still at 99%. I put it to sleep again and check again later that day. Back down to a very low value. Back on the charger, and within a short period of time it was at 99%.

After reviewing the forum, I saw a recommendation to update the firmware. She had 2.460/4 (if I recall correctly). I updated the firmware (I wish all firmware updates were so easy!) and the display went to 100%. That at least was new. (Incidentally, I updated mine, which was at 2.490 iirc.)

This morning I looked at it and it was at 27%. Put it on the charger, and within a few minutes it was back at 100%. About an hour later, it had dropped to 30%. I have checked it several times over the course of the day, and it has steadily dropped, but at least in a seemingly-linear fashion. After about 5 hours, it's down to 25%.

Any ideas? Is there a source for a replacement battery, or can I fabricate a replacement with standard cells?

Any help greatly appreciated. My wife started looking at available dive computers and she is not at all happy with the current crop. We have a Philippines tripped planned early next year so I need to get this sorted out fairly soon.

 

[RonR]

My wife and I both have Cobalt 2 dive computers (which we love). I don't recall when we originally purchased them, it was shortly after they were introduced (a friend recommended them, and told us to be sure to get the Cobalt 2).

Since our last big trip, the battery on my wife's computer has been draining more quickly. I used to be able to get by with putting them on the charger once every couple of months, but hers has been draining faster, so I've upped the charge ritual to monthly. Mine holds the charge, but it was replaced a few years back (maybe 2017 or 2018) after it locked up a couple of times at safety stops. I should note that when I do this cycle, the same charger is used for both. My wife's goes on the charger first, and then mine because hers might be pretty low when I get them out.

I've looked for a battery, but the shop told me parts are unavailable, and of course Atomic no longer sells them. (Although they do still have firmware downloads).

I've been assuming I'd need a new battery, but this charging cycle was odd. When I first checked it, it powered up but said the battery was 0%. Got it on the charger. Within perhaps an hour, it said 99%. (It hasn't gone above 98% or 99% for quite some time). Unplugged it, put it to sleep, then about 10 minutes later checked it. Still at 99%. I put it to sleep again and check again later that day. Back down to a very low value. Back on the charger, and within a short period of time it was at 99%.

After reviewing the forum, I saw a recommendation to update the firmware. She had 2.460/4 (if I recall correctly). I updated the firmware (I wish all firmware updates were so easy!) and the display went to 100%. That at least was new. (Incidentally, I updated mine, which was at 2.490 iirc.)

This morning I looked at it and it was at 27%. Put it on the charger, and within a few minutes it was back at 100%. About an hour later, it had dropped to 30%. I have checked it several times over the course of the day, and it has steadily dropped, but at least in a seemingly-linear fashion. After about 5 hours, it's down to 25%.

Any ideas? Is there a source for a replacement battery, or can I fabricate a replacement with standard cells?

Any help greatly appreciated. My wife started looking at available dive computers and she is not at all happy with the current crop. We have a Philippines tripped planned early next year so I need to get this sorted out fairly soon.

Thanks for the positive comments, we worked really hard to make the Cobalt easy to use, including updating the firmware for the Cobalt 2.

My first thought is that your wife's computer is exhibiting classic signs of a Li-ion battery reaching the end of it's life cycle- gradually decreasing capacity. The readings after the firmware update are most likely just the system calibrating itself. But it's also possible (but less likely) that something is causing the Cobalt to use too much power in sleep mode, or preventing it from going into sleep mode. This could happen because of something bridging the pins at the Cobalt's nose, for instance- or in a worst case scenario, because of a leak in the case. We should rule those things out as well. We can help with batteries, if that's what you need. I will send a direct message on ScubaBoard with information.

It's apparently true that Huish has completely stopped any support for Cobalt computers and is just offering a trade in program. We are doing what we can to continue support to Cobalt users.

There is a battery diagnostic screen built into the Cobalt's firmware, and it would be good to check that first:
To access the Cobalt's diagnostic and calibration mode, the user name needs to be changed to ATOMIC <space> <space><apace> A. That is, ATOMIC, followed by spaces, with an "A" in the last possible slot. When you have done this, if you navigate to the System Info screen, there will be a button at the bottom right labeled Diagnostic or Options, depending on the firmware version. Select this, then select battery from the sub-menu that pops up. If you can take snapshots of the screen, both without and then with the AC charger connected, that will let us know more about battery status and current draw. I'll give you information in the direct message as to where you can send the pictures.

From what you say I'm pretty confident we can get you wife's Cobalt back up to full function.

Ron

 

[SharkzBait]

Hi All, I had much the same behavior from my Cobalt 2. It was fine on a dive but the battery wouldn’t hold a charge for any reasonable length of time. I contacted Huish who informed me that it was “obsolete” and offered the trade in program. After reviewing the options, I felt that none of them lived up to the Cobalt. After finding the instructions to access the battery compartment (Thanks Ron!) I screwed up my courage and opened the unit. I was able to find a comparable battery on Amazon and install it. I haven’t dove it yet (hoping Sunday) but it’s held the charge above 90% for the past 4 days.

Pre battery change:



Post battery change:

 

[RonR]

Hi All, I had much the same behavior from my Cobalt 2. It was fine on a dive but the battery wouldn’t hold a charge for any reasonable length of time. I contacted Huish who informed me that it was “obsolete” and offered the trade in program. After reviewing the options, I felt that none of them lived up to the Cobalt. After finding the instructions to access the battery compartment (Thanks Ron!) I screwed up my courage and opened the unit. I was able to find a comparable battery on Amazon and install it. I haven’t dove it yet (hoping Sunday) but it’s held the charge above 90% for the past 4 days.

Pre battery change:

View attachment 800050View attachment 800049View attachment 800051

Post battery change:

View attachment 800052View attachment 800053

Thanks for that tip- we were not aware of the battery being available with a thermistor wire installed, but it sure looks like this should work. And being a replacement for a Logitech mouse I'm guessing it will remain available. I've ordered one to check it out. The only trick is having the ability to solder the connector on in place of the plug the battery comes with, but that is a very easy soldering job, most people will have someone they know who could do it.

Once we have confirmed that everything works, I'll post this as a sticky at the top of the thread- thanks again for posting this.

Ron

Edit: the Amazon link I originally posted seems to be broken- below is a description to search for. This is a battery we have tried for fit and compatibility. It is a 2500 mA capacity where the original Cobalt battery was 2000 mA, so the fuel gauge will slightly underreport the time remaining of a charge.

It is necessary to solder on the Cobalt battery’s original connector to the new batter to make the repair. Red=power, black=ground, the other color is the thermistor.

533-000132 for Logitech Battery G933, G933S, G533, G533S, G935 Headset Battery

 

[SharkzBait]

Thanks for that tip- we were not aware of the battery being available with a thermistor wire installed, but it sure looks like this should work. And being a replacement for a Logitech mouse I'm guessing it will remain available. I've ordered one to check it out. The only trick is having the ability to solder the connector on in place of the plug the battery comes with, but that is a very easy soldering job, most people will have someone they know who could do it.

Once we have confirmed that everything works, I'll post this as a sticky at the top of the thread- thanks again for posting this.

Ron

For the curious:

One of the things I did was to clip the wires to the little board and then solder the battery wires to those. It prevented having to desolder those wires but it added more “stuff” in the battery compartment. That being said, I installed the battery this past Sunday and now on Thursday, it’s still at 95%.

 

[teosails]

Thanks for the positive comments, we worked really hard to make the Cobalt easy to use, including updating the firmware for the Cobalt 2.

My first thought is that your wife's computer is exhibiting classic signs of a Li-ion battery reaching the end of it's life cycle- gradually decreasing capacity. The readings after the firmware update are most likely just the system calibrating itself. But it's also possible (but less likely) that something is causing the Cobalt to use too much power in sleep mode, or preventing it from going into sleep mode. This could happen because of something bridging the pins at the Cobalt's nose, for instance- or in a worst case scenario, because of a leak in the case. We should rule those things out as well. We can help with batteries, if that's what you need. I will send a direct message on ScubaBoard with information.

It's apparently true that Huish has completely stopped any support for Cobalt computers and is just offering a trade in program. We are doing what we can to continue support to Cobalt users.

There is a battery diagnostic screen built into the Cobalt's firmware, and it would be good to check that first:
To access the Cobalt's diagnostic and calibration mode, the user name needs to be changed to ATOMIC <space> <space><apace> A. That is, ATOMIC, followed by spaces, with an "A" in the last possible slot. When you have done this, if you navigate to the System Info screen, there will be a button at the bottom right labeled Diagnostic or Options, depending on the firmware version. Select this, then select battery from the sub-menu that pops up. If you can take snapshots of the screen, both without and then with the AC charger connected, that will let us know more about battery status and current draw. I'll give you information in the direct message as to where you can send the pictures.

From what you say I'm pretty confident we can get you wife's Cobalt back up to full function.

Ron

Many of us need this information, can you post for all to see how to get a new battery, please?
Thank you

 

[RonR]

Many of us need this information, can you post for all to see how to get a new battery, please?
Thank you

The link to a battery replacement is in post #4 above. It does require soldering the Cobalt's battery connector onto the leads from the replacement battery.
Instructions for removing the battery cover are posted in other threads, but here is the link: BatteryReplace.pdf
If you suspect other problems, or want us to do the service, you can contact me through ScubaBoard.

Ron

 

[teosails]

The link to a battery replacement is in post #4 above. It does require soldering the Cobalt's battery connector onto the leads from the replacement battery.
Instructions for removing the battery cover are posted in other threads, but here is the link: BatteryReplace.pdf
If you suspect other problems, or want us to do the service, you can contact me through ScubaBoard.

Ron

Thanks, Ron. I was really disappointed thinking it was going to have to go in the trash, but you have given me hope. I love this computer for all the reasons already mentioned; bright interface, large lettering, great buttons, great compass. As far as I am concerned it is the perfect computer.
Thanks again,
Ted

 

[RonR]

Thanks- hopefully we will be able to come out with a computer that you like even better before too long.
For now, there isn't much in the Cobalt that can't be repaired. We started this forum to support Cobalt users, happy to offer any help that is within our ability.

Ron

 

[FISCHEDA]

Hi All, I had much the same behavior from my Cobalt 2. It was fine on a dive but the battery wouldn’t hold a charge for any reasonable length of time. I contacted Huish who informed me that it was “obsolete” and offered the trade in program. After reviewing the options, I felt that none of them lived up to the Cobalt. After finding the instructions to access the battery compartment (Thanks Ron!) I screwed up my courage and opened the unit. I was able to find a comparable battery on Amazon and install it. I haven’t dove it yet (hoping Sunday) but it’s held the charge above 90% for the past 4 days.

Pre battery change:

View attachment 800050View attachment 800049View attachment 800051

Post battery change:

View attachment 800052View attachment 800053

How has the battery replacement held up during a dive and since you put the logitec battery in? My wife and I have Cobalt 2's that are 6 years old and the charge is not holding up more than a day or two in sleep mode now and it looks like we are in need of replacing our batteries to keep them usable.

Thanks