Fundamental Battery Issues with Nemo Wide?

[pcgriffith]

A few weeks ago I bought a Mares Nemo Wide from Leisure Pro. It arrived with 4% battery life, which prevented it from even turning on. Leisure Pro shipped it back at their cost and quickly sent a replacement. Just took it out of the box, checked the battery (naturally) and it reads 50%.

1) Shouldn't a new computer arrive with 95 to 100% battery life remaining?

2) This is two units in a row arriving brand new with low battery. Is there a performance issue to worry about? Do these computers blow through batteries?

3) Although the manual says the battery is "user replaceable" all the comments on this forum say to return it to a service center. If batteries don't last long, am I going to be essentially renting this computer from the service center?

Thanks for any insight.

Peter

 

[Phil Mintz]

Peter,

Some of these initially went out with bad batteries, I suspect the ones you received are just older stock. PM me your address and I will have a new battery sent to you.

Sorry for the inconvience.

Regards,

Phil

 

[Waterskier1]

I had battery issues with my Nemo Wide also. Same thing, no backlight on the first dive which was a night dive. After the dive, checked and it said 4% battery. I had a replacement battery, but the 0-ring was damaged when I took the cover off. I'm not sure if it was damaged during the installation, or during the removal. This is a very, very thin O-Ring, and wasn't available in the USA - it's metric. Zak was kind enough to send me one out of another computer so I could use mine on an upcoming trip. During that trip, I noticed that the computer shut off during a dive. I surfaced, started checking, and the battery was dead. This was 3 dive on a know good battery. I carefully took the battery cover off (so as not to damage the fragile O-Ring) and tested the battery. It was good. I replaced it, and it showed 100%. I took it out, cleaned the battery, reinstalled it, and it was at 4%. WTF? I took it out, put it back in and it was back to 100% - and still is after 2 months and around 25 dives. It seems there is something flakey in the battery connections/compartment, besides the very very thin O-Ring. I threw out the original battery in disgust so I’m not sure if it really was dead or not. It did read 100% earlier that day.

In any case, make sure you get an O-Ring with the new battery. If it is not lubed up, and battery cap carefully and gently installed, it is so thin it will pull and tear while bunching up on the opposite side.

BTW, has Mares received this O-Ring in stock for USA distribution yet? When mine went bad, they didn’t even have a Part Number for it, much less have any in the USA.

 

[Charlie99]

It seems there is something flakey in the battery connections/compartment, besides the very very thin O-Ring.

A common problem in devices that draw big surges of current at low duty cycle is excessive internal resistance in the batteries momentarily making the battery terminal voltage drop below the minimum operating voltage of the equipment. This is further aggravated with some types of lithium batteries where, when left in an unloaded or low current state for a long time, a chemical change occurs that will cause an extra large voltage drop the first time you try to draw a large pulse of current.

The end result is that the dive computer is very sensitive to which brand and/or specific model of battery you use.

I don't know if this is the problem with the Nemo, but it sure sounds like a good possibility. If this is what is going on, if you took the "4% remaining" battery and checked it on a voltmeter, it would look perfectly fine.

 

[Waterskier1]

A common problem in devices that draw big surges of current at low duty cycle is excessive internal resistance in the batteries momentarily making the battery terminal voltage drop below the minimum operating voltage of the equipment. This is further aggravated with some types of lithium batteries where, when left in an unloaded or low current state for a long time, a chemical change occurs that will cause an extra large voltage drop the first time you try to draw a large pulse of current.

The end result is that the dive computer is very sensitive to which brand and/or specific model of battery you use.

I don't know if this is the problem with the Nemo, but it sure sounds like a good possibility. If this is what is going on, if you took the "4% remaining" battery and checked it on a voltmeter, it would look perfectly fine.

I understand what you are saying, but that wouldn't explain why the same battery when reinstalled would show 100% and remain at 100% through 25 dives over 2 months, including 2 night dives with heavy backlighting use. Nor would it explain why removal and replacement of the same battery when showing 100$ would then go to 4% and then back again. It is interesting that the only two figures I've seen on this computer are 100% and 4%. I'm not sure the resolution of the battery display, but one would think if a random problem, it would come up with a different value at some point. I'll monitor mine, and am willing to perform any checks Zak, Phil or Scott would like (but I'd rather wait until I have a spare O-Ring ).

 

[pcgriffith]

Not just 4% and 100%... the replacement new unit they sent me reads 50%.

More info shortly, as I'm taking it by the service center this AM.

 

[Phil Mintz]

I had battery issues with my Nemo Wide also. Same thing, no backlight on the first dive which was a night dive. After the dive, checked and it said 4% battery. I had a replacement battery, but the 0-ring was damaged when I took the cover off. I'm not sure if it was damaged during the installation, or during the removal. This is a very, very thin O-Ring, and wasn't available in the USA - it's metric. Zak was kind enough to send me one out of another computer so I could use mine on an upcoming trip. During that trip, I noticed that the computer shut off during a dive. I surfaced, started checking, and the battery was dead. This was 3 dive on a know good battery. I carefully took the battery cover off (so as not to damage the fragile O-Ring) and tested the battery. It was good. I replaced it, and it showed 100%. I took it out, cleaned the battery, reinstalled it, and it was at 4%. WTF? I took it out, put it back in and it was back to 100% - and still is after 2 months and around 25 dives. It seems there is something flakey in the battery connections/compartment, besides the very very thin O-Ring. I threw out the original battery in disgust so I’m not sure if it really was dead or not. It did read 100% earlier that day.

In any case, make sure you get an O-Ring with the new battery. If it is not lubed up, and battery cap carefully and gently installed, it is so thin it will pull and tear while bunching up on the opposite side.

BTW, has Mares received this O-Ring in stock for USA distribution yet? When mine went bad, they didn’t even have a Part Number for it, much less have any in the USA.

They are in transit, should be a few weeks. Part number is: 44200723

Phil

 

[Phil Mintz]

I understand what you are saying, but that wouldn't explain why the same battery when reinstalled would show 100% and remain at 100% through 25 dives over 2 months, including 2 night dives with heavy backlighting use. Nor would it explain why removal and replacement of the same battery when showing 100$ would then go to 4% and then back again. It is interesting that the only two figures I've seen on this computer are 100% and 4%. I'm not sure the resolution of the battery display, but one would think if a random problem, it would come up with a different value at some point. I'll monitor mine, and am willing to perform any checks Zak, Phil or Scott would like (but I'd rather wait until I have a spare O-Ring ).

I would replace the battery, if you want us to do it we can. Then watch and see if this solves the problem, I suspect it will, but if not we will certainly get you a functioning unit.

Phil

 

[pcgriffith]

Phil arranged for me to observe the HEAD/MARES technician change the battery in my MARES WIDE yesterday (thanks, Phil). Best tip I can give for removing the battery is, simply using a quarter as a tool, take great care to unscrew the battery cap ALL the way, and it will fall off into your hand. There is no need to pull or pry. The O ring is indeed extremely thin. I plan on stocking a couple in my kit, with new batteries, in the event I need to change the battery while on a dive trip. Thanks again to Phil for the rapid customer service.

 

[Waterskier1]

I found a quarter worked best also. A large blade screwdriver would have too long a handle to keep even pressure all the way around the cover when reinstalling. Make sure you have enough silicon grease on the O-Ring such that the cover and housing will slide along the O-Ring and not pull and tear it. I too plan on stocking a few of the O-Rings when the become available. The batteries are a very common "button" style battery. No need to stock pile more than one of those.

I too must say that Phil and Zak are great to work with.