Perdix AI / Perdix 2 battery display changes during/after dives

[dberry]

There is at least one other thread about Perdix batteries being displayed with much lower voltages during dives:

Perdix 2 Energizer Ultimate voltage drop during dive

I bought a Perdix 2 recently and used it on its first trip. A strange thing I noticed which is leaving me in doubt, is that the stock Energizer Ultimate battery voltage seems to drop a lot during the dive compared to pre-dive. After only about 20 hours of diving it prompted me LOW BATT INT...

scubaboard.com

And following advice in that thread I looked at the plot of battery voltage during the dives. Not very informative, as they all show a straight-line with a voltage reading of 1.5V (what a fresh AA should have), even though the display definitely changed (a lot!) during the dive. I think the "plot" is just showing the expected voltage for a battery of the type inserted, not the actual voltage.

 

[Tracy]

Are you diving in cold water? That is pretty standard behavior up here in the Lakes. Batteries lose voltage at low temperatures.

 

[Whitrzac]

I tried getting sw to implement a "replace battery" notification after xx number of dives or xx hours. They brushed me off and tried to help me troubleshoot the "issue"

 

[clownfishsydney]

Do you have the battery type set correctly? I had a problem with mine when I bought it off a friend and he had the wrong type selected, so showed as low when I think it probably wasn't. I get at least 85 to 90 hours dive on my Perdix from Lithium, but not AI.

 

[jborg]

I had this with the lithium battery delivered with my Perdix 2. Not really cold water, roughly same as air temperature, but it lasted about five dives before it would show a warning every dive and then look fine after the dive. I replaced it with a Saft -- no vibration, but I don't really care, and this one appears to actually work.

 

[BlueTrin]

I see this in cold water when the battery is getting a bit used.

For info, in settings in advanced config you can see how many hours you have used the battery since the last change.

 

[Divin'Papaw]

I see this with the energizer ultimate lithiums I use in my Perdix AI & Perdix 2. I don’t rely on the battery gauge but rather use hours to determine when to replace the battery.

 

[LFMarm]

Do you leave the battery in the computer inbetween dives? I take it out if I am not diving the next day. I wonder if there is a small current draw even when off that reduces the duration of your batteries

 

[hedonist222]

Do you leave the battery in the computer inbetween dives? I take it out if I am not diving the next day. I wonder if there is a small current draw even when off that reduces the duration of your batteries

In my opinion, thats not a good idea. Whatever battery life you may be saving is in lieu of a potential flood.

I think by opening and closing the batter compartment, not only are you reducing the life of your o-rings with unnecessary wear, but you're likely to introduce a flood. One day the o-ring may not be sitting right and will allow water in.
Theres also a chance of dust, hair, or particles that will attach to an o-ring and cause a flood.

I never set the cap down on a table when I change the battery, nothing should touch the lubricated o-rings.

 

[inquis]

I wonder if there is a small current draw even when off that reduces the duration of your batteries

Ambient pressure is measured every 30 s [Edit: 5 minutes] when "off". Still, it takes a LONG time to be a significant battery drain. I'd be more worried about wear/contamination on the O ring with frequent removal/replacement.