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

[dberry]

My Perdix AI and my buddy's Perdix 2 both show the same odd behavior: the battery level appears full (or >90%) before the dive, but shortly after jumping in it drops 30-70% (and shows yellow instead of blue). After getting out of the water it recovers to about the same as before the dive. We're both using (edit) EverReady Energizer Lithium AA batteries. Needless to say, it's easy and cheap enough to swap out the battery after seeing it in the yellow during the dive but I didn't expect Li batteries to show any "rebound" effect and appear 90-100% after the dive. That's actually very misleading if you're deciding whether to change to a fresh battery.

Maybe this is related to the power drain when communicating with the transmitter (10 sec intervals)? FWIW, I have an old transmitter from a different AI PDC, but my buddy has a brand new Swift and we both see the same thing. My battery had ca. 35 dives on a fresh AA before hitting the yellow during a dive today.

Any thoughts?

PS I've been using my Perdix AI for about 150 dives and never noticed this behavior until recently. Something different in a recent firmware update?

 

[Alekseolsen]

I had similiar with rechargeables, I never bothered to change until it got red during a dive.
That said, SAFT batteriy lasts a few hundred dive hours and leaves you without a worry for a few $...

 

[mariner156]

My Perdix ai has done this once in a quarry (cooler water). It said that my battery was low while in the water then after the dive it was fine again. I always run the SAFT batteries too. Weird

 

[Mike1967]

Cold water?

 

[dberry]

First, these are NOT rechargeable batteries... just regular (edit) EverReady Energizer Li AAs. The water temperatures are ca. 87 F in Grand Cayman now (unfortunately!) Maybe 1 deg cooler at 100 ft than at surface. Fairly close to the air temperature of ca. 90-93 F, so I doubt temperature is a factor.

 

[LFMarm]

I am using the Energizer lithium that came with it and never experienced any quick battery drop.

 

[dberry]

I am using the Energizer lithium that came with it and never experienced any quick battery drop.

I edited my posts to correctly state I'm using Energizer lithium batts. And the in-water drop in battery level displayed doesn't happen until after a 20-30 dives. How long do your Energizers usually last?

 

[Whitrzac]

I get about 40-50 dives out of an energizer lithium. The last few dives def start exhibiting similar behavior before I replace them.

 

[Pavao]

If I’m not mistaken, this is a lithium related issue, they don’t discharge in as linear fashion as alkaline does, in other words, they may show ”full” for some time, and then suddenly drop. Again, if I’m remembering correctly that’s kinda the disadvantage over alkaline batteries.

And as to the “full” at surface, yellow at depth and “full” again I believe has to do with the amount being drawn from the battery at both scenarios, surface mode the “computer isn’t running” thus drawing less from the battery.

Again, I’m not 100% on this, and even if I am in the right direction here, likely someone can articulate this better.

 

[js1221]

My Perdix 2 has done the same thing.