Meg Battery Pack?

Parker

Hi,

Has anyone tried using Energizer AA Lithium 1.5v (L91) batteries to build Meg battery packs? It looks like, per the data sheet, that they have a pretty sharp drop-off at the end of their life. But that looks to be pretty standard with lithium batteries. They are available locally at approx $2US per battery and would be a nice alternative to the harder to get lithium 3.6v "C" cells for building packs if they will work ok and have a comparable life.

Any input and/or advice will be greatly appreciated.

Thanks!

Gilles

Do you have a mAH rating for these?

Normal Duracells/Energizers have about 2200 mAH. If memory serves, your 3.6V C cells have something like 10000.

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Gilles
http://www.dirrebreather.com

Parker

3000mAh. My understanding is that this number remains pretty constant under a load, unlike Alkaline, which experience a substantial drop under a load.

Explorer

I am using a few packs and enjoy the long life.

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REALLY FRICKIN' TRAIN WRECKED.....

Abbo

I tried using 9v Ultralife batteries. They're around 1200mAh. They don't last quite as long as the ISC packs, but they're a lot easier to get hold of. Being lithium, the voltage drops quite fast at the end of their lives. The best thing to do is pitch them when they get to 6.5v. I didn't once, and the voltage rapidly dropped low enough that it stopped driving the solenoid during a dive. It's a pain to add the O2 on ascent when you don't have a constant flow orifice to do most of the work for you. Speaking from experience, it's also quite tricky to explain to your buddy that you thumbed the dive because you weren't paying attention to your life support system...

I'm now far more rigorous about checking that there is a fat margin for error in the the voltage under load before I splash. As long as I am doing that, I am not too worried about precisely what battery I use: I take plenty of spares and change frequently. I was unable to lay my hands on a spare battery recently and chucked in a Sony Stamina EX 9v Alkali (probably not sold outside Japan). I have been unable to find out the mAh, but they are lasting longer than I'd expected. If it's going to be a long dive I'll start with new batteries.

Parker

The best I can figure, from studying the Energizer AA Lithium L91 data sheet, is that with a 5 cell pack of these batteries the voltage drop will get very non-linear at approx 6v. As you said- this could cause problems if system voltage isn't monitored properly. Ditching them at 6.5v should still provide for a nice service life- so I'm thinking.

My experience with lithium batteries is very limited so hopefully Ron and some of the other lithium battery experts will jump in and share a bit of their knowledge on the subject. I talked with Jerry at ISC earlier and he wasn't aware of anyone using the lithium AA's to build packs but seemed interested in getting feedback on their use.

divingabe

Hi I have not tried the Energizer AA, I am not able to cold sodder the batteries and it is my understanding that heat will damage the lithium batteries. Here is a link to a battery Primary Lithium thionyl chloride Battery C Size 3.6V 9.0 Ah , same as LS26500 and ER26500 etc - LM-ER26500 suppplier . I have been purchasing these C cells 3.6 volts with the optional soldering tab. I have had good success with these and as far as I can tell they last about 3 to 4 times longer than the AA packs. I was only using these in my primary and the conventional in the secondary and they lasted almost as long as 2 conventional packs in the secondary.

Parker

Thanks for the link. I have a tab/spot welder and the other material needed to build the packs, which is one of the reasons that I was inquiring about using the less expensive and readily available AA 1.5v lithium batteries in the Meg. But I didn't want to build the packs prior to asking the experts.