[hirudin]

This relates to the meg lithium posts otherwise on this forum, but from another angle...

I'm gearing up for a dive tomorrow, and replaced my primary's battery with a new set, a pack containing 5 lithium cells. When I switched on the primary, the voltage read 8.5V... I'm used to seeing 7-7.5...

Is this a bad thing? Is this too high?

Apologies if this is a bit of a nunce question, but wondering what's the upper end before things go wrong.

Thanks in advance for your replies.

-Jesse-

[Gilles]

In a telephone conversation last year with Steve Stolen of ISC, he had mentioned keeping the voltages down below 9V. That was with Apecs 2.01j.

Give them a call to make sure this still applies.

[Sulac]

Hey

Have U talked with ISC, and what did they say?

Claus

[Skipbreather]

I’ve experimented a bit w/ various batteries in my Meg and have talked w/ hatchery re potentially damaging actions. One explicit question I asked was: Will the voltage from a typical 9 volt transistor type battery harm my APECS 2.01 electronics? Answer was a clear “NO”. I then built up a small adapter to connect a 9 volt battery to the appropriate Molex connector. I did 4+ hour test dive w/ an Energizer 9 v alkaline and all worked fine w/o damage w/ load voltage at end of test reading in the low 7 v neighborhood.

I believe- but can’t be certain- that it was during these conversations that I learned that earlier, pre 2.01 versions of APECS (1.0 ? original 2.0?) only read up to 7.5 v on the system monitor page vs 10 v for the 2.01 version. What I’m getting at: if your APECS version is other than 2.01 and you want to try using a 9 v battery like I did then I’d suggest confirming it is OK by giving ISC a phone call to preclude an expensive smoke test.

Ken

[hirudin]

Thanks everyone for your input! Of course the moment I let the unit sit for a bit while I did a pre-breathe, the voltage dropped to 7.7V, which is more what I am used to. But it's interesting to read that people have followed up on this with ISC and their recommendations.

Thanks again!

-Jesse-

[Outlaw]

Quote: (Originally Posted by Skipbreather)

I’ve experimented a bit w/ various batteries in my Meg and have talked w/ hatchery re potentially damaging actions. One explicit question I asked was: Will the voltage from a typical 9 volt transistor type battery harm my APECS 2.01 electronics? Answer was a clear “NO”. I then built up a small adapter to connect a 9 volt battery to the appropriate Molex connector. I did 4+ hour test dive w/ an Energizer 9 v alkaline and all worked fine w/o damage w/ load voltage at end of test reading in the low 7 v neighborhood.

I believe- but can’t be certain- that it was during these conversations that I learned that earlier, pre 2.01 versions of APECS (1.0 ? original 2.0?) only read up to 7.5 v on the system monitor page vs 10 v for the 2.01 version. What I’m getting at: if your APECS version is other than 2.01 and you want to try using a 9 v battery like I did then I’d suggest confirming it is OK by giving ISC a phone call to preclude an expensive smoke test.

Ken

Ken,

are you talking about this battery? do you think that duration wise it lasts longer or less than the 5 small 1.5V batteries?

Thanks

Spyros

[Gilles]

Quote: (Originally Posted by Outlaw)

Ken,

are you talking about this battery? do you think that duration wise it lasts longer or less than the 5 small 1.5V batteries?

Thanks

Spyros

The illustrated 9v battery has something like 600 mAH (or so?) capacity. A standard pack of 5 1.5V cells welded in series provides something like 2800 mAH. Lithium C cells have something like 10000 mAH, but these also cost about 10x more (20x where I'm at).

Thus I expect your 5 pack to last about 5x longer than the 9v.

I use 5 packs all the time, and with my habitual manual flight, they last like 30-40 hrs.

[decoweenie]

Quote: (Originally Posted by Gilles)

Thus I expect your 5 pack to last about 5x longer than the 9v.

(Skipbreather) Ken's original intention for using the 9V was for save-a-dive instances when your main battery died unexpected on a trip.

So having a 9V (or a couple) will allow you to be able to finish off the trip - even if each will only last 5-8 hours.

I have copied Ken's idea for my last trip, but fortunately didn't have to test it...

[Outlaw]

Thanks guys for the information. so you are saying is best to have something as a back up. i want to ask you though, what do you use for connecting/welding the 5 small AA batteries togerther. any links available?

i have connnected a couple of times, but the job was kind of rough. do you get the connectors from anywhere?

Thanks.

Spyros

[Skipbreather]

Quote: (Originally Posted by decoweenie)

(Skipbreather) Ken's original intention for using the 9V was for save-a-dive instances when your main battery died unexpected on a trip.

So having a 9V (or a couple) will allow you to be able to finish off the trip - even if each will only last 5-8 hours.

I have copied Ken's idea for my last trip, but fortunately didn't have to test it...

Spot on, Phi.

The battery I tested was the Energizer brand equivalent of the battery pictured. In the common 1.5 v and 9 v alkaline battery world, Duracell and Energizer are prime competitors and pretty much interchangeable.

Some numbers: The ISC supplied 5 AA pack is said to use an industrial AA cell that yields 2800 mah. Most quality alkaline AA cells available over the counter are more in the 2100 ~ 2500 mah range. 9 v alkaline cells are mostly in the 400 ~ 500 mah range. One cell I have not tested yet but hope to eventually is the lithium equivalent of the 9 v alkaline. The voltage and form factor are identical to the 9 v alkaline, but they are advertised to have 1200 mah capacity.

9 v lithiums are commonly used in smoke detectors and some medical equipment and are reasonably available over the counter for about $7 ~$10 each and on line for under $6. They share the properties of all lithium batteries (long storage life, resistance to cold, high energy density) that make them a cell I definitely plan to test “eventually”.

Primary Lithium Battery 9V 1200mAh: Compatible with Energizer L522-9V / Ultralife, L522 - LM-9V1200

Ken