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Hello,

I am have been surprised by the behavior of my OSTC sport regarding battery (SAFT 14500 Lithium Cell) usage.
Hereafter an overview of the battery as reported by the logbook

Date - dive time - battery at end
11 June 2017 - 44min - 3.29V 94%
11 June 2017 - 47min - 3.31V 92%
10 Dec 2017 - 50min - 2.95V 75%
10 Dec 2017 - 52min - 2.69V 50%

11 Dec 2017 starting the OSTC the battery level is around 25% --> battery changed

11 Dec 2017 - 40min - 3.33V 99%
11 Dec 2017 - 48min - 3.32V 97%
13 Dec 2017 - 56min - 3.31V 95%
13 Dec 2017 - 93min - 3.30V 93%
13 Dec 2017 - 54min - 3.32V 91%
14 Dec 2017 - 62min - 3.29V 88%
14 Dec 2017 - 59min - 3.32V 86%
14 Dec 2017 - 55min - 3.29V 84%
15 Dec 2017 - 16min - 3.30V 83%
15 Dec 2017 - 06min - 3.31V 83%
15 Dec 2017 - 04min - 3.40V 83%
16 Dec 2017 - 53min - 3.31V 80%
16 Dec 2017 - 69min - 3.17V 77%
16 Dec 2017 - 65min - 3.30V 75%
17 Dec 2017 - 66min - 3.29V 73%
17 Dec 2017 - 62min - 3.28V 70%
18 Dec 2017 - 57min - 3.33V 69%
18 Dec 2017 - 67min - 3.34V 66%
18 Dec 2017 - 47min - 3.41V 65%
19 Dec 2017 - 58min - 3.27V 63%
19 Dec 2017 - 50min - 3.40V 61%
20 Dec 2017 - 34min - 3.29V 60%
20 Dec 2017 - 32min - 3.29V 58%
20 Dec 2017 - 63min - 3.31V 56%
21 Dec 2017 - 39min - 3.33V 55%
21 Dec 2017 - 56min - 3.33V 52%
21 Dec 2017 - 29min - 3.32V 51%

Today 4/1/2018 - 3.4V 49%

My questions:
-for the first 4 dives of the list: is it normal to loose that much in that few dives? Should I remove the battery when I am not diving for a long period ?
-As of the battery change: why is the voltage fluctuating up and down (while the % seems correctly reducing) - eg 3.40V showing 80%, 60% and 49%
-How many dives can I expect to do with with a new SAFT 14500 Lithium Cell ?
-As from when should I change battery (I guess from a % as the V display seems fluctuating)

Thanks in advance.

Br,
Jf

mapoubelle Wrote:
> My questions:
> -for the first 4 dives of the list: is it normal
> to loose that much in that few dives? Should I
> remove the battery when I am not diving for a long
> period ?

The OSTC consumes 1-2%/Week in st.By. So yes, if you don't dive for months remove the battery from the OSTC Sport.

> -As of the battery change: why is the voltage
> fluctuating up and down (while the % seems
> correctly reducing) - eg 3.40V showing 80%, 60%
> and 49%

Because battery % are not based on cell voltage. The % value is computed, not measured.

> -How many dives can I expect to do with with a new
> SAFT 14500 Lithium Cell ?

Heavily depends on ambient light and display brightness setting. I carry an OSTC3 backup in my pocket (No light, ECO setting) and the battery is fine for more then 100hours of use now. With brightness HIGH and much ambient light you'll get ~30hours.

> -As from when should I change battery (I guess
> from a % as the V display seems fluctuating)

Depends on the level of reliability your dives require. I'd recommend to replace the battery at 25% at the latest.

Regards,
Matthias