forum.heinrichsweikamp.com

Hello, I recently bought some rechargeable batteries from the HW online shop to use in my OSTC plus.

It seems that these are ~1mm longer than regular AA batteries and therefore can’t fit completely in the battery compartement of the OSTC plus. The battery compartement screw cap does not seem to close completely. Am I missing something here or is HW selling incompatible accumulators from its website ??

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Hallo,

The new battery is slightly longer, yes. But it has 1000mAh instead of the 840mAh which is much better then the older ones. If the O-Ring is completely inside the unit it's definitely good to use. In your case give it another 1/2 turn.

If you have the double spring in the battery cap, you can remove one spring which makes the battery cap shorter.

Regards,
Matthias

When I use a 1000mAh battery, can I adjust the OSTC plus charge counter?
Or isn't the 800mAh capacity hard-coded in hwos, so that it will reach 0% when there's still 20% left in the 1000mAh battery, and the larger battery is only for safety reasons?

The capacities are hard-coded, so the battery selection via the menu is the only way to tell the OSTC what type of battery is used. Caution with the mAh given by the cell manufactureres (or sellers): the bigger the numbers, the more overestimated they often are...

Thank you, makes sense.

Similar question: in the OSTC plus you allow battery type T0 (1.5V disposable). Which capacity do you assume for displaying the percentage? There are so many possible. Reading the hwos source code (which I don't fully understand of course) it looks like you don't reset the capacity and keep the setting of the previous battery, right? Why not use the voltage formula like in OSTC sport?

For the 1.5 V battery, there is a combination of power consumption calculation and battery voltage levels. The lower one determines the resulting percentage that is shown. Please note that 1.5V cells in the Plus model are intended for emergency use only, as this model internally runs on 3 Volt. So a lot of "up pumping" is required, which draws a lot on the 1.5 cell's life.

thank you, makes sense again. Would you mind checking my question about the voltage % display and battery warnings for disposable Saft 3.6V in OSTC sport in the other thread "Li-Ion Battery Life on OSTC Sport"? (I don't want to repeat here again as it's a different topic).

Well, i am still hoping Matthias takes over answering that post, as he's much deeper in all that battery stuff than me... ;-)

Ralph wrote: ↑Thursday 3. September 2020, 13:29 Caution with the mAh given by the cell manufactureres (or sellers): the bigger the numbers, the more overestimated they often are...

Indeed. We recently had a customer using this battery. It's rechargable, yes. But weights only half of our 1000mAh batteries and was tested to 125mAh only! No surprise that the autonomy was very bad...
regards,
Matthias

There are many "2500mAh" batteries on the market that actually have < 400mAh when measured:

https://lygte-info.dk/review/batteries2 ... %20UK.html

abcdef wrote: ↑Thursday 3. September 2020, 13:52 Thank you, makes sense.

Similar question: in the OSTC plus you allow battery type T0 (1.5V disposable). Which capacity do you assume for displaying the percentage? There are so many possible. Reading the hwos source code (which I don't fully understand of course) it looks like you don't reset the capacity and keep the setting of the previous battery, right? Why not use the voltage formula like in OSTC sport?

When using 1,5V batteries, we use the formula from the OSTC sport.

Our reference (And recommended) 1,5V battery is the Energizer E2 Lithium (Datasheet attached). It's reliable, can deliver enough current in cold water, relatively cheap and commonly available. Changing lighting conditions dramatically vary the current consumption of the OSTC since the backlight adjusts itself. So, it's difficult to predict a battery % reading that runs linear from 100% to zero.

regards,
Matthias

[quote=heinrichsweikamp post_id=22844 time=1599217493 user_id=148]
When using 1,5V batteries, we use the formula from the OSTC sport.

Our reference (And recommended) 1,5V battery is the Energizer E2 Lithium (Datasheet attached). It's reliable, can deliver enough current in cold water, relatively cheap and commonly available. Changing lighting conditions dramatically vary the current consumption of the OSTC since the backlight adjusts itself. So, it's difficult to predict a battery % reading that runs linear from 100% to zero.

regards,
Matthias
[/quote]

Yes. Working with electronics myself I know the behavior of these batteries ... however I think the OSTC sport is a bit special here, because you have only one battery type T0 for both Alkaline and Lithium. But these two battery types are very different. If you'd allow two different 1.5V battery types in hwos, then you could use a flatter function for the Lithium. And you could use two appropriate "low battery" warning levels, 1.15V for Alkaline and 1.3V for Lithium. Today the warning shows up at 1.2V which is early for Alkaline yet late for Lithium. At least I would describe it in the manual, because most OSTC sport users don't know this problem and some will be surprised how quickly the % drops at the end.