Suunto temperature error

[Carib_Diver]

Hi All,

Just bought a Suunto vyper which was on sale at Leisure Pro. The temperature readout on it seems to be faulty. It showed 86 degrees out of the box. Later on it went down to 70 (which is more accurate, room is at about 65 degrees). Is the skewed reading because it measures water temperature and not air temperature? The manual does not have an answer for this. Does it even matter? The only reason I'm asking is because I want to make sure I don't have a faulty unit.

Thanks!

 

[DuboisP]

Temperature display:
• Resolution: 1°C/1°F
• Display range: -20 to +50°C/-9 to +122°F
Display range: -9 to +50°C/-9 to +122°F
• Accuracy: ± 2°C/± 3.6°F within 20 minutes of temperature change

what's the accuracy of your room sensor ?

 

[Carib_Diver]

I don't have a room sensor per se, I was just looking at the thermostat

 

[Charles2]

Put your new computer in a bowl of pure ice water. It should read 0ºC or 32ºF. If you cannot calibrate it manually, then take it back to the dealer. If the temperature is off, you won't be able to trust any of the other readings either.

 

[tomfcrist]

Charles, where did you get that from? Computers rarely show precise temp readings. Wear two computers and see if they agree on temp. It's a rarity.

 

[Charles2]

Charles, where did you get that from? Computers rarely show precise temp readings. Wear two computers and see if they agree on temp. It's a rarity.

My apologies. I should have said "Put your new computer in a bowl of pure ice water. It should read 0ºC ±2ºC or 32ºF ±3.6ºF within 20 minutes." Although I suspect it would be rare, two computers could both be out of calibration by the same amount and direction.

Maybe it's just me being pedantic, but if I could not trust my computer to tell me the correct temperature (within reasonable parameters), how could I rely on the depth reading or the time calculation? The depth accuracy of this model is ±1% of full scale or better from 0 to 80 m/262 ft. at 20ºC/68ºF. That means that whatever depth is displayed, your computer is somewhere between 2.62 ft. above or 2.62 ft. below the actual depth. What if that was not calibrated correctly?

 

[DuboisP]

1% error on depth is nothing.
that's the same variation if you have your arm up or down
decompression is not computed by depth, but by pressure.
Suunto computes with a deeper depth (pressure) than the displayed one (see manual)
and diving at 262 feet with only one computer is crazy

 

[dmaziuk]

Maybe it's just me being pedantic, but if I could not trust my computer to tell me the correct temperature (within reasonable parameters), how could I rely on the depth reading or the time calculation?

Depth: you shouldn't because it's the pressure it's sensing, depth is back-calculated from that using some number, usually pre-programmed, for water density. The actual water density where you dive depends on the salinity and temperature at the time. So you should definitely not rely on the depth reading unless you accept +/- a meter as "reasonable".

Time: quartz oscillators are quite precise and have been used in clocks since 1930s, so I wouldn't fret about that too much.

 

[KenGordon]

Cheap micro controllers often come with a temperature sensor 'for free'. This saves some external circuitry and board space. Unfortunately they are a bit poor. Better than nothing though.

 

[RonR]

I’d suspect the temperature is coming from the depth sensor, as that reading is needed for calibration of the signal and it would give the best water temperature reading. But, as Ken says, there are other temperature sensors likely available. In any case, variations that slight could be caused by just holding it in your hand and heating the case a bit, and may take a while to equalize. I wouldn’t worry unless the reading is clearly very far off.

Ron