Never use a regular 9-volt battery; Not even a new one

**Chett.L** · 29th June 2008, 16:47

OK, I admit I was a big dummy this past weekend and overlooked a simple rule. My ego is not too big to admit that I made a mistake, and I am still very teachable & humble.

The lesson I learned was never use a regular 9-volt battery with the Prism Topaz; Not even a new one

Last Saturday, I ran the boat to Catalina to go diving with a group of friends. Before getting in the water, I did my pre dive checklist and calibrated my unit. I checked the battery output before I entered the water with the secondary and it tested absolutely fine, JUST LIKE NEW. Well, great, because it was new in a sealed box, I installed it the night before.

During the dive, I occasionally got a Red flashing light on the Left LED of the heads-up display, meaning LOW BATTERY. Looking at my secondary every minute or so, and maintaining a PO2 of 1.0 at all times, everything was fine except that every time the solenoid fired, I got that Red flashing light, just for a short time.

Discounting the brand new battery during the dive, I could not imagine what could possibly be wrong. I did not realize that the Battery was actually low because it was the wrong kind (Non-Alkaline) . Later this week I did a test at home by putting the secondary on Battery selection (B) with the electronics turned on, and found that every time the solenoid fired, the battery dropped low to 1.4 on the secondary display. That is not 1.4 volts; it's just a 1.4 on the display's scale. I figured out (with a Radio shack volt meter) that it was only when the solenoid put a load on the battery the voltage dropped off on the secondary display scale.

I now realize that I should have referred at the owner’s manual where this is covered. SMI recommends using high quality alkaline Duracell battery. And I should have reviewed my class notes.

• I now know to only use a High Quality 9-volt Alkaline battery

• I now know that even if the battery is brand new, it needs to be checked under load during set up with the electronics turned on with the solenoid firing a couple times to check the output of the battery level.
• I now know that if the heads-up display is flashing a red light all the way to the left, this really means low battery even if the battery is new.

I promise to continue to read ask questions and learn.

silent running · 29th June 2008, 21:39

Quote: (Originally Posted by ChettL)

• I now know that even if the battery is brand new, it needs to be checked under load during set up with the electronics turned on with the solenoid firing a couple times to check the output of the battery level.

Hi Chett, a good time to check battery voltage is during the electronics cal. You must do this with the 2dry on either the battery "B" setting or "SP", not on any of the sensors, for accuracy's sake. I always do it on the "B" setting to setting so I can see the voltage before I start the dive day.

Also keep in mind that if you're diving in cold water your battery life will be shorter. I dive only in warm water and get a minimum of 20 hours from a Duracell... -Andy

**Chett.L** · 30th June 2008, 02:37

Hi Andy,

Please explain 2 dry?
Also, when you say that you check battery voltage during electronic calibration are you checking with the electronics on or off?

Now when I check the battery output I will do so with the electronics on, as the solenoid fires a few times, I can see the load it puts on the battery while looking at the analog secondary on (B)

silent running · 30th June 2008, 06:48

Quote: (Originally Posted by ChettL)

Hi Andy,

Please explain 2 dry?
Also, when you say that you check battery voltage during electronic calibration are you checking with the electronics on or off?

Now when I check the battery output I will do so with the electronics on, as the solenoid fires a few times, I can see the load it puts on the battery while looking at the analog secondary on (B)

Hi Chet, 2dry is my abbreviation for secondary.

Did the guy who sold you the second hand Prism include an owner's manual? The Prism is very simple, but the owner's manual is still a necessity. During the electronic cal, the Prism 2dry must be on B or SP, not any of the 3 sensors as it can affect the cal values and then screw up the voting logic during operation.

There are 2 cals required to dive the Prism. The first cal of the 2ndry is only for the individual pots that drive the 2dry display. They have no effect
on the operation of the electronics and only affect the accuracy of the 2dry display. They are not necessary to do every day of a multi-day trip. The second cal is of the electronics and is done with the 2dry switched off the sensors to take a "snapshot" of the sensor values in 100% O2 on the surface. If they are within tolerance at 100%, they give the green flashing LED-ready to dive.

As for battery voltage, the Prism fires the solenoid twice every time it's powered up. My routine is to have the 2dry on the "B" setting when turning on the unit. If the battery is good, the solenoid firing twice will cause the 2dry needle to sag slightly without giving a low battery alarm and it will return to the green "battery OK" area of the gage. This means that the battery has at least enough power to complete a dive. Even when I have had a low battery alarm come on early in a dive, I have had more than enough power to finish the dive with the solenoid, even a 2+ hour dive. Even when the voltage dips below the amount needed to fire the solenoid, the electronics continue to provide PO2 and senor info. I once deliberately put in a weak battery when my solenoid failed for the last 2 days of a trip. I still had enough voltage to power the HUD and PO2 sensor info and I manually injected, but the solenoid never tried to fire, which was perfect for that situation. -Andy

NEwreckdiver · 30th June 2008, 11:37

Hi Chett,

More than likely the situation is as you describe -- low battery alarm due to a "soft" battery, but just an FYI we did see a problem similar to this once that was ultimately NOT battery related. Primarily when the solenoid fired we were seeing a low battery alarm - and at times the solenoid would not fire. We assumed the battery was weak and the load from the solenoid firing triggered the low alarm. This was happening intermittently, but persisted even after the "bad" battery was replaced with a new one - and voltage looked OK all along on the "bad" battery. You will see a dip in the battery voltage when the solenoid fires - that's normal, but ultimately in our case, there was short in the power cord and this was the cause of low battery alarms. So, if you see this happen again soon, you may want to trouble shoot the HUD, secondary or power switch for a potential short.

Cheers,
Heather

saveourseas · 26th July 2008, 00:59

Good info Chett. Thanks for sharing it.

29th June 2008, 16:47	#1 (permalink)
Chett.L Supporting Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2007 Location: LOS ANGELES Posts: 181	Never use a regular 9-volt battery; Not even a new one OK, I admit I was a big dummy this past weekend and overlooked a simple rule. My ego is not too big to admit that I made a mistake, and I am still very teachable & humble. The lesson I learned was never use a regular 9-volt battery with the Prism Topaz; Not even a new one Last Saturday, I ran the boat to Catalina to go diving with a group of friends. Before getting in the water, I did my pre dive checklist and calibrated my unit. I checked the battery output before I entered the water with the secondary and it tested absolutely fine, JUST LIKE NEW. Well, great, because it was new in a sealed box, I installed it the night before. During the dive, I occasionally got a Red flashing light on the Left LED of the heads-up display, meaning LOW BATTERY. Looking at my secondary every minute or so, and maintaining a PO2 of 1.0 at all times, everything was fine except that every time the solenoid fired, I got that Red flashing light, just for a short time. Discounting the brand new battery during the dive, I could not imagine what could possibly be wrong. I did not realize that the Battery was actually low because it was the wrong kind (Non-Alkaline) . Later this week I did a test at home by putting the secondary on Battery selection (B) with the electronics turned on, and found that every time the solenoid fired, the battery dropped low to 1.4 on the secondary display. That is not 1.4 volts; it's just a 1.4 on the display's scale. I figured out (with a Radio shack volt meter) that it was only when the solenoid put a load on the battery the voltage dropped off on the secondary display scale. I now realize that I should have referred at the owner’s manual where this is covered. SMI recommends using high quality alkaline Duracell battery. And I should have reviewed my class notes. • I now know to only use a High Quality 9-volt Alkaline battery • I now know that even if the battery is brand new, it needs to be checked under load during set up with the electronics turned on with the solenoid firing a couple times to check the output of the battery level. • I now know that if the heads-up display is flashing a red light all the way to the left, this really means low battery even if the battery is new. I promise to continue to read ask questions and learn. __________________ Chett. L Last edited by Chett.L : 29th June 2008 at 22:50. Reason: The letter O, got changed
(Online)

29th June 2008, 21:39	#2 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,832	Re: Never use a regular 9-volt battery; Not even a new one Quote: (Originally Posted by ChettL) • I now know that even if the battery is brand new, it needs to be checked under load during set up with the electronics turned on with the solenoid firing a couple times to check the output of the battery level. Hi Chett, a good time to check battery voltage is during the electronics cal. You must do this with the 2dry on either the battery "B" setting or "SP", not on any of the sensors, for accuracy's sake. I always do it on the "B" setting to setting so I can see the voltage before I start the dive day. Also keep in mind that if you're diving in cold water your battery life will be shorter. I dive only in warm water and get a minimum of 20 hours from a Duracell... -Andy
(Offline)

30th June 2008, 02:37	#3 (permalink)
Chett.L Supporting Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2007 Location: LOS ANGELES Posts: 181	Re: Never use a regular 9-volt battery; Not even a new one Hi Andy, Please explain 2 dry? Also, when you say that you check battery voltage during electronic calibration are you checking with the electronics on or off? Now when I check the battery output I will do so with the electronics on, as the solenoid fires a few times, I can see the load it puts on the battery while looking at the analog secondary on (B) __________________ Chett. L
(Online)

30th June 2008, 06:48	#4 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,832	Re: Never use a regular 9-volt battery; Not even a new one Quote: (Originally Posted by ChettL) Hi Andy, Please explain 2 dry? Also, when you say that you check battery voltage during electronic calibration are you checking with the electronics on or off? Now when I check the battery output I will do so with the electronics on, as the solenoid fires a few times, I can see the load it puts on the battery while looking at the analog secondary on (B) Hi Chet, 2dry is my abbreviation for secondary. Did the guy who sold you the second hand Prism include an owner's manual? The Prism is very simple, but the owner's manual is still a necessity. During the electronic cal, the Prism 2dry must be on B or SP, not any of the 3 sensors as it can affect the cal values and then screw up the voting logic during operation. There are 2 cals required to dive the Prism. The first cal of the 2ndry is only for the individual pots that drive the 2dry display. They have no effect on the operation of the electronics and only affect the accuracy of the 2dry display. They are not necessary to do every day of a multi-day trip. The second cal is of the electronics and is done with the 2dry switched off the sensors to take a "snapshot" of the sensor values in 100% O2 on the surface. If they are within tolerance at 100%, they give the green flashing LED-ready to dive. As for battery voltage, the Prism fires the solenoid twice every time it's powered up. My routine is to have the 2dry on the "B" setting when turning on the unit. If the battery is good, the solenoid firing twice will cause the 2dry needle to sag slightly without giving a low battery alarm and it will return to the green "battery OK" area of the gage. This means that the battery has at least enough power to complete a dive. Even when I have had a low battery alarm come on early in a dive, I have had more than enough power to finish the dive with the solenoid, even a 2+ hour dive. Even when the voltage dips below the amount needed to fire the solenoid, the electronics continue to provide PO2 and senor info. I once deliberately put in a weak battery when my solenoid failed for the last 2 days of a trip. I still had enough voltage to power the HUD and PO2 sensor info and I manually injected, but the solenoid never tried to fire, which was perfect for that situation. -Andy
(Offline)

30th June 2008, 11:37	#5 (permalink)
NEwreckdiver New Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Oct 2005 Location: Boston MA Posts: 48	Re: Never use a regular 9-volt battery; Not even a new one Hi Chett, More than likely the situation is as you describe -- low battery alarm due to a "soft" battery, but just an FYI we did see a problem similar to this once that was ultimately NOT battery related. Primarily when the solenoid fired we were seeing a low battery alarm - and at times the solenoid would not fire. We assumed the battery was weak and the load from the solenoid firing triggered the low alarm. This was happening intermittently, but persisted even after the "bad" battery was replaced with a new one - and voltage looked OK all along on the "bad" battery. You will see a dip in the battery voltage when the solenoid fires - that's normal, but ultimately in our case, there was short in the power cord and this was the cause of low battery alarms. So, if you see this happen again soon, you may want to trouble shoot the HUD, secondary or power switch for a potential short. Cheers, Heather
(Offline)

26th July 2008, 00:59	#6 (permalink)
saveourseas Matthew Addison Current Rebreather/s: Prism Topaz Other Rebreather/s: MK 15.X Join Date: May 2005 Location: New York, Los Angeles Posts: 7	Re: Never use a regular 9-volt battery; Not even a new one Good info Chett. Thanks for sharing it. __________________ A is A
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode