How long do the batteries last?

Ultralife brand lithium batteries typically last over 3 years in a production situation where they are alarming a few times a week and operators respond to the alarms in a few minutes. Their capacity rating of 1250 mA-hrs will allow 48 hours (2900 minutes!) of continuous alarming. The dual-battery option (a pair of batteries wired in parallel) should last twice as long. The shelf life if unused is 10 years.

How often should I change the battery?

Here are the recommended battery change schedule for units with a single battery from the instruction sheet. A dual battery will approximately double the capacity, but not the maximum lifetime of 10 years.

 

Alarms per Week Battery Change Frequency

Several daily ...................................... 1 year

Once daily . ..................................... 2 years

Once weekly ...................................... 4 years

Occasionally ..................................... 6 years

Never ................................................... 10 years

Can I get an off switch to silence the alarm?

The silencing alarm option allows you to silence the audible alarm, while the LED continues to flash as a reminder that the level needs correcting. Everything resets when the liquid level is restored. This is a separate alarm that replaces the standard alarm. It can be retrofitted into existing units.

Does the Tank Alarm have to be perfectly vertical to work?

Many tanks have domed tops and its not convenient to mount the Tank Alarms exactly vertical. That's OK as they can tolerate quite a departure from the vertical. As long as the angle is less than 30 degrees from the vertical it will work fine. If necessary, and angled feedthrough such as McMaster-Carr part number 3766K12.can be used.

 

Does it work in cold conditions?

Lithium batteries are the best performing class of batteries in the cold. Here is an answer to this question from Ultralife's website:
 

"Lithium ion batteries can be operated at -40 degrees, but the cell impedance at that temperature will rise dramatically, resulting in significantly reduced output current. This is not harmful to the battery, but it will operate at a significantly lower voltage at any given current. Available capacity to a given cut-off voltage will also be reduced, perhaps to less than 20 percent of the capacity at 23 degrees C. The reason for the increase in impedance is that the liquid electrolyte becomes viscous at very low temperatures, which reduces its conductivity."