meaning of "Battery Health Alarm Warning Time"

[BillP]

I have a recently purchased Smart-UPS 1500 with a Network Management Card.  In the web interface, under Configuration -> UPS, there is an entry for "Battery Health Alarm Warning Time" with the default value of 183 [days] (with an allowable range of -1 to 730 days).  The help entry for that particular entry says "Sets the number of days before the critical battery replacement alarm is displayed on the UPS LCD. Setting this to -1 displays no notification warning. " 

I do not understand this setting - perhaps my interpretation of the language is not flexible enough.  What starts this 183 day countdown?  The batteries are supposed to be good for 3-5 years, if rarely utilized, right?  So it isn't a battery lifetime counter.  If the battery health is detected as poor, why wait 6 months (or up to two years!) to display it on the LCD?  Is it that there are two levels of "replace battery" state - starting with a "non-critical" warning (based on what?) and then eventually a "critical" warning after this amount of time has passed?  Or is this something else altogether that I'm missing?

Thanks for your time.

[voidstar_apc]

On 7/13/2017 3:38 PM, Wayne said:

Is it that there are two levels of "replace battery" state - starting with a "non-critical" warning (based on what?) and then eventually a "critical" warning after this amount of time has passed? 

Almost -- the critical warning is based on predicted typical battery life based on usage and temperature. The non-critical warning starts X days before that, where X is the warning time you select.

In more detail: The UPS both detects bad batteries and provides a prediction of typical lifespan based on usage and temperature. The bad battery detection is enough for many people but batteries can also fail in ways that are difficult to detect, particularly if the UPS is very lightly loaded so the self-test isn't stressing the battery. The battery lifetime alarms covers that case and also lets you be as proactive as you like.

[BillP]

Thank you for the reply.  So there will be a warning at some point that the battery is nearly at the end of its lifespan (as determined by the UPS's algorithms) and in a practical sense, it means "buy another battery and schedule a time to replace it in the next X days before it becomes critical", and then after X days, the UPS tells you "hey, I warned you, now it really is critical!". 

[voidstar_apc · Accepted solution]

Yeah. Keep in mind this is predicted lifespan and tells you when the average battery should be replaced. Your battery may still be good. So whether you replace the battery when the lifetime alarm occurs or when the UPS finally detects a bad battery depends on how sensitive you are to cost of replacement vs downtime.