Can someone run a test on a P212S power supply?

[Ira]

I need to know if there is a voltage drop (and how much, if there is one) on a Elk P212S PS when it goes on battery power. I have a Elk P412 PS that goes down to 10.8VDC immediately when it goes on battery power, which causes a connected component (a LAN switch) to go into "fault mode". I can change the P412 for a P212S if it doesn't drop very much.
 
Can the P412 voltage drop be an indication of a battery going/gone bad?
 
Thanks,
Ira

 

[RAL]

Yes, I'd say the voltage drop you are seeing very well could be due to a bad battery.  The easy way to tell would be to measure the voltage right at the battery with a multimeter and see how fast it drops off.
 
If this is a new setup, did you allow the battery to fully charge for 24 hours before trying to run things off the battery?

 

[Ira]

The P412 setup is about three years old, which is why I'm questioning the battery. I would still like to know about voltage drop for a P212S on battery power though, because I want to use one for another purpose, even if I can "fix" the P412 with a new battery.
 
Thanks,
Ira

 

[gizzmo]

I consider a three year old battery as being dead. It make more sense to replace it than to make a return trip later. Anyway the best test is to place it under a load without the AC input connected. A siren is usually a good load. A bad battery will show and major voltage drop when the load is applied.

 

[RAL]

I made some measurements on my P212S.
 
When it has AC power, the output of the P212S is 13.3V and the battery voltage is also 13.3V
These measurements were made with a load of 1.2A.
 
When AC power is removed, the output of the power supply drops to 12.1V and the battery voltage
drops to 12.6V.  This doesn't happen instantly, but takes about 15 seconds to reach those levels.
 
The  P212S continued to hold at these voltages for several minutes, but over time, you can expect
both voltages to drop as the battery discharges.   How quickly that happens will depend on the
capacity of the battery and the load on the power supply.
 
One thing to note is that when the P212S is first turned on, after about 1 minute it conducts a
30 second battery test, which causes the output of the power supply to drop as noted above.
I believe it also conducts additional battery tests at regular intervals (once a day?).

 

[Ira]

Thanks RAL
 
I bought a new battery for my P412, so I will test it again tomorrow after it's had time for a full charge.
 
I have a standby genset, so I am never on battery power for very long. It sounds like the P212S will do what I want. I hope the P412 with the new battery will as well.
 
Thanks,
Ira

 

[RAL]

I think that with a new battery, the P412 will behave in much the same way, with similar voltage drops. 
 
I don't think the P412 does a battery test like the P212S does, though.

 

[Del91574]

The 412 is a dumb supply....no testing on the battery. A 3 year old battery is on it's downhill slide and I agree, it should be replaced if there are already concerns.
 
Keep in mind, many supplies typically lose a volt or more when the AC power is removed and they are running on DC only.....their circuits impose more load on the DC power from the battery.
 
I learned this the hard way on a good sized install with a remote bus on an M1. The white page on the LBC and Altronix is thanks to my install (and about 6 hours on the phone between Elk and Altronix).
 
If you need to maintain close to a 12V output on the supply, you need to make sure the supply is a 0V loss on DC only. They do specify, but you need to look.
 
If you really want to see the service life of a battery (contrary to a siren recommendation) the best way would be to use a 12V lamp or bulb with a filament. Defined load and no hearing protection needed....also no circuits involved.