[LARMGUY]

We have a customer where their fire alarm power supplies are eating batteries about every other month. There are 4 stories and all of the Honeywell supplies have been diagnosed over the phone with Honeywell engineers using the manufacturer's test points on their PC boards. All readings on all PCB's were within tolerances.

The batteries are always too hot to handle when checked. The storage rooms the panels are installed in are also incredibly hot. The rooms are about 10' X 15'. I'm guessing around 110 degrees. The Honeywell engineers suspect the heated rooms and dirty power, especially brown outs, are killing the batteries.

Today, I replaced two 1 year old, 12 Volt 18 Ah batteries. One had a corroded terminal and was leaking. They both read 10.8 volts. Today, the room was not hot. But I had to wait 5 minutes after unplugging them before I could handle them.

Do you guys think heat could be a causation of the shortened battery life or a combination like the engineers think?

What device would you guys recommend for A/C logging?

 

[Jlarson]

Have you actually checked the charger output? Especially ripple?

 

[brian john]

10 degrees over 77 F for 30 days cuts battery life in half. In addition the charging voltage and current need to be limited at higher temperatures. Lastly if there is a power quality issue it is with the CRAP chargers in the fire alarm panels. I'd bet there is a ton of AC ripple, which adds to the battery issues .

IT IS THE TEMPERATURE

 

[nrp3]

I remember seeing fire alarm panels in boiler rooms that never had good battery life, probably for the reasons mentioned above.

 

[oliquir]

overcharging?? the battery shouldnt be hotter than ambiant air once charged, what is the voltage output of the charger once battery is charged, it shoud be around 13.5-13.8V
anything higher will slowly destroy the battery
can you remove crap charger for alarm system and put a good external one.

 

[8V71]

10 degrees over 77 F for 30 days cuts battery life in half. In addition the charging voltage and current need to be limited at higher temperatures. Lastly if there is a power quality issue it is with the CRAP chargers in the fire alarm panels. I'd bet there is a ton of AC ripple, which adds to the battery issues .

IT IS THE TEMPERATURE

^^^^ What Brian said. They are probably gel cells or AGM which don't like high heat either. The batteries are drying out inside.

 

[MDShunk]

Heat is a big killer, but I'd like to see the charger's DC output on a scope. Probably looks more like AC on crack. Seldom do you find small chargers that make really nice DC. That said, I tend to like Altronix for NAC boosters.

 

[LARMGUY]

Great answers!
I'm gonna hook up ma scopey thingy and take a looksee.

I gots an old Tektronix ta use.


We are still interested in power logging. That is one factor that is always in the back of my mind when diagnosing a power problem.

 

[Jlarson]

Most manufactures recommend that ripple voltage be 0.5% or less of the DC float voltage.

For ripple current they rule of thumb is less then the batterer's 20hr rate. So divide the capacity by 20 to get max ripple current.

 

[LARMGUY]

My Tecktronix needs a fuse so I took my JDR.




This one is a dual trace with .2 volts per division on Y (DC) and 1 volt on X (A/C).

I see no difference between A/C and DC except for the voltage division.

That DC wave ain't DC.

 

[LARMGUY]

Bump!!!

 

[greenman]

We have a customer where their fire alarm power supplies are eating batteries about every other month. There are 4 stories and all of the Honeywell supplies have been diagnosed over the phone with Honeywell engineers using the manufacturer's test points on their PC boards. All readings on all PCB's were within tolerances.

The batteries are always too hot to handle when checked. The storage rooms the panels are installed in are also incredibly hot. The rooms are about 10' X 15'. I'm guessing around 110 degrees. The Honeywell engineers suspect the heated rooms and dirty power, especially brown outs, are killing the batteries.

Today, I replaced two 1 year old, 12 Volt 18 Ah batteries. One had a corroded terminal and was leaking. They both read 10.8 volts. Today, the room was not hot. But I had to wait 5 minutes after unplugging them before I could handle them.

Do you guys think heat could be a causation of the shortened battery life or a combination like the engineers think?

What device would you guys recommend for A/C logging?

Make a new battary box with a small a/c, mounted to the side of it. Hammond has some compact ones that work quite well.
www.hammondmfg.com

 

[Jlarson]

Yeah, AC on crack is a pretty good description here :laughing:

 

[LARMGUY]

Was called back today to check low battery alarms. Didn't have my scope but I replaced four sets of batteries.