What the heck happened here?

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nhfire77

Senior Member
Location
NH
I was working with a Bosch G series panel. Its their standard combo burg/fire panel. The batteries were old and swollen, that's why I was there. I pulled the batteries. The panel is designed to handle two 7 AH 12 VDC batteries in parallel. I hooked up positive and negative on the first battery fine. Then I hooked up the Negative terminal on the 2nd battery, then went to hook up the positive terminal...Pop!! The biggest Arc flash off a battery I have even seen

Needless to say, the panel shut down, powered back up and now the Zonex (data loop for expander modules) is bad!!!! Crap i just killed a fire panel!!!!

After all that I tried the batteries again, hooked them up without incident!!!!!! That is frustrating!!!

Besides the fact that two auxillary devices were hooked to the battery + terminal and panel - (common) what happened????

I understand that those other devices shouldn't have been on there but they had been operating fine for years like this. I didn't check what the battery terminals had on them before I changed the batteries (nothing else should be on there!!!) The wiring is messy anyway, I didn't put it in and the customer isn't interested in paying to having it neatened up.

After some looking around I found the two devices that were attached to the battery terminals for power were now ground faulted. They are mounted in the can with the panel and are not touching the can. The boards themselves are cooked not the devices attached to it.

I surmise that a surge( or electrostatic discharge maybe?) with the arc blew the main panel's data loop. I have never seen anything like this before. Oh and I did NOT reverse the polarity of the battery when hooking it up.

of course the company I work for looks like crap in the eyes of the customer for frying a panel, but I know I did nothing willingly wrong.

Here comes the brown stuff rolling down hill!!
 
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nakulak

Senior Member
did you have ac/dc power on when you hooked up the batteies ? (unit should have been powered down, then batteries, then ac/dc ?)
 

nhfire77

Senior Member
Location
NH
did you have ac/dc power on when you hooked up the batteies ? (unit should have been powered down, then batteries, then ac/dc ?)

No I didn't. That is not a requirement to change the batteries. Typically when you hook them up there is no arcing, if its on AC power then there is no draw on the batteries.
 

TwinCitySparky

Senior Member
Location
Minnesota
Every type of system I've ever installed from Radionics to GE specifies that the battery is to be unplugged last and plugged in first before transformer power is applied.

Once, many moons ago I was a low voltage (or should I say slow voltage guy :grin:)
 

Security101

Senior Member
Location
Northern Indiana
That is not a requirement to change the batteries. Typically when you hook them up there is no arcing, if its on AC power then there is no draw on the batteries.

I agree.

Usually it's no issue, but it depends on the panel construction. Equipment that needs AC first to start will only have the charging current on the battery leads and a mini spark is about all you see.

If on the other hand it's a panel that can be started with just the battery's (like a SilentKnight for example) then a large arc can occur equal to the total current draw. I have seen this :grin:

Now, if the battery's looked like you described, and the system doesn't have a extra power supply, and things are hooked up incorrectly - just about anything could happen.

Have you de-powered the data module (and the control) and re-connected the control - then the module?

Good luck!

Jim
 

nhfire77

Senior Member
Location
NH
Have you de-powered the data module (and the control) and re-connected the control - then the module?

Good luck!

Jim

These boards can power up with just the battery causing a spark, so to avoid that I attach batteries with AC power on.

Yes,

I did removed the devices from the battery terminals, placed them on the aux power. Then Installed a new board.

It went BAD... just like the original one, but no arcing. I phoned Bosch tech support, did some troubleshooting isolated the aux boards that were on the battery terminals as having ground faults, BUT, the ground fault monitor was on and it did not detect it. They are warranting the board becuase it should have detected the ground fault. It still would have blown, but since its not functioning properly that one is free.

I gave Bosch tech support the whole story and they are concerned about this. Sub Assembly boards should not be able to kill a main board like this. They are actually going to tear apart/diagnosis what is bad in the orginal board so we can determine where the issue started.

I am returning today with two of everything just in case.

I will be starting with AC power, earth ground and then wire by wire hooking everything back up.

Any input would be appreciated.
 
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Security101

Senior Member
Location
Northern Indiana
I too would figure it's on the power supply side - but there's no good way for us to check besides the basics. I opt we wait for Bosch to determine the board issue, unless someone has had the same issue prior.

I would however check each and every wire to ground and across them for any stray voltages etc - prior to re-connect - for sure...

Jim
 

nhfire77

Senior Member
Location
NH
Ok I got a new panel installed. I replace the D8125 and a D8130, they were causing ground faults, somehow. Also the D928 dual phone line card was replaced just to CYA. All is fine and well now.

I did discover that the main panel 12v aux and another separately derived 12v aux supply were tied together on + and -. Now the negatives can be tied together, but the positives, that cannot be good. Also the wiring was horrible.

I spent 90 minutes cleaning it all up. I tested each and every wire to ground before hooking anything up then powered it up and slowly connected all the non-12v wiring.

Its all good now, but, I still don't know what happened!!
 

nhfire77

Senior Member
Location
NH
Every type of system I've ever installed from Radionics to GE specifies that the battery is to be unplugged last and plugged in first before transformer power is applied.

Once, many moons ago I was a low voltage (or should I say slow voltage guy :grin:)

I looked into what the manual says on that. Initial power up its the battery first and AC second, but, when it refers to battery changes it does not specify, just states "observe polarity"

I'm not sure if it would have mattered in this case.

I agree though, Silent Knight and other commercial panels are different.
 

Smart $

Esteemed Member
Location
Ohio
...

Its all good now, but, I still don't know what happened!!
Did you check both unloaded battery voltages before connecting?

With new, off-the-shelf, same-model batteries, the likelihood of major arcing upon direct parallel connection is minimized... but it is always a possibility!!!
 

nhfire77

Senior Member
Location
NH
Did you check both unloaded battery voltages before connecting?

With new, off-the-shelf, same-model batteries, the likelihood of major arcing upon direct parallel connection is minimized... but it is always a possibility!!!

I checked them right after the arc. They were 12.75. Both new same brand Yuasa.
 

MichaelGP3

Senior Member
Location
San Francisco bay area
Occupation
Fire Alarm Technician
Question and 2 comments.....

Question and 2 comments.....

I've read the thread twice and I'm not able to tell. Was the required D122 battery harness present or absent?

While it has already been mentioned, I'd like to stress that nothing should be connected to the battery + captive screw terminal on the panel except the positive lug on the battery (or, in the case of a dual battery setup on a Radionics or Bosch panel, a D122 lead). As an old battery goes bad, their internal resistance increases. The power supply's charging circuitry begins to deliver more current to overcome this resistance, heating the battery, driving the resistance yet higher. The electrolyte cooks off, heat/pressure distorts the case.

Contrary to your thinking that paralleling the main panel's aux. 12 volt dc with a separate 12 volt dc source is automatically wrong, it isn't. Whether there was a good reason for this in your particular case, I don't know. There is factory documentation on this practice.
 

MichaelGP3

Senior Member
Location
San Francisco bay area
Occupation
Fire Alarm Technician
Questions & comments....

Questions & comments....

I've read the thread twice and I'm not able to tell. Was the required D122 battery harness present or absent?

While it has already been mentioned, I'd like to stress that nothing should be connected to the battery + captive screw terminal on the panel except the positive lug on the battery (or, in the case of a dual battery setup on a Radionics or Bosch panel, a D122 lead). As an old battery goes bad, it's internal resistance increases. The power supply's charging circuitry begins to deliver more current to overcome this resistance, heating the battery, driving the resistance yet higher. The electrolyte cooks off, heat/pressure distorts the battery case. During this process, components in the power supply/charging circuit can be stressed. I've not done this, but it would be interesting to watch with a meter what, if any, voltage fluctuations or spikes occur during this process, or, at the end of this process.....
Scenario #1: A crack develops in the case of the battery, and electrolyte drips out. When it contacts the floor of the panel, you have a ground fault on the charging circuit. Any other devices connected to the + battery terminal will be exposed to a voltage less than 12 volts, depending how 'hard' this ground is. Scenario #2: The battery has gotten so hot that something melts inside, creating a sudden open. Any other devices connected to the + battery terminal will see a spike in the voltage. Scenario #3: Scenario #1 happens, followed by scenario #2.

Did either the D8125 or D8130 smell burned or show any carbon traces? (could be the source of the ground).

Contrary to your thinking that paralleling the main panel's aux. 12 volt dc with a separate 12 volt dc source is automatically wrong, it isn't. Whether there was a good reason for this in your particular case, I don't know. There is factory documentation on this practice.
 

nhfire77

Senior Member
Location
NH
I've read the thread twice and I'm not able to tell. Was the required D122 battery harness present or absent?

While it has already been mentioned, I'd like to stress that nothing should be connected to the battery + captive screw terminal on the panel except the positive lug on the battery (or, in the case of a dual battery setup on a Radionics or Bosch panel, a D122 lead). As an old battery goes bad, it's internal resistance increases. The power supply's charging circuitry begins to deliver more current to overcome this resistance, heating the battery, driving the resistance yet higher. The electrolyte cooks off, heat/pressure distorts the battery case. During this process, components in the power supply/charging circuit can be stressed. I've not done this, but it would be interesting to watch with a meter what, if any, voltage fluctuations or spikes occur during this process, or, at the end of this process.....
Scenario #1: A crack develops in the case of the battery, and electrolyte drips out. When it contacts the floor of the panel, you have a ground fault on the charging circuit. Any other devices connected to the + battery terminal will be exposed to a voltage less than 12 volts, depending how 'hard' this ground is. Scenario #2: The battery has gotten so hot that something melts inside, creating a sudden open. Any other devices connected to the + battery terminal will see a spike in the voltage. Scenario #3: Scenario #1 happens, followed by scenario #2.

Did either the D8125 or D8130 smell burned or show any carbon traces? (could be the source of the ground).

Contrary to your thinking that paralleling the main panel's aux. 12 volt dc with a separate 12 volt dc source is automatically wrong, it isn't. Whether there was a good reason for this in your particular case, I don't know. There is factory documentation on this practice.

D122 was in place at the time. Scenario#1: No the battery had not leaked yet, there was no corrosion in the can. Scenario #2: Battery was less than 2V when I pulled it.

The charging circuit is limited to 1.4 A. As soon as you remove a battery the panel notices this. The charger actually turns off. You can verify this by looking at the LED's on the boad, its goes into "missing Battery" I have never had an arc changing batteries on a bosch panel, and I have changed batteries on hundreds of Bosch G panels. Other panels yes, Bosch never, that is why this is so frustrating.

None of the cards had burnt traces, I was confused as you were.

As for the power supply, there was actually no need for the second power supply, so combining them for an increase in capacity is fruitless. The total draw is less than 1A. Everything in the system is powered totally separate external power supplies.

I am almost sure, but cannot back this up with facts, that Bosch would not find it ok to attach another 12V power supply to the panel. When I powered it down for the first time, the second power supply was back feeding the panel through terminal 3 (aux power) keeping it on!!!! Talk about multiple disconnects!!
 
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Security101

Senior Member
Location
Northern Indiana
Contrary to your thinking that paralleling the main panel's aux. 12 volt dc with a separate 12 volt dc source is automatically wrong, it isn't. Whether there was a good reason for this in your particular case, I don't know. There is factory documentation on this practice.

I would like to see the documentation as I have never seen this as acceptable. Linking the ground/common/(-) is normal for data bus applications, but allowing the positive side to become involved could cause multiple issues as described.

I know there is a system out there that does do this with their own proprietary supply but no one else would allow this with a separate, non proprietary supply - to my knowledge...

Jim
 

nhfire77

Senior Member
Location
NH
I would like to see the documentation as I have never seen this as acceptable. Linking the ground/common/(-) is normal for data bus applications, but allowing the positive side to become involved could cause multiple issues as described.

I know there is a system out there that does do this with their own proprietary supply but no one else would allow this with a separate, non proprietary supply - to my knowledge...

Jim

And to further that, the second power supply was a seperately derived power supply, it was Bosch, but as an aux power not supplement to the panel
 
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