Breaker won't trip @ short circuit.

topper

I recently purchased a number of 100 Amp panel mount breakers from our host.. These have been wired up to my multiple string battery bank ( ie each string protected.)..
Breaker Line is connected to the battery and Breaker Load to the Main buss bar feeding the inverter + Side.. I thought I would test my "new" breakers by purposely wiring in a SHORT CIRCUIT trial run.. Breakers did not trip after 3 minutes of short circuit time..
My batteries are 6 strings @ 155 Ahr @ 24 volt.
Breakers are Midnite- MNEDC100's rated @ 100 Amp/135 Amp SC @ 150 VDC..
Any info would be appreciated..
Thx in advance.

waynefromnscanada

Re: Breaker won't trip @ short circuit.

I would HIGHLY suspect your batteries, for whatever reason, are not capable of shoving out enough current to trip the breaker. If they were, and there was a defect with the breaker, the short circuit you introduced would have resulted in smoking wires/battery terminals/ cables, and probably a fire.
To be honest, doing what you did, was an extremely dangerous thing to do.

Cariboocoot

Re: Breaker won't trip @ short circuit.

topper wrote: »

I recently purchased a number of 100 Amp panel mount breakers from our host.. These have been wired up to my multiple string battery bank ( ie each string protected.)..
Breaker Line is connected to the battery and Breaker Load to the Main buss bar feeding the inverter + Side.. I thought I would test my "new" breakers by purposely wiring in a SHORT CIRCUIT trial run.. Breakers did not trip after 3 minutes of short circuit time..
My batteries are 6 strings @ 155 Ahr @ 24 volt.
Breakers are Midnite- MNEDC100's rated @ 100 Amp/135 Amp SC @ 150 VDC..
Any info would be appreciated..
Thx in advance.

Let's get this straight: you ran a 155 Amp hour 24 Volt battery bank through a 100 Amp breaker and back to the battery with nothing else in between and it didn't trip? Nothing caught fire? Because the amount of current that would dump would definitely cause something to go, and it should be the breaker.

I can't imagine why you'd have six parallel strings of batteries either, but something about it all tells me the wiring was not quite as you think it is or as it should be.

Was it like this?

(-)BATTERY STRING(+)
|___BREAKER_______|

topper

Re: Breaker won't trip @ short circuit.

The Enersys 12v155's are MORE than capable of putting out over 3000 Amps SC.. Are the MNEDC breakers possibly current limiting????
And point taken Wayne.. ALL WIRING IS OVERSIZED TO MORE THEN HANDLE THE 100 AMP breaker capacity.. Indefinitely.... But I thank-you for your concerns.

topper

Re: Breaker won't trip @ short circuit.

YES Coot. You are rite on the money.. Breaker should have tripped instantly..

Cariboocoot

Re: Breaker won't trip @ short circuit.

This is where a clamp-on DC Ammeter is valuable: to see if any current actually is flowing and if so just how much. Depending on the size of wire (at least 0 AWG), amount of it, SOC of the batteries, and resistance of the connections it is possible the battery current flowed at <100 Amps initially, leading to rapid decline of capacity and doing nothing more than discharging the battery.

Did you check the SOC before and after the experiment?

BTW, not to be repetitious but ... this is not how we'd test a breaker. Normally you apply the power to a load and then increase the load in stages until it exceeds the current protection limit, rather than dumping to a dead short all at once. That way you can not only check that current is in fact flowing but at what point it will stop. The only way breakers limit current is by tripping when overloaded.

topper

Re: Breaker won't trip @ short circuit.

I do agree with you 100% Coot.. I had a "moment" yesterday and in my haste did a VERY dumb thing..... The proper procedure you describe is MUCH safer and HIGHLY recommended to all.. I will have to do a little investigating after work today.. See if I have any resistance issues, or a bad crimp..
But still, nothing got hot,.. Although I did not check SOC before, during or after..

I will inform when I know more and do the rest of my testing in a MUCH SAFER MANNER..

Reason for 6 strings???? $78 for a 22 KW battery bank 2 yrs old in Very good condition..

mike95490

Re: Breaker won't trip @ short circuit.

Sometimes, a breaker will have a bit of oxide on the contacts from sitting on a shelf. Cycle the handle several times, and check it with an ohm meter, to make sure it is conducting. If it was really conducting, and not opening, things should have gotten really exciting , real quick.

Thom

Re: Breaker won't trip @ short circuit.

Don't some breakers have polarity ?

Thom

Cariboocoot

Re: Breaker won't trip @ short circuit.

Thom wrote: »

Don't some breakers have polarity ?

Thom

Yes, but in this case that was observed:

topper wrote:

Breaker Line is connected to the battery and Breaker Load to the Main buss bar feeding the inverter +

Thom

Re: Breaker won't trip @ short circuit.

Well I got part right :0)

vtmaps

Re: Breaker won't trip @ short circuit.

Thom wrote: »

Don't some breakers have polarity ?

Yes, some do. The OP has Midnite panel mount breakers. They are NOT polarized. Curiously, they do have line and load markings, but they are rated to work as non polarized breakers. Robin and Ryan at Midnite have said (on their forum) that you can ignore the markings.

They are NOT rated to work in any position. The front of the breaker (with the handle) cannot be pointing up.

--vtMaps

halfcrazy

Re: Breaker won't trip @ short circuit.

if nothing caught on fire then I would say the battery is not capable of the current. Basically if you used the breaker to short Battery+ to Battery- it should instantly blow back off in your hand unless there is enough resistance to absorb the current some where. And if there was you are talking 100-125 amps so something would start smoking asap. The only explanation I have is the battery is soft enough it could not drive the 100-125 amps needed to trip the breaker.

If you where doing this and had a clamp on DC meter you could watch the current flow.

As far as corrosion on the breaker from sitting again if that was the case the breaker would have caught on fire. So all roads point back to the battery not having the punch

Ryan

waynefromnscanada

Re: Breaker won't trip @ short circuit.

halfcrazy wrote: »

if nothing caught on fire then I would say the battery is not capable of the current. Basically if you used the breaker to short Battery+ to Battery- it should instantly blow back off in your hand unless there is enough resistance to absorb the current some where. And if there was you are talking 100-125 amps so something would start smoking asap. The only explanation I have is the battery is soft enough it could not drive the 100-125 amps needed to trip the breaker.

If you where doing this and had a clamp on DC meter you could watch the current flow.

As far as corrosion on the breaker from sitting again if that was the case the breaker would have caught on fire. So all roads point back to the battery not having the punch

Ryan

Totally agree with each point.

topper

Re: Breaker won't trip @ short circuit.

And it all becomes so very clear. I put a load test on each battery. Turns out a number of you were right.
Looks like 1/2 the bank has NO punch. Voltage at rest but no jam. I'll limber up tomorrow and do some shelf shuffling.

topper

Re: Breaker won't trip @ short circuit.

Well. I would gladly go back to these vrla agm's anyday.. No watering. Clean install..Low almost no maintainance. Thanks for all of your redirection.

topper

Re: Breaker won't trip @ short circuit.

Well I did do some battery shuffling.. Matched 3 pairs of similar capacity 12 volt blocks.. Recharged and load tested, recharged, capacity tested, and recharged yet again. Looks like I now have 400 Ahr +/- worth of battery for a $40 investment ($78 initially - $38 for returned batteries).

Being bored and all.. I did attempt to add 20 ml of water to the dead/ no capacity blocks.. 2 of 6 gained just a little bit of capacity but are still dead to the world 10- 20 amp output MAXIMUM. The other 4 now have shorted cells after adding H20.. Days of trickle charging at 2 amps have not solved anything.. So my assumption is as many have said in the past, watering sealed AGM's does not work..
Blocks that were at 12.0-12.8 volts @ rest previously are now sitting at 4-9 volts after DAYS and DAYS of charging.. And still have no or less capacity..

BB.

Re: Breaker won't trip @ short circuit.

Watering will probably only help "open/low capacity" cells (if the capacity is the result of lack of water). Shorted cells will not be helped (the damage is already done and permanent).

-Bill

topper

Re: Breaker won't trip @ short circuit.

That does make perfect sense BB.. Watering a low capacity cell opens up all the Non active material resulting in a No capacity cell..
Which is why a previously 12 volt battery is now 6 volts and REALLY dead to the world.. I'm just happy I experimented with the already bad cells with no capacity.

waynefromnscanada

Re: Breaker won't trip @ short circuit.

JaxTruck wrote: »

Ensure the conductor isn't dirty either and don't forget a bit of rubbing alcohol to clean it up a bit if need be.
Weaker cells that drift back in capacity and will limit the battery so you might have to rinse the battery with clean, hot water from a low pressure hose.

It has already been established that the conductors and/or breaker wasn't the problem.
Re "rinse the battery with clean hot water" - - - HUH????

Cariboocoot

Re: Breaker won't trip @ short circuit.

waynefromnscanada wrote: »

It has already been established that the conductors and/or breaker wasn't the problem.
Re "rinse the battery with clean hot water" - - - HUH????

JaxTruck was a spammer. Gone now.