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Battery Explosion
5

Battery Explosion

Battery Explosion

(OP)
Hi I am having a problem with some Power brand batteries, they are located in a cabinet supplying UPS feed but they are blowing their covers and this is happening only in UPS with Power battery. Does anyone have an explaination or have the experience of seeing this happen.

RE: Battery Explosion

Is there any source of ignition in the cabinet, like a contactor or relay? An explosion of the hydrogen produced by the batteries while charging can easily blow off the battery covers.

RE: Battery Explosion


Has overcharging been ruled out?
  

RE: Battery Explosion

Do the same battery units repeatedly blow their tops?
If so, that could be an indication of a bad electrical connection within the battery unit.

RE: Battery Explosion

We are all assuming that the batterys concerned are lead/acid wet cell. Can you confirm that this is the case?
If so, they may be the wrong type of construction for a trickle charge, low load application, such as I would expect on a UPS. "Car" type batterys are made for high load and relatively high recharge rates and will sulphate up and distort plates to the point of shorting out and causing ignition of gasses if used on long term "standby" applications. There are batterys made more suitable than others for this type of application. A good manufacturer would advise on this.

RE: Battery Explosion

(OP)
DanDel, No there are no ignition source in the cabinet, it contains 400 batteries and five fuses making up five strings at fourty each.
Busbar, with the failure of the battery and the low cells voltage of some the charging current has increased to compensate for this low voltage.
Alehman, No other UPS units in our network with power batteries blow their tops.
Jre, the batteries are of VRLA type, and to you all can you tell me one of the better manufacturer for batteries of this nature.

RE: Battery Explosion

How long have the batteries been doing this? What has started this issue? Also, are the batteries sized properly for the application and the charger?

Good luck!

RE: Battery Explosion

(OP)
I discovered this in a 3KVA UPS last year and in June it happened in two 160KVA UPS operating in a parallel redundant system.

RE: Battery Explosion

It really sounds like overcharging or internal overheating. I'm surprised you are seeing this problem on systems which must have different types of batteries.

My question actually was - Do the same batteries repeated blow their tops? In other words, do you replace the tops and see them pop off again? Or do you replace those units right away. Are the battery cases fractured when this happens?

Low voltage? How low? The charging current should not increase due to low voltage if the UPS rectifiers are behaving corretly. You should get your UPS's checked out. What manufacturer are the UPS's?

Power battery makes VRLA and flooded cell types for many applications. As jre suggested, a consult with them would be worthwhile also.

RE: Battery Explosion

I would also suggest internal resistance testing to locate bad cells.

RE: Battery Explosion

Suggestion: Please, are those batteries with the blown top hot or cold? This will make a big difference since the hydrogen explosion may happen when the battery is relatively cold or warm only. Intensely charged batteries are usually very hot. Therefore, any blown top from such battery would also be very hot, similarly as the battery.

RE: Battery Explosion

(OP)
Alehman, No when the top is blown the battery case is fractured and they are usually hot and swollen. there are batteries as low as 9V. the UPS is manufactured by Powerware.

jbhartos,  The batteries with the blown top are hot.

RE: Battery Explosion

This is a way out remote possibility for your situation, but happened in the '80s to a similar system just after rare earth magnets became easily available and switch mode power supplies starting to be the norm .

Technician liked to stick notes/papers on the side of a power cabinet with magnets.  Long story short, one of his new SmCo magnets (held lots more papers) was placed just right so that a CT in a power supply was biased by the DC field and the output went overcurrent (control feedback lost due to the poartial dc saturation) with no one the wiser and no shutdown. Similar possibility in your case could cause overcharging on just that one UPS and lead to the hot/exploding batteries.  No magnets policy on the side of the PS 'fixed' the problem.

Submitted that happening as part of a lessons learned paper to IEEE Ind. Application Journal in '95, reviewer said journal never published 'hypothetical' cases!!

BTW, tried to 'blow up' a car battery when younger, only way to get it to do so was to charge at 100 A for 5 minutes with covers off and continuous ignition spark going - personal conclusion was it takes a real specific set of circumstances to blow a battery. Did know of some GTE techs in 80s killed by exploding Li Thional Chloride batteries.

RE: Battery Explosion

I managed to blow one cell of a car battery off in my youth.

It was gassing well with the filler caps screwed on and I generated a nice spark by shorting the thing with a piece of rubber coated automotive wire. (I liked the red hot wire & smoke you see).

Except that on this occasion, the cell nearest to the positive terminal popped and cracked the battery casing.

Result: acid all over the concrete floor which started bubbling away generating CO2.

Quite exciting really.

No real damage to me or the floor, and the battery was scrap anyway.

But I was very lucky.

rgds
Zeit.

RE: Battery Explosion

Sounds like an internal short in the battery. It could possibly be a behavior called thermal runaway which causes rapid overheating when charging current is too high.

See http://www.powerbattery.com/acro-file/PQ2000.pdf

My company has an 18kVA Powerware UPS with a cabinet full of VRLA Power batteries also. None have blown up yet. We have a twice yearly testing program - I guess I'll renew that contract...

RE: Battery Explosion

(OP)
Alehman, What type of testing do you do twice a year.

RE: Battery Explosion

Cell voltages, internal impedances and intercell connector resistances. Several companies make testers for this purpose, such as Albercorp's Cellcorder.

It's also worthwhile to do a full discharge test annually (with individual cell voltage recording) for critical systems.

RE: Battery Explosion

Suggestion: Concentrate on the proper and recommended battery charging by the battery manufacturer. Battery cell internal geometry varies from the type-to-type and so does the electrolyte or chemicals inside the battery cell, in general. The battery manufacturer is probably the easier contact. Optionally, the battery cell may be analyzed and tested by a nationally recognized testing laboratory for electrical parameters and proper charging including maintenance. Please, post the progress as you search for the solution.

RE: Battery Explosion

The best way to track and find problems with Valve Regulated batteries is to install a continuous monitoring system on them. You can then track and record current flow to the battery, and temperaures of each battery. The system will alarm before the battery explodes giving you time to perform preventive maintenance.

The cost of these systems initially can be expensive, but the reduction in maintenance costs usually pays for the system especially in catastrophic situations.

You can find a system at www.on-lineinc.com.

RE: Battery Explosion

Another battery monitoring equipment manufacturer is Vanner. Not a bad product, but an appalling outfit to deal with, in the UK at least. I think the p.o.s. sales guy we dealt with moved to the US. Watch out!

RE: Battery Explosion

hi mr bertramh
Is the battery enclosure well ventilated ,may be if required the enclosure can be kept open and performance observed. As well as the charging current may be reduced and the change in temperature may be verified.
Mouli11

RE: Battery Explosion

Depending on the age of your UPS it should be monitoring the batteries to prevent a runaway.  How old is the UPS and batteries??

RE: Battery Explosion

ScottyUK, check out www.on-lineinc.com for a reliable battery monitor if you are looking for a monitor in place of the Vanner unit.

RE: Battery Explosion

(OP)
Davemarz the UPS is five years old and it suppose to be monitoring the batteries but the UPS shows one hundred percent capacity but the batteries keeps exploding and I have since removed three strings from the system and it's still showing 100% capacity.

RE: Battery Explosion

Suggestion: If a battery is defective, it may explode without detecting anything on a very elaborate and expensive battery monitor, except the one that would monitor the temperature of each battery cell.

RE: Battery Explosion

This is a follow-up to my earlier post in this thread -

Our UPS batteries failed last weekend. This is a 12kW UPS with  a string of (20) 12V VRLA batteries (Power Battery). They have been tested at six month intervals with a brief load application, internal resistance and voltage at six month intervals. The last test was about 5 months ago and they were fine. Tuesday morning the UPS showed a battery alarm. The battery voltage was varying between 200 and 290 volts every few seconds(!).

The service company came and tested the batteries and found about half of the 20 jars showed infinite internal impedance. They could not find any problem with the UPS. I don't know if there was an extended outage because the event log overflowed with battery warnings after about ten minutes. The computers it supplies never shut down though. We obtained a set of temporary replacement batteries and installed them. They seem to function normally.

Fortunately none of the battery jars exploded. They are about 3 years old. It doesn't seem reasonable that half the batteries would go from good to open in five months. The manufacturer has not yet determined if they will provide any compensation via their ten year pro-rated warranty.

RE: Battery Explosion

VRLA batteries may not be expected to have a life of more than 5years.
The health of the batteries can be monitored by measuring the specific gravity of acid in case of vented type battery cells.
However, with VRLA batteries, the battery impedance monitoring (commercial devices are available)is the only available method apart from physical appearance like distortion, cell voltage on no-load / on load etc, which are not known to be all that reliable methods.
The manufacturing defect also can be an issue such as the cells gas more than they should while on charge thus causing excessive internal pressure build-up/explosion. The problem could also be with the battery charger settings.
Thus, the subject needs to be looked in to from different angles and I tried to present few of my thoughts.
Trust you find them useful.

RE: Battery Explosion

Do, they by the chance,wet cells with the catallyist tops, that recombine the H and 02 back to H20?, These heat up during equallization. A long shot, but these are sold after market.

RE: Battery Explosion

Thanks for the ideas. There was no obvious sign of pressure build-up (explosion, swelling, etc). The mfg. data does not mention any type of catalytic system. It does say the cells normally operate at "a small internal pressure". Any ideas on how I may tell by appearance if the catalyst exists?

The charger was set for 272 volts which is 2.27 volts per cell - within the mfg. recommended float voltage range.

They have offered me a 12% discount on a new string for the pro-rated warranty. I am looking at other manufacturers.

RE: Battery Explosion

2.27volts per cell for float charge seems on high side.

If my memory serves right, it should be between 2.23 to 2.25V/cell (at this voltage cells should not require any periodic equalising charge).

Normal vented type cells (not low maintenance variety) are maintained at 2.16 to 2.20 V/cell to limit the water loss.

RE: Battery Explosion

Power Battery recommends float voltage from 2.27 to 2.30 vpc (with a small temperature adjustment factor). I think this is fairly typical of high s.g. VRLA batteries. I am most confused as to why we would suddenly see such a large number go bad, esp. without a total discharge.

RE: Battery Explosion

Nature of the malfunction suggests that batteries may be a defective series from the manufacturer. Batteries from another manufacturer could be tried.

RE: Battery Explosion

power batteries are not the best in the world. i recived a set from the manufacture to in stall and found four passing there saftey seals. This is a concern as it will give rise to a high impedance value of the battery. Did any of the vent vales show signs of passing. what was the ambient temperature within the room where that batteries were situated as a 5 degree rise in teperature will reduve the life expectancy by half.

RE: Battery Explosion

(OP)
Gentlemen it's the same findings I had from the start of this thread, the batteries just go bad in batches. Since then I have switched battery manufacture on my two large ups systems. My conclusion is there is some defect with this brand of batteries since the supplier was unable to give me a reasonable explaination. I have a question for all of you, we are about to purchase a 100KVA ups and we are including a battery monitoring system in the tender, what is some of the systems available and do you know of any site I can take a look?

RE: Battery Explosion


Bertramh,

Our company just received a call from Eaton (Powerware) and they are replacing our UPS batteries for free due to batteries not in spec.  We have a 25kVA system.  They said some of their customers experienced problems, so they are changing all of these, even if the customer has not had problems.  The batteries in question have a case that is too thin and are cracking.

I would recommend calling Powerware.  I spoke with Allen at 919-870-3217.  Make sure you have the UPS model number.

Good luck.

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