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I just read your reply which gave the recorded cell voltages as low as 1.87V. WOW! If the voltages are that low then the battery is shot, you probably have internal shorts causing the low voltage. I would not rely on this battery to perform its function. I would remove them from service and...

Need a little more information to understand your problem. What do you mean the whole bank is breaking down? Has the bank started to show signs of degradation (low cell voltages, plate shedding, internal corrosion, loss of electrolyte, etc.). What kind of cells are you talking about (NiCd, lead...

Not really sure of your question, batteries are normally rated in amp hours not voltage. You can specify the "voltage rate" at any voltage. Normally, you would use the minimum voltage that the load could handle and then use the vendor supplied discharge curves to determine the discharge rate to...

IEEE standards (450 lead calcium, 1188 VRLA, etc) provide the recommended frequency for testing batteries. The vendor instructions normally follow the IEEE guidelines. Keep in mind there are two separate discharge tests that are specified, a capacity/performance test and a service test. The...

Does anyone have experience using a mercury sulfate half cell to take nagative and positive plate potential readings in a lead calcium station battery? I am trying to determine the state of charge on each plate.

IEEE 1188 specifies VRLA testing. The best way to detemine the "health" of a battery is a capacity test. As mentioned in previous postings Alber offers excellent test equipment for performing both discharge test and internal ohmic test.

I do not agree with ScottyUK's description of "fit and forget". This is a misconception with VRLA's, you might not have to add water but but do have a lot of maintenance. IEEE 1188 provides all the recommended maintenance activities for VRLA's, not much different then IEEE 450 and in...

gezcooke, Thanks for your reply. The capacity test we performed utilized a resistive load bank (contact current to a specified end voltage) and the analysis software plots each cell's ICV during the entire discharge. The cell performed well during the discharge just didn't appear to recover...

Look at IEEE 484, there is a small section on ventilation.

Does anyone have experience recovering from a low ICV on a large lead acid station battery? One cell in a sixty cell string dropped to 2.13V from the nominal 2.25 reading. We just completed a capacity test a week before the low reading was obtained and the cell along with the bank performed well...

Try SENCORE instruments. they have a meter (LC102??) that tests the caps at their rated voltage up to 999V. the meter tests for capacitance, ESR, leakage current, and dielectric absorption.

Try ledtronics, they will customize just about anything you want. http://www.ledtronics.com/

I have a 2W, 500 ohm potentiometer that has erratic resistance readings. Does anyone have a good web link for testing pots? I was thinking about setting up a test rig to put voltage across the pot and monitor the voltage drop across the pot (or across an in-series shunt) as the pot is cycled.

Have you put a load on the batterry? My guess is this cell will not do very well when a load is placed on it. It sounds like you are developing a short across the plates.

Let's not all jump on the band wagon. Ungrounded (or floating) UPS's are common in many applications in power generation stations. Power generation stations (especially nuclear) are not committed to NEC requirements and being ungrounded is not a code violation for these plants. Being ungrounded...

Does anyone have information on the use of water fuses? Certain inverter manufactures have allowed water fuses to be used during troubleshooting in place of normal fuses. This cuts down on the costs of blown fuses. The fuse wire looks like solder and is wrapped around lugs and immersed in water...

Verify hardware (i.e. nuts, bolts and washers) are correct size for the termination lugs and that they are torqued correctly. I have seen undersized bolts cause hot joints.

In our configuration the CVT was the normal power and the UPS output was the emergency power. The UPS and CVT were located in two separate rooms. If power to the CVT was lost the UPS would be cycled on. The original design had the ground at the UPS neutral and ungrounded at the CVT neutral. Poor...

It soounds like your CVT failed and caused the downstream faults. Check your grounding configuration of the downstream loads. We had a similar failure where a failure in the CVT caused a fire in a downstream UPS. The downstream fire was a result of a improper ground. As discussed in your other...

I have a transfer switch on a ungrounded system that switches both the hot and neutral. AS DYDT stated, the secondary of a CVT is isolated from the primary so you should be able to ground its neutral. You are correct in stating that if there were a fault on the secondary nothing on the...