Station Battery Load Testing 4

[TransD]

Hello,
It is time for our five year battery test at our powerhouse. It is a 134vdc system. We will be paralleling 12 volt batteries with our 2.2 volt batteries during testing. Other than verifying the polarity, are there other concerns I should look into? Thanks.

 

[bayoubare]

#1 Ensure that the 12 volt mono blocks are sized properly to support the connected load for the time peroid that you require.
# 2 match voltage leveles when parrelleling batteries.

 

[eeprom]

I have limited experience with batteries...but why would you parallel a 12v battery with a 2.2v battery? Are these jar batteries? Aren't you going to boil the liquid in the 2.2v cell?

 

[JG2828]

eeprom,
I'm pretty sure he meant he wants to parallel (11) 12v batteries with 60 2.2v batteries. Meaning each battery bank would have ~132v.

 

[eeprom]

Thanks. That makes some sense.

 

[TransD]

JG2828 is right. Thanks for clarifying. We have been told one cell will have to be replaced. Any advice on the best way to accomplish this? Thanks.

 

[TransD]

That is one 2.2v cell will have to be replaced. During the load test it went from 123% efficiency 5 years ago to 92% efficiency today. I was told at 80% they would have to jump it out. Thanks.

 

[ScottyUK]

Ensure that you exactly match the number of cells in the 12V blocs and the string of 2.2V cells. Adjust any mismatch by adding single cells as necessary, otherwise you could have real firework show. If JG2828's guess is right then you won't need any single cells. Make sure the 12V blocs are charged prior to connecting them.



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If we learn from our mistakes I'm getting a great education!

 

[oldfieldguy]

Scotty's right (like that's a big surprise...)

Lead-acid cells are typically around 2.2 volts. The common "12-volt" battery has six cells and if charged will show a bit over 13 volts. Look for 13.4 volts. You will note that this is a tenth of the voltage of your "134-volt" bank.

The 125 VDC (nominal)bank that is typical in most US installations has 60 cells, requiring ten "12-volt" batteries to replicate it. On my installations, that "125-volt" bank typically runs around 134 volts. But it's still called a "125-volt" bank. And it has 60 cells.

If you're trying to parallel 12-volt batteries, you need ten, and they should be fully charged. Using proper safety equipment, connect one end of the temporary bank, and then use a voltmeter to check the voltage difference at the other end before connecting it.


old field guy