Battery question: (254 X 1.5V) vs (32 X 12V)
Battery question: (254 X 1.5V) vs (32 X 12V)
(OP)
Hello,
we have a UPS system that uses 254 batteries if 1.5V in order to give 380V DC. My question is why not 32 batteries of 12V.
Thanks in advance
Costas
we have a UPS system that uses 254 batteries if 1.5V in order to give 380V DC. My question is why not 32 batteries of 12V.
Thanks in advance
Costas






RE: Battery question: (254 X 1.5V) vs (32 X 12V)
Mike
RE: Battery question: (254 X 1.5V) vs (32 X 12V)
RE: Battery question: (254 X 1.5V) vs (32 X 12V)
It could use 32 _batteries_ of 8 cells each.
Individual cells in a battery are hardly ever individually replaceable, and are often not even provided with access for individual cell testing. It is often the case that only one cell in a battery actually becomes unusable, but monolithic battery construction forces you to discard the remaining good cells with the bad one.
You are better off with individual cells. Someone probably paid extra to have the UPS constructed that way.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Battery question: (254 X 1.5V) vs (32 X 12V)
RE: Battery question: (254 X 1.5V) vs (32 X 12V)
Wet cells with 2.0V nominal (they are not 1.5V) per cell have proven their reliability in telecomm industry over a century now. (How often have you lost telephone service due to a power outage? I am speaking for USA or similarly developed nations)
The 12V batteries you are referring to sounds like car batteries...how many times have you seen/experienced a car battery die?..so there lies the answer.
RE: Battery question: (254 X 1.5V) vs (32 X 12V)
As I see from the messages of mpparent and rbulsara, reliability is one difference between 1.5V (or 2V) cell and 12V battery. The reason, if I understand correctly, is in battery chemistry as itsmoked wrote.
Q1. Is there a comparative measurement regarding reliability of various types of batteries? Any link, or even personal measurement would be appreciated. To rbulsara: In order to compare the batteries of the telecom industry with the batteries of the vehicle industry, I guess we need numbers like [failed units / total units], average and standard deviation of operation time before failure etc.
Q2. I thought that the common practice was NOT to change individual cells/batteries when some are found unusable. We supposed to change the whole series of batteries. How, individual testing/replacing is an advantage for the 1.5V cell?
Thanks again for any input.
Costas
RE: Battery question: (254 X 1.5V) vs (32 X 12V)
Q1 There is often quoted opinions on which batteries can cycle the most, float the longest, be discharged the most but in reality the way batteries are cared for trumps all the standard opinions.
If one's charger brutilizes the batteries they will die quickly. If the ambient temp is too high or too low they will die quicker. If they get cycled they will die quicker. If they etc etc.. So to answer your question is very hard since it even varies with your UPS usage.
Your failure numbers are almost impossible to state because of this.
As for type of batteries, automotive batteries are specially designed to provide whopping currents briefly for cheap. They are utterly worthless for UPS duty.
AS for Q2: Yes and no you can replace batteries one at a time. With that many batteries in series it is harder. But often a single battery fails in a group that large. Go ahead and replace it. You MUST replace it with the same type/capacity/voltage/chemistry thou!! Once they start to fail more often say 3~5 in a year instead of say..one or two it would be better to change out all of them as they are all going to reach end of life.