2008-01-08
Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, concerning the use of batteries in series in uninterruptible power supplies (UPS) below 13A, is answered by MGE UPS Systems:
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| A typical UPS battery. |
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Question: I have a question regarding two batteries used in series to make 24V. Take, as an example, a fire alarm system. If battery A fails (see attached drawing) and was left in this condition and battery B is OK on next inspection, would you replace the two batteries or just the failed battery A?
If one needs to replace both, what is the reason? If one only needs to replace battery A, could there be any damage to battery B?
Click on the button below to download the .jpg attachment (the battery circuit - 1.7MB file size).
Answer: This is an interesting question and is more a case of maintaining a chemical equilibrium within the battery system. Depending on the instability, the loss battery A causes to battery B is the deciding factor as to whether or not to replace solely the failed cell. However, the question should be considered in terms of the risk of not replacing, and also the reward gained in replacing the failed cell. This is purely down to site-specific situations. In one scenario, it may be worthwhile looking at the cost of replacing battery B on a call out cost basis, and on the inspection timetable.
When considering the Total Cost of Ownership (TCO) issues, mixing battery ages is typically not recommended and needs to be reviewed against engineer's time, MTBF, maintenance regime and TCO etc., and the service level agreed with the customer. MGE O.P. Systems, in this particular instance, therefore recommends swapping both batteries to minimise the risk of further issues. I hope this information assists.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link: http://www.voltimum.co.uk/consult.php?universe=consult.index.questions
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Related contacts
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MGE UPS Systems
Orion House, 171-177 High Street,
Wealdstone, Harrow HA3 5EA
Tel: 0845 077 1945
Fax: 0845 077 1946
Email: mgesalesuk@mgeups.com
Web: www.mgeups.co.uk |
MGE UPS Systems
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Source: MGE UPS Systems & James Hunt |
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