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UPS MALFUNCTION
vmac100, When a load is initially applied to a UPS the inverter uses the DC bus to supply the output. What you are describing is typical of a UPS that has a 'soft' DC bus - the sudden drag on the bus causes the bus voltage to dip below the inverter shut-off point sending the output across to...- gezcooke
- Post #14
- Forum: Electric power & transmission & distribution
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Reliability of gel-cell (VRLA) batteries
Kasane, Only just read your post - couldn't have put it better myself. Exactly my sentiments after 20 years in the business. Nice one!- gezcooke
- Post #3
- Forum: Battery engineering
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Low ICV reading
You're just seeing ageing effects beginning to take place - i.e. the inevitably rise of internal cell impedances after a few years in service. Interestingly, however, it looks like the cell you picked up on is actually very slightly better than the rest! Your readings show 98% of the cells with...- gezcooke
- Post #2
- Forum: Battery engineering
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Battery monitoring
Singh, I guess you mean swelling and deformity? If so is most likely a mismatch between the capacity required and the capacity of cell/s you are using. When used near typical short circuit currents cheaper cells will fail. A SLA batery will typically give you 20x AH capacity when short...- gezcooke
- Post #4
- Forum: Battery engineering
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How to measure Ripple current in th eoutput side of AC/DC
Oslec, If you're concerned with how long the UPS is going to work reliably then ripple current in the battery is the thing to watch. If this exceed more that 0.1CA then expect the battery to be on it's way out well before any electrolytics have died! I once measured over 125A of ripple on a...- gezcooke
- Post #3
- Forum: Circuit design
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How to Control a Relay with a PC
Bryan, Don't know how you are with programming or 'C' language but the most flexible way to do what you want to do is fit a PC relay card in your PC that controls the relays from software. Arcom make such a beast - available through RS components part ref 295-3748. Find it on their website -...- gezcooke
- Post #2
- Forum: Circuit design
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Battery monitoring
We have two of them - used quite often over last 3 years. Not a bad piece of kit but have had A/D failures on both so can't rave about reliability too much. Time/cost to repair isn't too good either. However, when properly set up you do get a fairly good report to baffle the Customer which...- gezcooke
- Post #2
- Forum: Battery engineering
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Lead-acid battery desulfating
Typically when SLA batteries are stored for a long period of time lead sulphate is formed on the negative plate of the cells. Keep batteries on a nice warm shelf (say 35 degrees) and the process can take as little as three months or so. Similar effect happens if you leave a battery deep...- gezcooke
- Post #2
- Forum: Battery engineering
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Low resistance??
Are you really sure you're measuring 4 ohms? If it's a UPS application based on 192 cells then I'm guessing your looking at around 100AH cells - as any lower and you would have probably stuck 12v blocks in. Typically Yuasa, Hawker, Exide, Chloride, etc, start doing big boys batteries for real...- gezcooke
- Post #8
- Forum: Battery engineering
