PPRuNe Forums - View Single Post - 787 Batteries and Chargers - Part 1
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Old 15th Mar 2013, 00:47
  #981 (permalink)  
Machinbird
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 77
Posts: 1,458
Originally Posted by cockney steve
Each of the 24 sub-cells should be heat and electrically insulated in a ceramic enclosure and connect to the cell's internal busbar/strap via a fusible link...thus any failed cell will automatically drop out and allow the whole battery to stay on-line at correct voltage (though capacity reduced by 1/3 due to the weakest link in the series-arrangement.
Wouldn't the battery take up a considerable volume with all those additional features?
How would you propose to detect that a portion of the battery's capacity has taken a vacation? Are you sure that the weaker cell will not just deliver more current per plate as it tries to keep up with the applied load and then completely destroy itself?

Maybe it would be better to discharge a defective cell under controlled conditions and then crowbar across it with a contactor. You would have full rated amperage at ~4 volts less potential. Would the loads still run satisfactorily under those conditions? Probably, although the engineers might have to tweak the load characteristics a bit.
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