AGM batteries on the Cheap

In November 2006 the telco here replaced a good number of batteries. I was wondering what would be the better way to go. For $21.20 each The Lucent 4VR125E is a 150 AH @ the 20 hour rate AGM, made by Deka. Every one that I have tested have been fully charged except the ones with cracked cases. One option with the 4VR125E is go with 3 strings @ 48 volts to get 450 AH at the 20 hour rate. These are 4 volt units Valve regulated AGM non spillable, and weigh 53 pounds. They have a design life of 12 years and have been floated to be ready in case of emergency backup by the phone company. Each 4 volt unit can be disassembled by taking the top off and exposing each 2 volt cell with the copper buss bars that connect them together. They would still be sealed units.. Very cool. So if one cell fails, just take it out and insert another one because there will be a whole string of spares. Each string of 150 AH @ 48 volts would be $254.40 or 150 AH @ 24 volts for $127.20. I was thinking of buying 4 strings and attaching all of them to a buss bar turning one string off for a month and using 3 strings to get 450 AH @ 48 volts. The other string could be switched on after a month and the next string could rest for a month making sure to charge the rested string before putting it back onto the buss bar. When any cell fails, it will just be a matter of replacing each cell or 4 volt unit as there will be spares available. Then they can be charged as 24 volt, or 12 volt strings and still rotate a smaller number of cells, but this would require more than a switch, and they would have to be physically placed in the string and rotated that way. So 450 AH @ 24 volts with an entire extra string of replacements would cost $508.80, or if I go 48 volts $1017.60. Not too bad for high quality maintainence free valve regulated AGM batteries. The terminals are in front and screw on type. Here is a link to them found by Jim (Thanks)

Is my reasoning sound? When most strings fail it is usually because of only a single cell or only a few, so if there are a whole string of spares it could keep the pack alive for the longest period possible. Is this a wacky idea? I was thinking about those off brand $145 L-16’s for $1160, but they wouldn’t have any spares and they would require much more maintenance than AGM batteries.

Thanks in advance,

Skip in Kansas City, Missouri