Is it 160 Ah, 159 Ah or 173 Ah?

The 1600 in the part number is the series designation. CSB's published ratings are 159 Ah at the 8-hour rate to 1.75 VPC, 173 Ah at the 20-hour rate, and 156 Ah at the 8-hour rate to a 1.80 VPC end point. None of these is wrong; they are three measurements of one battery at different rates and end voltages. For telecom float sizing, use the 159 Ah C/8 figure unless your plant documentation specifies another basis.

What is the difference between the TPL121600 and the TPL121000?

Capacity and case, in that order. The TPL121000FR is 100 Ah at C/8 in a 20.16 by 4.44 by 10.11 inch case at 84.4 lbs. The TPL121600FR on this page is 159 Ah at C/8 in a 21.54 by 4.94 by 12.72 inch case at 120.78 lbs. Both are pure lead, both are front terminal on an M6 bolt, both carry the 12-year design life and the 3-year CSB term. The 1600 is over two inches taller and 36 pounds heavier, so a tray built for the 1000 will not take it.

How is a 12-year design life different from the warranty?

Design life is CSB's engineering estimate of how long the cell can serve under ideal float at 25°C. The warranty is the three-year period CSB will replace a failed unit. The gap between the two is normal across the industry and it is not a catch. Design life is an engineering estimate; the warranty is what CSB will replace.

What torque do the terminals take?

M6 bolts into I2 threaded lead-alloy inserts at 44.9 in-lbs (5.1 Nm), with a tolerance of plus or minus 9 in-lbs. That is much lower than the 110 in-lbs a 1/4-20 top post takes, and over-torquing a lead-alloy insert strips it. Use a torque wrench set to that value.

Does temperature affect the twelve-year life?

Substantially. The 12-year figure is at 25°C (77°F), and the rule of thumb across VRLA chemistry is that life roughly halves for every 8 to 10°C of sustained elevation. A cabinet running at 35°C is not a twelve-year installation. If you know a site runs warm, tell us and we will talk about whether a high-temperature line is the better buy.

I have been buying the TPL121500. Is this a straight swap?

Electrically it is the upgrade path CSB points at, and the terminal type, bolt size and torque are identical, so the cabling does not change. Capacity goes up from the 150 Ah class to 159 Ah at the 8-hour rate. The check worth doing is mechanical: CSB has revised this case line and the published width and height on older TPL121500A sheets are a couple of millimeters off this one. On a tight tray that matters, on most it does not. Send the tray dimensions and we will tell you which one you have before you commit.

How do I confirm this is the right battery before ordering?

Send a photo of the label on the unit you are replacing plus the tray dimensions. Voltage, capacity basis, terminal type and footprint are the four that have to match. We would rather talk you out of the wrong battery than process the return.