Does remaining stock carry the same warranty as new production?

Yes. Any NSB100FT RED still in stock carries the same three-year EnerSys warranty, and that term goes on the quote in writing before you order.

Should I match the old battery or replace the whole string?

If the string is more than about two years into service, replace the set. A new cell in an aged bank gets pulled down to the weakest unit's capacity, so you pay for 100Ah and get whatever the tired cells allow. Matching one unit makes sense only on a young string or a documented single-unit failure.

Is the SBS-100F a drop-in for the NSB100FT RED?

It is the successor EnerSys names for this role and it fits the same front-terminal pattern, but confirm the tray dimensions and terminal hardware against your rack before you order. Send us the rack detail and we will check it against the SBS-100F drawing rather than let you find out on install day.

What is the difference between the NSB RED and the NSB HT RED?

They are separate sub-lines with separate documentation and different warranty terms, so the numbers do not carry across. If your site runs hot, the NSB100FT HT is the one to look at. If you are unsure which is in your rack, send a label photo.

Why is there a four-unit minimum order?

Each battery weighs 71.9 lbs and moves by freight, so a single-unit shipment costs nearly what four cost. The minimum keeps the per-unit freight sane and matches how these strings get built.