Help me maintain my 12V AGM battery for backup sump pump

[Barley]

I have a Wayne ESP25 12V backup sump pump. The original battery seems to have died. It seems to charge normally and shows good voltage, but can no longer power the load. I've read that this is a tell-tale symptom of an overcharged (and now dead) AGM battery.

I have a new Trojan 75ah AGM battery now, and want to keep it for as long as possible. The wall wart that comes with the backup sump pump system is 2.5a and seems to float the battery at 14.1-14.2V. I'm thinking I need a different charger to keep it at closer to the Trojan recommended 13.5V float.

I'm thinking I have 3 options: 1) just use the wall wart and get a new battery every 1-2 years, 2) Noco Genius G7200 in 13.6V Power Supply Mode, or 3) find a used Astron power supply (but it would float at 13.8V unless I can find a variable voltage one. Also, I don't know if I am capable of doing the required mods).

I know options 2 and 3 can be expensive but I would at least be able to use the devices to charge other batteries as well. Suggestions?

[NEOH]

Constantly over-charging at 14.1 - 14.2 Volts does reduce the battery life.
Selling you replacement batteries, may be part of their income stream.

It would be best if you purchased an off-the-shelf 3-stage AGM charger with Bulk, Absorb (14.4) and then Float (13.8)
They are not expensive.

[Barley]

It would be best if you purchased an off-the-shelf 3-stage AGM charger with Bulk, Absorb (14.4) and then Float (13.8)
They are not expensive.

Thank you Neoh. I have a BatteryMinder 1500 that does 1.5a 14.4 Bulk, Absorb and 13.4 Float, and a Battery Minder 2012-AGM that does 2a 14.7 Bulk, Absorb and 13.6 Float. Should I be concerned about the charger forcing bulk/absorb every time the battery is drawn down slightly by the pump? I was under the impression I should be looking for a straight float charger but maybe I'm wrong.

[NEOH]

If you only Float Charge at 13.7 Volts then it will take in infinity hours to recharge.
Recharge immediately ( Bulk and Absorb per Trojan's specs ), then Float forever,

[PNjunction]

The Noco 7200 would be the better idea. However these days, my most recommended charger for serious AGM maintenance on a system 100ah or less would be the Tecmate - Optimate 7 Select.

Safe and easy enough for Grandma (apologies to grandma's everywhere!), and battery nerds like me that like to take advantage of what the blinken-lights mean. Hook up and walk away, or geek out and watch with nothing to set. (aside from the 14.4 / 14.7v select switch depending on your agm).

Yeah, it's expensive compared to the usual suspects. But so is your battery. And the smartest float algorithm I've ever seen, especially for agm.

[Barley]

Thank you PNJunction. I've been reading many of your posts about chargers.

Is my concern about using a multi-stage charger unfounded? Granted, most of the time the battery will be simply floating. I intend to cycle the backup sump pump every few months by unplugging the main pump and letting the backup handle duties for a couple of hours. But what if the pump only comes on briefly for a temporary power outage and the battery is only slightly discharged? Or what if I wanted to use this very nice charger on another battery for a while? Would a full cycle of bulk/absorb/float overcharge the battery vs a constant float? I don't need the battery to charge very fast unless I'm in a long term power outage situation which should be very rare.

Given that should I use the power supply function on the Noco or Tecmate instead? Thanks for your insight.

[Barley]

I snagged a Tecmate Optimate 7 Select for $89.90 on Amazon. Wasn't going to buy one but couldn't resist the price. It's still available for that price when you select Amazon.com as the seller. They quote a 1-2 month delivery time but I can wait.