Short Answer: Deltran’s claim that the 1.25 amp Battery Tender Plus battery charger will charge a battery in the same amount of time as a typical 3 amp charger is based on the fact that the Battery Tender Plus charge current is very nearly constant during the bulk charge period, while a typical 3 amp charger, configured like so many chargers on the market, is not. Detailed Answer: You would think that a 3 amp charger would recharge a battery roughly 3 times faster (actually only 2.4 times faster) than a 1.25 amp charger. There are 2 main reasons why this is not true. First, the way a battery reacts to charge current is complex. The simplest approximate calculations for recharge time only work for about the first 75 or 80% of the charge and only if the charge current is nearly constant. Returning the last 20 to 25% of the charge to the battery is also a complex and time consuming process. It may very well take as long to return the last 20% of the battery charge as it took to return the first 80%. Second, and just as important, is the way that battery charger manufacturers rate the output current of their charger products. Let’s say that the 3 amp rating is based on a peak current value during the initial charge phase and the 1.25 amp rating is nearly constant for entire time that it takes to return 80% of the battery charge. Let’s also say that the 3 amp current only exists long enough to return 10% of the battery charge and then it tapers down to 1 amp for the next 70%. The dimensions or units describing electrical charge are the Coulomb or, more conveniently in the context of battery charging, the Amp-Hour. The abbreviation for amp hour is Ah. A battery charger delivers charge (amp-hours) to the battery by using an electrical current (Amps) at its output over a period of time (Hours). The numerical product of the electrical current and time period is the amount of charge delivered. This is true in a general sense for any charger. Now let’s do some math. For a 100 Ah battery, 10% = 10 Ah, 70% = 70 Ah, and 80% = 80 Ah. 10 Ah / 3 A = 3.3 Hours, 70 Ah / 1 A = 70 Hours, So this particular 3 amp charger takes 73.3 hours to return 80% of the charge to a 100 Ah battery that was fully discharged. 80 Ah / 1.25 A = 64 Hours, so a nearly constant 1.25 amp charger (that would be the Battery Tender Plus) takes only 64 hours to return 80% of the charge to a 100 Ah battery that was fully discharged. Marketing and sales people like big performance numbers because they believe that those numbers enhance the perception of value. The truth is that the best value for a battery charger should be based on the total cost of ownership for both the charger and the batteries that it is charging and maintaining. If a charger has a smaller output current rating, but recharges the battery in less time, and if it maintains the batteries in a full state of charge by employing a float / maintenance function those are both good things help to make the batteries last longer. Of course, the Battery Tender Plus does both of those things very well.