BatteryMINDer Plus $19.99 (Cyber Mon Sale) @NorthernTool.com

The float charger at Harbor Freight is nowhere near the equivalent of the Battery Minder. It does not have the desulfation feature and the quality is much less. I tried the HF device on farm equipment batteries over the winter twice and both failed in a couple of months. I had been using a Battery Minder on my motor home to keep the engine battery charged while parked for several years and switched to one at the orchard. Still working fine after five years according to the new owner.
Specs for the Battery Minder.
BatteryMINDer® Model1500 includes full-time automatic high frequency pulse desulfation (not high voltage), which helps extend the life of a battery up to four times over its normal life. The unit can maintain up to four 12 Volt batteries at one time when connected in parallel by using SmarTechnology™ Y-Connectors (part# 210AY) or customer supplied 18-Gauge insulated wire