Forget about decibel dweebs-those Civic-clad audiophiles addicted to hubcap-sized subwoofers and juice-sucking mega-amps. Off-roaders create vehicles with the most elaborate electrical systems. Winches, air compressors, halogen lights, fridges, CBs, and even a simple CD deck all combine to create a voracious volt-eating monster. Yes, that giant sucking sound you hear is your amp meter plunging to the right as you flick yet another toggle switch.
Which explains why multiple battery systems are becoming as common as lift kits and all-terrain tires. The OEs have offered dual battery options for years, usually placing the secondary battery in the engine compartment adjacent to the primary one. Dual battery mounting kits are promoted in the aftermarket as well. The trick with multiple batteries is keeping each one fully charged and ready to perform its appointed task.
This challenge inspired Painless Performance to introduce the MasterMinder (PN 40104), a 12-volt energy manager for any vehicle that uses more than one battery. MasterMinder allows you to power up accessories such as winches and high-voltage lights without leaving you stranded. According to Painless, it virtually eliminates the possibility of a dead battery. It sounds too good to be true, but the MasterMinder can make such a boast due to its sophisticated, microprocessor-driven innards. When properly installed, the MasterMinder automatically increases amperage for more positive starting and allows you to jump-start one battery with another with a simple turn of a knob. It detects voltage drops and automatically charges the needy battery to full strength and will alert you, via LED lights, to each battery's condition.
The MasterMinder is operated by a control panel with a six-position mode switch. In Main Only mode, the system totally isolates the main battery and no auxiliary battery connections are made. In effect, the vehicle is operating as though MasterMinder weren't installed.
When set to Normal, the auxiliary batteries are connected to the main battery for starting and charging anytime the ignition is switched on. At Normal, MasterMinder monitors the state of charge of all batteries. This is the setting most often used.
In Main+Aux 1 mode, the main and first auxiliary battery are connected at all times regardless of ignition switch position. Main+Aux 2 mode does the same for a second auxiliary battery. Maintainer mode connects all batteries to the optional Master/Maintainer charger (PN 40114), which runs on a 110-volt power source. Finally, there is Emergency mode, which ties all batteries together for max amperage.
To see how well MasterMinder performed in the real world, we recently installed one on a '96 Dodge Ram 2500 4x4 pickup with a Cummins Turbodiesel. Installation on the Ram was simplified somewhat by the factory, as the rig came with a factory-installed second battery. However, Dodge connected the batteries in series, whereas the MasterMinder requires auxiliary batteries wired in parallel. This was easily changed using the existing battery cables, as you can see in the photos.
You'll need a few extra goodies when installing the MasterMinder. Painless does not include battery cables or battery terminals because the possibilities for battery placement are endless. Painless recommends purchasing the highest quality battery cables you can find-minimum of two-gauge, with quality crimp-on terminals. You'll also need an inexpensive test light to search your fuse panel for an ignition-on hot wire.
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