Project Chevy Tahoe: Bringing our charging system up to PAR

Wrangler Power Products

Apr. 01, 2004 By Dean Waters
With the transformation of Project Tahoe into our chase vehicle and off-road play vehicle, we were in need of an electrical system upgrade. We had already plugged in one set of lights and plan on a full set of additional electrical accessories. We are even looking at installing a receiver-mounted winch.

We have used Wrangler NW Power Products in the past and know they are of excellent quality. W e decided to install a dual battery system with Wranglers trick battery manager and a high output alternator. Wrangler makes a dual battery kit for just about any vehicle, including most late models. Each kit can be customized to your needs and your application.

The dual battery kit for the Tahoe was the Chevy - GMC 1996-1999 kit. Our Project Tahoe already had a tray mounted opposite from the main battery on the drivers side - most won't have this, but it depends on the option packages from the factory. Our vehicle also has the 105amp alternator, which is larger than most. Most will have the 70amp alternator. We chose to upgrade to the Wrangler Powermate 155 amp alternator which is mounted in the same size case as our original but it will use an external regulator. The Powermate alternators are constructed with premium components. The Power Boss external voltage regulators feature visible LED's for diagnostics. The regulator will show red when battery power is on, green when ignition is on, and amber when field voltage is on.

The regulators are compatible with the OEM computer systems and come with a large finned heat sink to keep them cool. The regulator also features a secondary main battery sensing circuit so that the system will provide more accurate charge rate to the batteries for longer battery life.

This is the new Powermate on the left and our old alternator on the right.
All terminals on the new Powermate are VERY clearly labeled.
At the core of the dual battery system is the battery isolation relay. You can use the relay alone or with the optional battery manager kit. We chose to add the battery manager kit which includes a dash mounted mode switch. The battery manager definitely qualifies as "cool". With the battery manager you have three modes of operation that can be controlled from inside the cab.
  1. DUAL - ON _ MODE
    This is the normal position and the led is green. Switch is to the left. The vehicle starts using main battery only. Both batteries charge while motor is running. The batteries are totally isolated when ignition switch is off, start, or accessory position.

  2. AUX - OFF - MODE
    The switch is in the center position and the LED is clear. Only the main battery is charged. Circuits connected to the AUX battery still function. If the aux battery fails then the alternator is protected as the aux battery is totally disconnected.

    The switch is to the right and the red LED is lit. This connects both batteries when the ignition is off or on. You can jump start yourself if the main battery is too low to start the engine. Both batteries are joined.

This is the Power Boss external regulator with LED diagnostics.
Optional Battery Manager kit with dash mounted switch.
What else is in the kit? You will find heavy duty premium grade fine strand welding cable. All ends are pneumatically crimped and have polarity marked heat shrink tubing installed. Special side post battery hardware is included. These are also good just to replace the crummy OE side posts. The stud is machined out of brass and can be stacked to add a second power tap. Large 150 amp fused link is included. What else is needed? You will need a second battery. Bad batteries can cause alternator problems. We are big fans of the Optima Batteries. They are sealed and can be mounted at any angle. They are rated for 800 cold cranking amps, stand up to the abuse in an off-road vehicle, recharge quickly and require no maintenance. We used a red top but Optima also builds a yellow top deep cycle unit if that fits your needs better. The Optima's are UPS shippable and available from Wrangler NW right along with the rest of your order. You will need a good belt to turn the new alternator. It is important to use a premium quality belt such as the Dayco, Goodyear Hi-Miler or Gates Green Stripe. Installation
We started by installing the new Optima Red Top battery in the driver side tray.You will probably have to install a second tray also. Ours already had two.
Next we removed the serpentine belt and the stock alternator. The same brackets will be used for the new alternator.

The new Powermate alternator installed in the original location. You will want to install a NEW belt sized for the large alternator.
We mounted the new isolation relay and external voltage regulator on the supplied bracket. NOTE: We put a slight angle on the bracket so that it would fit in closer to the firewall.

It is difficult to see but the relay and regulator are mounted underneath the ABS brake module.
Next we attached the regulator harness and then routed that across the top of the motor to the alternator. It is protected by split loom covering.

We attached the new wires to the relay then routed one to the auxiliary battery and the other over the fan shroud and to the 175 amp fuse.
We attached the new 175 amp fuse then on one side the cable from the isolation relay, the main battery, and the OE cable feeding the main fuse panel. On the other side we connected the main charge cable to the new alternator and used one of the OE cables to connect to the utility stud on the alternator.

This shows the new charge wire from the Powermate alternator to the fuse.
You can see the cable coming from the relay over the fan shroud and the other new cable feeding from the fuse to the main battery.

The Battery Manager harness is connected to the Isolation relay.
The other end of the Battery Manager needs to be routed through the firewall. You will need a 1/2" hole to fit the end through. The red connector hooks to an ignition source that is ON in RUN position only.

The Battery Manager switch connects to the harness you passed through the firewall then can be mounted to your dash.
131 amps at idle! NICE
Summary All the components are top notch. Wrangler NW Power Products has Dual Battery kits and high output alternators to fit just about any vehicle. Each kit is then customized to fit YOUR application. Take your time and the installation is not that difficult. The Wrangler NW tech support should be able to help you through any snags that you run in to. If you plan on upgrading your charging system we think Wrangler should be at the top of your list.
Contact Information

Wrangler Northwest Power Products
1-800-962-2616 | 503-235-4110

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