C4x4.com

The other day, before leaving on a camping trip in the family truckster, the GMC Suburban, I hooked up the electric trailer brake controller that the previous owner had unplugged from the 12V source at one of the factory dual batteries. After that, the truck would not start...just a nice click when the key was turned. I had noticed some corrosion around one of the terminals that may have been the culprit. A check across the batteries showed 12V on one and 10.7 on the other. the 12v battery was the starting batt, supplying current to the starter. The low batt was the one activating the starter solenoid which it was doing, but 10.7V with no load is not so good. Either it was not getting a charge or it was failing.

Looking at it further, I found corrosion on the kead to the starter motor and this was causing the starting issue. Since I had two issues: poor connections and a low battery charge on one batt, I fihured it would be a good time to ensure we could get to our destination and back without having to Fred Flintstone the 'Burban.

I chose two Optima Red Tops, known for good starting performance and rugged construction. I chose to repalce both batteries at the same tiem to give them an even chance of charging well together.

To begin with, I disconnected the negative cables fom each old battery. I don't want to practice welding with a box wrench from getting things grounded out!

i found out one of those nasty little surprises that makes working on a truck so much fun. It should have been real simple to onbolt the factory battery hold-down block from the driver side battery tray, but it was seized to the captured nut in the pastic tray. Spin, spin, spin. I had to pry the battery out and unbolt the entire tray, cut the bolt and nut out with an angle grinder and a thin cut wheel and then cut a regular bolt to fit the hold down. OK...back to installing things.

The Optimas come with all kinds of widgets to adapt then to various vehicles. For the GM, you need the shaped triangle thingy in my hand. It fits the shape of the battery and replaces the factory one.

I have used silicon grease on all electrical connections on my builds and rigs for years. It seemed like a good idea here as well once I cleaned all the corrosion off the battery cables. Voila! A turn of the key and we have starting power, baby! I also confirmed that both batts were getting a good charge from the alternator. Good to go.