Dealing with Dual-Battery Electrical Gremlins

While I am usually a stickler for having things in tip-top shape on the 4Runner, this past winter beat out of me the desire to chase down some electrical weirdness going on with my dual battery setup.  With warm weather here, and the desire to have 2 fully juiced batteries, it was time to face the beast electrical beast.

First, a little background on my setup for the past ~3 years I have been using the IBS-DBS dual battery system in the 4Runner.  The system was simple to install and automatically connects/disconnects the batteries based on whether the truck is running/not running.  The system features a 200amp engine-bay mounted relay and a cab-mounted monitor/interface.

I also chose to install an optional Relay Booster Module (“RBM”), which basically lowers the likelihood of ruining the 200amp relay if you need to jump the truck from the aux battery, and the starting battery is at super-low voltage.  To be honest, I don’t have the capability to explain exactly the mechanics/engineering behind it, and I may have fallen victim to some decent marketing…

With the IBS system I have been running Sears Die Hard Platinum Batteries: a massive Group 31 in the starting position, and a group 34 in the Aux position.  If I had to do it over, I would run a group 34 in both spots – the group 31 is MASSIVE and overkill in this application as a starting battery (weighs over 70 pounds…).

Up until about 4-5 months ago, all was well and good with the system.  Then, all of a sudden, some weird things started happening.  First, the aux battery didn’t seem to hold a charge.  Even in mild 50-60 degree weather, the aux group 34 battery was low on voltage from powering the ARB fridge, whereas a healthy full-charge battery would last at least 2-3x that duration.

I also experienced some inconsistency in the IBS linking the batteries while the truck was running and the aux was low on voltage.  I assumed this was due to a battery issue, but it being cold (and me being lazy) decided to deal with it when the weather got warmer.

Then, things got weirder.  I started getting an intermittent “buzz” coming from behind the dash, or least that’s where I thought it was coming from.  Nearly drove me insane.  I finally traced it back to the IBS system’s 200amp relay, which was linking and unlinking so rapidly that it was buzzing.  I assumed I had a bad connection somewhere and added it to the list of things to address, and figured maybe the same bad connection was draining the aux battery.

So, with camping/adventuring season upon us, it was time to get this crap sorted.  Step one was to redo my original battery connection with higher-quality crimps.  Mark and I systematically redid all of those connections one Saturday afternoon and hoped for the best.  Unfortunately, the same battery weakness and buzzing came back!

On to the next step – I assumed the relay itself was bad.  Fortunately Sierra Expeditions has replacements for $29.99, so I ordered one and hoped that’d cure my woes.  Nope.  I had about 5 minutes of buzz-free driving before it came back and I was tempted to aim the truck at the next telephone pole I passed.

At this point, I knew I needed to do what I had been avoiding, and take that group 34 battery back to Sears.  The Die Hard Platinums come with a 48-month full-replacement warranty, and I had my original receipt, but I have heard recent forum rumblings about Sears not honoring their battery warranties.  With that in the back of my mind I trekked to the local mall and braced for what surely would be a tussle.

Fortunately, I found the folks at Sears to be helpful.  They tested and attempted to recharge the battery, but were pretty quick to declare it “no good” and set me up with a brand-new replacement.  They did ask me to pay a ~$30 price difference for the new one (I got the original on sale).  In exchange, I had a new sales receipt with a fresh 48-month warranty.  Score!

Feeling great, I muscled in the new 50lb+ group 34 and assumed that everything was good (new connections, new relay, and new battery).  Wrong again.  Like clockwork, the bus still showed up.

With the truck running and the relay buzzing, out of frustration I started shaking battery cables and wires.  On that little fit I hit the Relay Booster Module mounted next to the relay and the buzz turned to stutter and stopped momentarily.  I had found the culprit!  At some point, water must have gotten in a mucked it up.  Since the RB is an optional add on, I quickly removed it, reconnected everything, and voila!  No more buzz, 2 perfectly charged batteries, and a camping-ready electrical setup.

There’s no golden lesson in this story, but here’s what I did learn from this:

• Electrical problems will drive you insane
• There may be more than one problem (I had both a bad battery and a bad RBM)
• Be systematic in checking for problems, and better yet, use a multimeter (I didn’t, but should have)
• Save receipts for big, warrantied purchases!
• Once you do finally figure out WTF is wrong and rectify it, you sure do feel good!

Happy Camping (and wiring, and troubleshooting)!