01-07-2020, 02:38 PM
Join Date: Jul 2016
Battery Issues / No Starting / lessons learned
January brings with it battery weirdness. I've been struggling with several JK issues which I have discovered answers for. If you've ever turned your ignition key and heard nothing more than a click, let me share what I found.
The Chrysler OEM battery lasts about a year. Standard disclaimer: I'm sure your battery lasted longer. Mine dropped from 12v to 6v overnight and required me to swap it out. I've read others have issues with the OEM battery as well.
The Wrangler battery terminals are junk. Standard disclaimer: I'm sure your battery terminals work fine. My problems started when I removed the terminals during maintenance. One month later I had a dead battery. Last January with a new, recently installed battery I turned the key and the Jeep went totally dark. The shop wiggled the cable and it started right up. The issue is the design. You cannot properly tighten the OEM battery terminals. Even after a mechanic better qualified than myself tightened it, he was still able to pop it off with a simple yank using no tools. I swapped them all out and am much happier.
The replacement battery terminals are a time-tested design where the bolt tightens from the side, not from the top. I can only guess Jeep changed the design of their terminals to make it faster to install batteries on the production line. As the outside temperature rises and falls, the terminals loosen and build up resistance between itself and the post. This causes a voltage drop so the battery is starved for voltage when charging and the starter sees less voltage when cranking. When the voltage drops across the terminal to below 11v the computer gives up.
The alarm system, armed by the electronic locks, is useless and draws additional power for no good reason. Standard disclaimer applies. I've taken the advice of others on the forum who lock it manually. I also unplugged the rear hatch lock so it must be operated by key only.
Swapping the battery and terminals, and locking the Jeep manually without the "noise maker" alarm system got me 90% of the way there. There's another huge current draw - the computer(s).
"Normal" current draw while sitting in the parking lot hovers around 80ma. This doesn't sound like a huge number but during the math on an 80Ah battery is 1000 hours of stand-by power, or about 4 weeks on a fully charged battery. Most batteries won't be at 100%, so it isn't surprising that people are finding dead batteries after a week or two. They don't have to be totally drained, just low enough to drop below 11v while cranking.
I've resorted to tossing a 450ma solar panel on the dash to trickle charge the battery while it's parked. I'm not sure it's doing anything but it makes me feel better.
That leaves what all mechanics tell me, "You're not driving the Jeep enough to keep it charged." I know people have heard this from their dealer. I've searched to find the magic number is about 10km necessary to drive to top off the energy needed to bring the battery back after cranking. I'm just around that number during my daily commute.
So, I still find it necessary to throw the battery on the charger once or twice a year. It doesn't sound like a lot of maintenance but I've never had to do this with my 1997 Pathfinder. I've heard, "The alternator won't recharge a depleted battery." So, Why not?
Is there any way to increase the charging current to the battery so that I do not have to charge the battery manually? Or, am I stuck with driving a vehicle which requires recharging once or twice a year?
How often are others putting their batteries on a charger? If you drive more than 20km/day you probably "drive enough to keep the battery charged." I'm asking this of those who drive infrequently or less than 20km/day.