[Nicko]

Anyone else getting the 'Stop Start Not Ready, Battery Charging' message on their Jeep Grand Cherokee? It popped up on mine, and I’m trying to figure out if it’s just a minor annoyance or something more serious. Could it be related to the main or auxiliary battery? Let’s troubleshoot this together!

I've had that 'Stop Start Not Ready, Battery Charging' message pop up on my Grand Cherokee too, and yeah, it’s annoying as hell. After doing some digging, I found out this usually means the Stop-Start system is acting up because of one of the batteries, or something in the charging system. Here’s the lowdown from my own experience:

1. Auxiliary Battery

First off, the smaller auxiliary battery is the usual suspect. It’s the one that powers the Stop-Start system, and if it’s not holding a charge, that message is gonna keep popping up. If your aux battery is getting old, this is probably why you’re seeing the message.

Grab a multimeter and check the voltage on that little battery. You’re looking for something around 12.6 volts when it’s fully charged. If it’s way lower, time for a new one. Replacing it isn’t the hardest thing, but it’s a bit of a pain because of where they’ve stashed it—get ready to squeeze into some tight spots.

2. Main Battery

Don’t forget about the main battery either. If it’s not charging properly, the car might focus on keeping it juiced up instead of running the Stop-Start, so you get that annoying message. This can happen if your main battery is getting up there in age, or if there’s something funky with the charging system.

Check the main battery’s voltage too. If it’s under 12.4 volts when the car’s off, or if it drops like a rock when you start the engine, you might need a new one. If both batteries seem fine, the alternator might be having a bad day, so it’s worth checking that out too.

3. Battery Management System (BMS)

Another thing to consider is the Battery Management System (BMS), which keeps an eye on the charging process for both batteries. If the BMS is on the fritz, it might not be charging the aux battery properly, hence the message.

You can try resetting the BMS by disconnecting the negative terminal of the main battery for about 10-15 minutes and then hooking it back up. Sometimes, this little reset does the trick. But if the BMS itself is busted, that’s a whole other headache, and you might need to get it checked out by someone who knows their stuff.

4. Parasitic Drain

If you’ve swapped out the batteries and that damn message is still there, you might be dealing with a parasitic drain. Basically, something in your Jeep is secretly draining power even when everything’s turned off, leaving your batteries low.

To track down a parasitic drain, you can use a multimeter to check the current draw when the Jeep’s off. If it’s higher than it should be, you’ll need to pull fuses one by one until you figure out which circuit is the sneaky culprit.

5. Software Updates

Believe it or not, sometimes it’s just a software glitch. Jeep has rolled out some updates that address these battery issues and the Stop-Start system being all weird. If you haven’t updated the software in a while, it might be time to hit up the dealership.

Swing by your dealership or a good mechanic and ask them to check for software updates. These are usually free if your Jeep is still under warranty, so it’s worth a shot.

And hey, if all else fails, just remember—it’s probably not the end of the world, just another one of those Jeep quirks!