QX Hybrid Battery Issues: Starting Problems & Dim Lights

Hey there! I've had some experience with hybrid systems (medium level expertise here). Actually went through something very similar with my 2018 Infiniti Q50 Hybrid last year, and my owns a QX50. The symptoms you're describing sound exactly like what I faced weak starts, dimming lights, the works. Turned out my 12V auxiliary battery was failing, not the main hybrid battery. Took it to my trusted workshop, and they confirmed it with proper diagnostics. Total fix was around 290€ including labor and a new battery. Before jumping to conclusions though what's your mileage and how long have you had these symptoms? Also, did you notice if it gets worse in cold weather? This info would help confirm if you're dealing with the same issue I had. Quick tip: If it is the 12V battery, don't wait too long to get it fixed it can start affecting other electrical systems.

Thanks! My QX has 196404 KM on it now, and yeah these symptoms started showing up about two weeks ago. It definitely gets more noticeable in the mornings when it's cooler. Just had my latest service a month back, and everything was fine then. Your battery situation sounds spot-on with what I'm experiencing. Really helpful to hear it wasn't the main hybrid system. Think I'll get the 12V checked first before looking at anything more complex. Did you notice any warning lights on your dash before replacing the battery?

Hey again! Yes, I remember dealing with this exact situation on my Q50 Hybrid. Before I got the battery replaced, I did notice the battery warning light would come on intermittently, especially during cold starts. It wasn't constant though would flicker on and off, which actually made it more confusing to diagnose at first. With your mileage at 196404 KM, it's definitely in the range where 12V batteries typically need replacement. Mine was showing similar symptoms around 180000 KM. The timing of your symptoms (two weeks, worse in cool mornings) is exactly how mine started too. The fact that it began after your service is probably just coincidental these batteries tend to fail gradually and then suddenly get worse. One thing I didn't mention in my first reply I also noticed that my key fob seemed to work intermittently before I got the battery replaced. Did you notice anything like that? It's another common symptom with failing 12V batteries in these Infinitis. Just a heads up when I got mine replaced, I made sure to get an AGM battery specifically designed for hybrids. Made a huge difference in performance and longevity. Worth the extra cost if you ask me!

Thanks so much for all this detailed info! You just described my situation perfectly even the key fob acting up occasionally, which I hadn't connected to this problem until now! I'll definitely look into getting an AGM battery specifically. Really relieved it's likely just the 12V battery and not something more serious with the hybrid system. Going to call my local workshop tomorrow and get this sorted. The fact that yours started having issues around 180000 KM makes me feel better about my situation at 196404 KM seems like this is just normal wear and tear. Really appreciate you taking the time to share your experience. It's saved me a lot of worry about potentially bigger issues!