Hi everyone, I’ve seen a few questions about bulging car batteries and thought I’d summarize the most common causes and what you should know. When a car battery starts to swell, it’s not normal and usually means the internal chemistry is being damaged. What is a “swollen” or “bulging car battery”? A swollen or bloating battery means the battery case is expanding or looks puffy. This can happen with lead-acid car batteries, AGM batteries, and lithium batteries. If your car battery swelling is visible, that’s already a warning sign. ️ Main causes of battery swelling Overcharging Overcharging makes the battery produce gas internally faster than it can release it, causing pressure buildup and bloating. High temperature Heat speeds up chemical reactions and can damage the battery plates. Extreme heat under the hood can make swelling worse. Faulty charging system If the alternator is sending too high voltage, the battery can be forced to overcharge and expand. A bad voltage regulator can cause this too. Old or failing battery When a battery reaches end-of-life, internal damage can cause gas buildup and bloating. Internal short circuit Internal damage (like plate separation) can cause rapid gas buildup. Again, this is a sign the battery may be failing. ️ Is a swollen battery dangerous? A bulging car battery should definitely be taken seriously. It can leak chemicals or stop working unexpectedly. If you see swelling, it’s best to stop using the battery and ask a qualified mechanic or technician to take a look. 🧪 Does swelling mean the battery is done? In most cases, yes. A swollen battery is usually no longer reliable and replacing it is the safest path. How to avoid battery bloating keep the charging system healthy avoid extreme heat when possible replace old batteries before they completely fail use the right charger settings choose quality batteries from reputable brands If you notice battery bloating, car battery swelling, or a bulging car battery, it’s a warning sign—not something to ignore. It usually means the battery is failing internally, and professional inspection or replacement is recommended.

Hi everyone, I wanted to share what I found about charging the 12-volt battery on the Mazda CX-90, since it’s a common question and is basically the same idea as “How To Charge A Car Battery,” but with a few Mazda-specific notes. First — where is the 12V battery located? On the Mazda CX-90, the 12-volt battery is usually located in the engine bay (depending on model/trim). Even if you have a plug-in hybrid version, the car still has a regular 12V battery that powers electronics, just like other vehicles. How to safely charge it (general process) Turn the vehicle completely off Key out All lights and accessories off Connect the charger Connect red clamp to the 12V battery positive (+) Connect black clamp to a clean metal ground point or negative terminal Use a smart charger A low-amp “smart” charger is recommended. It automatically stops charging when full. Avoid high-amp “boost” modes if possible because those can stress the battery. Plug in the charger Let it charge slowly. Some will take a few hours depending on how low the battery is. ️ Important Notes Don’t attempt to charge if the battery looks damaged Avoid sparks near the battery area Make sure the charger is for 12-volt automotive batteries Some versions of the CX-90 have safety electronics that prefer slow charging Jump-starting vs. charging Jump-starting only gives a temporary boost. A charger actually restores the battery. If the car repeatedly has low battery issues, there might be something draining power, and it’s better to have it checked by a professional. When to get help If you’re unsure, it’s totally okay to ask a parent, guardian, or a mechanic to assist—car batteries involve electricity and should be handled safely. Conclusion Charging the 12V battery on a Mazda CX-90 is pretty similar to charging any car battery: Turn car off Positive to positive Negative to ground Slow smart charging Safety first Hope this helps anyone who ends up searching like I did