Chargers
Charging problems & solutions
Problem → explanation → risk → solution → tool → product. Find the right charger and steps for dead battery, won't hold charge, slow charging, overcharging, wrong charger, wrong voltage, and parasitic drain.
Charging problems usually fall into a few categories: the battery won’t hold a charge (dead or failing), it charges but goes flat again (parasitic drain, alternator fault, or end-of-life battery), charging is too slow (wrong mode, low charger output, or battery capacity), or something is wrong with how you’re charging (overcharging, wrong charger type, or wrong voltage). Each problem has a different cause and a different fix—using the wrong charger or leaving a battery flat for too long can make things worse.
On the pages below we walk through each problem: what’s going on, what can go wrong if you ignore it, and what to do next—including which charger or tool to use and when to consider battery replacement instead. If charging doesn’t fix the issue, we link to our diagnostics and Battery Fitment Finder so you can decide whether to replace the battery or investigate the charging system and parasitic drain.
Dead Battery
When your battery won't hold a charge or fails a load test, charging may not fix it. Learn when to recharge vs replace.
Battery Won't Hold Charge
If the battery charges but goes flat again, causes include parasitic drain, alternator fault, or end-of-life battery.
Slow Charging
Charging takes longer than expected? Check charger output, battery size, and that you're using the right mode (AGM/EFB).
Overcharging
Overcharging damages batteries. Use a smart or float charger with the correct voltage and avoid leaving conventional chargers on indefinitely.
Incorrect Charger
Using the wrong charger type (e.g. lead-acid only on AGM) can reduce life or damage the battery. Match charger to battery type.
Wrong Voltage
12V batteries need 12V chargers; 6V systems need 6V. Wrong voltage can cause dangerous overcharging or undercharging.
Battery Draining
Battery drains when parked? Parasitic drain, faulty alternator, or a failing battery. Diagnose before choosing a charger or replacement.
Parasitic Drain Support
When you have a known parasitic drain, a maintainer can keep the battery topped up until the drain is fixed.
If charging doesn't fix it
A battery that won't hold a charge after proper charging may need replacing. Use our battery diagnostics and Battery Fitment Finder to find the right replacement.
Explore the chargers pillar
Move between charger types, use cases, battery compatibility, problems, guides, and tools. For diagnostics and battery choice, use the links below.