When you charge your battery, the charger gets hot after a while. It doesn't matter if it's a small cell phone charger or a bigger EV vehicle charger — this is something users commonly notice. So why does this happen, and what can you do about it to better protect the charger and extend its working life?
Why Do Chargers Get Hot? The Root Cause
Put simply, the charger body temperature increase is due to energy loss from inefficiency. Not all energy can be converted from AC to DC at 100%. Some power is lost in this conversion process — typically as heat.
Normally a charger efficiency is 93–95% at best. This means that 5–7% of the input power is converted into heat rather than useful charging energy. This is fundamental physics and cannot be completely eliminated — only minimized through good engineering.
The maximum surface temperature of the BSL metal enclosure is ≤ 65°C, with stable temperature rise and efficient heat dissipation over the wide operating temperature range of −34°C to 50°C. Our charger components are rated to withstand up to 60°C / 140°F without damage.
This is a normal situation — the components inside can tolerate temperatures up to 60°C/140°F without damage. BSL chargers can withstand environment temperatures of 50–55°C / 122–131°F while still working properly (the unit will automatically derate output current to avoid component failure).
Most BSL chargers come with an IP68-rated cooling fan for heat dissipation. We are also continuously working to increase efficiency and develop fan-less designs for our IP65 product range with equivalent performance.
4 Causes of Abnormal Heat — and What to Do
A slightly warm or warm-to-touch charger is expected. However, if the charger feels burning hot, that's a signal to investigate. Here are the four most common causes and practical solutions:
Excessive Continuous Working Hours
The maximum designed working hours for BSL chargers is 24 hours. Normal industrial use is 8–12 hours per charge cycle for better shift management. If the charger runs for too long, it will accumulate more waste heat over time.
Outdoor Sun Radiation
Direct sunlight is one of the most common causes of high surface temperature in IP65 chargers — and one of the most overlooked. We've observed this in many real-world deployments. When a charger works outdoors mounted to a vehicle, direct solar radiation can raise surface temperature significantly above ambient.
High Ambient Temperature
When the weather is very hot, the charger surface temperature will naturally rise higher. We have encountered extreme temperature cases in the India market where high ambient heat caused charger derating — the unit automatically reduced output current to protect components, resulting in longer charging times.
Fan Malfunction
In real-world use, the cooling fan can occasionally fail — though this is a rare event. A malfunctioning fan means heat cannot be dissipated properly, causing the charger to overheat quickly.
Summary: When to Worry, When to Relax
A hot-to-touch charger does not automatically mean it's malfunctioning. We regularly receive customer inquiries worried that a hot charger might explode — this concern, while understandable, is generally not warranted when the charger is operating within its rated parameters.
The key is that heat needs to be channeled away efficiently. Our practical recommendations:
- Ensure good ventilation around the charger at all times — never block airflow vents
- Verify the cooling fan is spinning during operation (you should hear it)
- Protect the charger from direct sunlight when used outdoors
- Respect the recommended charging cycle length (8–12 hours for industrial use)
- If the charger is burning hot and the fan is running — contact us for a professional diagnosis
If you're uncertain about your charger's behavior, send us a message with photos and operational details. Our engineering team will provide a professional assessment and, where needed, replacement parts under warranty.