Home Battery chargers Can you overcharge a battery with a trickle charger

Selecting a battery for your cherished vehicle, take into account its maintenance aspects. The automotive part is to last up to 5 years. Replacing it every year would be wasteful and impractical. Therefore, the charging mode matters. Which charger to use: regular or trickle? Let’s highlight the matter.

Battery types and technologies

Nowadays, there are several battery types. Modern ones are slim, durable and handy. However, all of them are toxic and ecologically unfriendly. Top-quality components are relatively safe. The risk of exploding and fire still exists.

As to the trickle charging technology, it can be safely applied to the batteries that are:

  • lead-acid
  • NiCd
  • NiMH

Lithium-ion technology is not adjusted to the method. Being trickle charged, a Li-ion battery can get overheated or even explode. The batteries that are applied in mobile phones and notebooks are charged fast. They can’t be trickle charged that is longer than overnight. It would cause heating up and burst. Car (lead-acid) batteries are not much safer in terms of fire prevention.

Automotive battery categories

Commonly, car batteries belong to a lead-acid type. They fall into the wet cell and VRLA (Valve Regulated Lead Acid) categories. Traditional, wet cell accumulators are known as flooded batteries. They do require regular maintenance. The liquid that consists of water and sulfuric acid requires replenishing. Check its conductivity and add distilled water, if necessary.

Modern VRLA batteries are sealed. They contain the semi-solid electrolyte. Therefore, these batteries don’t evolve gas. They are safer, able to be stored and recharged in non-ventilated places and small garages. VRLA batteries are easier to maintain. Meanwhile, modern accumulators can be trickle charged anyway. The ambient temperature is to be below 20°C, when the battery is charged. Its life would be much longer.

Wet cell automotive batteries are different. For example, deep cycle batteries that are used for marine applications are designed for withstanding long-time charging. They are to be charged slowly. Being recharged fast, the batteries get hot and start discharging. So, trickle charging is the best, ideal, and, maybe, the only possible method for these batteries.

But the most common type is SLI. They need some power to Start, Light and Ignite the car. The batteries can’t be fully discharged. That’s why they need to be trickle charged. Let’s focus on their operation.

Why prefer slow (trickle) charging

A starter (SLI) battery contains as many lead plates, as possible. They are thin, but their surface area is maximum. Therefore, internal resistance if the battery is low. It decreases by the end of discharge. So, the STL battery charge is always to be over 60%. Otherwise, the battery is prone to premature aging.

Why the best trickle charger is recommended? It’s safer than a regular one. Quite naturally, being stranded on the road, you would need an immediate response. Rush the process with a jump charger.

On the contrary, a trickle charger supplies low voltage. It provides a constant current, offsetting the battery loss. For example, 2-amp charger adds about 1 ampere per hour. Overcharging is just impossible, because:

  • loading speed can’t overpass the natural self-discharge
  • when the battery charge is refilled, its internal resistance rises
  • when resistance rises, the current falls

The charging process is slowed down. Quite naturally, it’s recommended to test the voltage. Prevent overcharging, disconnecting the clamps in time. If you prefer the charger that doesn’t need babysitting, use a maintenance device. It switches off when the battery is fresh. You may leave it connected. Prefer a smart, top-quality charger. It prolongs your SRL battery’s life.

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