What Is A Float Charger? How It’s Different From A Trickle Charger?


There are plenty of different battery types on the market. Just the same, there are also different charger types, each with unique benefits. Float chargers, trickle chargers and multi-stage chargers; how are they all different?

A float charger will keep a battery at 100% without causing an overcharging condition. That’s because it can sense when the battery is full and stops charging. Then, when the battery loses some of its power, it’ll resume charging to restore the battery to maximum capacity. That’s different from a trickle charger that continues charging regardless of if the battery is full.

This guide will help you understand the differences between float and trickle chargers. You’ll also discover how multi-stage chargers factor into all of this and how each charger type can benefit you the most.

What Is A Float Charger, And How Does It Work?

A float charger is a tool used to recharge your battery, whether for your car, motorcycle, snowmobile, or anything else. 

The charger requires electricity, so you’ll plug one end into your wall socket. Meanwhile, the other end connects to your battery’s terminals through which the device delivers the electrical charge.

Like all other chargers, a float charger will restore the battery’s charge to its maximum capacity of 100%. However, it does it in such a way that it doesn’t hurt the battery if you leave it on for too long.

Usually, leaving a battery connected to a charger for too long will cause internal damage. The longer you do that, the more it’ll disrupt the battery’s internal chemistry and spoil the components inside.

You’ll often see that happen after winter has ended. Many people end up with ruined batteries after leaving them connected to a charger for extended periods.

That overcharging problem doesn’t happen with a float charger. 

Float chargers have electronic components that can sense when the battery is full and stop the charging process. Then, as some of the battery’s power dissipates naturally, it will continue recharging to push it back to 100%.

Float chargers are designed to repeat this process, keeping the battery ready whenever you need it. For that reason, float chargers are also called ‘battery maintainers’.

Read: Why Your Car Sputters When Starting But Then Runs Fine

Float Charger Vs Trickle Charger, What’s The Difference?

Float chargers aren’t the only option you have on the market, as trickle chargers also exist. The most straightforward way to understand both chargers is this: trickle chargers are manually operated (so you have to turn it off yourself). In contrast, float chargers are automatic (they’ll stop charging when the battery is full).

Trickle chargers are also designed to recharge your battery to full. However, they work differently and can ruin your battery if you misuse them.

A trickle charger works as its name suggests: it delivers a continuous trickle of electrical power into the battery. But, of course, there’s absolutely nothing wrong with that on its own.

The problem with trickle chargers is that they continue delivering that charge even when the battery has reached 100% capacity. Instead, they work at a fixed voltage regardless of if the battery is heavily discharged, only needs a bit of recharging, or is already full.

That will quickly lead to an overcharging condition with symptoms such as:

  • High battery voltage readings
  • Seepage or leakage of battery fluid
  • Bulging or curving of the battery case
  • Overheating of the battery and more

Overcharging your battery with a trickle charger can sound pretty scary. However, it’s not a problem if you disconnect the charger once the battery is full.

For example, suppose you’re going to recharge the battery for a few hours using a trickle charger. In that case, you have nothing to worry about. 

However, long-term charging overnight, or worse yet, over weeks and months, will undoubtedly overcharge and destroy the battery.

There are no such concerns with a float charger (a.k.a. a ‘battery maintainer’ which will shut itself off when the battery is full).

Read: Does a Car Battery Charge When Idling?

What About Multi-Stage And Smart Chargers?

Multi-stage and smart chargers offer the best of both worlds, combining the advantages of trickle and float chargers in one device. They’ll adjust their voltage to recharge the battery as efficiently as possible and stop charging when it is full.

A multi-stage or smart charger is capable of sensing the battery’s condition. For instance, if the battery is heavily discharged, the charger will recharge it at a higher voltage.

The charger will slow down and eventually stop charging as the battery approaches its full capacity.

These chargers are often referred to as ‘smart’ models because they can adjust according to the battery’s needs. So not only are they effective at maximizing your battery’s health, but they’re also helpful if you’re recharging several different batteries.

The adaptability of the charger will ensure that each battery receives the personalized treatment it needs when recharging to its maximum capacity.

Read: Does Jeep Have an Electric Vehicle?

Should You Use A Float, Trickle, or Multi-Stage Charger?

With so many options for battery chargers, which one should you use?

Well, here are some thoughts as to when float, trickle, and multi-stage chargers will be useful to you:

  • Trickle charger: A trickle charger will be convenient if you plan on recharging batteries for only a few hours a day. For example, suppose you want to restore a battery until it’s full to be used immediately. In that case, a trickle charger is perfectly fine.
  • Float charger: A float charger is helpful if you want to keep your battery full over an extended period, and you might need to use it on short notice. For example, it will keep a battery charged over the winter when you’re not using it. It’s also great for emergency preparedness, where you’d potentially need a fully charged battery read-to-go at a moment’s notice.
  • Multi-stage charger: A multi-stage or smart charger is excellent as an all-rounder solution. Suppose you have several batteries to take care of, each with different discharge levels and wear conditions. A multi-stage charger is incredibly convenient as a plug-and-play solution, as it’ll determine what the battery needs and adjust accordingly.

Naturally, these chargers also differ in price. Generally speaking, the more capable a charger is, the more it’ll cost you.

But don’t be tempted to buy the cheapest battery charger you can find. Whether it’s a trickle, float, or multi-stage charger, a cheap one from an unknown brand can be a more significant threat to your battery than anything else.

The best thing you can do is to invest in a high-quality battery from a brand you trust and then choose between a trickle, float, or multi-stage charger to suit your needs the best.

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Final Thoughts

The most important thing to remember is that not all chargers are made the same. For example, trickle chargers will deliver a continuous charge to the battery. Still, you must be around to shut it off once the battery is full. 

On the other hand, a float charger will always keep the battery fully charged. It’ll shut off when the battery is full and resume charging when some of its power dissipates naturally.

Finally, a smart or multi-stage battery offers a lot more flexibility. They can sense the battery’s condition and deliver the correct charge level, also shutting off once it’s full.

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