Why Does My Black & Decker Charger Say ‘Flo’?

If you're wondering what the code "Flo" that's flashing on your Black & Decker charger's display screen means, you've landed on the right page. We've researched what it stands for, and we're sharing the answer with you.

"Flo" stands for floating mode. It means that the battery is already fully charged, and the charger has transitioned to the maintenance stage of charging. It will monitor the battery charge level and send a small current when needed so that the battery will stay at full capacity.

Keep on reading to learn more about this code on your Black & Decker charger. We'll also tell you about the fault codes that you should watch out for. This article will also answer if you can leave your charger on the battery and how long it'll take a Black & Decker charger to recondition a battery. Let's begin!

What does 'Flo' mean on a Black & Decker charger?

It's always handy to have a battery charger in your tool kit. You never know when you're going to need it. Your car battery might die when you're stuck in traffic during a hot summer day as you've got the AC on high with your stereo blasting to keep boredom and irritation away. These electronics can take their toll on your alternator and battery.

A Black and Decker portable car battery charger

Instead of requesting roadside assistance and having your vehicle towed, you can recharge your battery so that you can be up and running again within a few minutes.

It's better when you have a Black & Decker charger with you that features a 75 amp engine start that allows you to start your vehicle in just 90 seconds. It also comes with a built-in alternator checker so that you can determine if it's doing its thing in maintaining your battery charge.

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Besides, Black & Decker charges 40% faster than other chargers, so you can be back on the road in no time. It's portable, easy to use, and versatile. It can be used on AGM, GEL, and WET battery types. You can also use these chargers not just for your car but also for lawn tractors, RVs, boats, and snowmobiles, among other equipment.

You just connect the charger clamps to the right battery terminals and press "charge." These are automatic chargers, so they'll do the monitoring for you. 

The best part about these chargers is that they make communicating with you so easy. You know the status of your battery charging through the digital LCD display screen with its easy-to-understand lights, icons, and codes.

Black & Decker chargers undergo a 3-stage charging process. Once the battery reaches its full capacity, the charger automatically switches to the maintenance stage.

When you see 'Flo' on the display screen, it means that the charging process is already in Float mode. The Float Charge light on the LED indicator should also light up. This is the maintenance stage of charging wherein the battery is already fully charged, and the charger will only send minimal current to the battery, just enough to keep it full. This way, it is ready for use and can be expected to be at its top performance.

What does the fault code on my battery charger mean?

A Black & Decker multi-voltage battery charger

To understand how your Black & Decker charger works, you need to know what the fault codes stand for. This is your charger's way of communicating with you to guide you on what to do next so that you can charge your battery to optimum levels.

These are Black & Decker's chargers fault codes that tell you why it's not charging your battery. We've also included what you need to do in each scenario.


This code could mean two things. The charger can't proceed with sending current to the battery because there's more than enough load on the battery, or it is internally shorted.  

Check the electrical loads connected to your battery while charging and remove those that are not important so that the battery won't be overloaded.

An internal short in a battery or short circuit can have different causes, that's why you need to have it checked at your auto service center to find out what can be done about it.


This tells you that the battery is not connected properly. It could also mean that the battery's voltage has gotten too low to the point that it cannot be charged anymore.

Check the wiring in the battery and see to it that it is connected properly. If this doesn't fix the issue, you can use a voltmeter to find out your battery's voltage. If it is indeed too low to accept any charge, you need to take it to your trusted auto service center so that they can take a look at it.


Again, this could indicate two things: the battery is not charging because of sulfation, or there is an internal open cell. 

If sulfation has occurred, you can try to recondition the battery. Black & Decker chargers have a "Battery Reconditioning Mode" that can help dissolve the formation of lead sulfate crystals on the surface to make it easier for the battery to receive a charge.

If it's an internal open cell, take the battery to the auto service center to see if it can still be saved. 


The battery won't accept a charge anymore after charging it for 18 hours or more. This isn't supposed to happen since you can leave a battery connected to the charger for an indefinite period. It could indicate an internal problem with the battery, so you need to have it checked by a pro.

It could also be that you've set the battery charge rate to a low setting. In this case, you just need to set the charge rate higher. 


The booster cables positive terminal and negative terminal with charging car battery by car jump cables.

Black & Decker chargers have safety measures to prevent overheating because it could damage your battery when it happens.

When you see this fault code, disconnect the charger and give it time to rest so it'll go back to regular temperature. Thirty minutes of cooling time is recommended. You should also check if there's good ventilation in the area to ensure that there's proper airflow.


This is your charger's way of warning you about reverse polarity. It means that the charger clamps are attached to the wrong battery terminals. This could lead to battery damage if it isn't detected.

Make sure that the clamps are connected to the right terminals before you proceed with charging.


The system has detected that the alternator is not behaving properly. Its output is not normal. You need to have it checked at your auto service center.

You can also call Black & Decker's customer support for assistance when you encounter problems while charging your battery.

Can you leave Black & Decker batteries on the charger?

Battery being charged with a small battery charger

It is dangerous to leave batteries on the charger after they have been fully charged. This can lead to overcharging wherein the battery cells are overheated. This makes them lose charge faster. If this happens frequently, it can cause permanent damage until you can no longer use your battery and you have to buy a new one.

But advancements in technology have enabled modern chargers to monitor the battery charging status and automatically stop sending current to the battery once it is fully charged. This way, both undercharging and overcharging can be prevented. There are also safety measures in place to avoid overheating the charger.

So, to answer the question above, Black & Decker chargers are automatic chargers that are safe to leave connected to your batteries for an indefinate period.

If your battery charger comes with a maintainer function, it'll switch to "maintenance" or "float" mode once the battery is fully charged. Batteries lose charge even when not in use, so the charger continues to monitor its capacity and sends a small amount of current when needed to keep the battery fully charged.

How long does it take to recondition a battery on a Black & Decker charger?

Black & Decker charging process, Why Does My Black & Decker Charger Say 'Flo'?

Some batteries that haven't been used for a long time get drained or lose all their charge. Sulfation can also happen wherein lead sulfate forms on the battery's surface when it is stored in a warm area. This makes it harder to charge the battery and can lead to its failure.

Reconditioning can help revive dead batteries. The charger, if it has the capacity, will recalibrate the battery by overcharging it in a controlled manner. This will increase the battery's voltage and will help dissolve the lead sulfate crystals that have formed on the surface. This means that you don't have to buy a new battery just yet since it is expected that reconditioned batteries will function like before.

Understandably, it will take some time before the battery is reconditioned. For Black & Decker chargers, the process may take up to 24 hours. But all the wait is worth it since you can use your battery like before.

You will know when reconditioning is complete when you see "000" flashed on the LED display screen.

Take note that not all batteries may be reconditioned, especially those that have been sulfated already. You will be guided by the codes on the display screen if the battery can still take charge and when you should proceed with the Battery Reconditioning Mode.

Final Thoughts

Familiarize yourself with the codes used in your Black & Decker charger so that you will know how to optimize its features and other uses.

If you also want to read about Dewalt batteries, you may visit the following posts:

Can You Leave Dewalt Batteries On Charger?

Dewalt Battery Won’t Charge – Why? What To Do?

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