Milwaukee Brushless Hackzall Review | M12 Fuel 2520-21XC

Milwaukee Brushless Hackzall Review | M12 Fuel 2520-21XC


The following are some of the most common issues with Milwaukee’s new brushless motor. These are not all the possible issues, but they are the major ones that have been reported so far.

1) Voltage drop between battery and controller (VSR).

2) Overheating of the motor.

3) Slow speed and high RPM.

The voltage drop problem is one of the main reasons why many users have trouble with their motors running at full power. Most users report that it occurs when they run them at higher than recommended voltages (usually around 20 volts).

The VSR will usually shut down or overheat if it gets too close to these limits.

When the voltage drops too low, the motor may start to lose efficiency and slow down. When it starts losing efficiency, it stops spinning altogether.

This is because there isn’t enough current flowing through the motor to keep it turning. At this point, the motor is no longer producing any torque and becomes useless. If left unchecked, this issue can cause your brushless motors to stop working completely!

The main cause of the VSR shutting down is the battery. If you’re running a 20v battery, then there is a high chance that the VSR will kick in at around 18v or less.

This means that the voltage will keep dropping until it reaches 16v and lower. Even if you’re just using an 18v battery, the issue might still occur. This is because most manufacturers tend to fill their batteries up with more energy than their official specifications state. This means that you can only expect them to provide the same voltage until they reach a certain discharge level.

In this case, it usually happens around the 15-17% range. The battery might be providing 16 volts or more when it’s fresh, but by the time you start using it, it will already start to drop and the VSR will kick in at a lower voltage.

Milwaukee Brushless Hackzall Review | M12 Fuel 2520-21XC |

This means that you will not get the full 20 volts that your battery can provide.

To solve this problem, you can:

1) Use a lower voltage battery.

2) Make sure the battery is fully charged.

3) Increase the voltage limit of your VSR to at least 20v.

The second problem, which is also related to the battery, usually occurs when people use cheap batteries or discharge them too much. This is because these types of batteries have a lower quality control and are designed to fail sooner.

Cheap batteries are usually used to make cheap tools. Sometimes these types of tools last long enough for most users, but they won’t last as long as their more expensive counterparts.

It’s important to remember that the cost of the tool doesn’t necessary dictate its reliability or lifetime span.

To solve this problem, you can:

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1) Use a better battery.

2) Charge the battery more often.

3) Limit the current drain on your batteries as much as possible.

The third problem, which involves lowering the speed of the motor and increasing the RPM, usually occurs when the VSR kicks in at relatively high voltages (around 18v or above). This means that the tool will start to lose power around this range.

If your tool is running off a battery that only provides 18v, then there’s not much you can do to keep it running under these conditions.

The general rule of thumb is to not use a battery that has less than 2 volts per cell when discharging it at high loads. This means that if you’re using a 2-cell battery, then it should be no lower than 4.0v.

If you’re using a 3-cell battery, then it should be no lower than 6.0v and so on.

The fourth problem with the VSR system, which involves the sudden stopping of the tool when the batteries are low, can be solved by disabling the VSR or by using better batteries.

Using Better & Custom Batteries

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The first solution to all these problems is to use custom batteries. This is because you can program the batteries to provide more or less voltage at any time.

For example, you can tell a battery to slowly lower its output voltage from 20v to 5v over a period of time. Another thing you can do is tell a battery to instantly drop from 20v to 0v if certain conditions are met.

This is why people are using these types of batteries for drones and remote control cars.

However, these batteries are pretty hard to get a hold of and they tend to be very expensive. Although they can solve all your problems, they may be out of the price range of most people.

Next is using better batteries, such as the ones that Tesla uses in its cars. These batteries do not suffer from the same level of quality drop that normal batteries have and can last for decades if taken care of properly.

There is another type of battery that is similar to the one that Tesla uses, but it isn’t as good. It’s called the LG Chem RESU.

It has a longer lifetime than most batteries that you can buy, but it doesn’t last as long as the one that Tesla uses.

One battery that is worth mentioning is the EBLeasyBATT. This is a cheap and easy to find battery that you can buy online.

It’s a bit pricy at $10 per battery, but it’s a huge advancement from your typical Harbor Freight battery.

Last is using modified commercial batteries. This involves taking batteries that are designed for specific tools and modifying them to have custom voltages.

This is the most difficult solution as you need to know what you’re doing, otherwise you might burn up the battery or blow yourself up.

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You can also buy cells from the internet and assemble your own battery. There are cheap Li-Ion 18650 batteries on Ebay that you can purchase.

There is another type of 18650 battery called the Jamunda Ultra that can be bought for around $4 per cell. It has a very low internal resistance, so it can output a larger current.

The main problem with buying cells off the internet is that you never know what you’re going to get. There are many companies on the internet that claim to sell genuine 18650 batteries, but they are actually selling counterfeits.

This is because it’s very hard to authenticate a genuine battery without spending an exorbitant amount of money. Even if the batteries are genuine, they can easily be defective.

The most well-known batteries that are commonly modified are the Panasonic UR18650PF and the Sanyo UR18650NSX. They both have a high energy density when compared to other batteries, but they suffer from the nasty “quality drop” issue.

It’s best to not buy 18650 batteries from Ebay or Amazon and go for safer options.

Last but not least, you can buy battery holders and create your own custom packs. This is the safest solution as you’ll be able to pick and choose what types of batteries you wish to use.

You can buy AAA battery holders that are sold on Alibaba for around $1-2 per cell. You can also buy AA battery holders, however these are a lot more expensive at $6-7 per cell.

When you begin to solder these battery holders together, you need to remember the voltage of each individual cell. For example, if you had two 2500mah 18650 batteries, you’d have 4.5 volts.

If you had four 2500mah 18650 batteries, you’d have 6 volts. If you had three, you’d have 4.5 volts and so on.

This is where it can be a bit of a hassle, as you need to find suitable batteries that are able to fit in together. For example, if you had four 2700mah 18650 batteries, you’d have 6.6 volts when all put together in series.

This is way too high and can be dangerous.

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It’d be best to stick with something around 4.2 volts per battery holder, so if you had 8 cells at 2500 mah each, you’d have 4.2 volts.

Ideally, you want to get a few holders that are under 4.5 volts and then add those together in parallel.

For example, if you had two 4 cell holders at 4.2 volts and 2 cell holders at 4.2 volts, you’d have everything in parallel and end up with 2 cells at 4.2 volts and 2 cells at 1.1 volts.

If you’re unsure of what to do, you can always get a 9Volt battery clip to connect your battery to so you don’t have to solder anything together.

Connector Placement

When you begin attaching the cells together, you’re going to need to decide where to place the connectors. You have two options for this:

Option 1

This is the most common option and involves having the positive terminals of two cells connected together and the negative terminals of two cells connected together. So you’d have two “+” connectors and two “-” connectors.

When doing it this way, you can’t charge the entire pack with just a single connector as you would with a normal battery. You need to solder additional wires onto the connector so that each individual cell gets charged correctly.

Option 2

Milwaukee Brushless Hackzall Review | M12 Fuel 2520-21XC - Picture

You can also place the connectors exactly in the middle of two cells. This would require you to solder three wires onto your connector so that each cell gets charged correctly.

It looks a little neater, but it’s a bit difficult as it requires extremely precise and delicate soldering.

Charge Controllers

Once you have your pack built, we need to find a way to safely charge it without destroying anything. This is done with a device called a charge controller.

Charge controllers allow you to safely charge your batteries to their maximum potential without over charging them or even causing an explosion. There are two main types, these are PWM and MPPT.

PWM stands for Pulse Width Modulation. This is the cheapest and most common method of controlling battery voltage.

Sources & references used in this article: