February 8, 2022

How to charge a cordless battery without a charger

Prepare the equipment

Learning how to charge a cordless drill battery without a charger requires one to know the needed power source. To provide power, you need power. In this case, it comes in batteries to charge your drill battery.

Batteries have a store of power, meaning you can access this power storage by transferring it to another Dremel battery. Find batteries with a charger, and you should have the means to connect to them and access their power. For a successful operation, you need electrical tape, standard electrical wires, and AA batteries with a charge. 

Electrical tape or insulating tape helps to keep the charging unit held together. Use any piece of wire as an electrical current that can transfer power through it. Use enough AA battery voltage to match the voltage of your power tool’s battery. Look at the voltage identification on the lithium battery, or the battery voltage in the instruction manual. 

Set up the battery

Once you have gathered all the equipment, assemble your charging equipment. Connect the AA battery to your tool’s battery via a conductive wire, and the lithium unit gets a way to charge as it will draw current from the AA battery. Do connect one AA battery to your drill power unit because it will not give enough power.

Connect the AA batteries in series to create a single unit. The AA batteries must be connected positive terminal to a negative terminal. Connecting the AA batteries negative to negative or positive to positive, no current will flow. The connection between the batteries must be firm without any gaps.

Secure the connection using the electrical tape to fasten them together – end to end. Once all the batteries are connected, you should have a chain of connected AA batteries with one end positive and the other end negative.

Connect and Charge

The final step is to connect your chain to your Li-ion battery, for your Li-ion battery to gain charge. To connect positive to positive and negative to negative. That is the opposite of connecting the AA battery chargers.

Connect the positive end of your AA chain to the positive terminal of your device. Connect the negative end of your AA chain to the negative terminal of your Li-ion battery. That is how you get the connection. The power from the AA batteries should transfer into your power tool battery.

Tape the AA chain to the battery and stay present during the charging process to observe an accident, and wires could work loose, or a fire could start. Stay present for any quick reaction to any change in circumstance. The process may take a while to get a full charge. 

Connecting directly to terminals

This may seem risky, but the insulation on the wires should prevent shorting out. The batteries should not come into contact with each other because any link in a chain of batteries will cause a short circuit. Check for overheating or fire before disconnecting the battery from the charge. Make a connection from one terminal to another. That powers the charger immediately and does not use the battery pack.

Ensuring the voltage is just right.

Too much voltage overcharges the battery, and it gets hot. In the worst cases, it may explode. Use a charger that has voltage to match your batteries. Voltage should be within a set range for the power system to work safely. If voltage is too high, the equipment gets damaged, and if it is too low, the equipment can operate poorly or stall.

How to charge a li-ion battery without a charger

Use a solar panel

Charge your lead acid battery and get a charger controller. The solar charging system cannot charge any battery without a charger controller. You can also get a solar inverter.

Use a clip charger

Take out the battery from your gadget. Place it on the charging platform of the clip charger and plug in the charger on the power board and switch on it. 

Use a car battery

Charging the battery by connecting it to your car battery comes with a lead-acid battery and uses small light bulbs to regulate the current flow.  Wait for 10-15 minutes, and your battery will get enough charge for use.

Charge drill battery with laptop charger

Standard laptop chargers are for 18-20V, suitable for charging an 18V battery. Understand the type of connector your laptop charger has. Connect the female connector to the internal battery connections. Match the positive with positive and negative with negative.

Make a cut-hole for the female connector to sit in, and you can charge your battery without the charger. Another way is to get an off-the-shelf two-pin connector set. Make connections in a way positive aligns positive and negative with negative. 

Check the output voltage ratings on the back of the charger. Connect the positive terminal of the laptop charger with the positive terminal of the battery you are charging. Connect the negative terminal of the laptop charger with the negative terminal of the battery you are charging.

Homemade drill battery charger

  • Cut two wooden blocks to hold the battery pack in place. 
  • Cut a second side for your battery holder. 
  • Add copper contacts to your battery holder. 
  • Screw on both sides of the battery holder. 
  • Build the circuit. 
  • Test the charging circuit.
  • Add two spacers.
  • Put the last screws and try the battery.

How to charge a drill battery with a different charger

If you have another drill battery with a working charger, you can use that drill battery to charge your battery. Make sure the other battery is of the same voltage and charge and connect the terminals in the same polarity.

Why is my Dremel charger not working

The battery pack is not connected to the charger. If the battery pack has not latched into the charger, it is not making a good connection with the charger. A perfect connection is in the click sound and remove the battery pack and insert it in the charger again.

How to charge Dremel battery without charger

When charging the Dremel battery without a charger, attach the positive first, then negative. When disconnecting the cables from the old battery, disconnect the negative first, then the positive. Connect the new battery in the reverse order, positive rather than negative. Below are alternatives.

  • Charge a cordless drill battery with the car battery
  • Charging a Cordless Drill Battery with a Laptop Charger
  • Charging battery with off the shelf 1.5V AA Cells
  • Charging battery with Cheap Voltage adapters
  • Charging battery with another drill battery
  • Charging battery with solar panel

How to tell when the Dremel battery is charged?

There is a green LED on the charger that indicates charging, and that is when the charger plugs into the battery pack. While it is charging, the light continues blinking. When complete, the light will stay steady green. 

When the Dremel battery is charged, the LED on the charger turns off. It takes approximately 3 hours to charge the battery. 

David D. Hughes
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