How can I reduce voltage on a battery.

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watersteps

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I have a 24 volt dc battery that I want to use on an 18 and 20 volt tool. I have built an adapter to mount the 20 volt tool to the battery. When I mount the tool on the adapter and then on the 24 volt battery nothing happens. Well the light on the tool goes out when I pull the trigger.
Lets go back to the beginning, I have several 24 volt SunJoe and SunSnow batteries, I also have several 10 and 20 volt DeWalt power tools that I could use extra batteries for. No one that I know of makes an adapter for this use. So I built an adapter out of a 2amphour Dewalt battery by removing the batteries and charging electronics board. I purchased a DIY adapter for the SunJoe 24 volt battery. This adapter is bolted to the 2amphour battery casing and wired the positive and negative wires from the DIY adapter to the connections in the 2 amphour adapter.
I have been told that if the DeWalt tools were brush type tools this would work fine, but they are not brush type tools. So, can I install a voltage regulator to reduce the voltage from 24 to 20 and maybe even 18 volts??
I have attached some pictures to help explain what I am doing.
--- Updated ---

I will add this info that may help find an answer. I have an adapter from DeWalt that allows me to use 20 volt batteries on 18 volt tools. The adapter works just fine. I opened this adapter up and find a small electronics board with these items mounted to it. One small round can with 100-35v-VT printed on it and another small can with 220-16v-VT printed on it, a small coil of copper wire with 220 printed on it. It also has a usb connection on the board.
 

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Gaber Mohamed Boraey said:
Umm, yes need heat sink
--- Updated ---

What

the solution you have?
--- Updated ---


What the solution you
Click to expand...
I have no solution because I don’t have enough information. But I do have enough information to know that 9 Watts is going to:

1) require a large heatsink
2) waste a lot of energy heating up that heat sink.
 

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barry said:
I have no solution because I don’t have enough information. But I do have enough information to know that 9 Watts is going to:

1) require a large heatsink
2) waste a lot of energy heating up that heat sink.
Click to expand...
I have seen lm317 a lot , it’s on little heatsink , maybe here in this application different values and so a lot heat and maybe terrible solution as you say

What size of heat sink is 9watt heat sink need for dissipate?
 

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Gaber Mohamed Boraey said:
What size of heat sink is 9watt heat sink need for dissipate?
Click to expand...
Likely a finned one about 3" x 3" x 1"
It also has to be in ambient air, not in an enclosure.

I suggest to you look for a switching buck regulator rated for the voltage and current you need.
It will be much more efficient, and not require an added heatsink.
 
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Based on your description, you are trying to use a 24V SunJoe battery with DeWalt 18V and 20V tools. You have made an adapter, but the tool does not respond when connected, and the light turns off when you pull the trigger. Here are some potential reasons and solutions:

Possible Issues

1. Excessive Voltage: Your tools might have overvoltage protection mechanisms, preventing them from operating at 24V. Most 18V and 20V tools are designed for voltages below 20V. The 24V might trigger protection circuits or damage the electronics.

2. nsufficient Current: The 24V battery might not provide enough current to meet the tool's demand, even if the voltage is appropriate. The tools might require more current than the battery can supply, causing a voltage drop and preventing the tools from starting.

3. Adapter Issues: The homemade adapter might have poor contact or connection issues, causing the battery to fail to supply power correctly to the tools.

Solutions

1. Using a Voltage Regulator: You can use a buck converter to step down the 24V battery voltage to a level acceptable for your tools, such as 18V or 20V. Choose a regulator that can handle the current demands of your tools.

- Selecting the Regulator: Ensure the regulator's input voltage range includes 24V, the output voltage is adjustable to 18V or 20V, and the maximum current output meets your tool's requirements.
- Installing the Regulator: Connect the regulator between the battery and the tool, adjusting the output voltage to the desired level.

2. Checking Connections: Ensure the connections in your homemade adapter are secure and making good contact to avoid any loose or poor connections.

Example of Using a Voltage Regulator

Assuming you choose a regulator that can step down 24V to 18V or 20V, here are the basic steps to connect it:

1. Connect the Input: Connect the input side of the regulator to the 24V battery.
2. Set the Output Voltage: Use the potentiometer or adjustment screw on the regulator to set the output voltage to 18V or 20V.
3. Connect the Output: Connect the output side of the regulator to the tool's power input.
4. Test: Before connecting all components, use a multimeter to test that the regulator's output voltage is stable at the desired voltage.

Precautions

- Safety: Ensure the power is off during connections to avoid short circuits or other safety hazards.
- Heat Dissipation: Voltage regulators can generate heat during operation, so ensure the regulator has adequate cooling to prevent overheating and damage.

By using a voltage regulator, you can safely reduce the 24V battery voltage to a suitable level for DeWalt tools, achieving your goal. If you have any questions or need further assistance, feel free to ask.
 

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If a buck is used could its transient response trigger in tool power
control a shutdown due to low perceived battery V ?

Not expert here, just asking....

Same for 3 terminal regulator, although here, if its C tolerant, use a large
low ESR output C to minimize V drop during tool startup....

One possibility use a power Zener, not ideal for sure, but no appreciable transient
response. Or Zener feeding base of power NPN, emitter to tool.




Regards, Dana.
 
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