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Sub-C Cells and Batteries
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Sub-C cells are sometimes called:

  • Sub C rechargeable cells for building battery packs for cordless power tools and drills
  • Sub C rechargable batteries for RC (remote control) cars
  • Sub-C batteries with tabs for Battery packs paks

The Size, Dimensions, and other details of Sub C cells vary somewhat from manufacturer to manufacturer. Some of these variations of sub-c rechargeable cells are:

  • Type - NiMH (nickel metal hydride) or NiCD (nickel cadmium)
  • Overall Design
  • Diameter and Length
  • Positive terminal design - size and height
  • Covering - paper (cardboard) or plastic
  • With Tabs or without Tabs
  • Tab dimensions - length, width, thickness
  • Tab material types
  • Power output and charging rate

Sub C cell size inches - Sub-C cells vary in size depending upon manufacturers. Typical dimensions are shown. A 4/5 Sub C cell or battery is 80% the length of a standard Sub-C cell.

When changing cells in battery packs the size is critical, but if you were to build a Rambo Battery™ or Porta-Pak™, the elastic pockets will accept any diameter of Sub C cell.

sub-c and 4/5 sub c cells and batteries showing dimensions and sizes

Sub C cell size millimeters - The same Sub-C cells as above, but shown with sizes in millimeters.

You can click on the pictures to enlarge them.

These 2 cells happen to be NiMH (nickel metal hydride) rather than NiCD.

Some of the information here is from the Rambo Battery™ Build It™ Guide. We make the most accurate guides with the clearest pictures and detail for easy learning.

sub-c and 4/5 sub c cells and batteries showing dimensions and sizes in millimeters

What Are Batteries? - Batteries are composed of 1 or more cells. A cell is the building block. A cell is also called a battery. Depending upon the chemisty a cell can be 1.2 to 3.6 volts and might or might not be rechargeable. An alkaline cell is 1.5 volts. A NiCD (nickel cadmium) or a NiMH (nickel metal hydride) cell is 1.2 volts. A lead/acid cell is 2 volts. A Li-ion cell is 3.6 volts. We will be using Sub-C cells only. A 4/5 Sub-C is 20% shorter than a Sub-C cell. Notice the tab. It is spot welded to the terminal. Soldering wires to terminals of rechargeable batteries should be avoided because it lowers the life of the cell.

sub c sub 4/5 c alkaline Li-ion NiMH NiCD AA C D cells batteries

Identifing Positive Terminals - The positive terminal is typically a round button in the middle of the cell and it is insulated from the tall cylinder that is the negative terminal.

Notice the Sub-C cell on the left. It has a paper (cardboard) covering or sleeve that is crimped over the positive end of the cell for insulation purposes. The Sub-C cell on the right has a thin plastic covering that is shrunk over the cell. It serves the same purpose as the paper covering.

Plastic and paper coverings on subC cells with positive terminals
Identifying Negative Terminals - The Negative terminal is the entire bottom and cylinder of the cell. If the tab on the positive terminal were to touch the cylinder of the cell you would have a short and sparks would fly. The tabs on the negative terminal can not reach the positive terminal, so you don't need to be concerned about a short between the negative tab and the battery housing.
negative terminals of sub-c batteries with paper and plastic coverings and insulation
Tabs on Sub C Cells - Tabs are usually made of nickel. The cross section area of the tab is the most critical thing to carrying current, so there is a relationship of the thickness to the width. Some tabs are only .003 thick and are not recommended. Look for tabs that are .008 thick or 2mm or thicker. Because it is damaging to the cell to solder a wire to the terminal, Sub-C batteries are sold with tabs spot welded to them. Notice the cheap battery on the left with the poor spot weld which is weak and not a very good electrical connection. The right SubC cell has tabs .012 thck.
tabs with good and bad spot welds on sub c cells

Cell Terminals - Sub-C cells are designed with various properties. We want high current high drain cells to run power tools. Notice the groove around the positive end of the cell. Visually the positive terminal is easy to distinguish from the negative terminal.

Cells are sold with or without tabs. Be sure you buy cells with tabs if you plan on soldering them into a battery pak.

4/5 sub c cells showing groove identifying the positive terminal

Soldering on the Tab - The cell on the left has no insulation and the cell on the right has plastic insulation shrunk around it and another insulator (white) covering the positive terminal. If you were to solder on the tab (blue arrow) it could melt through the insulation causing a short. This would be VERY bad.

Because we need to solder on the tabs in this area we will put high temperature teflon tape under the tab to prevent the possibility of short. We only need to do this on the positive terminal. (last paragraph from the Rambo Battery™ Build It!™ Guide.

Bare SUB-C battery and yellow sub c cell showing insulation

Current Rating - Ah, mAh - The power that a cell can output is rated in Amp hours. A milli Amp hour is 1000th of an Amp hour. Of the 4 Sub-C cells, one is a NiMH. All cells come from China and their rating is not always accurate (surprise). The 1800 mAh cell is the cheapest and has the lowest power. The 2400 mAh is a very high output for a NiCD cell. The NiMH cell at 4500 mAh has a very high current rating and that is why they cost more money. You need to determine your needs and balance that with price.

Various subC cells showing their mAh ratings

Parallel Circuits - The cells are connected in parallel. All the positive are connected together and all the negative are connected together. Parallel circuits multiply the current (amperage) and the voltage stays the same.

Each cell is 1.2 volts. You could connect 100 cells this way and the output voltage would still be 1.2 volts.

3 green sub c batteries in a parallel circuit

Series Circuits - Series circuits are what you will be building. The series circuit multiplies the voltage, but the currect (amperage) stays the same as the rating of one cell. Because we have 3 cells the output voltage is 3 x 1.2 = 3.6 volts. Each cell has a currect of 4500 mAh and that is the output current for this circuit.

To build an 18 volt battery we need:
15 cells x 1.2 volts = 18 volts

3 green Sub-C cells in a series circuit

Short Circuit - A short circuit is a direct connection across the positive and negative terminals. The motor in the circuit supplies resistance to the circuit, so the current from the battery flows slowly from negative to positive.

A short has no resistance and therefore the total current flows through the shorting wire causing it to get hot or glow red hot - enough to easily start a fire.

Showing what a short circuit is

Dewalt 18 Volt XR+ - Here is a SubC cell from a Dewalt tool battery.

It measures:

.892 dia. x 1.68 long (over tabs)

Showing what a short circuit is

Craftsman 19.2 Volt EX - Here is a SubC cell from a craftsman tool battery.

It measures:

.883 dia. x 1.68 long (over tabs)

Showing what a short circuit is

Milwaukee 14.4 Volt - Here is a SubC cell from a Milwaukee tool battery.

It measures:

.883 dia. x 1.7 long (over tabs)

Showing what a short circuit is

Black & Decker Firestorm 14.4 Volt - Here is a SubC cell from a Black and Decker Firestorm tool battery.

It measures:

.890 dia. x 1.707 long (over tabs)

Showing what a short circuit is

Sub C cell battery variations:

It appears that the manufacturers of cordless tool batteries use cells that are fairly close in size.

After market Sub-C cells are another story and can vary up to 2 mm (.080) in length and/or diameter. If you are going to build a battery pack, be sure to verify the cell dimensions and sizes before ordering. Just 1mm too long and the case will not close. If you are planning on building a Rambo Battery™ or Porta-Pak™ (1 battery runs all your tools - any brand - any voltage) then any Sub C battery will work because the pockets that hold the cells are elastic and will accept any Sub-C cell made.

You can also learn how to scavenge cells from old batteries to build new ones. Save money and the environment by using scavenged cells.

Other Options:

If your NiCD batteries are weak or dead it is not the end of the line for them. You need to resurrect them. The Battery Resurrection® Guide Pro Version shows you, with clear easy to follow instructions like on this page, how to bring your nicad batteries back to life. You can read the hundreds of testimonials from major skeptics that were blown away with the amazing results. The guide also shows you the correct way to replace cells in tool batteries and in tools with built in batteries. You can also see how to build new battery paks for a dustbuster, vibrator, and coleman powermate compressor.

 
 
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The Rambo Battery and Porta-Pak are sold as kits that are easy to assemble. You either scavenge cells from other tool batteries such as Dewalt, Craftsman, Ryobi, Black and Decker, Makita, Milwaukee, Porter Cable, Hitachi, Skil, or Kawasaki, or buy new cells.

Of course new Sub-C cells with tabs are the best choice but can be pricey. The more expensive brands of tools such as Dewalt, Craftsman, Milwaukee, and Makita use higher quality cells with more power output and with a higher charge rate and higher discharge rate. Cheap cordless power tools like drill master from Harbor Freight use the cheapest NiCD Sub-C cells. You can't expect much from these cells and they should not be used in a Rambo Battery™ or Porta-Pak™ Power Station™. Some other companies make some really cheap models of tools also like Skil and Coleman.

Battery Chargers that are the best to use are the universal chargers that will charge NiCD and NiMH batteries and detect voltages of 7.2 to 19.2 volts and some good chargers we like are the Makita and Milwaukee Universal battery chargers.

We just tested the new Craftsman Charger Li-Ion and NiCD charger and it charged a NiMH and NiCD Rambo Battery and Porta-Pak and the cells only got a little warm. We only charged one Porta-Pak made with Tenergy 2400 mAh NiCD cells with a Ryobi 1 hour charger and it cooked the cells, so we say do not use the Ryobi 1 hour Charger.

The little cheap charger that many companies make like Black and Decker, Skil, Hitachi, Firestorm, Coleman, Drill Master, and Bosch can be used to charge most Sub-C cells because the current output is only about 200 to 600 mAh. Since most Sub-C cells are 1200 mAh or greater there is little risk of cooking the cells when charging.

The big risk with the cheap little chargers is overcharging the batteries because they don't have a brain to turn off the charger when it should be turned off. Most Quality companies like Dewalt, Craftsman, Makita, Milwaukee, Ryobi, Porter Cable, Black and Decker and Bosch offer smart chargers that turn off the charging when the battery is full.

Battery Resurrection will get you more life from your NiCD rechargeable rechargable batteries. Our Rambo Battery™ will replace many other brands of batteries when Resurrection will no longer work, such as Dewalt, Craftsman, Makita, Milwaukee, Firestorm, Bosch, and Ryobi cordless power tool batteries.