Converting Cordless to Lithium Li-Po




As time moves we find that our drill don't cut it any more as now there are all of these new powerful cordless drills with lithium but the price of one of them cost about an arm or leg so what do you do?

Convert them to lithium,

Motor technology has been the same since 20 years ago and it's still the same in all new drills "DC Brushed Motors"

Up on opening my "Old" drill and having a look at my motor my motor looked very new and the brushes ware far from worn if not still would go strong for many years to come.

On the other end the battery's ware totally on the end of its life.

Step 1: Opening Your Battery Pack

When you open your battery pack your going to find sets of sub c battery's which are most Likely cheap cells depending on your make of your drill since we only care about the enclosure you can throw away the cells or keep them for a different project doesn't matter what we need to know is the inside dimensions as that will tell us how big the battery can be.

Order a smaller battery then the dimension as it will allow you to move the battery around.

Step 2: Soldering the Power Connector

Once you have found the best location for your battery you have to solder the power connector to your original battery connector

Always do one lead at a time solder the positive wire then heat stink the connector and then the negative wire and then heat shrink it.

Also helps to add a deans connector to make charging very simple.

Step 3: Closing the Battery Pack

At this stage you can close every thing up and drill a hole for your balancing connector and call it a day.

And if your like me then you want a battery pack with no loose wires hanging out then the next step is for you.

Step 4: Soldering DIN Connector

The connector used was a 5 pin DIN connector,
male for the charger and the female end for the battery as their are glued to the battery cover for a nice flush finish

I'm always throwing my tools around and this is the best method as it doesn't interfere with any thing or get pulled.

Step 5: Enjoy the Power of Lithium

What old drill ? Lithium power baby

The power gains I received was very amazing and even tested it with a power meter my battery's are well within the power the motors requires

As along as you don't let your voltage drop low then your all fine

Step 6: Charging Your New Lithium Battery

Due to many comments talking about its a bad idea to charge your battery with your original Ni-CD / NI-MH Duhh you don't say!

I dint think in this day and age that I will still think people will charge lithium battery's on a NI-CD/ NI-MH

Lithium battery's are no longer new and I'm guessing if your on this site then I'm sure every one knows about the charging procedure.

But you still get a few saying its a bad idea because in your low IQ head you think I'm using the original charger think why would I go through the trouble of fitting a DIN connector as a balancing connector. any ways.;

You must use a lithium charger to charge your battery packs!

The set up I'm using is a very simple LI-PO charger made by Hobby King HKE4.

Which iv set the charge rate to about 1.8 amps and removed the dial.

ATM I'm running the charger off a 12v battery in my shed but an ac adaptor is the best option for taking it to site.

Step 7: Low Voltage Cut Off

This is one topic that I will be adding as ATM I'm using a cheap LIPO buzzer and I would like some sort of low voltage light or cut off.

The problem I'm facing ATM is that I want it to draw 0 current.

When I sort this issue out I will update it.



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    68 Discussions


    Tip 10 months ago

    You can use an adafruit trinket pro and a piezo speaker for detecting voltage. It will draw about 15mA out of the box, but you can drop that down to 3mA by following this guide.


    2 years ago

    Just all to know, for RIDGID & AEG tools you may use original new & cheap li-ion PowerStroke battery with some adaptation, here is video manual -

    1 reply

    Reply 10 months ago

    If you register your RIDGID power tools within 90 days, you will have a lifetime warranty on standard (non high capacity) batteries.


    5 years ago on Introduction

    Nice Mod BUT, you can buy an 18v. 1/2" Hammer Drill for $54.99 add an extra battery for $14.99 without any hassle @ Harbor Freight. For $70 it will do the job for most DIY's, if it breaks just throw it away and get another. It doesn't get much better than that.

    2 replies

    Reply 2 years ago

    It gets much better than that, to buy something from a major brand that lasts 4X as long for only 1.5X as much money. Plus, no don't just throw it away, the batteries are toxic to the environment and the rest, senseless landfill waste.


    Reply 10 months ago

    I concur. Your local Best Buy can recycle them for you. But if you spend the extra money for a good power tool set, you will be much happier than buying HF junk. I was given 2 old Milwaukee 18v sets and they still outperform any budget tools.

    If you don't have a tool set, then I would recommend buying Rigid from Home Depot. If you register your power tools within 90 days of purchase, they will give you a lifetime warranty on it, including the batteries.

    I would have gone that route, but when I already have the older impact, 2 hammer drills, 2 hatchet sawzalls, 2 circular saws, and a cordless jobsite radio, its far more cost effective to upgrade the batteries than to replace the tools.


    1 year ago

    very helpful instruct able. I would like to replace the battery of a nicd bosh drill that runs on 18v . I was thinking of buying one 22 volt lipo battery , do you think this would work? If you think I should stick to 18 volt , do you know of a way of arranging 1 3.7v and 1 14,8 to work with the drill? Can I connect them in series and have 18volt output? And if so do I have to charge them separately afterwards? Thank you

    For the simplest radio shack, or maybe car parts store LVC circuit, i'm wondering.... Using a potentiometer and a relay. If you wired the pot in series with the coil, and perhaps a shunt. I think you might create a magnetic switch that will fail if there is an insufficient sustenance voltage. Wiring it up series on either the negative or positive side may also provide a useful feedback voltage drop. The nice thing about this would be it would draw 0 current until the trigger is pulled.


    5 years ago on Introduction

    Hi henal,

    Great project! Just one small correction: judging by the images, I believe you'll find that you're not using a BNC connector, but a DIN connector.


    2 replies

    Reply 2 years ago


    For safety reasons lithium based batteries must be used with a BMS circuit which monitors per-cell voltage and preferably temperature and ensures cells are balanced. This is even more important where battery pack is consisted of several cells connected in series. Disbalance between cells can result in cell inversion, especially in the high load situation such as cordless drill

    Lack of a BMS can result in failure, expolsion, toxic fumes.

    Lipo are even more sensitive than LiIon and more prone to thermal runaway.

    Cordless drill takes tens of amperes of load from the cells and this increases the risk.

    Do not mess with lithium batteries if you are not qualified for it. Yes you will probably get lucky and get away with it but you should not take such big risks.

    Behind every power tool battery pack are thousands of engineer hours spent on designing and testing the BMS and battery pack. The BMS is there for a reason.


    Reply 1 year ago

    I 100% AGREE! My company uses Lithium and LiPo batteries by the carton - the dirty brown carton - and you should NEVER charge these battery types without a BMS (Battery Monitor System) aka Battery Balancer.

    There are about ten circuits on Google if you want to make one.


    5 years ago

    Also, lipos have a threshold. If you discharge the batteries beyond this point, they won't recharge. So if you run the drill down to where it quits, you've likely ruined your lipos.

    8 replies

    Reply 2 years ago

    True but if you open the case and disconnect the balancer, you can use a power supply to get the voltage up past the threshold and connect everything back together it will start charging again.

    I have done that several times with laptop batteries that would not charge because they were discharged below the threshold voltage.

    For what it is worth, I have the Craftsman C-3 Series tools and switched from NICADS to LITHIUM - Sears provides the battery packs so re-building is not the issue. But, your comment does not comport with my experience (over 18 months now) witht the lithium batteries and chargers that Sears provides. I am using the tools that came with NICADS and the Sears lithium batteries. I regularly use the tools unitl it 'quits.' Then, pop it in the charger, then use it again. BTW They have a charge guide built into the Sears litium battery unit - you prss a button and it glows, Green, Yellow or Red to indicate the state of charge.


    Reply 5 years ago on Introduction

    you are using Lithium Ion batteries, which are the defacto standard for power tools. they put out 3.3volts per cell, versus the 3.7 volts of LiPo. Li-Ions are also composed of a more stable cell structure and do not heat up and have a danger of fire when run below 3.2-3.4 volts.
    the reason LiPo batteries are more popular in radio control is that they have a higher amp draw than Li-Ion.


    Reply 5 years ago on Introduction

    D'oh! you're right! I was confusing the voltage rating between Li-Ion and Li-Fe.. The rest of what I said still stands, but I apologize for the voltage mix-up


    Reply 5 years ago on Introduction

    I didnt know about Li-Fe batteries, will have to have a look at them.
    I build small solar power systems and use Li-ion to store power as smaller, lighter and more efficient than Lead-acid.

    That is probably true for the Sears pack. I would bet most people who are rebuilding these packs do not have any kind of charge protection on the lipos they put in their pack. So, we both are right!


    Reply 5 years ago on Introduction

    The batteries you are using have a charge controller. They track the cells state of charge, and if you are about to dip below the safe point, they shut the pack down. Typical, older RC batteries won't include the controller. If you abuse them beyond the safe point, you kill them.