REPLACE NI-CD BATTERIES WITH LI-ION TYPE

[pgr2002]

I have one "KRAFTtech" drill machine (model CDP02CN-1) wherein it has 5 ni-cd cells of 1.2v & 1200 mah each. Now I would like to replace these cells with Lithium type cells (18650) of 3.7 volts. Since originally it works with 6v, Lithium cells required will be 2. Now the question is - should I go with only 2 cells (in series) or 4 cells or more in parallel (2+2 in series, or more depending on the availability of space). Should I increase capacity from 1200 mah to higher ones or not?

 

[Audioguru]

Where will you buy high quality 18650 cells? There many fake ones sold today.
An 18650 rated at only 1200mAh or higher than 3500mAh will be full of rice or you-know-what.

I took some used Name-Brand 18650 cells from an old laptop and replaced the garbage Ni-Cad cells in a portable vacuum cleaner and they work fine. I charge them overnight at a fairly low current.
Increased capacitor does not increase the current, instead it increases the run time before recharging is needed.

 

[BradtheRad]

NICADS are successful consumer batteries because they're able to take abuse.

Li-Ion type require that you give careful attention to the range of operation you subject them to. To my understanding you must avoid charging or discharging them outside a certain voltage range. Cells from reputable manufacturers have built-in protective circuitry. There are corner-cutting manufacturers whose cells are substandard.

If you monitor voltage of your Nicads when running the drill, voltage drops 50 percent or so (in heavy use). Yet it doesn't harm them. Their bulk allows them to carry a few Amperes (C size or bigger). They heat up a bit in use or charging. It doesn't necessarily shorten their useful life.

Li-Ion are the type in news reports for causing fires and explosions.
To stay within their intended operating range I imagine you'll want 2+2 series-parallel. Keep track of their temperature during use and charging.

 

[pgr2002]

Where will you buy high quality 18650 cells? There many fake ones sold today.
An 18650 rated at only 1200mAh or higher than 3500mAh will be full of rice or you-know-what.

I took some used Name-Brand 18650 cells from an old laptop and replaced the garbage Ni-Cad cells in a portable vacuum cleaner and they work fine. I charge them overnight at a fairly low current.
Increased capacitor does not increase the current, instead it increases the run time before recharging is needed.

I removed 6 cells from old laptop. Some of them were in the range of 3,65, others showing 2,45. After charging these it improved a bit by 0.35v to 0.5v. but the drill could not take on with 2 cells & voltage dropped back.

 

[Audioguru]

An 18650 with a voltage less than about 3V is damaged and might catch on fire or explode if it attempted to be charged.

 

[pgr2002]

NICADS are successful consumer batteries because they're able to take abuse.

Li-Ion type require that you give careful attention to the range of operation you subject them to. To my understanding you must avoid charging or discharging them outside a certain voltage range. Cells from reputable manufacturers have built-in protective circuitry. There are corner-cutting manufacturers whose cells are substandard.

If you monitor voltage of your Nicads when running the drill, voltage drops 50 percent or so (in heavy use). Yet it doesn't harm them. Their bulk allows them to carry a few Amperes (C size or bigger). They heat up a bit in use or charging. It doesn't necessarily shorten their useful life.

Li-Ion are the type in news reports for causing fires and explosions.
To stay within their intended operating range I imagine you'll want 2+2 series-parallel. Keep track of their temperature during use and charging.

I will be using BMS for the li-ion cells to protect them from overcharging, etc

 

[c_mitra]

I will be using BMS for the li-ion cells to protect them from overcharging, etc

You should be fine. If you can squeeze them in the available space, then it is better to use onNICADS are successful consumer batteries because they're able to take abuse.ly two of the 18650 cells.

If possible, put the BMS (charge/ discharge controller) close to the cell pack. Then perhaps you can use the same charger...

NICADS are successful consumer batteries because they're able to take abuse.

So the advertisement goes. They say you can charge /discharge NiCds 1000 times.

One good thing about NiCds and Li-ions is that they do not leak. At least I have not found one.

Batteries are the least reliable part in any electronic circuit- treat them with great care and gentleness.

I knew one person who used to supply batteries to the military.

 

[Audioguru]

Ni-MH replaced Ni-cads 30 years ago. Ordinary stores sell Ni-MH batteries today, not Ni-Cads anymore.
Even cheap solar garden lights replaced old Ni-Cads with Ni-MH.
A Ni-MH cell has a higher capacity than a Ni-Cad.
New Ni-MH cells hold a charge for one year. A Ni-Cad maybe a couple of months.

 

[vfone]

Other types of batteries may provides much longer run times than comparably sized and weighted NiCad batteries.

But nothing can beat the cycle life, charge time, operating temperature range, load performance, and cost per cycle, of NiCad batteries.
There are functional satelites launched 40 years ago still using NiCad batteries.

 

[Audioguru]

All the Ni-Cad batteries I used 30 and 40 years ago soon failed shorted. Then I used Ni-MH batteries instead and none became shorted and they have a higher capacity and hold a charge much longer if not discharged.

 

[vfone]

I was lucky I guess. I have a SAFT battery pack (similar with the one in the link) which is 43 years old (1978) and which is still alive. May not have initial capacity, but is not shorted..

www.batteries4pro.com www.batteries4pro.com

Ni-Cd batteries are banned in many countries due to their toxicity, but they are still being considered in few areas as, satellites and medical devices, which require long cycle life.

http://www.jpl.nasa.gov/nmp/st5/TECHNOLOGY/battery.html

1998ESASP.416..715C Page 715

Regarding toxicity, I don't know, I think is relative. Once, accidentally I cut with a sharp blade a cell phone Li-ion battery. In the room was so much toxic smoke that more than a day I was not able to enter in that room. To get the same toxicity I supose I had to burn 10x more similar Ni-Cd batteries.

 

[Audioguru]

People who eat batteries die faster if they eat a Ni-Cad one.

 

[pgr2002]

I will be wiring 4 18650 cells of 2500 mah in 2S-2P way. As shown in the attached file. I will be using 4s bms board as shown. The wiring that I will be doing is as per the diagram drawn by me. Is it the correct way to wire the cells with 4s board. If there is any improvement / mistake kindly let me know what should be done.

 

[FvM]

Your schematic shows a 3s BMS board but you need 2s board.

 

[pgr2002]

Your schematic shows a 3s BMS board but you need 2s board.

Sorry I did not see the board. Herein with 4s BMS board the wiring that I will be doing is shown here. If this is the correct way I will go ahead otherwise I will seek your suggestions put forth by you. How will the wiring look like with 2s bms board. Please clarify.

 

[Emic89]

I'm using Dewalt drill and its run on 20V lithium-ion batteries and there is no need to add extra power, brushless motor helps to do effortless and high performance work and 15 clutch settings available to work right.