Converted tool battery pack from NiCad to Lithium


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Crimp Daddy

Member
Joined
Feb 21, 2018
Messages
973
This was my first project where I converted a Snap-On NiCad battery pack to Lithium... just wanted to share and get any input!

No BMS, but I use a hobby charger to charge. These cells can really deliver some power!

I've owned this Snap-On impact gun for at least 8-10 years now...


image_sxmqbk.jpg


Its a damn good gun, but back in those days Lithium wasn't really an option, and those Nickle Cadmium batteries it came with have faded away over the years. Surprisingly its lasted this long, so I guess those Japanese made batteries held up pretty well but one of the packs went completely dead. After a full charge, only takes a month of sitting to see 0 volts.

I looked at replacements and those are $100 each, no way am I paying that for Nickle Cad packs...

I looked at a replacement, new Snap-On, and wasn't in to mood to shell out $600 on a set setup.

I looked at the Milwaukee M18 fuel 1/2 impact and its not bad at all for $350, but a brand new impact still has similar specs as my 10 year old Snap-On! Impressive for something I bought that long ago considering its still very valid today.

So with only the packs holding me back, I decided to rebuild them, but I wanted Lithium.

I set off to find some beast mode lithium cells and came across the Samsung INR 25R. These are high discharge / high drain cells. After reviewing the spec sheet I purchased a few to play with.


image_lmtoiu.jpg


After testing individual cells, I started assembling them into a 5S1P (5 series 1 parallel) pack. That gives me a max of 21v fully charged. Its the most I could fit into the stock pack.


image_gaeost.jpg


I marked the tab locations for the series connections...


image_uhjnas.jpg


Its recommended to use a spot welder, but I dont have one, so soldering it is. Its helps to scuff up the surfaces and flux for good flow and adhesion.


image_ncuwio.jpg


I wanted to be able to balance these lithium packs as well, so I made a custom balance cable with the intention of having this port externally accessible. I made the dongle and routed the balance leads accordingly.


image_eamrqn.jpg


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Using a high quality hobby charger typically used for RC hobby stuff, I checked the balance leads. I can now monitor and balance each individual cell along with being able to charge the pack itself.


image_qxivma.jpg


Everything looked good, tested well, so I started packaging it all up and made it secure in the original pack with Anderson Power poles so I can service or rebuild the pack for the rest of its service life.


image_oghyui.jpg


image_rhkles.jpg


Because I used Anderson connections, I can easily open the pack for testing. Here is my inline amp meter I used for testing performance.


image_ajtnak.jpg


Here are the results from my 4Runner with lugs @ 83 ft/lb. 23 amps / 460 watts! It literally spins the lugs off like butter. Also well within the battery performance specs.


image_admazd.jpg


image_jpbrlo.jpg


image_sauzzo.jpg


Here are the results from my Chevy Silverado with lugs @ 140 ft/lb. 41 amps, 712 watts! Its a beast... works like new, and still throw those lugs off with authority. I am really impressed with how much current those cells can deliver. Really impressive for a single series string of batteries.


image_iqwsca.jpg


image_ldjeqk.jpg


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All in all, a successful project and a new love for a tool I have had for a long time. I really enjoy how light the new packs are too, its easier to handle and just less weight to swing around.


image_fbchso.jpg


The only thing that has really changed is charging. I use a hobby charger now but its worth the trade off.

I no longer have to worry about my packs going dead in storage, or on the trail. Those Ni-Cads could have left me stranded. There were times it felt full, the the packs loose juice over time.

I always have power and it never fades in storage. Since my charger is DC, I can easily charger it off the trucks 12v battery.


image_vloqln.jpg


New life to an old tool, and it really does work better as well or better than it did when I got it. I have already started converting other old Hitachi drill pack to Lithium.
 

daromer

Moderator
Joined
Oct 8, 2016
Messages
5,662
Good work!
I just want to point out that scuffing or sanding the surface is not needed and will make it corrode over time! Especially in moist or in garages ;) I have seen it happen alot. For adhesion just use proper solder and soldering iron and its not a problem. You will never be able to remove that solder before you destroy the battery :p

Sidenote is that i just got a couple of laptop packs where they have scuffed the surface before spot welding of some reason... They were all corroded away :/
 

Crimp Daddy

Member
Joined
Feb 21, 2018
Messages
973
Interesting... I got a decent regulated iron and the first battery I tried felt like it was coated in Teflon non-stick. Brand new cells, not recycled.

I solder good quality solder, kester 44 63/37 at 350C and it didnt want to flow until a gave it just a little scratch. Im limiting the area to where the solder will be.

Ill give it a try again on the cheaper cells so I dont over heat my new cells.

I still need to poke the balance cables though the housing of the battery for easy maintenance and balance charge, but I generally do a 4.1 max charge and store it around 4.0 so its still ready to use.

Impressed with these high drain cells... lots of power.



image_ftebmh.jpg
 

Wattsup

Member
Joined
Feb 19, 2017
Messages
512
Good job!

Lithium is quite amazing compared to the earlier chemistries.

I wouldn't rough up the surface of the cells either. I know some cells are harder to solder than others. Samsung 30Qs are the same.You can try giving them a rub with isopropyl alcohol, it sometimes helps.

Good high drain cell the 25R :rolleyes:
 

daromer

Moderator
Joined
Oct 8, 2016
Messages
5,662
Yeah in worst case clean them is my recommendation. just because the soldering station is big that doesnt say that it will do the job properly :)
Here you can see how easy it flows when I do it:

I have not soldered many new cells so it might be they are coated and need to be cleaned first?
 

Crimp Daddy

Member
Joined
Feb 21, 2018
Messages
973
I saw a far ammout of scuffing going on in that video my friend :)

Your iron does have a lot more thermal mass than mine... maybe I will upgrade. I am already using the largest chisel tip I have, and the solder does flow without too much time, but not as effective as what you have going on.

These days I am leaving some nickel strip on my cells which actually makes it easy to solder to, but these new cells were really something else. Without some light scuffing, it just looked like a cold joint, the second I scuffed it, it flowed beautifully. The heat wasnt the problem...

Ill let you know how it goes on the next pack, this was only my first...
 

Wattsup

Member
Joined
Feb 19, 2017
Messages
512
CrimpDaddy said:
I saw a far ammout of scuffing going on in that video my friend :)

Your iron does have a lot more thermal mass than mine... maybe I will upgrade. I am already using the largest chisel tip I have, and the solder does flow without too much time, but not as effective as what you have going on.

These days I am leaving some nickel strip on my cells which actually makes it easy to solder to, but these new cells were really something else. Without some light scuffing, it just looked like a cold joint, the second I scuffed it, it flowed beautifully. The heat wasnt the problem...

Ill let you know how it goes on the next pack, this was only my first...

Could be somthing different with the high drain cells coating, as I've never had issues soldering laptop cells??
 

daromer

Moderator
Joined
Oct 8, 2016
Messages
5,662
Could most likely be a coating for sure.
 

Headrc

Member
Joined
Jan 27, 2018
Messages
258
Excellent job ..very nicely done. I have done one so far myself ...and many more to come. More power, holds charge better ...and a great way to use cells you might not use in a big project. I might even try some of these hard cased prismatics that I found for this.
 

The-J-Man

Member
Joined
May 2, 2017
Messages
260
Cool mod!
You havent mentioned anything about the low voltage cutoff. At what Voltage does the electronics in the Snap-on shut off?
Wouldnt want to deep discharge your cells :)
 

Crimp Daddy

Member
Joined
Feb 21, 2018
Messages
973
Thanks, there are no voltage protections, electronics, or BMS... everything is externally managed just like it would be in a RC LiPo pack (hobby charger and or CellLog for monitoring).

Over discharge is of little concern since this isn't used continuously in a production environment like in a busy shop. I just need it to hold a charge for emergency use on the road, the trail, and the occasional vehical maintenance tasks in the garage.
 

hauburger

New member
Joined
Jun 29, 2021
Messages
1
This was my first project where I converted a Snap-On NiCad battery pack to Lithium... just wanted to share and get any input!

No BMS, but I use a hobby charger to charge. These cells can really deliver some power!

I've owned this Snap-On impact gun for at least 8-10 years now...


View attachment 16857


Its a damn good gun, but back in those days Lithium wasn't really an option, and those Nickle Cadmium batteries it came with have faded away over the years. Surprisingly its lasted this long, so I guess those Japanese made batteries held up pretty well but one of the packs went completely dead. After a full charge, only takes a month of sitting to see 0 volts.

I looked at replacements and those are $100 each, no way am I paying that for Nickle Cad packs...

I looked at a replacement, new Snap-On, and wasn't in to mood to shell out $600 on a set setup.

I looked at the Milwaukee M18 fuel 1/2 impact and its not bad at all for $350, but a brand new impact still has similar specs as my 10 year old Snap-On! Impressive for something I bought that long ago considering its still very valid today.

So with only the packs holding me back, I decided to rebuild them, but I wanted Lithium.

I set off to find some beast mode lithium cells and came across the Samsung INR 25R. These are high discharge / high drain cells. After reviewing the spec sheet I purchased a few to play with.


View attachment 10756


After testing individual cells, I started assembling them into a 5S1P (5 series 1 parallel) pack. That gives me a max of 21v fully charged. Its the most I could fit into the stock pack.


View attachment 6362


I marked the tab locations for the series connections...


View attachment 18019


Its recommended to use a spot welder, but I dont have one, so soldering it is. Its helps to scuff up the surfaces and flux for good flow and adhesion.


View attachment 12088


I wanted to be able to balance these lithium packs as well, so I made a custom balance cable with the intention of having this port externally accessible. I made the dongle and routed the balance leads accordingly.


View attachment 4767


View attachment 3183


Using a high quality hobby charger typically used for RC hobby stuff, I checked the balance leads. I can now monitor and balance each individual cell along with being able to charge the pack itself.


View attachment 15241


Everything looked good, tested well, so I started packaging it all up and made it secure in the original pack with Anderson Power poles so I can service or rebuild the pack for the rest of its service life.


View attachment 13059


View attachment 15540


Because I used Anderson connections, I can easily open the pack for testing. Here is my inline amp meter I used for testing performance.


View attachment 1800


Here are the results from my 4Runner with lugs @ 83 ft/lb. 23 amps / 460 watts! It literally spins the lugs off like butter. Also well within the battery performance specs.


View attachment 1592


View attachment 9235


View attachment 16147


Here are the results from my Chevy Silverado with lugs @ 140 ft/lb. 41 amps, 712 watts! Its a beast... works like new, and still throw those lugs off with authority. I am really impressed with how much current those cells can deliver. Really impressive for a single series string of batteries.


View attachment 8486


View attachment 10438


View attachment 14204


All in all, a successful project and a new love for a tool I have had for a long time. I really enjoy how light the new packs are too, its easier to handle and just less weight to swing around.


View attachment 5587


The only thing that has really changed is charging. I use a hobby charger now but its worth the trade off.

I no longer have to worry about my packs going dead in storage, or on the trail. Those Ni-Cads could have left me stranded. There were times it felt full, the the packs loose juice over time.

I always have power and it never fades in storage. Since my charger is DC, I can easily charger it off the trucks 12v battery.


View attachment 19009


New life to an old tool, and it really does work better as well or better than it did when I got it. I have already started converting other old Hitachi drill pack to Lithium.
Sir can you show or tell how you attached the negative and positive wires to the terminals? Also what type of connector did you use for the power balance cable?
 

Crimp Daddy

Member
Joined
Feb 21, 2018
Messages
973
Sir can you show or tell how you attached the negative and positive wires to the terminals? Also what type of connector did you use for the power balance cable?

I used a soldering iron to connect the leads to the OEM terminals, and also used Anderson Powerpole (crimped) connectors as a disconnect between the battery and the pack. The balance leads are standard JST connectors.
 
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