Making the battery Makita won't.

[Rabid Badger]

This is long-winded. For the payoff, scroll down to the red arrow.

I like my Makita tools. They're dead reliable, have excellent ergonomics and build quality and are consistently the best of the big brands when it comes to NVH. Unfortunately, I also like watching Torque Test Channel. They've been steadily sowing seeds of discontent in my mind regarding the stagnation of battery technology for the LXT line. They assembled a 21700 battery pack for LXT tools that radically increased their performance, but it also lacked basic safety features like cell balancing, low voltage cutoff, et cetera. I didn't see any better alternatives, so I soldiered on with my 5Ah batteries.

Fast forward 10 months or so and I came across this battery on Amazon:



It advertised 21700 cells and:

A) The picture wasn't a render.

B) It looked like it might be decent quality.

For $50, I took a chance and ordered one. When it arrived I was surprised at how solid the housing felt. It's polycarbonate, just like OEM Makita batteries. When I opened it up I was even more surprised to find a management board with a microcontroller, bms chip, cell balancing, temp sensor, shunt resistors for current monitoring, and 3 110A mosfets for emergency cutoff.



The battery also contained Lishen LR2170LA cells. Lishen is a lesser known Chinese manufacturer, but everything I found said these cells perform somewhere between Samsung 40Ts and Molicel P42As. In other words, pretty damn good. The only real problem was the thermistor on the board wasn't bonded to the cells, but that was an easy fix. For $50, this battery was an absolute steal.

I ordered another. When I opened it up I was pleased to see the thermistor had been properly bonded to the cells, but instead of the Lishens, this pack contained Samsung 30Ts. These are quality, high-current cells, but they add up to 6Ah, not 8. I was disappointed since I wanted a pair to use in my lawn mower, by far my highest-draw LXT tool.

Then it happened. I found the same battery shell/circuit boards being sold as a kit on Aliexpress for $16 each. I ordered two, along with 20 Molicel P45Bs. Today, I fired up my home-built battery spot welder and got to work:



The build went smoothly, all the parts are well made and fit together nicely. I added some additional nickel strips to the positive and negative terminals on the circuit board for extra current capacity, assembled the pack and threw it on the charger.



A while ago, YouTuber Tools and Stuff did a runtime test of the XGT and LXT versions of the Makita dust blower. The LXT version ran for 12.5 minutes. At the end the 5Ah battery was extremely hot and had to be cooled down before it could be charged.

My results: 25.5 minutes, and the battery pack was barely warm. After the pack recharged, I opened it up and checked the voltage of the cells and all of them were within 0.002V. This is better than the 0.05V balance the cells had when I assembled the pack, so I think it's safe to say the cell balancing works.

I'm going to call this a success.

 

[PowrKraftsman]

Very interesting. Thanks. No way I’d be able to assemble that or know for sure myself if I was getting a battery that was as advertised or safe to use. My only battery powered Makita tools are my old drill and driver, new XPH14 drill and XDT19 driver, and 2x18 mower. My 5ah and lower batteries are fine for my needs, and I happily rely on corded versions for other power tools, but I admit that the current state of the LXT battery lineup has me confused and a bit worried.

 

[engineer2]

I agree that Makita is moving to their 40V platform. All their recent advertising focuses on it.
18V (really 20) will be around for a while, but new tool offerings will diminish, in my opinion.
Coby7 on the Snowblower forum has also been posting about building Makita batteries.
It's nice that other products are available that use Makita batteries. I bought a soldering iron that runs off of an 18 V LXT battery and it's a great tool.

 

[drmarkr]

This is long-winded. For the payoff, scroll down to the red arrow.

I like my Makita tools. They're dead reliable, have excellent ergonomics and build quality and are consistently the best of the big brands when it comes to NVH. Unfortunately, I also like watching Torque Test Channel. They've been steadily sowing seeds of discontent in my mind regarding the stagnation of battery technology for the LXT line. They assembled a 21700 battery pack for LXT tools that radically increased their performance, but it also lacked basic safety features like cell balancing, low voltage cutoff, et cetera. I didn't see any better alternatives, so I soldiered on with my 5Ah batteries.

Fast forward 10 months or so and I came across this battery on Amazon:



It advertised 21700 cells and:

A) The picture wasn't a render.

B) It looked like it might be decent quality.

For $50, I took a chance and ordered one. When it arrived I was surprised at how solid the housing felt. It's polycarbonate, just like OEM Makita batteries. When I opened it up I was even more surprised to find a management board with a microcontroller, bms chip, cell balancing, temp sensor, shunt resistors for current monitoring, and 3 110A mosfets for emergency cutoff.



The battery also contained Lishen LR2170LA cells. Lishen is a lesser known Chinese manufacturer, but everything I found said these cells perform somewhere between Samsung 40Ts and Molicel P42As. In other words, pretty damn good. The only real problem was the thermistor on the board wasn't bonded to the cells, but that was an easy fix. For $50, this battery was an absolute steal.

I ordered another. When I opened it up I was pleased to see the thermistor had been properly bonded to the cells, but instead of the Lishens, this pack contained Samsung 30Ts. These are quality, high-current cells, but they add up to 6Ah, not 8. I was disappointed since I wanted a pair to use in my lawn mower, by far my highest-draw LXT tool.

Then it happened. I found the same battery shell/circuit boards being sold as a kit on Aliexpress for $16 each. I ordered two, along with 20 Molicel P45Bs. Today, I fired up my home-built battery spot welder and got to work:



The build went smoothly, all the parts are well made and fit together nicely. I added some additional nickel strips to the positive and negative terminals on the circuit board for extra current capacity, assembled the pack and threw it on the charger.



A while ago, YouTuber Tools and Stuff did a runtime test of the XGT and LXT versions of the Makita dust blower. The LXT version ran for 12.5 minutes. At the end the 5Ah battery was extremely hot and had to be cooled down before it could be charged.

My results: 25.5 minutes, and the battery pack was barely warm. After the pack recharged, I opened it up and checked the voltage of the cells and all of them were within 0.002V. This is better than the 0.05V balance the cells had when I assembled the pack, so I think it's safe to say the cell balancing works.

I'm going to call this a success.

Please provide a link for Amazon?? I'm not seeing that battery anywhere on there?

 

[Rabid Badger]

Please provide a link for Amazon?? I'm not seeing that battery anywhere on there?

The pre-built one? They go in and out of stock, so they don't always show up in search:

https://www.amazon.com/gp/product/B0CKHLN394?tag=atomicindus08-20

The kits came from Aliexpress. I haven't seen them anywhere else:

https://www.aliexpress.us/item/3256806803364276.html

The Molicel P45B cells came from here:

Molicel 21700 P45B 4500mAh 45A Battery

Buy the Molicel 21700 P45B 4500mAh 45A battery, a high-performance power cell with exceptional cycle life and low temperature operation. Fast charge and low impedance for reliable use. Available now!

www.18650batterystore.com

If you need a spot welder, this one seems decent for under $50:

https://www.amazon.com/WESTOBiG-Combination-Adjustable-0-1MM-0-25MM-Stainless/dp/B0D49F7LKH?tag=atomicindus08-20

 

[Rabid Badger]

Coby7 on the Snowblower forum has also been posting about building Makita batteries.

He's going to run into problems with those. He's putting in the highest capacity cells he can find. That will work just fine running an LED lamp, but power tool batteries need cells with a high current rating.

There is a inverse relationship between current rating and capacity in most cells. I could have filled my battery with higher capacity cells, but the P45Bs are the best compromise between capacity and current rating right now, as long as you aren't talking about tabless cells.

 

[Mandres]

Very interesting! That board and enclosure kit is a great find. How is the quality of the spring latch compared to Makita oem?

Think I'll order a couple to play with

 

[Rabid Badger]

Very interesting! That board and enclosure kit is a great find. How is the quality of the spring latch compared to Makita oem?

Think I'll order a couple to play with

If anything the latch is a little nicer than regular LXT batteries. They essentially copied the XGT design. The springs they use are strong; the batteries snap in with a very satisfying click.

 

[American Locomotive]

I agree that Makita is moving to their 40V platform. All their recent advertising focuses on it.
18V (really 20) will be around for a while, but new tool offerings will diminish, in my opinion.
Coby7 on the Snowblower forum has also been posting about building Makita batteries.
It's nice that other products are available that use Makita batteries. I bought a soldering iron that runs off of an 18 V LXT battery and it's a great tool.

Makita is still releasing new product for the LXT platform, however.

It will be interesting to see if they do something about the batteries, however.

 

[Rabid Badger]

Makita is still releasing new product for the LXT platform, however.

It will be interesting to see if they do something about the batteries, however.

That was another thing I forgot to mention: I think Makita was planning on releasing 21700 cell batteries for the LXT line. These batteries fit just fine in my mower, and look at this:



That thing was designed for 21700 batteries.

 

[Rabid Badger]

Update:

Today I put the new batteries to the test after letting the grass in my backyard grow for a few weeks.

With the factory Makita batteries I would have to mow 1/3 the width of the mower on each pass when the grass is this long, and the batteries would be hot to the touch afterward. Using the new packs the mower powers through stuff that would have stalled my old Honda gas mower, and the batteries stay a comfortable temperature. The difference is staggering.

I'm now even more certain that Makita's engineers intended this mower to be powered by batteries with 21700 cells that got cancelled to avoid internal competition with XGT.

 

[WildBill]

The battery shell/circuit board kit is down to $8.26 today. I'm grabbing a couple, thanks Mr.Badger!

Edit - I lied, that was for just the case, sorry.

 

[manac]

Damn you Garage Journal, another project I have to build.
I was just reading the thread about people bitching about the cost of 18V batteries and I stumble on this.
$35.05 + $118.84. Tax and shipping. Anticipation…

 

[Dixie_Flatline]

Damn you Garage Journal, another project I have to build.
I was just reading the thread about people bitching about the cost of 18V batteries and I stumble on this.

Agreed! Been needing some extra batteries but was hoping for a sale of some sort since they think a lot of the factory units!

 

[Formerjeeper]

@Rabid Badger what are your thoughts about these?

Ceenr 8.0Ah Battery For Makita 18V 4 Pack | Model BL1860B

The Ceenr 8.0Ah Battery is a powerful replacement option designed for Makita 18V power tools, featuring compatibility with Makita's BL1860B model.

ceenr.com

 

[Rabid Badger]

@Rabid Badger what are your thoughts about these?

Ceenr 8.0Ah Battery For Makita 18V 4 Pack | Model BL1860B

The Ceenr 8.0Ah Battery is a powerful replacement option designed for Makita 18V power tools, featuring compatibility with Makita's BL1860B model.

ceenr.com

I just saw those for the first time earlier tonight. The build quality and BMS are not great. It's too bad, because the cells they're using are pretty good.

 

[manac]

@Rabid Badger thanks, received the battery packs today and slapped one together. Looks good. Haven’t charged it yet. I want to babysit it for the first charge.

Used the Fnirsi SWM-10 spot welder you linked to. Work’s really well.

Just a heads up the 21700 batteries don’t fit my 36V chainsaw or circular saw. Don’t think it’s a big deal the packs are heavy and I don’t think I’d want to carry them around on the saws.

I’ll post pictures of assembling the second one. It’s really quick and easy.

 

[Rabid Badger]

@Rabid Badger thanks, received the battery packs today and slapped one together. Looks good. Haven’t charged it yet. I want to babysit it for the first charge.

Used the Fnirsi SWM-10 spot welder you linked to. Work’s really well.

Just a heads up the 21700 batteries don’t fit my 36V chainsaw or circular saw. Don’t think it’s a big deal the packs are heavy and I don’t think I’d want to carry them around on the saws.

I’ll post pictures of assembling the second one. It’s really quick and easy.

That's awesome! Looking forward to the build pics.

 

[manac]

Second one is done, 20 minuets or so. The hardest part was screwing the case together. Had to drill out the holes the T10 screws wen into so my driver wouldn’t cam out. I haven’t done much resistance welding but the welds came out very strong.
This is a 10 cell pack in a 5S2P 5 series 2 parallel configuration.
You end up with 5 times the voltage and twice the capacity of a single cell.


Load the cells into the battery carrier. Two screws hold it together. The carrier is marked +/- for the battery orientation.


Place the battery management board on the carrier. Fit the balancing tabs to the board.


Now the fun part. Tack weld the end plates to the batteries.


The Fnirsi comes with some Nickel strapping. I practiced on some old batteries to get it dialed in.
The weld cycle is:
Preheat (no idea what that does for a weld)
Pulse - the weld.
Interval - time between welds
Dots - number of welds in the same location.
I kept it simple. Left the preheat alone and only one weld for 18 ms.


Next solder the tabs to the board
Assemble the case and your done.

18650 5Ah 3” wide 22.4Oz. 635g
21700 9Ah 3.25” wide 32.5Oz. 920g


5, 9Ah

1.5, 5, 9Ah

 

[dnschmidt]

Makita charges over $350 for two 6.0 batteries. If they made this they would charge $500 each. Love their tools but absolutely hate their business practices. Milwaukee, FLEX and Dewalt are having MAJOR Black Friday promotions. Makita BUTKIS. They act more like Festool every day which is fine if you want to keep a 5-10% market share. When your batteries cost more than your tools do something is fucked up.

 

[manac]

@dnschmidt wrong thread, there’s a Makita battery price bashing thread already.
This threads about building fun stuff.

 

[Rabid Badger]

It's a little annoying how well these cheap welders work considering the time, effort and money I put into mine...but I digress.

Preheat is a brief pulse that helps to burn off contaminates and oxides prior to the main weld pulse.

Edit:

Hang on...



They've upgraded that BMS. Two additional mosfets and a third shunt resistor.

Looks like I need to order some new boards.

 

[Yoke17]

It's a little annoying how well these cheap welders work considering the time, effort and money I put into mine...but I digress.

Preheat is a brief pulse that helps to burn off contaminates and oxides prior to the main weld pulse.

Edit:

Hang on...



They've upgraded that BMS. Two additional mosfets and a third shunt resistor.

Looks like I need to order some new boards.

Hey thanks for the recommendation. aftermarket? 4 pack battery build kit you linked and built it with molicel p42As. Everything went together seamlessly. The first 2 i didnt realize the thermistor wasnt touching the battery so I desoldered the board and bent down the thermistor so it would touch a cell. The other 2 I built were done correctly afterwards


Do you have issues using an oem makita charger? I own an old dc18ra and a couple year old dc18rc and both of them give me a bad battery indication on all 4. Maybe its known that makita chargers won't touch aftermarket bms's and im late to the party?

Thanks in advance.

 

[manac]

Mine have been working and charging well. What’s your pack’s voltage? The Mikita chargers may not charge if the pack is at too low a voltage. I think I charged my cells and checked their capacity before I built them into the packs.

 

[Yoke17]

Mine have been working and charging well. What’s your pack’s voltage? The Mikita chargers may not charge if the pack is at too low a voltage. I think I charged my cells and checked their capacity before I built them into the packs.

My pack voltage is around 20v. I bought an xtar 8 bank charger and charged all 40 cells before installing them. I haven't run a pack down yet. I ran one of them down just one light bar and decided to give charging a try. Thats when I found out none of them would charge.

 

[Rabid Badger]

Hey thanks for the recommendation. aftermarket? 4 pack battery build kit you linked and built it with molicel p42As. Everything ewent together seamlessly. The first 2 i didnt realize the thermistor wasnt touching the battery so I desoldered the board and bent down the thermistor so it would touch a cell. The other 2 I built were done correctly afterwards


Do you have issues using an oem makita charger? I own an old dc18ra and a couple year old dc18rc and both of them give me a bad battery indication on all 4. Maybe its known that makita chargers won't touch aftermarket bms's and im late to the party?

Thanks in advance.

Mine work fine on the new dual-slot chargers, aside from the fact that they're programmed to stop charging at 6Ah, so I have to re-seat them to get a full charge sometimes.

 

[Yoke17]

Mine work fine on the new dual-slot chargers, aside from the fact that they're programmed to stop charging at 6Ah, so I have to re-seat them to get a full charge sometimes.

I haven't run any of them down far but I just confirmed #1 out of 4 charges. It didnt work a few days ago. I messaged the seller but they have been slow to respond. All they said was to check pack voltage and send a picture of the board.

I didnt think i spent too much time with the soldering iron on the board overheating anything. Board level repairs are beyond my experience.

I guess the only other thing I can do is probe the thermistor.

I set up the makota open battery information tool to attempt to read diagnostics. Im not sure if that works woth aftermarket batteries but it gage me a communication error. I confirmed the tool works with an oem battery.

Ill give the seller a few more days to respond before I escalate the issue.

 

[duneslider]

Curious how people's experience is continuing with these? I need a few batteries to abuse in a blower and trimmer and didn't want to risk my expensive makita batteries and thought about trying some of these? Am I better off not using the makita chargers?

 

[Yoke17]

Curious how people's experience is continuing with these? I need a few batteries to abuse in a blower and trimmer and didn't want to risk my expensive makita batteries and thought about trying some of these? Am I better off not using the makita chargers?

I built 4 of them and think I did a decent job of it. 3 out of 4 charge on aftermarket chargers only. 1 doesnt charge on anything but works fine. Waiting on the seller to send me a new BMS to rework the 1.

 

[duneslider]

I built 4 of them and think I did a decent job of it. 3 out of 4 charge on aftermarket chargers only. 1 doesnt charge on anything but works fine. Waiting on the seller to send me a new BMS to rework the 1.

I'm having trouble finding the same ones that you all used, I just seem to be coming up with 12ah version which is bigger than I wanted. I'm not great at Aliexpress searching...

 

[Rabid Badger]

Mine are working fine. I've also built 4 more batteries; two more with P45B 21700 cells and two with P30B 18650s to use with my leaf blower. I also upgraded the BMS boards on my older set to the new 5 mosfet version. All of them are charging fine on Makita chargers.

I'm not sure what is causing Yoke's issues. I don't think I would expect these to work with Makita debugging software, though. That would require a level of reverse engineering that would draw the attention of lawyers.

 

[Yoke17]

Mine are working fine. I've also built 4 more batteries; two more with P45B 21700 cells and two with P30B 18650s to use with my leaf blower. I also upgraded the BMS boards on my older set to the new 5 mosfet version. All of them are charging fine on Makita chargers.

I'm not sure what is causing Yoke's issues. I don't think I would expect these to work with Makita debugging software, though. That would require a level of reverse engineering that would draw the attention of lawyers.

I received the replacement board and plan on soldering it in soon. I do have a question about the bars though. The through holes for the bus bars are significantly wider than the bars themselves. Are you going out of your way to fill all the gaps or just enough solder to connect the side of the hole that is making contact? The concern is that I overheated it

The thermocouple is pretty short and just requires bending down to go through the case. I wish it was significantly longer so I could bond it to a cell instead of just relying on the force of the wire pressing the probe to the cell.

 

[Rabid Badger]

I received the replacement board and plan on soldering it in soon. I do have a question about the bars though. The through holes for the bus bars are significantly wider than the bars themselves. Are you going out of your way to fill all the gaps or just enough solder to connect the side of the hole that is making contact? The concern is that I overheated it.

It's pretty hard to overheat the connections with a normal soldering iron set to 350C. What kind are you using?

The way I do it is to position the tab so it is touching one end of the slot. Once a solder bridge is formed between the two parts, I start dragging the tip of the iron down the joint, feeding solder in just ahead of it. Make sure to keep the tip of the iron in the solder so both the tab and pcb are getting heated.

One thing I did notice that might have been the cause of your failed board:



A solder ball rolling around inside the battery housing could definitely kill a BMS.

The thermocouple is pretty short and just requires bending down to go through the case. I wish it was significantly longer so I could bond it to a cell instead of just relying on the force of the wire pressing the probe to the cell.

I put a dab of thermal adhesive in spot where the thermistor sits right before I put the BMS in place. This is the stuff I use:

https://www.amazon.com/GENNEL-Conductive-Silicone-Adhesive-Compound/dp/B072MSXHJD/?tag=atomicindus08-20

 

[Yoke17]

Good catch on the solder ball! I'll be more careful of that next time. That might explain the bad PCB but I doubt that would cause the issue with not charging on Makita Chargers. I'll be extra careful with this next one and see if it charges on OEM.

Thanks for the recommendation I just ordered that adhesive

 

[Rabid Badger]

Good catch on the solder ball! I'll be more careful of that next time. That might explain the bad PCB but I doubt that would cause the issue with not charging on Makita Chargers. I'll be extra careful with this next one and see if it charges on OEM.

Thanks for the recommendation I just ordered that adhesive

That was the other question I meant to ask: What Makita chargers are you trying to use and how old are they?

 

[Rabid Badger]

 

[jorp_porp]

Watched this video recently. Made me hyper critical of off brand lithium batteries.

 

[esben57]

This is interesting. Do not dabble with electricity at all myself but youngest son could take this on.
I bought a fake battery to fit my LXT tools, 5ah for £25. It's pants, and lasts minutes in drill or hedge trimmer. Case is ok though and it is just unscrewed to get inside. May look into this.

 

[jorp_porp]

This is interesting. Do not dabble with electricity at all myself but youngest son could take this on.
I bought a fake battery to fit my LXT tools, 5ah for £25. It's pants, and lasts minutes in drill or hedge trimmer. Case is ok though and it is just unscrewed to get inside. May look into this.

I had an off brand 40v battery that I pulled out of service after watching that.. It's concerning that they needed CT scans to identify good vs bad.

 

[Rabid Badger]

Watched this video recently. Made me hyper critical of off brand lithium batteries.

That's why I use top quality cells in my packs.