Makita 18V LXT batteries....

[itguy07]

thoses are not regular li co cells, (in factroy batteries), those cells can take overchrge, and are made for high current, and no, li ion cells do not balance automaticly, in those batteries, since there is no balance circuit. just monitoring of last cell in the pack. take one apart you'll see what i'm talking about.
i have few li ion drils at work that are used almost daily, we had no problems so far with batteries, all still work fine.

Then Makita is selling some junky LiIons. Even the lowly Ryobis have a cell balancer built in. Look at this page:
http://toolboyworld.com/eBay/Ryobi_Batt_Rebuild.htm

Lots of circuitry and you can see that there are connections to the motherboard from each cell.

Also Miwaukee states they have balance circuitry in their batteries:
http://www.milwaukeetool.com/lithium-ion
http://www.facilitiesnet.com/equipmentrentaltools/article/Building-a-Better-PowerTool-Battery--3001#

Good LiIon tool batteries need to have balancing built in, either in the battery or the charger.

 

[alpg88]

i beg to differ, makitas work just fine, that i see firsthand, for years, how they do it, makes no difference to me. they use sony cells btw.

Good li ions are those that work good, and makita does just that, if they can acheave it with simpler circuit, good for them, not a negative point by any means, ime.

 

[Chodes]

deleted
missed "reply with quote" - post made no sense without ti..

 

[Chodes]

theoreticly yes, but why???

all cells charge fully with factory charger, even thou most get overcharged in the process, but cells chemistry allows it somewhat. and you would have to take apart the pack, and solder balance tail to it. and at the end, you will, most liklely, not get any improvment, over factory set up. not to mention good bye warranty

I believe Lurveleven suggestion was for Therapyo to balance charge the pack he was unable to chage with makita charger due to first 2 cells (same problem with his knockoff pack).
He had pack apart, so hope was to balance charge to restore pack then continue to use with Makita charger.

 

[dwminer]

Does this problem still exist with the newer 18volt XLT batteries and
the DC18RA charger? Thanks Dave

 

[alpg88]

Does this problem still exist with the newer 18volt XLT batteries and
the DC18RA charger? Thanks Dave

i,m not aware of any changes made to makita batteries or chargers lately, neither i'm aware of any problems they have, i have few of them at work that are used daily, no problems with either.

 

[SemiMan]

On a related note, had a similar issue with a Lenovo laptop battery pack. The laptop was broken and one of the internal cell connections for the balancing, not the power connection, came off. No worries thought I, just a little bit of solder and we are good to go. Unfortunately, the battery management chip bricked the battery pack and there was nothing that could be done about it. Went on the web and found numerous complaints about situations where the pack just bricked even though it still had a lot of capacity and nothing could be done about it.

Bad corporate citizenship at the end of the day .... along the lines of bricking printer cartridges but I would say in this case even worse as battery packs are likely a small replacement market overall.

Semiman

 

[Nate154]

Can someone speak to whether you can replace your battery, if defective, regardless of warranty, like someone above mentioned? I called Makita and they weren't having that.

 

[mucek]

I have started reverse engineering on the Makita LiIon battery pack. So far it's clear, that the communication between the MCU and charger is done by UART on MCU (MCU connects to battery management chip via I2C). There will be plenty of thing to find out until the hacking of the locked chip will be possible. In addition, there's also EEPROM in the battery management chip, which may also contains some "lock".

In next days I'll first try to replace battery managment chip between locked and unlocked battery to see, if the issue is in MCU's eeprom or in battery management chip. (first option is more possible) I'll also try to "sniff" on the data lines to see, what messages are exchanged between the battery and the charger. Lots to doo, so if any has some more information on the protocol itself, I'd be glad to know it ...

Follow this for more details: http://www.ecat.si/2013/09/makita-hacking-part-i/?lang=en

Regards,
Gregor

 

[elduderino970]

Hi Guys,
This thread is great! Glad I found it!
I have an 1830 battery that is giving the red/green flash from the factory charger. I know this sequence has happened at least twice. Hopefully the control board isn't already bricked. I opened up my pack and found one cell showing 0 volts. I have tried to charge just that cell with my Accucell 6 charger but it won't take a charge. So, that means I am down to replacing the cell. I have read above that these packs actually use Sony LiMn instead of the usual LiPo 18650s. I have lots of 18650s but none are LiMn. I am concerned that it isn't safe to mix the two types in the same pack. So far, I haven't found any info to that idea on google. Do you guys know if I can drop a LiPo into the mix with the LiMn cells?
Thanks!
John

 

[Bullzeyebill]

Do you guys know if I can drop a LiPo into the mix with the LiMn cells?
Thanks!
John

Welcome to CPF. The answer is no, do not mix different chemistries. Please start your own thread with this question as it is OT here. Thanks,

Bill

 

[elduderino970]

Welcome to CPF. The answer is no, do not mix different chemistries. Please start your own thread with this question as it is OT here. Thanks,

Bill

Thanks for the welcome. I tried to join several months ago and I was auto-banned. I found this thread and some more searching lead me to the faq on the IP/domain whitelist issue. I used another email and it worked!
With my new found knowledge, I will be shopping/diving for some LiMn cells. Thanks again!
John

 

[mucek]

Try to search for Konion LiIon cells - those are "the ones".

In the midtime I already did some research as well as some analisys. Looks like that protocol is not UART (regardless that it's UART0 pins of the microprocessor are used).
I have recorded some data with good and locked battery, you can check here for the osciloscope image as well as data (.CSV)
http://www.ecat.si/2013/10/makita-hacking-part-two/?lang=en

Regards,
Gregor

 

[delus]

I have eight of these batteries and lock most of them in my truck toolbox year round. It's gotta get pretty hot in there in the summer, and cold in the winter. Have not had a failure since I switched to makita two years ago. I am quite impressed with makita tools all around.
Thought I'd sneak in my slightly off-topic trick for getting Makita tools on the cheap.

They have a few of those display trucks that travel to events around the country. FIND ONE. They attend a lot of NASCAR and Motocross events. Trade shows. You might ask the right person at your closest Makita factory authorized repair center. The makita website has an events calendar. Just figure out some way to FIND ONE of those trucks.
Go to the event with some C-Notes, and wait until it's over. Wait until almost everyone has gone home. Wait until they are just about to pack up and leave. The guys in that truck are now ready to deal.
Walk around and don't look too interested, say something like "i have a few DeWalts now, but I liked your stuff every time I used one."

With this technique in 2011 I got a 15 tool set, the biggest set they offer, for $1050, which is $450 less than it is offered anywhere else.
A few weeks ago I got a BRUSHLESS impact-driver and drill set for $230, which is $50 less than I've seen the non-brushless kind.

 

[keithwins]

Have not had a failure since I switched to makita two years ago. I am quite impressed with makita tools all around.

Interesting point I just figured out: in watching a youtube video disassembling a Makita BL1830 battery pack http://www.youtube.com/watch?v=3yBnY54o2vw, I noticed he said he was working on the newer style, within the last couple years (video was posted a year ago). I realized, as I watched, that his battery was different than mine, and had leads to each set of parallel cells. So the newer Makitas are capable of balance charging, whether or not they actually do it (I would assume they do). This is actually sort of interesting, and even makes me wonder if I could add official Makita balancing to my current batteries: all the leads are there except a couple short internal wires inside the battery itself... I had noticed that the Makita battery connection had just enough leads for a balance charger, but in mine they aren't used. I've been gearing up to try to recondition/repair/swap cells in some of the 5 dead batteries I have lying around, and even splurged $20 for an IMAX B6 charger for the project. I regret I don't have the newer Makita battery/charger, and I may open up my charger to see if it has balancing set up, just for kicks. I also imagine that ebay no-name cheap batteries may not have this balancing set up... In fact, both the batteries I've just open are precisely that, but I've got several dead official Makita batteries also, I'll check them soon. Most of these are 3-6 years old.

Note, in the two batteries I've opened, one or two sets of cells were dead, and everything else was reading near 3V or better, so they should be salvageable, though the control chip in the battery bricks the battery if it's registered as dead and recharge is attempted 3 times, as I understand. I can't help but wonder if setting up the official Makita balancing system wouldn't reset this... Hmmm. Gotta wonder.

Keith

 

[elduderino970]

The good news is the Makita Girls are working today. The bad news is that they are in Alaska. Makita Appearances
Makita has a separate calendar for trade shows and is empty for the rest of the year. Tradeshows

I just talked to someone at Interstate Batteries. He said he has worked there for six years and was capable of discussing LiMn etc. He said they are similar enough to replace with a Li-Ion. I am wondering about the experiences of others in this 3 year old thread, several have replaced cells. I wonder if any have been non-LiMn and how that is working out...

 

[keithwins]

So: I'm realizing now that Makita has officially released a balancing charger, which presumably interacts with the newer batteries. The older Makita batteries are definitely not wired for balancing, though all the contacts are there. The newer "rapid" chargers are the dc18rc, vs. the older dc18ra. I don't know of any way of identifying whether the batteries you have are the newer balancing type by looking at them, although one could measure the voltage across the balancing leads without having to open the case... Now that I'm down to one working battery, next time I have money I might switch over to the newer system, but it would end up costing several hundred dollars...

 

[mucek]

@keithwins:
Can you please post some macro shoots of the PCB for 18 V BMS circuit inside the battery? Currently I am only working on a protocol analisys with 36 V batteries, which DO HAVE some balancing incorporated through bq77pl900 battery managment chip, but I am not sure about the 18 V; I assume they should use quite the same protocol for the smaller batteries (need to get one ).

I also noticed, that Makita uses a BIG safety reserve on a charging voltage, as cells, charged with Makita charger, only reach 4,00 V per cell. Usual charging voltage for this cell type is 4,10 - 4,20 V, which practically means around 25% of the usable capacity (tested with 4 36 V packs, used for caving hammer drill - charged with Makita charger, 8-9 holes were drilled before the battery went empty; charged with custom charger (and balancing) to 4,15 V, 12-13 holes were drilled (which isn't significant, if you first have to climb in a cave for several hours to get to the point, where you do the drilling!).

However, charging to lower voltage for sure increases battery lifetime, but having set limit to 4,00 V is just a bit to low for my taste. Well - if they would like to have a REAL lifetime, then they should protect the cells from over-DISCHARGING! (Which they don't! Machine runs slower and slower and slower ... As the battery doesn't have some MOSFET or something to disconnect it when one of the cells is (too) low, I would expect that the drilling machine would have done it. But - as the machine work also without BMS circuit, only the full pack voltage can be measured - if even so?!)

I am working on a simulating the communication between the charger and the Makita BMS and then I'll see, if faking only initial pulse is enough to make the charger "alive" or more will have to be done ...

Regards,
Gregor

 

[keithwins]

Hi Gregor:

I only have the old-style Makita 18v batteries, that don't have balancing built in. I would expect that they might dare come closer to fully charging the battery when using a balancing charger, but I have no idea if that's true. I also wonder if you fixed dead cells in a dead battery, and re-wired it to balance, and used a balancing charger, would it notice/care that it had been "bricked" by a non-balancing charger? As far as I can tell, there's no reason for it to, since the charger would be able to tell that each of the cell pairs is fine. But that comes down to how they build/program the BMS. I don't know that much about batteries, honestly, but it does seem like over-discharge protection would be nice... Other people use my tools, and I just can't get them to stop using them after they start to slow down, they often run them dead. Hence my big pile of dead batteries.

I'm going to try to attach a pic, but it's not going to be that helpful I think: I can't take a pic of the back of the BMS PCBs without removing them, and I can't do that without desoldering/cutting, and I don't feel like doing that, since I don't need to. You might be able to find this elsewhere, or get someone like drbass on youtube who I believe regularly dismembers these batteries.

 

[Bullzeyebill]

Your image is not working.

Bill