I did a lot of research on the net about early failure of Makita lithium batteries. My conclusion: this
battery has design flaw that shuts down these batteries prematurely. If the battery sits discharged for a long
time, it's very likely to spuriously fail. The symptom is flashing red and green lights on the charger, for a battery with infrequent use. [This is not the same as an actual worn out battery that is several years old and has many charges on it, say 500 charges or more. That is normal wearout, not the premature failure I mentioned. See below for some ways to fix a worn out battery.]<br><br>The good news is Makita will replace the battery free if it has a low charge count (for sure under 150, some say under 300), regardless of warranty. The bad news is you lose time and money dealing with it, and a lot of people don't know about the free replacements. Makita should recall the batteries, but they are quietly ignoring the problem. Most people just buy a new battery, so Makita has a conflict of interest here. Most of my power tools are Makita, and they usually last for years, top quality. I'm very surprised at the way Makita is (not) dealing with this lemon.<br><br>Background: Lithium batteries
can burn or explode if abused. They need monitoring, for safety reasons.
So Makita put in a smart control board in the battery
pack. The control board monitors charging voltage, current, battery
temperature, number of charges, and remembers all that. Good idea,
right? But.. there is a design bug. The battery control board draws
power only from the first cell of the 5 cells in the battery. If you
leave it sitting for a while, the control board will deep discharge that
first cell to zero, while the others remain charged. To the control
board or possibly the charger, that looks like a shorted cell, which
could overheat, and the control board remembers it. If you try to charge
it more than 3 times with an apparently deep discharged cell, the conservative software in the control board locks the battery permanently! The
control board tells the Makita charger that the battery is unsafe to charge,
and prevents charging in the Makita charger. Once "bricked", the battery cannot be reset.<br><br>This is a design bug. The
key evidence is the apparent dead cell is almost always that first cell, the
one that powers the control board. Once locked, the control board can't be reset. This problem is so common that Makita Service Centers will replace your dead battery if it shows very low usage, under 150 charges, regardless of warranty status. So, they know about the problem, but have not recalled the battery officially. They let you buy a new battery instead! That's not right. We should not have to deal with premature failures
caused by a known design defect. Who has time on the job, and who has
money to throw away?<br>
<br>If you have a locked battery with low use, contact the Makita Service Center near you for a replacement. If they won't replace it, it may still be usable. The workaround is to charge it on third party chargers, that ignore
the control board. Aftermarket chargers cost about $60 on eBay, a lot less than a new battery. They take longer to charge the battery, 2 hours instead of 20 minutes for the Makita charger. No free lunch, but at least you can save your perfectly usable battery from landfill.<br><br>I can think of many engineering changes to fix this. For
example, Makita could reprogram the battery control board or charger so
it did not lock up a good battery, or the control board could draw power
from all 5 cells so this is less likely to happen to a single cell, or
use a separate coin cell for the control board, or ... well, as you can
see there are many technical options. My point is that
Makita's engineers need to pick a solution and fix this problem.<br><br>This serious
problem has been identified, and it needs to be fixed. In my opinion,
Makita should recall these batteries and fix this problem, and release a revised battery design for new sales. If not, Makita's reputation will
continue to suffer, and there could be a class action lawsuit too.
Makita is infuriating customers and harming its reputation. <br>________________<br><br>Worn out lithium batteries: If your batteries are many years old and have had a lot of use or been subjected to high heat, they could simply be worn out. That's a different problem. Lithium cells do wear out, and they also permanently lose capacity each year - about 20% per year, faster if stored hot. Makita knows this and they derated these batteries to allow for shelf life. The cells are actually good for 2400 Mah when new, but Makita rates them as 1500 Mah to be conservative. <br><br>You can repair these batteries by replacing cells, either some or all. Watch this youtube video on how to open the battery pack: <br><br>http://www.youtube.com/watch?v=Z5taguEdlkY<br><br>The cells are Sony 18650 size in 2400 mah capacity. These are not sold retail, only to manufacturers and repair centers. You have to get them from another Makita pack, or many laptop batteries use them. There are 5 in the 1815 battery, 10 in the 1830 battery. If the failure is just in the first cell, I'd take it to Makita for possible replacement. <br><br>You may be able to trickle charge a cell and bring the pack back to life. The Tenergy Combo charger is a safe charger for this:<br>http://www.amazon.com/Combo-Special-Tenergy-Balance-Charger/dp/B00466PKE0<br><br>If more cells are bad, measure the voltage on each cell or cell pair,
and replace as needed. If you have more than half bad, replace them
all, becasue the rest will go soon. If you replace them all, they don't
have to be Sony, just any quality cell, 18650 size 2400 mah or better,
from a good maker. You can find them on ebay.<br><br>Here is a website that deals with repairing an older NiCd pack. The cells are different but the procedure is similar. Good photos step by step:<br>http://www.kichline.com/chuck/fixit/makita/Default.htm<br><br><br>
