Archived from the Tools In Action forum (Makita). This thread is read-only.
hello,
I noticed heavy inconsistencies between Makita batteries, both in real life usage and in their marketing.
Their 2Ah 18V battery should last about 3 times less than a 5ah battery. If a 5Ah lasts 15 minutes on a tool, then 2ah should last about 5 minues, but in reality it lasts only 2-3 minutes before you get 1 bar flashing.
The 2Ah has 5 cells in 18650 format, all in series, I presume 2000 mAh cells, so in order to provide 200W of current, one cell needs to be able to discharge at least 40-50A. And 200W is not much because higher-powered tools are advertised to have power around 500W… So basically it means that the 2Ah battery only works on low-power Makita tools..
Then on the 40V platform they advertise the power output at around 1000W, and even 2000W !
A 40V 4Ah battery has 10 cells in it in 21700 format. In order to reach 4Ah capacity and 40V all of them would need to be wired in series (3.7 x 10 = ~36V). That means that each of the cell would need to have 4000 mAh capacity, which is fine… but in order to provide 1000W current, a cell would need to be able to discharge over 250A ! Which is crazy. There is no such battery at this format that can reach such discharge rates. And they market the BL4040F “high-output” battery to be able to handle 2000W tools. That is over 500A discharge per cell. Even if it’s a tabless cell, there is no way it can discharge more than 100A, when 50A is the standard for 21700 cells nowadays.
The math doesn’t make any sense to me..
Everything is fine, just something wrong with the math.
Let’s try to solve this mystery then.
The BL1820B which is 2Ah LXT is using most likely VTC4 cells. This is 5s1p which is 5 series 1 parallel. The VTC4 is able to provide 22A, and 5s give us around 18V nominal. So if we multiply 22A by 18V we got around 396W
Now let’s take a look at BL4040F, that one is best as it’s using latest tech which is tabless cells. It’s Murata VX40. It’s being able to output 34A and it’s connected 10s1p so 10 series 1 parallel. When we multiply 36V (yeah it’s 36V nominal and 40V max) by 34A we got astonishing 1.2kW!
Last beast is the BL4080F, I’ll leave the task for you, it’s using 10s2p connection with VTC6A capable of 30A. The question is what’s the output power of this battery?
30*36*2 ?
YES! Because it’s 2p then it’s 30A *2 so it’s 36V*60A = 2.16kW