As I’m talking to our vendors today at our annual tent event, I found some of the information that they’re sharing on the insides of their batteries to be quite fascinating. So here’s the breakdown of what’s different between Milwaukee V28, Bosch Litheon and Makita LXT.
V28 is made up of multiple 4V cells. They’re all wired in series and are 3Ah cells, making for 28V 3Ah batteries. The simple diagram looks like below:
Litheon (36V, anyway) is made up of 20 battery cells, each being 3.6V and 1Ah. They basically use two rows of 10, making each battery cell in parallel with another and then in series with 9 other such sets. The result is a 36V, 2.0Ah battery.
Makita did things similar to Bosch, but they used a different number of cells to achieve 18V instead of 36V.
What’s the big deal?
So what’s the big deal about having one or two rows? Well, not much with a new battery. However, Lithium depends very much on having the same charge across all cells. If one gets out of whack (temperature can create this problem), then all of the cells may or may not get fully charged or be able to fully drain. Strike against the two rows.
However, suppose you do have a cell go bad prematurely. With the two row setup, you have some level of redundancy, so the battery isn’t totally useless. So long as only one of the cells in each parallel configuration ever goes bad, the end result is that you’ve got a (slightly) usable battery, even with half of the cells going bad. Strike against the single row.
Now, take into account that more Ah = less stable battery architecture and you’ve got a second strike against the single row because each cell in the dual row design has a lower Ah rating.
Either way, there are issues. When Panasonic releases their Li-Ion, they’ve got a different monitoring technology at the cell level that they say will be improving upon the power tool Li-Ion industry, so I’ll have to add a new diagram at that point. But for now, you’ve got 6 in one and two half dozens in the other.