I wanted to share some experience with mainstream Greenworks power tools batteries. Although they don’t pack the same energy density as what custom battery builders can achieve with quality cells, there are still a few advantages and are a viable entry-level option for EVs. As long as you know what they can and cannot do.
First, they are widely available, and reasonably affordable (hard/expensive to get quality cells for a battery build, and not that many battery builders in NZ), and trustable compared to dodgy batteries from aliexpress or the plethora of fake cells that abound. Greenworks have their own factories, they produce also for Stihl. That’s kind of legit. And there’s a 3yrs warranty.
Their form factor, fully encased, detachable means that they are quite robust and easy to handle, easy to travel with. (they look much less threatening than a wrapped up pack of cells with some wires poking out it which can easily look like an IED…)
Being detachable, they can fit a few different EVs, they can be removed and separated from the vehicle for storage, charge, etc… Easy to have multiple 3d printed cradles, one on the bike, one on the board (the width of a LY EVO tail), …
Anyway, that’s part of the reason I used them, and I feel reasonably safe having those close to my body.
They’re only 4Ah, which isn’t exactly much, but still very suitable for most of my short range travel. I can milk out about 10-12kms out of them at good fun cruising speed. I pack a second one in my backpack if needed. It also means that for short travels, there’s only limited weight to lug around.
In terms of capabilities, Greenworks calls them 40V, which is of course marketing bullshit targeting people who can’t comprehend the reality of nominal voltage. But to their defence, DeWalt did it first! Anyway inside, you’ll find your typical 10S2P, Li-Ion setup. With cells that can push 20A with a limited 2AH capacity. (yeah, modern cells would outdo that easily). Still 40A is reasonably decent for most usages. I know from vesc logs that I can’t sustain such a draw for too long before I reach uncomfortable speeds. Few seconds at full throttle is plenty for me. (but I’m a pussy, and self preservation kicks in quite early around 40km/h, unlike some of you nutters!)
Link for the cells:
Interestingly, the charger seems to limit the charging voltage to 41V instead of pushing further to your typical 42V, apparently so as to prolong battery life and claim stability over more cycles.
Here are some pics of internals:
Anyway, hope this helps !
