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6ah and 9ah battery coming!!!


Trident167

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Also it's worth repeating the advantages of Milwaukee's 9Ah battery appllies to every M18 tool they make. You only get to take advantage of the 18vx2 36v Makita system on those specific tools, no matter how nice they are. That being said there are disadvantages where you probably won't want to use the 9er on a tiny impact driver or other smallish one handed tools where the size and weight would just make it unwieldy and tiresome.

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The angle grinder would just love a 9ah battery. They drain the 5ah battery so quickly, the other battery you just drained, doesn't even have time to start charging (cooldown mode) before you have drained yet another one.

 

You nailed it. Not many tools are super hard on batteries, but a few are...the grinder, blower, etc...can really use a big boy. 

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The two row batteries is a nice all-rounder, but a single (2ah) and triple row (9ah) is nice in a couple of cases.

And no, in easy words, it doesn't really matter if you have two batteries connected in parallell or if it's one that connect it in series. Or that you have one large pack.

What count is as some people have said, is the load each cell sees. The easiest way is just take the total wattage of the tool and divide it between total number of cells.

This is the easy way. Sure, there are a few smaller differences in reality, but it is barely worth noting in this context. The example of a tool that connects two batteries in series would be the most efficent and best. Since it will have slightly lower losses in the wiring/winding, and could get away with slightly less copper, making the motor slightly lighter.

The two other examples would perform identical. If you have two batteries in parallell, or just a double sized battery pack.

In this context, the 9Ah is just an extra row, not two, so it will be the inferior in every comparison, except weight of course

Ps: Connecting two batteries in parallell would half the total internal resistance. Just like using two resistors in parallell.

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Lets get the whole power thing straight. We can really ignore voltage and current and just work with power.  Batteries have a max power output dependent on the number and type of cells independent of their arrangement.  Over this the batteries heat up too much. The motor also has a max power before it overheats. Between these two theres an essentially lossless limiter so the power limiting part is not overdrawn or overdriven. In a tool like an impact driver the motor will always be a limiting factor so increasing the battery size wont help but for a circular saw or rotary hammer power is limited by the battery so the 9Ah will give more power IF the power limiter is set to draw more power from it.

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Are you saying the circular saw ( a tool designed when 4 and 5 amp batteries where the norm ) will gain in power when you put a 9 amp on it ?

Or do you mean that a newer and bigger circulzr saw could be made to take advantage of the 9 amp batteries ?

Option 1 doesnt seem logical. Option 2 does :)

 

I think this can happen (Option1) when the original battery ampage was the limiting factor, rather than the tool motor.

 

In contrary to jeff's statement above, Impact Drivers do see power increases from larger batteries. You often see higher torque rating on kits with larger capacity batteries, and I have tested and confirmed that the difference can be noticeable. (i tested with Dewalt 20V)

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Kornomaniac, an old circular saw definitely could get that 50% more power if milwaukee built in the compatibility.  Those are some pretty high power motors.  

 

I think this can happen (Option1) when the original battery ampage was the limiting factor, rather than the tool motor.

 

In contrary to jeff's statement above, Impact Drivers do see power increases from larger batteries. You often see higher torque rating on kits with larger capacity batteries, and I have tested and confirmed that the difference can be noticeable. (i tested with Dewalt 20V)

That's surprising.  The motors in those are so small I would not expect the battery to be a limiting factor.  How much of power difference was it?  I know there can be a small increase because the reduced internal resistance that gives a smaller voltage drop across the battery, but nothing like the potentially double power output between a 2 and 4Ah battery using the same cells.

 

I guess this needs a disclaimer that this is mostly from experience with other power electronics.  Depending on how manufacturers build the control circuits or lack thereof the tools could differ considerably from that ideal case.  With economics of scale it would almost certainly be more cost effective to use the same internals between premium and budget tools, but just tell program one to run at lower power, or better yet design higher capabilities and re-release the same tool programmed to be more powerful after a year or two.

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That's surprising.  The motors in those are so small I would not expect the battery to be a limiting factor.  How much of power difference was it?  I know there can be a small increase because the reduced internal resistance that gives a smaller voltage drop across the battery, but nothing like the potentially double power output between a 2 and 4Ah battery using the same cells.

 

 

Certainly not double the power, i guess you can check some manufacturer specs. From memory it might drop the  torque ~10%. But in a tough test (like coach screws), that seems to make more like a ~25% time difference.

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Would not have thought that a small impact driver would have anything in the range of 10 % decline, but sure, I have not tested it so I just might be true. 

 

In theory, that is to be expected. Since the voltage drop would be twice as much at the smaller compact batteries. Probably in the range of 0,5V on normal 5Ah batteries, and 1V on compact batteries at peak load. 

On a fully charged battery, that means the motor would only see around 19,5V VS 20V. And certainly, the motor performance would be a bit lower. 

 

This difference rises with rising load, and thats why I didn't thought drivers would pull enough juice for it to be relevant. :)

 

 

I'm planning a larger test next year with some pretty decent test equipment on a couple of makita power tools. More focused on just the fun stuff, numbers. Measuring amp draw, voltage, input power, resistance (ESR) in batteries, charging curve, and a more sophisticated testing rig for power output. At least, thats what I'm hoping to do. Really seeing how the equipment differs at different loads. Really putting a lot of theese interesting questions to rest. Also, if accuratly enough, it will be possible to really find the sweet spots and weak points.

Sad part is that I don't have more power tools to test. :( But that's a worry for another day. 

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Interesting discussion. Milwaukee has been enabling more torque on tools with larger batteries attached for a while now. They listed the original Fuel drill as having 725 in-lbs of torque with an XC battery and 650 in-lbs with smaller batteries, roughly 10% difference.

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  • 2 months later...

6.0ah and 9.0ah coming soon, at least in the UK anyway!

 

Interesting the 9.0ah is only £30 more expensive than the 6.0ah and the new pack with 2 x 9.0ah batteries, fast charger and kit box is only £349.00 (ex VAT)!  Pretty good price!

 

These are taken from the latest Heavy Duty News on the Milwaukee UK website.

 

Martin

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