Cordless Circular Saws and the Battery Systems That Go With Them

[caleb]

I'm looking at cordless circular saws, and I'm a bit lost.

I realize I'm buying into a new battery system, and I'll likely end up with a variety of tools from that system. Right now, the only battery tool I own is a Black and Decker drill that's slowly dying, so I'm pretty much starting from scratch.

Looks to me like the options are Bosch, Makita, Milwaukee, and DeWalt (but I'm not buying DeWalt).

I just spent two hours reading reviews and watching YouTube videos, which got me nowhere.

Before I just go to Trade Tools and buy whatever they say, does anyone here have opinions?

[wsteve464]

Makita for the win. I bought a 1/4 inch impact and drill combo 10+ years ago and they are still going strong. Last spring I bought the battery weed eater with the 2 5 amp batteries works great and does my yard on one charge. based on the weed eater I just bought the 12 inch chain saw and the small blower. The biggest I have cut so far is about a 5inch dia dry branch, no problem.

They seem more expensive than others but the selection of tools and the quality make it worth it IMO. Plus once you have the batteries and charger you can buy just the tool. Haven't tried them yet but you can get knock off batteries.

[Matthew Strongin]

All my Makita stuff is awesome. I can’t speak to the circular saw, but I’ve been very happy with my drills etc.

[rec head]

It depends on how much use the saw and batteries will get. My personal philosophy these days is that for all my cordless tools Ryobi is good enough. I have zero complaints with any of my Ryobis. I don't use them enough to buy into an expensive battery system again. For corded power tools its a different story.

[Too Tall]

Not mine. I recently used a borrowed Milwaukee M18 Fuel circular saw. That thing was pretty darn perfect.

[thollandpe]

+1 on Milwaukee.

[ides1056]

These are top of my list:

MAKITA Brushless X2 Tools | Maximum Performance. No Cords Needed

Just don't buy them at Home Depot- not the same tool you will get elsewhere.

[guido]

I haven't used the circular saw from them but, I have had great luck with the DeWalt 20v tools. The most recent addition to my set is the angle grinder. Really tough and solid on both concrete and metal projects. My 20v driver did a fantastic job on driving concrete screws that attached my insulation panels and framing to the walls of my basement. The included batteries are light weight and run time, but for super long run times the DCB606-2 20V MAX 6.0Ah packs are the best I have seen.

[caleb]

@Too Tall and @thollandpe, have either of you used Makita for comparison?

What makes the Milwaukee stand out?

[Mark Kelly]

Particularly with a circular saw, the major determinant of performance will be the current draw on the battery pack.

The manufacturers don't give power figures for the BLDC motors used in these things but you can derive one from the torque figures of some of the other tools, such as the high end impact drivers: for anything that rotates, power = torque x speed* so 1700 Nm @ 2000 rpm = 350W. The saw motors are larger than that but smaller than the mains powered tools (1 kW and up)* so let's go somewhere in the middle and assume they are around 600W. Some of the smaller saws will have smaller motors but this will affect performance, you won't be able to keep a constant blade speed under load

If you use a tool with a single 18V battery , the peak current draw is thus about 33 Amps. For a 5 - 6 Ah battery that's a discharge ratio of 5 or more, which is going to limit battery life: Li Ion battery performance is inversely proportional to discharge ratio.

If you use a tool with 2 x 18V battery, the current draw is halved so performance and battery life will be considerably improved. On these grounds the only one of the tools you mentioned I would consider is the Makita with the dual battery system.

FWIW I use a Makita BLDC drill to stir my chardonnay barrels, a bastard load due to the high torque required to get 500l of wine moving well enough to stir up the lees. By the time I've stirred all the barrels the battery is completely drained from a fresh charge but the tool has held up very well to this abuse.


* Yes I realise that the BLDC motors are more efficient than the motors in the mains powered tools but I've also taken that into account.
** In SI units this is a straightforward calculation if you use speed in radians per second (roughly RPM / 9.5). In other units you are on your own.

[j44ke]

Milwaukee. M18 Fuel is their "pro" line I think. It is what two of the carpenters who seem to live at the house site have. And what I borrow from the landlord upstate here. I own an M12 drill/driver and an M12 mini-Sawzall, which are helped by upgrading to a higher amp-hour battery but the M18 stuff seems better balanced as far as power-to-job requirements ratio.

Remember when you're pricing things, a lot of places sell "bare" tools, which means no battery. And read the amp-hour rating for any included battery package.

edit: Obviously I'm not an electrical engineer, so Mark's analysis likely trumps my seat of the pants recommendation.

[j44ke]

This is the Milwaukee I was looking at. Maybe Mark can comment on its motor etc. as comparison to the Makita.

M18 FUEL 7-1/4" Circular Saw Kit with Battery, Charger | Milwaukee Tool

[Too Tall]

That's the one J.A. Nice nice nice.

[Mark Kelly]

According to Milwaukee, their BLDC motor is a 720W unit, so the current draw from an 18V battery will be 40A. At 5 Ah that's a discharge ratio of 8 which doesn't auger well for battery life.

My limited experience with Milwaukee tools bears this out: before we bought the Makita for the barrels I used my Milwaukee M12 drill and I burned through two battery packs in six months; one of them won't charge at all any more, the charging unit detects a fault and shuts down. The other day I dropped this charging unit and it died: the main transformer had torn itself out of the PCB, I was able to fix this but I wasn't hugely impressed by the build quality when I had it apart.

[rowdyhillrambler]

Let me ask what you are going to do with it? Like how often and what do you expect out of it?

I make a living with my hand tools-near and dear.. I always used Milwaukee when I was in the city, but switched to DeWalt.. only because it is far more available-they also make a lot of tools for that battery system that Milwaukee doesn’t. If it is going to be occasional use or even weekly use-you will not wear out Milwaukee, DeWalt or Hitachi. But look at their sites for the tools they make. Dewalt makes an inverter that works like a generator.. I use it all of the time, off the grid, and it’s the best tool I own.

One company that I see Lowe’s now carries is Metabo-German made and hard to kill. Not a huge line up of tools but very well made.

What will you use it for and what do you expect?

[j44ke]

According to Milwaukee, their BLDC motor is a 720W unit, so the current draw from an 18V battery will be 40A. At 5 Ah that's a discharge ratio of 8 which doesn't auger well for battery life.

My limited experience with Milwaukee tools bears this out: before we bought the Makita for the barrels I used my Milwaukee M12 drill and I burned through two battery packs in six months; one of them won't charge at all any more, the charger pack detects a fault and shuts down.

So would that be why the Milwaukee ships with the new HD 12 Ah battery? Trying to wrap my brain around this - sorry Caleb if I am co-opting the thread.

[caleb]

sorry Caleb if I am co-opting the thread.

Nah, this is exactly the rabbit hole I went down this morning. Too many models, many with their own sub-model battery variations.

[j44ke]

Nah, this is exactly the rabbit hole I went down this morning. Too many models, many with their own sub-model battery variations.

Headache definitely. This is the saw I was looking at because it has the foot that is compatible with their saw guide, but that's as far as I got. When I last had a saw, I used an edge clamp guide a lot, but the Makita looks more akin to a Festool guide with the special foot and doesn't clamp directly to the piece.

Makita USA - Product Details -XSH8Z

[Mark Kelly]

So would that be why the Milwaukee ships with the new HD 12 Ah battery? Trying to wrap my brain around this - sorry Caleb if I am co-opting the thread.

A 12 Ah battery is a much better idea, reduces the discharge ratio to about 3. What does it cost?

[caleb]

Let me ask what you are going to do with it? Like how often and what do you expect out of it?

Mostly just homeowner-stuff: I'm going to build a bunch of storage shelving in January, and a woodshed next summer.

Anything will probably meet my needs. Except DeWalt. Growing up a friend's contractor-uncle had a garage full of DeWalt stuff. Fourteen year old me thought he was a d-bag, so we stole his beer and I've never bought anything DeWalt.

But there are needs, and then there are needs. Growing up, I saw my dad build a barn with hand tools, a drill, and a circular saw. You can do anything with a circular saw. Part of the need filled by a good circular saw - one that exceeds my functional needs - is subconsciously holding out the possibility that one day, when the world floods and burns, I'll move back up north and build a barn for my herd. I'd speculate that this second sort of need sells a bunch of pro grade tools. Perhaps what I'm looking for is the Peter Lugers of circular saws.