The Fresh Loaf

A Community of Amateur Bakers and Artisan Bread Enthusiasts.

List of KitchenAid mixers with brushless DC (BLDC) motors

burnchar's picture
burnchar

List of KitchenAid mixers with brushless DC (BLDC) motors

Brushless DC (BLDC) motors have many advantages over other motor types in terms of durability, noise, efficiency, and consistency. A well-designed induction motor system can be competitive, but for home appliances is usually considered inferior.

BLDC motors/controllers are complex to design and expensive to build so are usually included only in higher-end appliances.

I researched which KA mixers have a BLDC motor because my wife has expressed interest in breadmaking. The following is an exhaustive list of KA's residential mixers with BLDC motors:

  1. KSM7586P* (currently marketed as the "Pro Line Series 7-Qt Bowl Lift Stand Mixer"
  2. KSM6573* (currently marketed as "6-Qt. Professional 6000 HD" and sold at Amazon, Costco, and certain other retailers but not directly by KitchenAid). This one has an unusual bowl design making it incompatible with certain KA accessories.
  3. KSM6521* (currently marketed as "Professional 6500 Design™ Series bowl-lift Stand Mixer").

Note the * is a wildcard for any submodel. For example, KSM6521XCA is a red KSM6521 with a glass bowl.

Several KA employees told me that their commercial mixers (all 1 of them) do not use a BLDC motor, but they also told me that the commercial mixers are handled by another department. The mostly useless KA website implies that the motor is the same as used in the Pro Line series, but this is speculation.

I don't make bread but in my research, I found this site's forums useful so decided to contribute back.

burnchar's picture
burnchar

It appears my earlier information may have been from an unreliable source. As mentioned in the original post, I contacted several KitchenAid employees. Most recently, one got back to me with a statement that no KA mixer has a brushless motor. I asked about the previous contradictory statements from KA, and received the following:

Dear Mr. xxxxx,

I apologize for the confusion. Here is the direct quote I got from the factory this morning.

"We do not have any brushless motors.  The DC motor mixers and the 6 quart motors have brushes that are an internal part of the motor, and cannot be replaced separately and very rarely need to be replaced. Other models have brushes that can be removed and replaced if necessary."  The models you mentioned do have DC motors. I hope this help.  
barryvabeach's picture
barryvabeach

Bunchar, thanks for the info.  Good luck in your continued search for a mixer.  

danbrown's picture
danbrown

Burnchar, thank you for the information. I was thinking about looking for a second mixer, and this is helpful.

Recently, I did some work on my KitchenAid K5SS. I bought it new in approximately 1980, and have used it frequently since then. After 36 years of significant use, the motor brushes were only partially worn. I replaced them anyway, I hope to get another 36 years out of the K5SS. At least on my unit, the motor brushes are not a significant problem.

The primitive motor does have an advantage: the control electronics are simple, and replacement parts are probably available. At work, I am designing electronics for stepper motors. Finding replacement parts in 2052 is likely to be more of a problem.

burnchar's picture
burnchar

Ultimately I bought a KSM8990NP.

It has the brushed 1.3HP DC motor and has a few benefits over the slightly more expensive Pro-Line. Specifically, It's much quieter than the outgoing HD600, ships with a stainless steel (rather than aluminum) beater and bread hook and semi-stackable bowl, though the commercial and home bowls are mostly interchangeable.

The warranty is shorter at 2 years, but that's 2 years of commercial use, which I hope means that it will last many decades of occasional use.

I found replacement motors online for about $70.

.

doughooker's picture
doughooker

We had an extensive discussion of KitchenAid commercial mixers here a while back. They seem to embody the old-school KitchenAid workmanship from the Hobart era.

I think you made a good decision getting a KA commercial mixer. That's what I'd get were I to buy a new mixer.

burnchar's picture
burnchar

I typed that up in a bit of a hurry. Corrections:

  • The Pro-Line is slightly *less* expensive.
  • The HD600 is not pro-line so noise is not one of the differentiating factors between Commercial and Pro-Line. The HD600 does not use a DC motor, for example.

I am happy to hear that the Commercial (and I suspect Pro-line) is similar in design philosophy to the Hobart-Era mixers. My mother's eventually died (a motor replacement would likely have fixed it; its behavior was of a motor with a worn brush) but she had it for a very long time.

I still wonder why KA declines to use brushless motors in their high-end lines. One possible reason is that brush motors have 100% torque available from 0 RPM, though their torque declines as speed increases. (Brushless motors tend to take a little while to build up torque). Low-end torque is likely very useful for starting the mixer in tough dough. That's my speculation on their reasoning -- that and their brushed motors seem to be pretty durable.

doughooker's picture
doughooker

The commercial mixers are made by a different division. This has been confirmed with KA.

I don't think it necessarily follows that the Pro Line embodies the old Hobart standards.

seekmocha's picture
seekmocha

I recently replaced the brushes and repacked grease in the gearbox in a Kitchenaid KSM6573, the one from Costco, so it can be done.  However, the brushes are not sold in the U.S. I got them from a U.K. vendor via eBay. Total cost with shipping was $28.  Since a complete new replacement motor with gearbox is $80, replacing only the brushes may not make financial sense. I charged the customer $126, that's $80 labor, $28 for brushes and $18 for food grade grease.  If I had just replaced the entire motor and gearbox assembly, it would have been $40 labor, $80 motor = $120.

Replacing the brushes is not easy: the existing brushes are permanently wired, so I had to cut the wire and crimp the new brushes into place. The whole process was a bit fiddly, and requires tools most people don't have.

The mere fact that the brushes are not easily replaced would make this model of Kitchenaid very undesirable for me, and I'll not recommend it to anybody.

doughooker's picture
doughooker

I just bought a KSM6573 which has a DC motor. I'm surprised to learn that it has brushes. I thought the DC motor would be brushless. Was I mistaken?

An earlier post in this thread said the following:

The following is an exhaustive list of KA's residential mixers with BLDC motors:

KSM6573* (currently marketed as "6-Qt. Professional 6000 HD" and sold at Amazon, Costco

Then there was this correction from KitchenAid:

"We do not have any brushless motors.  The DC motor mixers and the 6 quart motors have brushes that are an internal part of the motor, and cannot be replaced separately and very rarely need to be replaced. Other models have brushes that can be removed and replaced if necessary."  The models you mentioned do have DC motors.

For a DC motor it sure puts out a lot of audible 120 Hz hum.

barryvabeach's picture
barryvabeach

It can be confusing.  Yes, a DC motor can either be brushless  ( BLDC ) or it can have brushes.   For example, toys that have a battery to run the motor are DC ( because the battery is DC not AC ) and the motor has two brushes which make physical contact with a portion of the motor called the commutator - and that contact tells the motor which part of the armature gets power, which in turn causes it to spin.  In contrast, in a BLDC, the motor uses circuitry and a sensor to turn on and off the supply of current to different parts to get the motor to spin, and nothing actually touches the portion of the motor that spins.    This page has an explanation of the various types  https://en.wikipedia.org/wiki/Electric_motor#Universal_motors

 

For our purposes, we want a motor that can handle heavy torque, and won't burn up, and can be adjusted for speed.  While BLDC motors have some advantages over brushed DC motors,  I would not make that a major decision in your purchase.  One major benefit of BLDC is lower weight, which is why that feature is advertised for cordless power tools, but really is of very little benefit to a mixer that sits on a counter all day.  While BLDC can last longer since there is no brush rubbing against a spinning commutator, outside of commercial applications, we don't need a motor to last 10,000 hours of use , which is an estimate for some BLDC motors.  I would be somewhat concerned that KA has designed a motor that uses brushes that can't be replaced separately, since they will eventually wear out, but hope that they have designed it so that the last a very long time.    I would look for reviews that use the mixer in a commercial setting - bakery, school, etc, since their hours of use in one year would probably be more than most of us use in our lifetimes, so they can give a good estimate of how long it will hold up. 

Melbourne Park's picture
Melbourne Park

I'm Australia, but I'd like to refresh what is being said here.

There are two DC motors used by kitchenAid's mixers - one in the "Mini" 3 quart machine, and one used in the 7 quart and the 8 quart "Commercial" machine. All other mixers use AC motors.

The "Pro" line "lift bowl" mixers have mixed histories and motors. 

The "5" generation 1950's machine is still sold. It resembles the design of the lift stand mixers. Namely, a seperate motor and gearbox, the motor being AC. These units have a 5 quart bowl and are fairly quiet. Their gearbox is connected by a shaft to the motor. The gearbox is all metal but for a single nylon gear. This gear fails if the machine is jammed. The gear is cheap to replace. The "5" is closest to a Hobart machine, who owned kitchenAid before selling it to Kelvinator. The size of the fastenings inside the machine are much more robust than the lighter screws in the bigger capacity "Pro" machines. For accessory use, the machine is stiffer torsionally than all other 'Pro" machines. It will not flex downwards with accessories loaded at the end of it. It lacks a beater height adjustment screw to alter clearance on the beater bottom to the bowl's base. To adjust that clearance, one has to go inside the stand and adjust the spring tension. 

The 600 or 6 quart "pro" lift machine, uses a more powerful AC motor, and it uses a similar shaft and gearbox arrangement. It's gearbox includes a single nylon gear, the rest being metal. This machine is very similar to the two other Pro line machine (the 7 quart and the 8 quart being basically the same machines, but using some different parts). Its speed controller is motherboard based, unlike the tunable 5 generation "Pro" machine. The downside on the 6 quart for consumers, is that its noisy. Also, its gearbox can tear up its "designed to fail" nylon gear.

Finally, the DC "Pro" machines. Both have the same stand, motor and gearbox. The gearbox is described as all metal - i have not seen one torn apart but I have not seen any nylon in the cut away drawings and pictures. The motor is integrated into the same casing as the gearbox. A DC motor even even with brushes will have more steady speeds and will be more efficient, hence will run cooler and have lower power draw for its torque in its operating speed range. And they are much quieter. The noise in the 600 / 6 quart machine is not from the gearbox - its the motor noise. 

The differences between the 7 litre and the commercial depend on where its sold. For instance in Australia, the Commercial has a stop button on the side of the stand, for operational safety reasons. Food standards require stainless steel fittings, and easy cleaning. So the 7 litre "Pro" model lacks stainless beaters and dough hooks. in some countries the base of the commercial machine attachment area is all stainless steel. The guard is for safety and is stainless. The bowl conforms to cleanliness standards too. 

While the 7 quart should have a roller on its lift handle. This is easier to use, but for a commercial environment, its tough er to keep hygienic, hence its not used. 

Hope this helps. 

As far as longevity goes, the 7 litre and 8 litre have the same wear items, they'll last the same depending on usage. The motor/gearbox can be replaced too. But I am unsure on the cost of doing so. 

Cheers all.