Hot rodding a cordless vacuum cleaner.

[jman093]

I have a Craftsman C3 cordless vacuum cleaner. The Craftsman C3 line of power tools is identical to the Ryobi One+ line of cordless power tools. Up until a couple years ago, there was a Craftsman and Ryobi version of each tool, but with Sears slowly going bankrupt, the Craftsman line hasn't gotten the newer tools that Ryobi has, including a more powerful vacuum. So I got the bigger motor assembly out of one of the new Ryobi vacuums. I have made the modifications necessary to mount it in my Craftsman vacuum, but want some input before wiring it.

The old vacuum is a simple two wire circuit. The battery, a 30A fuse, a toggle switch, and the motor. The new one has a circuit board with a lot going on and the switch has three wires on it. I very much want to just ditch all that and wire the DC motor in directly like the old vacuum is. Obviously Ryobi did this for a reason on their new vacuum, and didn't on their one from 12 years ago, but in all likelihood, am I really going to fry my battery pack wiring the new motor up without the circuit board. There is no fuse on the new vacuum, so the board must take care of that, and I wouldn't need the board for that circuit, but perhaps I do need it for other purposes.

Is it THAT likely that the bigger motor will fry the lithium battery pack on shut down and the magnetic field collapses, and I have to have the circuit board, when the original was fine without them?

Is it THAT likely that I'll ruin the battery pack without the caps on the board, when the original motor was fine without them?

Is it THAT likely there is something else the board is doing I haven't thought of that will wreck my battery?

I'm no electrical engineer, so I figured I'd ask before doing something dumb. Googling this kind of thing just mainly brings up endless articles on "free energy" and "perpetual motion devices." That kind of nonsense seems to be Google's standard result for any search about anything electrical in nature.

 

[Bluejets]

The bigger motor may "fry" ( or rather light up rather spectacularly) your battery but it has nothing to do with shutdown and more to do with max current ability.
Having said that, there may be components such as free-wheeling diodes on the board which protect electronic bits and batteries do at times contain electronic bits as part of bms systems.

 

[jman093]

Not worried about max current ability. As I said, Ryobi and Craftsman are identical. If the Ryobi batteries can handle it, so can the Craftsman. The batteries just have a different case. Internally, they are identical and rolling off the same Hong Kong assembly line.

Obviously, there is a whole lot of circuitry internal to the battery packs, and the necessity of things like "free-wheeling diodes" to protect it, when there was nothing at all on the marginally smaller motor, is what I'm inquiring.

 

[(*steve*)]

It is likely that the older motor was a traditional DC motor and that the new one is a BLDC (brushless DC) motor. The circuit board with the newer motor (if I am correct) is essential since a BLDC motor can't be connected directly up to a power source.

Whilst DC is part of the name of a BLDC motor, they actually require a three phase AC signal to operate them. That circuit board provides the signals required.

If the old motor has 2 wires, and the new one has 3, that may be confirmation of the above.

 

[Bluejets]

Is it THAT likely that the bigger motor will fry the lithium battery pack

Not worried about max current ability.

seems to me like you are.......

 

[jman093]

It is likely that the older motor was a traditional DC motor and that the new one is a BLDC (brushless DC) motor. The circuit board with the newer motor (if I am correct) is essential since a BLDC motor can't be connected directly up to a power source.

Whilst DC is part of the name of a BLDC motor, they actually require a three phase AC signal to operate them. That circuit board provides the signals required.

If the old motor has 2 wires, and the new one has 3, that may be confirmation of the above.

Thanks. I should have mentioned that in the original post. It's a plain old brushed DC motor. Just a little physically larger. It does pull a couple more amps than the smaller one when powered up with a bench power supply.

seems to me like you are.......

Please stop. The larger motor won't come close to maxing it out. My whole post was about the necessity of the circuit board, not whether the motor was too big for the battery.

 

[dave9]

I have a Craftsman C3 cordless vacuum cleaner. The Craftsman C3 line of power tools is identical to the Ryobi One+ line of cordless power tools.

Apparently this statement is untrue. A different generation of tool, whether made by the same (TTI) manufacturer or not, is not magically the same. It might as well be a different brand, using a different battery, no?

Up until a couple years ago, there was a Craftsman and Ryobi version of each tool, but with Sears slowly going bankrupt, the Craftsman line hasn't gotten the newer tools that Ryobi has, including a more powerful vacuum. So I got the bigger motor assembly out of one of the new Ryobi vacuums. I have made the modifications necessary to mount it in my Craftsman vacuum, but want some input before wiring it.

Craftsman went to 19.2V a few years back and Ryobi never did. You later stated the motor was marginally larger and drew a (mere) couple more amps, could it be that the larger motor has about the same power rating at 18V that the Craftsman did at 19.2V? Could it be that the Craftsman vac was designed for NiCd packs and the Ryobi, Li-Ion?

The old vacuum is a simple two wire circuit. The battery, a 30A fuse, a toggle switch, and the motor. The new one has a circuit board with a lot going on and the switch has three wires on it. I very much want to just ditch all that and wire the DC motor in directly like the old vacuum is. Obviously Ryobi did this for a reason on their new vacuum, and didn't on their one from 12 years ago,

There you go, there is some reason. Does it simply not fit or the switch doesn't? Could you build up a new switch cradle with epoxy or a sheet aluminum bracket screwed in? Why not just switch over to Ryobi since as you already stated, Craftsman is a dead end tool line, except that Black & Decker has started producing their own designs.

but in all likelihood, am I really going to fry my battery pack wiring the new motor up without the circuit board. There is no fuse on the new vacuum, so the board must take care of that, and I wouldn't need the board for that circuit, but perhaps I do need it for other purposes.

Here's where the fun starts. You reverse engineer the circuit a bit to see what it does.

Is it THAT likely that the bigger motor will fry the lithium battery pack on shut down and the magnetic field collapses, and I have to have the circuit board, when the original was fine without them?

Maybe it's not fine, maybe the back EMF slowly wrecks the batteries.

We don't have the circuit board in front of us. You can either figure out what it does or leave it out at your own peril. I would (and did, but from a different brand not Craftsman) just switch over to Ryobi tools because they have so many of them, and they're available as bare tools so you don't have to keep buying new batteries and chargers with each one.

What happens if you make the best vac on earth then your batteries wear out, when Craftsman goes out of business and B&D isn't making the old style batteries any longer? You then have to settle for crappy generic batteries which probably have a low current capacity then you're bottlenecking the motor. Ryobi now has 9Ah batteries! I suppose you could rebuild your own packs, but this all starts to get a bit burdensome (might need to spot-weld new cells in if there isn't clearance in the pack like there was to solder up the old NiCd packs to tabbed sub-C cells, and expensive if choosing high quality Li-Ion cells) compared to just switching to Ryobi... one tool at a time, then with fewer tools using your Craftsman packs, they'll last longer too.

Googling this kind of thing just mainly brings up endless articles on "free energy" and "perpetual motion devices." That kind of nonsense seems to be Google's standard result for any search about anything electrical in nature.

If you're the pioneer doing this exact thing, Google won't be able to give anyone search hits until YOU provide that content by detailing the results of your work.

 

[jman093]

Apparently this statement is untrue. A different generation of tool, whether made by the same (TTI) manufacturer or not, is not magically the same. It might as well be a different brand, using a different battery, no?

Craftsman went to 19.2V a few years back and Ryobi never did. You later stated the motor was marginally larger and drew a (mere) couple more amps, could it be that the larger motor has about the same power rating at 18V that the Craftsman did at 19.2V? Could it be that the Craftsman vac was designed for NiCd packs and the Ryobi, Li-Ion?

The 19.2v line debuted back in 2002 when everything was Ni-Cad. The tools are identical to Ryobi's except the case. Trust me on this. I have made a small side business fixing C3 tools. The secondhand prices for them have skyrocketed since most of the line has been discontinued. The internals are the same, when ordering repair parts I can look up the Ryobi version of whatever part I need, or the Craftsman version, and the part number will be the same. There only exception would be a few unique C3 tools that were made by a Chinese conglomerate named Chervon. And obviously new Ryobi releases over the last couple years there is no Craftsman version of. The newer shop vac is the one tool I envy. The Craftsman C3/Old Ryobi one does indeed date back to Ni-Cad days.

The reason for the 19.2v nomenclature instead of 18 like Ryobi, was back in Ni-Cad days, the Craftsman batteries had one extra cell located in the battery's stem giving it 1.2 more volts. When everything went lithium, the batteries are the same 5 series lithium as the Ryobi. Same cells, same circuit board, just a different stem and case. So, the 19.2v C3 lithium batteries technically have an 18 volt nominal rating (3.6x5=18), not 19.2 volts, but Craftsman kept using 19.2v in their marketing to avoid consumer confusion since they're interchangeable. Many companies rate their 18v nominal tool line as 20v, since the peak rating of a 5-series lithium battery pack when 100% charged is over 20 volts. This kind of marketing is legal in the US, but illegal in many other countries, notably European ones. That's why the DeWalt 20v max line is marketed as 18v in Europe.

There you go, there is some reason. Does it simply not fit or the switch doesn't? Could you build up a new switch cradle with epoxy or a sheet aluminum bracket screwed in? Why not just switch over to Ryobi since as you already stated, Craftsman is a dead end tool line, except that Black & Decker has started producing their own designs.

I could fit it all in there and somehow mount the switch if I had to, but am hoping to avoid. And I don't even want to know how much it would cost to replace all my perfectly good C3 tools I've had since high school with another brand (and if I did, it wouldn't be with the new Stanley Black and Decker Craftsman tools. They are taking their lowest rung Black and Decker tools, rebranding them as Craftsman, and charging more. They are atrocious. Frankly, 15 year old C3 tools are better than that new V20 line being hocked at Lowe's).

Maybe it's not fine, maybe the back EMF slowly wrecks the batteries.

Here's where the fun starts. You reverse engineer the circuit a bit to see what it does.

I wish I could. I made my post hoping for insight in that regard, because I'd probably do better at deciphering ancient hieroglyphics. Frankly at this point, I'm just going to wire the larger motor and hope for the best. If it fries a pack whether sooner or later I'll update this thread.

We don't have the circuit board in front of us. You can either figure out what it does or leave it out at your own peril. I would (and did, but from a different brand not Craftsman) just switch over to Ryobi tools because they have so many of them, and they're available as bare tools so you don't have to keep buying new batteries and chargers with each one.

What happens if you make the best vac on earth then your batteries wear out, when Craftsman goes out of business and B&D isn't making the old style batteries any longer? You then have to settle for crappy generic batteries which probably have a low current capacity then you're bottlenecking the motor. Ryobi now has 9Ah batteries! I suppose you could rebuild your own packs, but this all starts to get a bit burdensome (might need to spot-weld new cells in if there isn't clearance in the pack like there was to solder up the old NiCd packs to tabbed sub-C cells, and expensive if choosing high quality Li-Ion cells) compared to just switching to Ryobi... one tool at a time, then with fewer tools using your Craftsman packs, they'll last longer too.

I have a spot welder and rebuild dead battery packs. I use Samsung 2.5ah cells or, if I can get them, LG 3.0ah cells. With the LG cells, I have 3.0ah single packs and 6.0ah C3 double packs. I've thought about buying one of those Ryobi 9.0 batteries, soldering a C3 top case half and contacts onto the board, and 3D printing an extended C3 bottom case to fit the larger internals with its 3rd row of cells. It would then be a C3 9.0 battery, that fits in all C3 tools and chargers. It'd only be something to do just to do it though. The 6.0 double packs are already more than I need. I can edge my whole lawn with the trimmer and blow the clippings with the leaf blower in the street after mowing, and the gauge usually still shows full charge.

 

[Bluejets]

Just be aware of the dangers of "playing" with these battery packs.
Here is a quick video of a much smaller phone battery blowing it's top, just to give you some idea.

 

[jman093]

I went ahead an wired it in directly last night. On first start-up, it immediately blew the 30 amp fuse. Start-up current draw of the larger motor is obviously over 30 amps. I bought some 40 amp fuses tonight from O'reilly. The vacuum is working fine. Definitely has a lot more suction that it did. I did notice the air coming out of the blower port is quite warm. Hopefully the vacuum can handle the extra heat load. The one thing I don't like about my upgrade is the vacuum is now very loud, whereas before it was the quietest vacuum I'd ever heard. I had read complaints about how loud the new Ryobi P770 vacuum is, and yeah, I now have the extra noise with all that extra power too.

As of right now, the upgrade is a success. If that changes and vacuum ever melts, breaks, or ruins my battery, I'll update this thread with the carnage.

 

[dave9]

If you've blown 30A fuse(s), you might need to upgrade the wiring too, now or wait for molten insulation.