Over Volt a Hand Held Vacuum?

[OCMike]

Hi,

Kind of a screwy question but I can't find information on the web and this is likely a place where I can find good information.

I bought a 12 volt hand held vacuum for my car. I cut the power cord, put some anderson power poles on and hooked it up to a 3 cell Zippy 8ah battery. Works fine . And now I can use it anywhere. But the vacuum is sort of weak in the suction department. I'm thinking to hook it up to a 6 cell Zippy.

So, I want to over volt a 12 volt 1200watt vacuum cleaner and feed it 24 volts.

What do you think will happen? Immediately fry? Run for short period of time before frying? Or just work like a charm?

Thanks ... I'd rather not just fry it ... that would be like burning $40

 

[Ykick]

I dunno about your vac but I've repowered a few items around the house. I can tell you that 3S RC Lipo is kinda lame with most 12VDC automotive devices. 4S (14-16V) works very nicely for everything automotive I've ever tried.

6S (20-24V) is pretty damn hot although I have some 18V rated cordless power tools I re-powered using 6S RC Lipo and the motors are still holding up??? They run fast but seem to be holding up okay. But what you're considering is nearly double the intended voltage of the vac? Might work for long time, might not...

 

[Punx0r]

I'm guessing your 12V vac is actually 120W powered by a 540 can motor. It's always going to be lame compared to a ~2000W mains-powered vac

My prediction for running on 6S would be option 2: run better for a short while, then die...

 

[OCMike]

Can I put a resistor inline?

I think the vacuum draws constant amps. So the voltage drop would be constant. I think I want an 8 volt drop. I think the vacuum draws 10 amps (but I'm not sure - that estimate could be way off). Assuming it does draw 10 amps would I need a .8ohm resistor to get a 8 volt drop in voltage? Does this make sense?

I could just wait until one of my 6S goes sour and make a 4S from its parts.

Thanks for the input guys ...

 

[Punx0r]

R = V/I

R = 8/10 = 0.8 ohms

But:

P = IV = 10 * 8 = 80W heat disipated in the resistor = BIG resistor on a heatsink. Plus it's completely wasted battery power.

 

[cal3thousand]

I think motors like this succumb to total power over a period of time. I think it will be fine at 24V, but don't expect to run it for the same lengths of time and if you do have some type of obstruction, you'd better be quick with the power switch.

Do this to test: Put a CA or other wattmeter in between the battery and vacuum and run it at 3S, on free air. Then plug it with your hand and watch the draw. It should jump up as the motor strains to overcome the stall. Then do it with 6S and note the difference. I'm interested to see what would be the results.

 

[OCMike]

R = V/I

R = 8/10 = 0.8 ohms

But:

P = IV = 10 * 8 = 80W heat disipated in the resistor = BIG resistor on a heatsink. Plus it's completely wasted battery power.

Could I put a 80watt 12v light bulb inline as my resistor and heat sink all in one? I don't know if a 80watt 12v light bulb exists. Is this a good idea? I don't think I need to be precise with the voltage drop I seek ... I want to target 7.5v-8v. Any drop in voltage between 5v and 9v I would see as success. Even if it's off I can play with my starting SOC - 22v-25v for a 6S.

I think someone here was suggesting I get 3 4S batts instead of 2 6S batts just so I'd have more options. Wish I had ... I'd like to have a 4S right now

What I've got is 6 6S batts and 3 3S batts. And that's enough money on batts!

Thanks again gents ...

 

[Ykick]

Be patient, sooner or later you'll have some 4S bricks, LOL....

I only buy 6S bricks even if I actually only need 2, 3, 4, 5S - once you have the skill easier to rework 'em to whatever cell count ultimately needed than attempting to predict at purchase.

tip - buy some Hobby King large 50-100mm shrinkwrap if you want them to look nice. Otherwise, just wrap 'em with plastic wrap followed by a good layer of filament tape.