Vevor 11lb/5Kg Jewelry Tumbler

[chaosdsm]

Jun 30, 2024 9:22:41 GMT -5 liveoak said:

I keep wondering if you could make the Vevor have adjustable speed.
Fast & auto reverse works great for grinding, but if you could slow it down then for pre-polish & polish.......

Patty

That's my goal, I'd like to cut the speed at least in half, maybe even a bit more.  I really want to try a 6.4V battery setup first, but I'm not finding a reliable Battery Management System for 6.4V LiFePO4 batteries, so looks like I'll need to go straight to 12.8V.   

Fortunately, it's easy and cheap to control speed on DC motors.  A $10 - $30 controller will allow full speed control from OFF to 100% and anywhere in-between!!!

[chaosdsm]

Found a pair of cheap 6.4V LiFePO4 6AH batteries that claim to have built in battery management.  

Got them hooked up and running the Vevor tumbler:  drum weight 9lb 4.12oz



Video record rate 30 frames per second, 115 frames to make 2 revolutions = 57.5 frames per revolution = 1.9167 seconds per turn = 31.3 RPM, so a little less than half the original speed!!!

Unfortunately, the AC power runs the auto-reverse feature and the timer...

[chaosdsm]

Two 6.4V 6AH batteries in parallel (6.4V @ 12AH) ran the tumbler for just a little over 16 hours, which means the tumbler is pulling about 0.75A of power or about 5 watts.  So I can run this directly from my 50Ah batteries for approximately 66 hours if hooked up as a 12.8V battery without solar charging.


Since 12.8V will allow for higher speeds when wanted, it makes the most sense to hook it up this way.  I'll then place a voltage controller in line to control the speed of the motor, and setup a solar charge controller to recharge the batteries when the sun is out.  I'll be using a single 25W 18V polycrystalline solar panel, so it will still be able to charge even under cloudy conditions, although at a much reduced efficiency.  

To hook it up, I just simply cut the two red wires coming from the rectifier (rectangular piece with 2 red wires, a blue wire, and a black wire.

After looking a bit closer, it appears I could have left everything intact and just unhooked the spade connectors and plug the battery directly in where the rectifier leads go....

[chaosdsm]

So, I plugged in the AC cord, and verified, that with AC power, the auto reverse function still works, but somehow the speed controls and timer do not. Those are both non-issues for me, as I would prefer a rock tumbler be only on or off, and a voltage controller will be handling changes to tumbling speed.

But, with the auto reverse feature going, battery life seems to be GREATLY increased. I stopped the 2nd test at the 15 hour mark to recharge the batteries. BMS cut off for the batteries is likely around 5.0v to 5.2v. I checked both batteries, and they're still sitting at 6.5V after the 15 hour runtime, at 15 hours they should have been around 5.8v to 6.0v.

So I now have test 3 running to see how long the auto-reverse feature extends battery life by!!!

[chaosdsm]

Test 3 complete, without auto reverse, and batteries now operating at full capacity, runtime is right at 24 hours.  With auto reverse turned on, runtime was 29hr 40min, an extra 5.67hrs!!!   


I have now moved forward to the next step in the process:  Checking out the full battery, and voltage control:


This battery setup should let this tumbling setup run for at least 5 full days of heavily cloudy skies.  I've decided to go with a 100W 18V portable solar panel for charging.  I realized quickly a 25W panel would be undersized under typical summer rain pattern here in Florida.   With the 100W,  even if I do get several heavily cloudy days, it still won't take long to fully recharge once the sun does come out!

Controller will not turn the tumbler at all when it's under 38% voltage.  40% voltage is about 15rpm which is about the slowest I would want it to run anyway!!!

Now I just need to pretty things up a bit.... build an enclosure and battery box - the voltage controller will be mounted onto the enclosure.  I'll also have a battery management system added to the battery box to protect against over charging / over discharging.

[chaosdsm]

Oh my word....  I did not expect this....  

This Vevor tumbler runs VERY efficiently on battery power   - still no solar hooked up.  

I started it on the final test last Tuesday at 8PM (6 days ago) with the loaded drum weight at 9lbs 7oz.   I set it to run at 6.15v which gives rotation speed of about 39 RPM - compared to the Vevor factory set rotation speed of 64 RPM at lowest speed setting.  

As to efficient running... battery pack voltage at start of test was 13.27v   After running for 6 days the battery pack voltage only dropped to 12.74v that's just 0.53v used in 6 days or 0.08833v per day.    After a 30 minute rest following a full charge, the battery pack voltage should be 13.4v to 13.7v.  Ideally, you don't want to discharge these batteries lower 2.7v per cell or 10.8v for the battery pack, which would give about 2.9v of usable charge @ 0.08833v per day, this battery pack should last around 30 - 33 days without any charging.  

Best thing is, these batteries should last between 10 & 20 years & they cost me just $72 for a set of 4.  This machine ran at about 25w on AC power, that's almost $3 per month in added electricity cost at my current electricity rate.   So, if I figure in the cost of the batteries, 100w solar panel, BMS, & solar charge controller, that's about $300 total expenditure to take this tumbler off of AC power.  That's about 100 months to the break even point.... that's 8.3 years which isn't spectacular, but at least I don't have to worry about cost of electricity increasing or power outages.   If I also move my vibratory tumbler over to DC operation, which is spec'd at 1.5A @ 120Vac or 180W, that greatly decreases the break even time, even if it's only used a few days out of the month.