Supercharged 3-Ball Tennis Ball Pressurizer?

travlerajm

G.O.A.T.
I recently bought a 3-ball Tennis Ball Saver.

These ball savers work well to quickly restore a used ball to about 90% of its original bounce height (this is my guesstimate, not measured yet). The once-used recharged balls bounce higher than once-used balls stored without the device, but supposedly takes a month or more to recharge used balls all the way back to 100% original bounce.

The Tennis Ball Saver stores the balls under approximately 14psi, which is the same pressure inside a can of new tennis balls. It works by compressing the air inside the can to about 1/2 of its volume, which doubles the pressure. The problem is that 14psi is not quite enough to ‘fully’ revive used balls - a bit more pressure is needed for that.

My idea is to see what happens if I fill up some of the air space between the balls with incompressible material. This way, when I close the device, it will compress the air volume to 30-40% of its uncompressed volume, rather than 50%. I have not done the math yet, but I figure this might give me something closer to 20psi rather than 14psi.

I expect the 20psi pressure will double or triple the recharge rate, and hopefully give me a fully revived 100% bounce height within 24h. I don’t want to use too much pressure, because that might give me an overcharged super ball that bounces 110% as high as freshly opened ball.

Today I bought 2 bungee cords for $1 each at Home Depot. One is 3/4” x 1/4” rectangular cross section, and the other is about 3/8” round. I cut these into 7” lengths so that I can bend them into rings to fill up some of the annular shaped space between the balls. I used a 3/8” ring at the bottom, the larger rectangular cord in the two annuli between balls, and another 3/8” ring at the top.

For now, I left it to charge my thrice-used Penns, which are beat up enough to have patches bare of felt, but still have 90% pressure due to being stored in the saver between uses. I can tell that the pressure is substantially higher than before because the end of the device is bulged convex a little.

Next time out, I will crack a fresh can and start them off afterward in my augmented saver, and bring a yardstick to compare bounce height ratio of new vs recharged.

The experiment begins.
 
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travlerajm

G.O.A.T.
I recently bought a 3-ball Tennis Ball Saver.

These ball savers work well to quickly restore a used ball to about 90% of its original bounce height (this is my guesstimate, not measured yet). The once-used recharged balls bounce higher than once-used balls stored without the device, but supposedly takes a month or more to recharge used balls all the way back to 100% original bounce.

The Tennis Ball Saver stores the balls under approximately 14psi, which is the same pressure inside a can of new tennis balls. It works by compressing the air inside the can to about 1/2 of its volume, which doubles the pressure. The problem is that 14psi is not quite enough to ‘fully’ revive used balls - a bit more pressure is needed for that.

My idea is to see what happens if I fill up some of the air space between the balls with incompressible material. This way, when I close the device, it will compress the air volume to 30-40% of its uncompressed volume, rather than 50%. I have not done the math yet, but I figure this might give me something closer to 20psi rather than 14psi.

I expect the 20psi pressure will double or triple the recharge rate, and hopefully give me a fully revived 100% bounce height within 24h. I don’t want to use too much pressure, because that might give me an overcharged super ball that bounces 110% as high as freshly opened ball.

Today I bought 2 bungee cords for $1 each at Home Depot. One is 3/4” x 1/4” rectangular cross section, and the other is about 3/8” round. I cut these into 7” lengths so that I can bend them into rings to fill up some of the annular shaped space between the balls. I used a 3/8” ring at the bottom, the larger rectangular cord in the two annuli between balls, and another 3/8” ring at the top.

For now, I left it to charge my thrice-used Penns, which are beat up enough to have patches bare of felt, but still have 90% pressure due to being stored in the saver between uses. I can tell that the pressure is substantially higher than before because the end of the device is bulged convex a little.

Next time out, I will crack a fresh can and start them off afterward in my augmented saver, and bring a yardstick to compare bounce height ratio of new vs recharged.

The experiment begins.
I just checked the old balls after the first half hour. They are already at about 95% pressure of a brand new ball (based on thumb squeeze test). I expect they will be above 100% by morning.

Also, I should note that it takes noticeably more force to screw down the lid against the higher pressure. I should do a calculation of the pressure - it might be higher than 20psi.
 

BenC

Rookie
I've read reviews where people have installed tank valves to measure and add pressure to the ball savers, with good effect.
 

travlerajm

G.O.A.T.
After 8h in the supersaver (pressure augmented with 4 annular segments of bungee cord), the old balls are now feeling equivalent in firmness to 100% fresh balls (using the thumb squeeze test).
 

Injured Again

Hall of Fame
I bought one of these several months back:



When I first got it, I tried using it at 25 PSI with several different types of mid-tier tennis balls that were used once. Even sitting as much as one week at nearly double the internal pressure of the ball, recovery was minimal. It is really for maintaining the remaining bounce after the balls have been used. The leaking of pressure into the ball should occur at the same rate that pressure leaves a ball when it is just sitting without being hit, so it's a very slow process.

Using carbon dioxide should help as that is more soluble in the rubber used in tennis balls but that's a lot of effort.

The picture shows what I have in there currently - US Open balls that have been used for a couple of hours. My experience with these balls is that they lose pressure very slowly so pressure gains are equally slow. It only takes a minute to get the balls pressurized so I do more to test the longevity of the PressureTube than anything else. I've probably used it 50 times and it still works perfectly with no leakage, and especially with the mid-tier balls lets them be used a second time without all that much change in performance.
 

travlerajm

G.O.A.T.
The old balls in my augmented saver can now feel slightly firmer than 100% after 24h. I will do a measurement with a yardstick tomorrow.
 

travlerajm

G.O.A.T.
36h into my test of my supersaver vs beat-up balls.

I took the balls down to the garage with my yardstick to measure bounce height.

The balls were bouncing to about 62% of their drop height.
Since the international specification for bounce height of a fresh ball is between 53% and 58%, this means that my used balls are officially too bouncy now!

These balls now are roughly 110% charged!

All it took was a run-of-the-mill Tennis Ball Saver can, 4 pieces of bungee cord, and waiting a couple of days. I still need to calculate the pressure, which is probably really high.
 
I bought one of these several months back:



When I first got it, I tried using it at 25 PSI with several different types of mid-tier tennis balls that were used once. Even sitting as much as one week at nearly double the internal pressure of the ball, recovery was minimal. It is really for maintaining the remaining bounce after the balls have been used. The leaking of pressure into the ball should occur at the same rate that pressure leaves a ball when it is just sitting without being hit, so it's a very slow process.

Using carbon dioxide should help as that is more soluble in the rubber used in tennis balls but that's a lot of effort.

The picture shows what I have in there currently - US Open balls that have been used for a couple of hours. My experience with these balls is that they lose pressure very slowly so pressure gains are equally slow. It only takes a minute to get the balls pressurized so I do more to test the longevity of the PressureTube than anything else. I've probably used it 50 times and it still works perfectly with no leakage, and especially with the mid-tier balls lets them be used a second time without all that much change in performance.
I have had a PressureBall tube for about a year. I got it after my long time favorite, the Tennis Ball Recharger (which worked great for 16 plus years) failed. The PressureBall is not as effective as the Tennis Ball recharger was but it does have the advantage of being available.
I am a self admitted "ball snob". Currently I have settled on the RS Black Tour as my favorite. I had purchased a case of the RS Tour White for use on har tru. Hope I get to use them sometime soon:)
 

travlerajm

G.O.A.T.
I've found that the temperature effect is more pronounced and obvious with my augmented supersaver (I noticed the temp effect even before I augmented the pressure). The device is designed like an insulating thermos, with the air layer between shells. Compressing the air lowers the temperature inside the can (and inside the balls). After opening the device (assuming the device has not been charging continuously longer than a couple of days), it takes about 10 minutes for the re-charged balls to warm up back to room temperature (they feel really cool to the touch when I first re-open the device). The balls are much harder/firmer after 10 minutes compared to when I first open the can. This means that the act of opening and re-closing the can (allowing 10 minutes for temperature equilibration before re-closing) will enhance ball pressure. even if you Tennis Ball Saver is not augmented like mine, it is useful to do this the day before you plan to use the balls, in order to maximize pressure.
 

travlerajm

G.O.A.T.
I bought one of these several months back:



When I first got it, I tried using it at 25 PSI with several different types of mid-tier tennis balls that were used once. Even sitting as much as one week at nearly double the internal pressure of the ball, recovery was minimal. It is really for maintaining the remaining bounce after the balls have been used. The leaking of pressure into the ball should occur at the same rate that pressure leaves a ball when it is just sitting without being hit, so it's a very slow process.

Using carbon dioxide should help as that is more soluble in the rubber used in tennis balls but that's a lot of effort.

The picture shows what I have in there currently - US Open balls that have been used for a couple of hours. My experience with these balls is that they lose pressure very slowly so pressure gains are equally slow. It only takes a minute to get the balls pressurized so I do more to test the longevity of the PressureTube than anything else. I've probably used it 50 times and it still works perfectly with no leakage, and especially with the mid-tier balls lets them be used a second time without all that much change in performance.
Something doesn't quite add up about your Pressure Ball experience. It should work better if the pressure inside is actually maintained at 25psi (did you keep it fully charged or just leave it? If you just let it be, that might explain why it didn't work well, as the driving pressure will drop as air leaks into the balls). I calculated the pressure inside my augmented Tennis Ball Saver can, and it's somewhere between 20 and 25 psig. The balls reached >100% revived pressure in less than 36h (starting from about 85% bounce height).

I will next try it on fully dead balls - I expect it will get to 100% within a few days as long as I vent and equilibrate the temperature daily, but I could be wrong.
 
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travlerajm

G.O.A.T.
After only a half-hour in my augmented Tennis Ball Saver can, fully dead balls were recharged to half-dead playable condition. I think I can get them to nearly 100% within a few hours if I vent and temperature equilibrate hourly.

But I stopped the experiment for now, because I want to store my used overcharged old balls in the device to test them out on puddly courts this afternoon.
 

travlerajm

G.O.A.T.
travlerajm is once again high on claims but low on a proof.
I played with the balls this afternoon. It was the 4th 2.5h session this week, but the first time with pressure boosted by the augmented pressurizer. They had excellent pressure roughly equivalent to new balls, if not a little more, but the felt was so far gone that the bald balls played really fast and scooted, and didn’t curve quite as much in the air. Points were shorter because it was easier to hit winners with the zippier balls. One of the 3 balls broke after the first 3 sets, so we retired the other 2 and played with different once-used balls for the 4th set (this time we played for 3h, because with faster balls we got less tired).
 

Injured Again

Hall of Fame
Something doesn't quite add up about your Pressure Ball experience. It should work better if the pressure inside is actually maintained at 25psi (did you keep it fully charged or just leave it? If you just let it be, that might explain why it didn't work well, as the driving pressure will drop as air leaks into the balls). I calculated the pressure inside my augmented Tennis Ball Saver can, and it's somewhere between 20 and 25 psig. The balls reached >100% revived pressure in less than 36h (starting from about 85% bounce height).

I will next try it on fully dead balls - I expect it will get to 100% within a few days as long as I vent and equilibrate the temperature daily, but I could be wrong.
I have a high end bicycle pump that has a gauge accurate to within +- 3%, and I always use 25 PSI in the Pressure Tube. The tube itself doesn't get noticeably softer over time so air doesn't significantly leak out or into the balls. My experience is just that it is hard for air to permeate in or out through a couple of mm of pretty dense rubber. Balls that are open and just sitting there are good for several days. They only lose pressure when they are hit and the squashing creates really high internal pressures that probably can then escape more quickly through the areas of the rubber casing that are under the highest shear. But the balls that sit there are leaking as fast as the 12 PSI inside the ball can push air out, and it is slow. So, having 13 PSI trying to push air in should be equally slow. I'd expect some pressurization over about a week or so, but I never find any noticeable pressure change after a day. I mean, bicycle tires have 100 PSI and the air leaks out pretty slowly through a butyl rubber tube that is probably only 0.5 mm thick, one fourth of the thickness of a tennis ball core.

Undoubtedly, once-used balls that sit in the Pressure Tube for a couple of days have better bounce than once-used balls just sitting in the bag, but that difference is pretty slight too.
 

travlerajm

G.O.A.T.
I have a high end bicycle pump that has a gauge accurate to within +- 3%, and I always use 25 PSI in the Pressure Tube. The tube itself doesn't get noticeably softer over time so air doesn't significantly leak out or into the balls. My experience is just that it is hard for air to permeate in or out through a couple of mm of pretty dense rubber. Balls that are open and just sitting there are good for several days. They only lose pressure when they are hit and the squashing creates really high internal pressures that probably can then escape more quickly through the areas of the rubber casing that are under the highest shear. But the balls that sit there are leaking as fast as the 12 PSI inside the ball can push air out, and it is slow. So, having 13 PSI trying to push air in should be equally slow. I'd expect some pressurization over about a week or so, but I never find any noticeable pressure change after a day. I mean, bicycle tires have 100 PSI and the air leaks out pretty slowly through a butyl rubber tube that is probably only 0.5 mm thick, one fourth of the thickness of a tennis ball core.

Undoubtedly, once-used balls that sit in the Pressure Tube for a couple of days have better bounce than once-used balls just sitting in the bag, but that difference is pretty slight too.
Do you use 25 psig or 25 psi absolute?
 

travlerajm

G.O.A.T.
I will start an experiment tonight on fully dead balls in my pressure-augmented Tennis Ball Saver can and report back on how long it takes to revive them, speeding it up by frequent venting.
 

travlerajm

G.O.A.T.
25 PSI absolute. So about 13 PSI over the 12 PSI internal pressure of a new ball.
I think you mean 25 psig (40 psi absolute).

Mostly dead balls are probably only about 5 psig (20 psi absolute).

This means your starting driving pressure is 20 psi differential. But more than half the volume of the bag is occupied by the balls. If you do the math, it works out that the driving pressure quickly drops to so low that you never quite get to the full 15 psig inside the balls because there is not enough total molecules of air inside the device. The average pressure at equilibrium would be about 27 psi absolute (12 psi gauge) which is less than the 30 psi absolute pressure inside a new ball (15 psi gauge). In other words, leaving it for infinite time will not get you to a fully charged ball.

Of course, a 3-ball saver left unattended would have an even worse problem than the pressure bag (only about 9 psi gauge at equlilibrium), which is why these devices are not as successful as they could be with better engineering and better user instructions.

Recharging periodically to the starting pressure would fix this by adding air molecules to replace the air that leaks across into the balls to maintain the driving force reservoir.
 
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travlerajm

G.O.A.T.
After first 8h in the supersaver, the dead balls have gone from fully dead to half dead, so still a long way to go. But noticeable improvement from the starting point.
 

Injured Again

Hall of Fame
I think you mean 25 psig (40 psi absolute).

Mostly dead balls are probably only about 5 psig (20 psi absolute).

This means your starting driving pressure is 20 psi differential. But more than half the volume of the bag is occupied by the balls. If you do the math, it works out that the driving pressure quickly drops to so low that you never quite get to the full 15 psig inside the balls because there is not enough total molecules of air inside the device. The average pressure at equilibrium would be about 27 psi absolute (12 psi gauge) which is less than the 30 psi absolute pressure inside a new ball (15 psi gauge). In other words, leaving it for infinite time will not get you to a fully charged ball.

Of course, a 3-ball saver left unattended would have an even worse problem than the pressure bag (only about 9 psi gauge at equlilibrium), which is why these devices are not as successful as they could be with better engineering and better user instructions.

Recharging periodically to the starting pressure would fix this by adding air molecules to replace the air that leaks across into the balls to maintain the driving force reservoir.
I'm an old guy - that was my last post of the night last night and clearly I got that wrong.

The Pressure Tube doesn't soften as it sits, even for a week or more. After squeezing tennis balls for so long, I can tell when a ball has a couple of PSI drop and the Pressure Tube feels the same at the beginning as it does at the end. This has been true with Pro Penn Marathon, Penn Championships, Dunlop ATPs, Dunlop Championships, and US Open balls. In my experience, the Pressure Tube is really a pressure maintainer because it restores pressure so slowly.

I'm not sure I understand why you believe the driving pressure goes down so much. The tube itself has the capacity to hold eight balls and I never put any more than six in there. With 25 PSI over atmospheric, and with a ball having about 12 PSI fresh from the factory, there should be a 13 PSI difference between the inside of the tube and the inside of the ball driving permeation of air. The volume outside of the balls is at least twice that of what is inside the balls so if that 25 PSI equalizes throughout the volume as if the balls were completely flat, it should stabilize at about 16 PSI.
 

travlerajm

G.O.A.T.
I only have one Saver Can, and since I’ve been playing regularly, I’ve been storing the balls I play with every time out until the felt is gone. As long as I remember to vent and temperature equilibrate daily, the balls still have 100% pressure when the felt finally comes off.

So I still haven’t tried my experiment to see how long it would take to revive completely dead balls, but based on what I’ve seen so far with half-dead balls in the Supercharger, I’m still confident I could do it in less than a week.

Hopefully I’ll get around to the Frankenstein back-from-the-dead ball experiment soon.
 

Rafedovic

Rookie
I only have one Saver Can, and since I’ve been playing regularly, I’ve been storing the balls I play with every time out until the felt is gone. As long as I remember to vent and temperature equilibrate daily, the balls still have 100% pressure when the felt finally comes off.

So I still haven’t tried my experiment to see how long it would take to revive completely dead balls, but based on what I’ve seen so far with half-dead balls in the Supercharger, I’m still confident I could do it in less than a week.

Hopefully I’ll get around to the Frankenstein back-from-the-dead ball experiment soon.
Thanks for the info. I just bought a “Tournament Restore” version of the re-pressurizer you have and was wondering if I should reduce the volume of the inside of the container or just store the ball in it until the next use. I only play socially around once per week, so that may be enough time for it to work as is, by the sound of it.
 

travlerajm

G.O.A.T.
....so you have the bungee cord in there to reduce the volume or do you use as is?
I've been using 6 pieces of 7-inch-long standard 3/8" round bungee (the kind that has a slippery braided nylon sheath). I cut these from a single 48-inch bungee that cost less than $2 at Home Depot. One piece at bottom, 2-pieces in each slot between balls, and one piece at top. This bumps the pressure from 14 psi to >20. Then venting daily keeps the pressure from dropping below 20. I could probably get the pressure above 30 psi if I refined my volume-reducing pieces to occupy more volume.
 

BenC

Rookie
I was inspired to pick up a ball saver too but my Costco Penns don't seem to hold up more than 2 hitting sessions before the it feels like the rubber itself is breaking down. Premium balls will probably yield better results ...
 

travlerajm

G.O.A.T.
I was inspired to pick up a ball saver too but my Costco Penns don't seem to hold up more than 2 hitting sessions before the it feels like the rubber itself is breaking down. Premium balls will probably yield better results ...
The limiting factor on my Costco Penns is that the felt gets chewed away until the crusty glue layer that holds the felt on is exposed. The modified pressurizer can keeps the balls bouncy like new, but with no felt the balls start to play too lively and light, more like racquetballs.
 

GeoffHYL

Professional
I have stored used balls at 25 psig in a Pressureball for extended time, maybe 2 months. They are quite bouncy, in fact too bouncy, more so than new balls. These are Penn HD, used for a couple of hours of light hitting before going into the Pressureball. Even after a few days out of the Pressureball they are still at least as bouncy as new balls from a freshly opened can. YMMV.
 

Rafedovic

Rookie
I bought a Tourna Restore ball pressurizer and add pieces of spear gun rubber to reduce the air space inside. The trouble I’m having is air leaks out before the container is fully screwed in. I’m trying out only half screwing in the can then screwing it in a little more each day but this seems like defeating the purpose of reducing the air space. Has anyone else had this trouble?
 

travlerajm

G.O.A.T.
I bought a Tourna Restore ball pressurizer and add pieces of spear gun rubber to reduce the air space inside. The trouble I’m having is air leaks out before the container is fully screwed in. I’m trying out only half screwing in the can then screwing it in a little more each day but this seems like defeating the purpose of reducing the air space. Has anyone else had this trouble?
I’m not quite following. My can has a gasket that seals well enough after the first thread is engaged. It seals at roughly the same place regardless of how much extra volume is filled.
 

zinzan8

Rookie
I bought a Tourna Restore ball pressurizer and add pieces of spear gun rubber to reduce the air space inside. The trouble I’m having is air leaks out before the container is fully screwed in. I’m trying out only half screwing in the can then screwing it in a little more each day but this seems like defeating the purpose of reducing the air space. Has anyone else had this trouble?
Not sure anyone other than you and OP have tried this. Maybe reduce the added material? Clean and lubricate/moisturize the seal?
 

Rafedovic

Rookie
I don’t think the o-ring can hold the extra pressure. Is your gasket an o-ring? Mine is new and lubed up with silicone lube. Maybe vasso will work better as lube because it’s thicker, I’ll give it a try.
 

travlerajm

G.O.A.T.
It’s leaking past the gasket, which is new and lubed up with silicone lube. Maybe vasso will work better because it’s thicker, I’ll give it a try.
It’s possible that the design of the Tourna Restore is not quite the same as that of the original yellow Tennis Ball Savers, which have a draft angle on the surface that mates with the gasket, so that the seal tightens as you close the can further.

I’ve also had the Gamma ones, which also seal well. I used these for lab experiments at work where I needed to pressurize porous materials submerged in water to high pressures.
 

Rafedovic

Rookie
The o-ring doesn’t protrude very far so I’d imagine the inside wall diameter is the same all the way through. Maybe I need to try a different model?
 

esgee48

Legend
OP - This trick may help speed up the repressurization. When you close the "can", do it in a cooler environment. Where you let the "can" rest is also important. Ideally, you want that temperature to be higher, so leaving it next to a heat or in a sunlit window space will help. The increase in temperature does 2 things; it increases pressure inside the "can" by increasing the kinetic energy of the air molecules, which enables better penetration of the rubber, which has now been expanded by the rise in temperature. I believe that the increase in rate is roughly the sqrt(TF)/sqrt(T0) where T is measured in Kelvin.
 
Here's my tank, bought a water container with a rubber o-ring seal.
Drilled a hole in the lid and used a bicycle inner tube, silicon sealed from the inside.
Holds 25psi nicely, two year old balls bounce better than new, I only pump it up once and it doesn't drop below 20 psi in a week with 70 balls inside.


Sent from my FIG-LX1 using Tapatalk
 

SFrazeur

Legend
Here's my tank, bought a water container with a rubber o-ring seal.
Drilled a hole in the lid and used a bicycle inner tube, silicon sealed from the inside.
Holds 25psi nicely, two year old balls bounce better than new, I only pump it up once and it doesn't drop below 20 psi in a week with 70 balls inside.


Sent from my FIG-LX1 using Tapatalk

Do not put more than 20PSI in that.

Have a link or product page for the container used?
 

travlerajm

G.O.A.T.
Update:

I’ve discovered that the key to rapid repressuruzation with this modified device is frequent venting.

I can start with a half-dead set of balls, get in the car, and have full bounce when I arrive at my courts half-hour later if I vent every couple minutes or so at every stoplight. Frequency of venting is more critical than time.

As the balls get closer to full bounce, the amount of hiss (from more air rushing in to fill the vacuum) will get less and less. When the balls are maxed out (about 105% bounce compared to fresh can), there will be no more hiss.
 

travlerajm

G.O.A.T.
How many times can you vent these things before it breaks?
I’m starting to notice that the seal is starting to wear, so that the venting hiss is not as forceful and loud anymore. I should probably order some replacement o-rings to maintain peak prime performance.
 
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