How to Make a Super Long Life 9V Battery (Answer Inside)

[Dai H.]

pete's trick of rubbing does work. Try it next time the remote control batts. die on you. I rub them on my thigh... 

one of those little tricks to impress your friends like spinning an egg to tell the diff. between a boiled one and uncooked one, lol...

re: the DIY Lithium, it's neat but is there a big advantage versus buying a 009P 9V Lithium which don't seem to be that much more than USD$6? Maybe very difficult to find in some parts of the globe?

[Eric H]

Pete, I'm not entirely convinced that warming your TV remote batteries is what brings them back to life. The infra-red LEDs in a TV remote are pulsed briefly at high currents, and this commonly causes electrochemical corrosion between the battery and the metal of the terminals contacting the battery. Often, when a remote seems to have 'died', all you have to do is open up the battery compartment and roll the batteries around their long axes to break the thin corrosion film and restore the contact. Of course, removing and replacing them will achieve the same effect.

I'm with Ge here --I've been doing this for years, though I didn't realize it was the  LEDs. Thanks for the info.

-Eric

[petemoore]

Often, when a remote seems to have 'died', all you have to do is open up the battery compartment and roll the batteries around their long axes to break the thin corrosion film and restore the contact.
  Been a while, I forget if I put this in the early post on the subject of my remotes dead batteries new longer lives, but the first trick that is easy to do is roll them around in there while pumping the on button, that didn't work, I didn't expect it to since the contacts are all brand shiny new looking.
  Whether it's the heat or the agitation...next time I"ll try slamming them first and see how long that method makes them last...not exactly 'clinical lab results' but good enough for battery work.
  Whatever...the case with these cells is that they didn't wake up before dieing, then lived many longer lives after being agitated with heat or movement.

[soggybag]

I bought a ringtone a couple weeks ago and it's pretty amazing. One of the best Ringmods I have used.

Of course I had to open it up and take a look inside. I noticed it had a MAX charge pump in it. Not that I want to get into disecting the Ringtone. I was talking with a friend about it, I figured the Ringtone wasn't running on more than 9V (which is my guess), my friend suggested that it might use the charge pump to generate 9V from a 9V battery that was putting out less than 9V.

Is this possible? If so it's pretty ingenious!

[Paul Marossy]

re: the DIY Lithium, it's neat but is there a big advantage versus buying a 009P 9V Lithium which don't seem to be that much more than USD$6? Maybe very difficult to find in some parts of the globe?

No special advantage that I know of. It's just a way to use some batteries that I had lying around that I couldn't otherwise use. 

[Seljer]

I bought a ringtone a couple weeks ago and it's pretty amazing. One of the best Ringmods I have used.

Of course I had to open it up and take a look inside. I noticed it had a MAX charge pump in it. Not that I want to get into disecting the Ringtone. I was talking with a friend about it, I figured the Ringtone wasn't running on more than 9V (which is my guess), my friend suggested that it might use the charge pump to generate 9V from a 9V battery that was putting out less than 9V.

Is this possible? If so it's pretty ingenious!

yep, Mr Vex noted in some thread (the last thread on charge pumps here) that he used it like that so that the tone generator wouldn't de-tune itself as your battery died.

[Herr Masel]

my friend suggested that it might use the charge pump to generate 9V from a 9V battery that was putting out less than 9V.

Is this possible? If so it's pretty ingenious!

From wikipedia (definately one of the best things to happen to the internet!):

Charge pumps use some form of switching device(s) to control the connection of voltages to the capacitor. For instance, to generate a higher voltage, the first stage involves the capacitor being connected across a voltage and charged up. In the second stage, the capacitor is disconnected from the original charging voltage and reconnected with its negative terminal to the original positive charging voltage. Because the capacitor retains the voltage across it (ignoring leakage effects) the positive terminal voltage is added to the original, effectively doubling the voltage. The pulsing nature of the higher voltage output is typically smoothed by the use of an output capacitor.

I would of given my own explanation, but all my knowledge of charge pumps comes from that paragraph so what the hell. Question for the advanced: does this fall under the definition of "bootstrapping"?

[Dai H.]

re: the DIY Lithium, it's neat but is there a big advantage versus buying a 009P 9V Lithium which don't seem to be that much more than USD$6? Maybe very difficult to find in some parts of the globe?

No special advantage that I know of. It's just a way to use some batteries that I had lying around that I couldn't otherwise use. 

I see that's cool. Just some resourceful experimentation, eh?... 

[Paul Marossy]

Just some resourceful experimentation, eh?...

Yep! I always share ideas like this one just to give people ideas.

[Dr Ron]

I'm surprised that noone has suggested or tried a small solar panel to provide a trickle charge while the pedal is not in use.

Will this work?

[Paul Marossy]

I'm surprised that noone has suggested or tried a small solar panel to provide a trickle charge while the pedal is not in use.

Hey, that's a nifty idea, too. You could have a little solar cell right on your stompbox. 

BTW, last night I built that battery recharger circuit mentioned earlier in this topic. I'm going to try recharging a few old alkaline batteries that I have and see how well it works. 

[christobean]

does anyone who uses the 'recharging' method find that the batteries last significantly less time after charging?  just curious

[Paul Marossy]

does anyone who uses the 'recharging' method find that the batteries last significantly less time after charging?

Based on my experience with rechargeable batteries, I would say that the answer would be yes after maybe 3-4 rechargings. But I'm not an expert on alkaline batteries, either...

[RaceDriver205]

I'm surprised that noone has suggested or tried a small solar panel to provide a trickle charge while the pedal is not in use.

Thought of that a while ago. Experimentation yeilded that, considering you need to pump up the voltage, and that the power ouput for a small cell is very small anyway, you need to leave your pedal out in the sun all the time for there to be any usefull charging.
Also came up with an idea for using an LC circuit tuned to 50Hz for tesla-style energy sucking. Didn't work though, maybe I did it wrong.

[Paul Marossy]

Well, last night I tried recharging a somewhat depleted alkaline 9V battery with that afrotech battery charger circuit. Whaddaya know, it works! The only thing is that you kind of have to watch over it so it doesn't get overcharged. I stopped it at 9.8 volts. It seems that when the DMM reads 2V higher than what you want the battery charged to, it is ready. I'm using a 9VDC 300mA wall wart which seems to work just right.

So, I wonder, can you add a voltage controlled switch to it so when it reaches a specific voltage it will shut off?

[stm]

I'd like to add here that I successfully recharged a pair of 9V alkaline batteries after Mark Hammers post stating he did.

The difference in my approach was the following:  I used 5mA only, so as to be fully certain that internal bubbling, overheating and explosion risks were under control.  Simply I used a 12V wallwart (which in fact puts out around 16Vdc), and one 2N5458 JFET tied as a current regulator (gate and source connected) in series with the battery.  I put two of these devices, one for each battery, and left the batteries recharge overnight.  They didn't even get warm.

Battery A had initially 8.2V while battery B had around 7.4V.  Battery A took about 12 hrs to rise up to 9.5V, while battery B was left like 6 hrs more until it reached about 9.5V.  Battery A was a total success, It lasted for about two months without measurable self discharge.  Battery B self discharged to 9.2V within the first couple of days, and lost its voltage faster than battery A.  I always used both batteries in series to power up an 18V Deluxe Fetzer Valve.  After two months of weekend use (approx one hour per week), battery A is around 8.9V and battery B has depleted down to 7.2V.  It is pretty apparent that battery B suffered some kind of permanent damage due to the inital abuse/deep discharge.

How to complete the circuit?  I believe a zener diode in parallel with the battery might help prevent overcharging.  I wouldn't try to put more than 9.5V to a battery, since this is like the fresh condition voltage.  Doing otherwise might shorten its useful life and promote risk of running into trouble.

A refined yet simple circuit is shown here:



This circuit doesn't allow current flowing out of the battery, and at the same time limits both the maximum charging voltage and current to  reasonable values.

I can't guarantee that explosion and/or leakage risk are not present, so you better assume it is experimental and dangerous.  Use at your own risk and keep away from children, unaware persons (like grandma), pets and expensive furniture (you know what Murphy has to say about this: the risk of battery leaking is exponentially proportional to the cost of the furniture it might ruin )

P.D.  It just ocurred to me that if you replace D1 with a RED LED and D2 with an 11V zener you could get visual indication of the charging current...

[Paul Marossy]

Thanks for the ideas STM. I think I'll try out some of them. 

[Paul Marossy]

Here's an update:

Down to 9V from starting at 9.3V or so. Been playing my wah pedal with this battery inside it nearly every day for at least one hour at a time. So far, so good...

I made two more of these battery packs with the rest of the batteries that I have lying around with no real use - until now!  Boo wha ha ha ha ha

[RaceDriver205]

Lol stm, the battery companies won't like this! Id be watching out for men in black suits and black sunnies paying a visit!

[Paul Marossy]

stm-

On your battery charger schematic, is the drain of the FET connected to the 12V DC? I am assuming so, but want to make sure. Also, what other FETs could I use? I do not have any 2N5458s on hand.

That afrotech mods charger that I built I think is too hit and miss. Out of two batteries to try recharging, one was a success and the other one resulted in a bulging battery. Yours looks a lot safer.