When is a 9v No Longer a 9v?

[AnthonyD]

Question for the techie electrical engineer types...

How can I proactively gauge the remaining life in a 9v? I only play out a few times a year, so I am leaning towards popping in a new one (and new two) before every performance to be safe. I seems a bit obsessive and a bit of a waste though.

I have a electrical-tester doodad that measures the voltage of a 9v - the new ones go in at about 9.5v. Do they drain in a linear fashion? Is there a safe threshhold? Can I check and have some reasonable expectation of remaining life or do they hold their voltage steadily and then drop-off rapidly?

Curious if anyone has and thoughts on this... Also interested in your own methods of dealing with the issue... Thanks!

 

[midopa]

I read somewhere that rechargeable batteries (maybe specifically NiMHs) discharge in a somewhat logarithmic fashion. That is, they hold their voltage for sometime and then suddenly start discharging rapidly. From my experience with NiMHs, I thyink this is true. Regular batteries discharge in a linear fashion, I bleeb.

Of course, some use the toungue test. *zap*

 

[Figjam]

Tongue test here.

 

[tiffles]

Of course, some use the toungue test. *zap*

reminds me of my time in therapy *twitch*

 

[Dr Stankface]

Tounge test. Don't be a wuss.

 

[AnthonyD]

Tounge test. Don't be a wuss.

Wuss I am!

Besides... I spent $30 on the tester thing...

So if the alkalines drain linearly (is that a word?), where is the "hurry - replace the battery zone"?

9.0v? 8.9v? 8.8v?

 

[Kevan]

If I said, "Ask Eric Johnson", would anyone giggle?

At my old workplace, we would replace them at 8.0V or less. That wasn't based on any major tech report; just company policy.

 

[Steve Dude Barr]

Wet nipple test here.

 

[tiffles]

argh!! visual picture. thanks alot steve.

 

[Steve Dude Barr]

No prob...anytime.

 

[tkarter]

I generally change mine when they show 8.5 volts. They still work there so I am unsure how much more discharge has to take place before you have a non working MM bass.

tk

 

[Motojunkie]

I change mine about once a quarter. Really there's not much thinking that goes into it - the batteries last a long time if you unplug your bass when you're done using it.

I remember seeing where someone added a battery indicator on a guitar. It looked really neat, but it was for an application (Variax) where batteries last a whole lot less than on a MM bass.

 

[Colin]

Tongue test here.

I believe it may be an urban myth, but I'm told 3 people die each year from doing that. So if that's true, Steve's method theoretically is the safer and kinkier way to go.

 

[Steve Dude Barr]

Well, I used to do the stick it on the eyeball test but that just hurt too damned much.

 

[Steve Dude Barr]

ps: I'm a total tard about not unplugging my active basses before passing out at the end of the night and I've never had a battery die on me due to normal use ever. Everytime I pickup the Oakland it's dead because it's generally been plugged in since the last time I played it. I go through more 9 volts than I do condoms these days and buy the big packs of em at Costco.

 

[Motojunkie]

I go through more 9 volts than I do condoms these days and buy the big packs of em at Costco.

Can't get yer hand pregnant......

So, do you just buy the 2-packs of batteries then?

 

[Steve Dude Barr]

That's not the reason.....one word.

"Vasectomy"

 

[Colin]

That's not the reason.....one word.

"Vasectomy"

It seems like only yesterday you where sitting in front of the computer with a bag of frozen peas in your lap. Where does the time go?

 

[Steve Dude Barr]

LOL...don't forget the Percocet...never forget the Percocet. All's good down there except now I have to "fill the cup" twice in a row to get the final clearance.

 

[niftydog]

Really hard to nail this down, there's just no easy answer as it would depend on a lot of factors like how you use your bass (lots of boost will drain faster) etc.

Normal batteries aren't just gonna suddenly die on you. They'll give you a fair bit of warning before hand. Listen for distortion or low output level, then you know it's time to change.

Keep in mind that rechargeable 9V batteries are never exactly 9V. They are multiples of 1.2V cells, meaning that their nominal voltage is actually only 8.4V.