How will I know when to switch batteries?

[denti alligator]

Will it be a gradual loss of power? Or will it be sudden?

I'm not keeping track of hours, but I imagine I'm close to 100 by now, if not over. Still sounds great. But if low batteries make only subtle difference, then I won't hear it.

[Paul Birkeland]

You'll hear it. 

While there is a slow degradation that isn't as easy to pick up on, there's a point where the distortion gets really heavy and you'll know something is up!

You can also measure the voltage of the 9V stack and your D-cells, I think PJ has written about the limitations of the circuit in terms of voltages.   

[earwaxxer]

Its funny, I havent noticed a difference in sound as the battery voltage goes down. I have the chokes, so that may have something to do with it.

With the heater batteries, the sound will just stop when the voltage is too low. Not sure what voltage that is, but usually when I ck the battery after that happens, the battery is effectively 'dead'. I use rechargeable AA's. With the grid power, I use NMH packs, and they have gone as low as 16V at times and I didnt notice that they were that low. Full charge is 30V.

I have experimented with different grid voltages from 20V to 65V. I'm not sure if I heard a difference that I can put my finger on. Half of the time I think the high voltage sounds 'better', and the other half the low.

[Paul Joppa]

The manufacturers are careful to avoid specifying the minimum filament current on these battery tubes, though they will admit that 1.6 volts is the absolute maximum. However, a few of them show up in mil-spec versions where you can find usually a minimum filament voltage of 1.0 volts. Since the terminals are exposed on top, this is easily measured.

The simplest rule is: When either D-cell drops to 1.00 volts with the preamp on, replace all the batteries.

The circuit adapts itself to falling high voltage; I designed it to operate down to 24 volts but of course it may sound OK below that. My recommendation would be to replace the HV when it drops to 24 volts, which should normally happen about the same time as the D cells drop to 1.0. This matching of the lifetime depends a lot on the manufacturing of the particular batteries, and their storage history - and you have no control over either one. If I was using a Quickie a lot, I would probably get my supplies in bulk (Costco or Radio Shack or some place that has a high turnover rate) and calibrate the first couple sets.

You may be able to find an old-fashioned analog voltmeter and install it across the filament of one of the tubes. It won't deplete the battery noticeably. I went to Mouser, looked up analog panel meters, and the cheapest ones were around $10-$15 for 0.5mA full scale. Add a series resistor to get 1.5v full scale, and calibrate it against a decent digital meter to find the 1.0v point, and you're golden. Heck, at that price get two!

[Zimmer64]

Here're my 2 cents: I can run 2 sets of D-cells with one set of the 9 volts. Same result with Duracell Alkalines or rechargeable NIMH batteries.

As Doc said, the Quickie stops playing once the D's go below 1 volt. I ran the HV grid down to 10 volt and it kept playing.

Best

Mike

[proud indian]

Get this

http://www.ebay.com/itm/New-Rechargeable-Battery-Tester-AAA-AA-C-D-1-5V-9V-Button-Cell-Volt-Checker-/221058755022?pt=US_Battery_Testers&hash=item337820e9ce

his store is
http://stores.ebay.com/applegate1999?_trksid=p2047675.l2563

in case I got it wrong. For a couple of bucks, its a great tool, even to know if you have charged your battery's fully, or have mixed them up while changing them and do not know the charged ones from the uncharged ones. This normally happens when you drink and listen at the same time

No stress, and has made my life easy.


shreekant

[earwaxxer]

I also like those 'old fashioned' testers with the meter. I still have an old radio shack one. I use it all the time.

[4krow]

I believe that my truck automatically turns off the headlights after a few hours.


   Sorry, the smartass gene is a tuff one to fight. Eric on the other hand fights the dumbass gene....GOD!! there it goes again.

[earwaxxer]

Sorry Greg, I hate to be the one to tell you, but YOU were the bastard child between mom and the milkman!

[earwaxxer]

Back to the topic of batteries and drain etc. The interesting thing I have noticed, is that I can never assess the voltage output of my batteries by the sound. I use NMH, so the voltage does decrease gradually, compared to Lipo's. I remember some fantastic listening sessions with friends where I was surprised to find that the voltage was quite low for most of the session. I'm talking low 20's to the high teens. My peak voltage on that pack was 30v, but with good reserve power. Anyway, interesting variables with the battery power.

As far as Greg is concerned - I tread lightly there. I try to complement him as much as possible. Quite fragile you know.. He's trying though.

[4krow]

Since you have forced me into additional therapy sessions, I am tempted to send the additional charges your way......if a doctor can't cure you is it ok to reverse the charges?

[earwaxxer]

Dearest Greg - I have told you before, that there is no cure for what I have. You can waist your money on therapy if you wish. I dont recommend it though...

[4krow]

Have I missed something, or has no one answered the question, 'how many hours do the batteries last?'

[proud indian]

Back to the topic of batteries and drain etc. The interesting thing I have noticed, is that I can never assess the voltage output of my batteries by the sound. I use NMH, so the voltage does decrease gradually, compared to Lipo's. I remember some fantastic listening sessions with friends where I was surprised to find that the voltage was quite low for most of the session. I'm talking low 20's to the high teens. My peak voltage on that pack was 30v, but with good reserve power. Anyway, interesting variables with the battery power.

The 9v will lessen the volume when they need a change. If you keep you amp at a constant volume, you will notice the drop in volume. Next will be the distortion, after which you have no choice. The 1.2 on the other hand become "bland" before croaking.

shreekant

[Paul Joppa]

Have I missed something, or has no one answered the question, 'how many hours do the batteries last?'

It's in the archives, somewhere - there have been a few threads. The search is not always as helpful as you'd wish though.

Basically, fresh alkaline batteries that meet the manufacturer's specs will last around 150-200 hours. Most aren't that fresh, and/or the specs are a little optimistic, but you should see at least 100 hours from a set.

When they drop to 2/3 of the nominal, I say dump them. That's 1.00 volts on the D-cells, and 24v from the 9-v pack, or 6v per 9-v battery. If you built it stock, they are easy to measure. But as others have noted you can still get music out of them.