Battery switching

Rockin Mike · #1 03-23-2013, 07:00 PM

I want to wire a bass with a 9V preamp and a double battery box. One of the knobs would have a push/pull to switch the circuit from one battery to another.

I think this would be preferable to an active/passive switch for cases when a battery goes dead.

Is it possible?

line6man · #2 03-23-2013, 07:02 PM

It's possible, but rather silly.

The current draw of a preamp is ridiculously low, so all you have to do is change batteries every year and forget about it.

nolezmaj · #3 03-23-2013, 07:04 PM

Interesting and quite possible idea, although I would not prefer it over active/passive switch, because it has other benefits.

ddnidd1 · #4 03-23-2013, 07:06 PM

Some people on TB are just obsessed with the FEAR of preamp batteries going dead.

The battery life in a normal preamp is actually pretty darn impressive. Just change them periodically and forget about all the elaborate 'cures'.

OR if you're intent on spending money and being able to sleep at night without the unbridled fear of battery failure, get one of these - http://www.keithmcmillen.com/batt-o-meter/overview

Rockin Mike · #5 03-23-2013, 08:00 PM

I have had batteries fail during gigs. I play enough that they last me a few months at best. If I leave the jack cord in the bass the battery only lasts a few weeks.
Nothing wrong with the bass, I have several active basses of different brands and they're all like that.

It would also help me avoid throwing out half-dead batteries before a gig "just to be safe" which is a money saver and better for the environment.

Rockin Mike · #6 03-23-2013, 08:04 PM

Quote:

Originally Posted by ddnidd1

OR if you're intent on spending money and being able to sleep at night without the unbridled fear of battery failure, get one of these - http://www.keithmcmillen.com/batt-o-meter/overview

I have one of those. The probe that's supposed to go in the input jack doesn't work for me at all. I can test batteries by holding them against the side, but obviously I would like to avoid taking the control cover off, removing the battery for testing, and putting it all back together.

Testing AA batteries is worse. You have to hold the positive terminal against a contact on the side of the unit and somehow touch the probe against the negative terminal on the battery, and somehow hold down the test button on the other side of the unit. Very clumsy.

I wouldn't buy it again.

Rockin Mike · #7 03-23-2013, 08:05 PM

In a perfect world there would be a battery meter builtin to the bass and a little red LED would come on when the battery gets low.

I'm not holding out hope for that but if anybody knows of such a kit, that would be awesome!

line6man · #8 03-23-2013, 08:14 PM

Quote:

Originally Posted by Rockin Mike

In a perfect world there would be a battery meter builtin to the bass and a little red LED would come on when the battery gets low.

I'm not holding out hope for that but if anybody knows of such a kit, that would be awesome!

It takes more current to do that than your preamp draws to begin with. Lol.

ctmullins · #9 03-23-2013, 08:17 PM

Three comments:

1. Don't leave your cable plugged in.

2. If you're willing to invest in a double battery box, I suggest using it to run your preamp at 18V. This will give you more headroom for dynamic transients. It will also provide more time until the supply voltage that the preamp sees reaches a critically low state.

3. John East has a nifty-looking battery life indicator on his website - the BLI-01. It looks to me like it should work for any preamp, not just a John East preamp. And even though it doesn't appear on BBG's website, I'm quite sure that those guys can special-order it for you.

kreider204 · #10 03-23-2013, 08:20 PM

Spend the $7 to get one of these:
http://www.homedepot.com/p/Commercia...602H/202353291
Test your batteries before gigs. Rest easy.

Rockin Mike · #11 03-23-2013, 08:50 PM

Quote:

Originally Posted by ctmullins

John East has a nifty-looking battery life indicator on his website - the BLI-01. It looks to me like it should work for any preamp, not just a John East preamp. And even though it doesn't appear on BBG's website, I'm quite sure that those guys can special-order it for you.

At $38 US on the John East website it looks reasonable. Also would allow the double battery box to be used for 18v application.

Thanks for the tip!

FunkMetalBass · #12 03-24-2013, 11:36 AM

Just wire your batteries in parallel instead. You'll get more than double the life out of them between battery changes.

khutch · #13 03-24-2013, 01:23 PM

Quote:

Originally Posted by Rockin Mike

I want to wire a bass with a 9V preamp and a double battery box. One of the knobs would have a push/pull to switch the circuit from one battery to another.

I think this would be preferable to an active/passive switch for cases when a battery goes dead.

Is it possible?

Yep, when I got my first active bass I was going to do the same thing except I would have made the switch automatic with a light to tell me the backup battery was in use so I could swap in the dead battery with a fresh one before the backup died. I had the whole thing designed, parts located, and was about to order the parts before I sat down and measured the preamp current and calculated how long the battery would last.

At that point I realized all I needed was a light that would come on when the battery was near its end of life. The parts I used come in surface mount packages that virtually require you to assemble them by doing the soldering under a stereo microscope. But if John East makes one you are good to go and the Audere preamp has one built in, if you like those preamps. A battery minder circuit will draw some current but you can keep that to 10-20% of the preamp current so it really isn't an issue.

Ken

Medford Bassman · #14 03-24-2013, 01:26 PM

Get an Audere. You can wire them for 9v or 18v and they have a blue LED on them that you can tell battery strength when you plug in. Plus, when battery is too weak, it flashes 10 times.

Never failed me at a gig and I leave it plugged in during breaks. Draws very little juice.

Rockin Mike · #15 03-24-2013, 01:29 PM

Quote:

Originally Posted by khutch

Yep, when I got my first active bass I was going to do the same thing except I would have made the switch automatic with a light to tell me the backup battery was in use so I could swap in the dead battery with a fresh one before the backup died. I had the whole thing designed, parts located, and was about to order the parts before I sat down and measured the preamp current and calculated how long the battery would last.

At that point I realized all I needed was a light that would come on when the battery was near its end of life. The parts I used come in surface mount packages that virtually require you to assemble them by doing the soldering under a stereo microscope. But if John East makes one you are good to go and the Audere preamp has one built in, if you like those preamps. A battery minder circuit will draw some current but you can keep that to 10-20% of the preamp current so it really isn't an issue.

Ken

Yeah I'm going with the John East BLI-01.
Audere preamps are too polite for me.