Using a 12v automotive battery pack to power stomp boxes

[dai h.]

That's the Pedal Juice unit, and yes it comes in between $170 and $200. That may be great if you're a touring pro musician and can spare the expense, but for most basement warriors that's kind of pricey. Hence, all the discussion about NiCad/NiMH options.

(oops sorry Steve! I didn't realize it was that expensive. They do seem to be a bit less here though--around USD$150 vs. 97 at Amazon dot com vs. dot jp.)

[Knasher]

I would pop out and buy an inverter like this perhaps. Changes 12v DC to 230v AC.

4-in-1 Multi Function Power Inverter: Amazon.co.uk: DIY & Tools

This is a european one. Dont know what your local voltage is but im sure their available.

[Mark Hammer]

A box that has 4 jacks, and a stompswitch, such that one or more pedals plugged into its send/receive jacks can be completely bypassed mechanically. Just about the simplest and most consistently useful DIY project you can make.

I'll leave out discussion of the relative merits of true bypass vs other forms of switching, and let this thread do what it's supposed to.

[Mark Hammer]

That's the Pedal Juice unit, and yes it comes in between $170 and $200. That may be great if you're a touring pro musician and can spare the expense, but for most basement warriors that's kind of pricey. Hence, all the discussion about NiCad/NiMH options.

[Bill Moore]

One of the mail order catalogs came in this weekend, and there was a blurb about a Sanyo?, rechargeable supply for pedal boards. Looked the same size as a MXR pedal. The downside would be the $200 price!

[imaradiostar]

what is a true bypass box?

jamie

[Guitarist]

At the electronics store, I found a $2.00 6 x 1.5 plastic battery clip (don't try and make your own. I put a switch on it, an LED at the 4th cel or so, a fuzz tap at around 4.5V (you could go 3V for sicker fuzzz) and throw it into a true-bypass pedal. Without the LED one might forget to shut it down No ground loops.
This lasts ages, with general effects. But for digital delays/reverbs, larger batteries might be better.
I put this into a true-bypass box with a small treble tone cap for too-bright distortions.

[Teleman55]

Steve,it's about time this came up.I dabble in RC airplanes and rechargeable batteries are the hot fuel source.I have some 9.6v 3800mh NiMh battery packs that I have used for my effects.They worked fine and I have used a single battery pack for 5 hours of practice.I know that my RC plane will draw 20 amps for 8 to 10 minutes-.Places like- ALL Battery -sell pre made packs for a variety of uses.

[Steve A.]

Mark: I suspect that it was aliens from outer space who teleported down something actually useful and not total crap to your dollar store.

I was browsing on-line for sources of 9.6vdc NiMH battery packs and chargers. The nice ones run about $60 with shipping. I found a Tenergy 2000mAh 9.6vdc battery pack and cheap charger for about $30 (or get a 2nd battery pack for another $12). One of the reviews on Amazon mentioned that the charged packs put out around 11vdc, which is okay for RC cars but could cause problems when used with electronic circuits. Scratch that one off the list. And then it occurred to me to put a 9vdc zener diode between the two leads to keep that under 9v. With 2 packs I could have one with a zener for sensitive pedal and one with for the ones that will work with 12vdc.

Or I could get 8 AA eneloops for about $24 and use my own chargers. Either way I expect them to be good for quite a few hours (with the Eneloops lasting longer). One advantage with a battery pack (or a battery) is that you have no potential AC hum or noise from them.

Thanks for all of the suggestions!

Steve Ahola

[Mark Hammer]

I have a 2W battery-powered amp that I made. Runs on 8 rechargeable C-cells. Runs for a long time, too. Not sure how they got there, but the rechargeables were purchased for peanuts at a dollar store.

[Steve A.]

Thanks for all of the suggestions! The "automotive battery pack" is used for jump starting your car, some with a cigarette lighter jack and some with a bright light. I have a big one which is pretty hefty and then a smaller easy-to-carry one I picked up at Kragen/O'Reilly's when it was on sale in 2008. I didn't get around to labeling the power wall wart and haven't been able to figure out which one it is. :-(

I got some of those Eneloop rechargeables and they work great! They are rated at 2000mAh compared to regular cells with up to 2700mA, but their selling point is that they hold their charge for several months. Also because of their design they handle heavy loads better. I bet the Eneloops would last for quite awhile. An suggestions for battery holders for 8 AA's? Mouser?

BTW I'm drawing a total blank about how to wire up the zener. In series with the positive lead or from the positive to the negative? 3 volt or 9 volt?

Thanks again for all of the help!

Steve Ahola
"If it ain't broke, I think I can do something about that."

[jmaf]

Someone mentioned isolation above. The outputs of a device like this would be isolated from the wall, but they wouldn't be isolated from each other: they would share a common ground, so ground loops would still be possible.

You're right, I stand corrected about the regulators and ground loops.

A car battery can melt a good-sized wrench.

Here where I live you'll still find old school car electricians who measure battery charge by how big the spark is. Who needs a multimeter. There are wrenches and screwdrivers just for this purpose, high tech specialized tools with carbonized and dented ends.

[R.G.]

Laptop computer battery packs

[Ronsonic]

Just go to somebody like batteryspace.com and buy a 9.6V or so battery pack of NiMH cells and a charger. Total cost will be low and you'll have the mA/Hs to run pedals for days. The entire battery pack and charger won't be as large as a lead acid cell of any type and it will weigh a hell of a lot less. For a long time I had repurposed a mountain bike lighting battery pack (in a water bottle format) to run my board.

[Steve Conner]

Yeah, those are the ones, VRLAs is yet another name for them. It is technically correct, because they aren't quite sealed, they have valves to relieve any pressure inside.

DO NOT buy them surplus. They have a shelf life of only a few years, so get fresh ones. The cheap surplus ones are tempting, but every one I've ever bought has been shot. That's why they are so cheap.

The DC-DC converters are nice, but each one costs as much as a smaller SLA battery.