Modifying electronics.

July 5, 2008 7:53 AM

I bought the POWER TOUR Amp and it's really awesome. However I want to modify it and I don't know much at all about electronics.

The unit uses 4 C batteries, adds up to 6 volts. The back of the unit says 2.9W.
I'd like to find a wireless phone battery to plug there instead. Would it be as easy as finding a 6 volt battery and plugging it there? Would the battery fry the amp if the amperage is too high?

Say I have a 6v, 1000mAh battery, would a direct connection to the unit power it on and play properly?

Thanks!!

posted by PowerCat to sports, hobbies, & recreation (8 comments total)

Unless they are packed end-to-end like in a flashlight, it's possible that the batteries are hooked up as 3V or even 1.5V, by putting them in parallel instead of series.

As long as you're right about the voltage, then the amplifier should work from any source that provides that voltage. You may be disappointed with the battery life, though. An alkaline "C" battery has a capacity of 7800mAh. A 1000mAh battery would run the same load for about 1/8 as long.

It's possible that discharging this battery at a high rate (1 A hour 6 V / 2.9 W is about 2 hours) will cause it to heat more than it should. Monitor the battery's temperature and be prepared to unhook it if it gets too hot.
posted by jepler at 8:19 AM on July 5

A 6 volt battery should be fine. 1000mAh is a measure of charge, not current. If the unit draws 2.9 W at 6 volts, that means about 483 milliamps of current are flowing through the circuits when the unit is on. Your cell phone battery will probably not fry your unit as long as it really is a 6V battery, and it would give you about 2 hours of playing time before needing a recharge.

Why would you want to use a phone battery instead of rechargeable C batteries though? Then you don't need to rewire anything.
posted by mkb at 8:19 AM on July 5

Oh yes, and what jepler said.

Is there an AC adapter plug for this toy? It might say something about the DC voltage in.
posted by mkb at 8:20 AM on July 5

It only runs on batteries. I'm 100% positive that the batteries add up the charge - the back of the amp says 6v / 2.9 w and they are stacked on each other.


So if I put 4 rechargeable C batteries, how easy would it be to also add a plug for an AC adapter that would recharge them while in use or not, without taking out the batteries?
posted by PowerCat at 8:31 AM on July 5

Add up the current...
posted by PowerCat at 8:33 AM on July 5

You wouldn't add a plug for an AC adapter, you'd add a whole battery charger, including the logic that tells it when to trickle, when to fast-charge, and when to stop.

Just get two sets of rechargeable C batteries and a battery charger. Then there's always one set charging.

On the other hand, putting in an AC adapter that powers the amp (with the batteries removed, or with a switch in the AC adapter jack that disconnects the batteries) ought to be straightforward if you'll be playing somewhere you can plug in.
posted by mendel at 8:59 AM on July 5

I've added power jacks from radio shack to my camera and other devices. A regular power supply (just a bit more voltage than the batteries) differs from a battery charger in that it won't fast charge. Otherwise, usually OK, depending on what type of battery. Don't use lead acid, as that will overcharge and you may be awoken by the fire department banging on your door because a neighbor complained about toxic fumes emanating from your place.

Some rechargables have extra circuits and custom chargers, but these usually do fancy things like have a chip that calculates how much power has been used, so the remaining power can be displayed. They don't have much to do with actual charging. Except with fast charging.
posted by StickyCarpet at 9:30 AM on July 5

They don't have much to do with actual charging. Except with fast charging.

A good charger should be turning the charge cycle off once the cell is full, keeping it from being hot unnecessarily, which in turn prolongs the cells useful life. That's should though.. In practice, you might be right..
posted by Chuckles at 12:10 PM on July 5