electrical question - guitar pedals - decrease amps?

ok here is what i am trying to do:
i have an external laptop battery that is a 9v @8000ma
i have a couple of guitar pedals that run off of 9v batterries but are only rated at 15ma or so.

my idea is to get rid of the small square batteries inside of each pedal and run a daisy chain out of the external battery to these pedals.

it doesn't seem to work right now though.

is it because there are way too many milliamps going in?
how can i decrease the milliamps?

thanks a ton!

 

An electrical load will only draw as much current as it needs to operate. If the applied voltage is the same, you aren't going to "force too many milliamps" through the load.

The milliamp rating on the battery is the MAXIMUM it can supply. If you connect a 15 mA load to it, you will only draw 15 mA from the battery. Limiting the maximum available current would be done with a fuse in series with the circuit, and would be a good idea to prevent wiring from burning up in the event of a short circuit, but has nothing to do with reducing the current drawn by the pedals.

There are any number of reasons why your rig might not be working, but "too many milliamps" isn't one of them. Check all your connections, and the polarity (+ and -) of the applied voltage. If individual pedals work OK from the external power source, but stop working when connected together, you may have a problem with the way the battery is connected internally in the individual pedals (positive or negative ground), and there isn't much you are going to do to correct that short of redesigning the internal pedal electronics.

 

thanks ellis, here is what i have done thuse far:
the battery has a barrel connector that is [outside -] [inside +]
all of the guitar pedlas are usually opposite. [(+)] [o-]
i spliced the connector the proper polarity and got nothing.
(i am plugging this into the external barrel connection on the pedal)
i reversed the polarities to see if i had done something wrong and it still didn't work.
the pedals work with a regulay internal 9v batt.
they also work with a normal 9v power supply.
so either i am doing it wrong or there needs to be some fuse/resistor or something that i am now familiar with.
any ideas?

 

There are umpteen variations on those stupid "barrel" connectors, with varying internal and external diameters. Are you SURE you have the proper ones to mate with the pedal connectors? A small difference in the internal diameter can prevent proper contact. Do you need to throw a switch to convert from internal battery to external power? Most of those type sockets switch automatically when a plug gets inserted, but again a slight difference in plug size can cause a failure here.

If you have access to a voltmeter, can you verify proper voltage/polarity on the plug before plugging it into the pedal?

 

yes, i actually spliced into a barrel connector madefor the pedal. followed up by checking the pol. with my voltometer.
the power switches from internal batt to ext when the barrel is inserted.
but still nill~

 

Can you somehow measure voltage while the pedal is connected and turned on? A couple of needles stuck into the wire insulation might work for probes. Can you get inside the pedal to verify that voltage is present when the external battery is connected?

The situation as you describe it makes little sense, unless the laptop battery you are using incorporates some circuitry that prevent drawing current from it without some kind of "handshaking" with the intended laptop. Does the battery simply have a 2 wire connection, or are there multiple contacts for charging, monitoring, etc.? You might be reading battery voltage through a high series resistance, but once the pedals are connected, the voltage gets dropped across the series resistance and the pedal sees nothing.

Can you connect a simple load like a 9V light bulb to the battery to make sure that it can source current into a load?