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Battery charger output Answered


I have a Black and Decker 14.4 Volt Drill. The diode on the charger doesn't light up anymore so I don't know if the charger is working properly. It can use one of two different battery chargers. I measured the voltage where the battery plugs into the charger and I get 0.04 volts. I'm not a guy who understands electricity so I'm trying to find out what the voltage should read where the battery plugs into the charger. I'd appreciate any help.

1. FS14C


Thank you



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1 year ago

You PMed me that you buy a new charger. good.

To elaborate why and whats maybe happening here:
The 40mV (0.04V) can be because it puts a small high impedance-voltage onto the terminal and checks if this voltage drops. That way the charger knows: Now something which draws current is attached to me! Lets start the more powerhungly part of the circuit and supply the output with proper power.
Your Voltmeter is VERY high impedance. It may not be enough to lower the voltage sufficiantly to trigger the sens.
Another thing: Often, those packs have a digital communication-line as well. Some argue it is for proprietry.reasons, other say it is for a legitimate use for the fuel-gauging... I wont discuss that.
But as you may not talk to the charger sufficiently with your non-communicating multimeter, the charger simply doesnt start up as it never got the proper command from the battery to do so.
This 40mV may also be a pulsed DC: Very short duration higher voltage to talk to the battery and a long 0V-Duration to wait befor the charger tries again...