14.4V charger repair

[MadMan2021]

Greetings all,

I've just been handed a 14.4V drill battery pack charger that needs to be repaired, simple circuit as you will see in the pictures below.
Looks like a trace has blown and what I think looks like a resistor.

Could one of you smart guys help me figure out what the component is which has blown in half.

Any help is appreciated.

Battery pack is a DRAPER 14.4V Battery Pack. It states for use with 3-5 hour charger.

Regards
Jordan

[mikerj]

The broken looking component is a resistor, which is used to limit the current through the LED.  Unfortunately it's value would have been encoded using coloured bands on the outside which have been burnt off.

More importantly you are completely missing a high power resistor from the middle of the board (the empty blackened area), and without that that charger simply won't work at all.  If you replace the big resistor with the correct value, the charger will work, but the LED won't.  The LED is connected across the big resistor, so it only lights when charging current flows, so if you replace the big resistor and measure the voltage across it, we can work out a sensible value for the smaller resistor.

[Seekonk]

It has a very crude charger and you could start with a 10 ohm 5-10W for the big resistor and 330 for the little one.  For the little resistor to burn up the battery has to be shorted along with the LED now being dead.  I can't imagine this whole drill set being nothing but junk when a battery needs to be replaced.  This is nicad, right.

[MadMan2021]

The broken looking component is a resistor, which is used to limit the current through the LED.  Unfortunately it's value would have been encoded using coloured bands on the outside which have been burnt off.

More importantly you are completely missing a high power resistor from the middle of the board (the empty blackened area), and without that that charger simply won't work at all.  If you replace the big resistor with the correct value, the charger will work, but the LED won't.  The LED is connected across the big resistor, so it only lights when charging current flows, so if you replace the big resistor and measure the voltage across it, we can work out a sensible value for the smaller resistor.

Thanks for your input, from what I was told there was nothing in the emptry slot in this middle which confused me also. I'll go back and ask him if he is sure nothing was in the casing.

Ether way I'll get my hands on the resisters and solder them on see what i can do.
What would be the best way to check if the battery is shorted ? Thank you

[Kleinstein]

Th check the battery pack, one could charge it at low current (e.g. C/20 - something like 50-100 mA) for something like 5 hours, than load it at a similar current for somthing like 30 min (to get rid of the initially higher voltage) and than measure the voltage. It should be a little higher than the nominal 14.4 V (e.g. 14.7 V) - if its much lower one or more cells are likely dead (0 V or even reverserd). Even with 1 or 2 cells dead the pack may be still usuable, though at lower power.

If you have acces to the individual cells its even easier.