Electronics 2000

Hi

Hope someone can help with this - i've managed to fry a resistor in a battery charger for an 18v strimmer battery (by putting the wrong battery in it, oops). I've tried using various resistor calculators to find out what i need to replace it, as i know next to nothing about electronics so want to get a few matching results to be sure it's the correct one, but some of them simply won't let me put the colours in, like such a combination is impossible!

The colours are Black, Grey, Grey, Gold (as far as i can tell - it's a bit burnt!) and it's quite big - i ordered what i thought was the correct one from RS components but it was much smaller and probably not right.

Here's a picture if that helps:



Anyone have any idea what I should be looking for? Any help would be much appreciated cheers

It won't be black grey grey as that is 1,800,000,000 ohms or 1.8 giga ohms! Maybe worth just looking for a new battery charger.

Hello,
I have had similar situations in my life, and I feel I have to try and make a useful contribution to solving this problem in a technical manner.
After a substantial temperature rise, it is likely that all colours will turn to grey (ish).

Starting with the size of the resistor, it looks like a 1 Watt.
Assuming that it will have 12 volts dropped across it (probably not, but it is a start), the resistance would be:
R = V² / P, so 12 ² / 1 or 144 ohms.

In reality, the volt drop is likely to be less and the power too, so I would purchase a few resistors with the following values, all 1 Watt:

120 ohms
100 ohms
82 ohms
56 ohms.

Fit each one in turn, and check the functioning of the charger.


As an afterthought, try to measure the resistance with an ohmmeter. Resistors are often quite robust. If the resistor has some value around 120 ohms, then the problem may be elsewhere on the board...

In the photo it appears that the resistor is burned or over-heat. All code must have changed color because of the heat. In general for the charger circuit, which has a 1W power resistor has a value below 1K. Thus, the possibility that the value 1K resistor, 500 ohm, 200 ohm, 100 ohm ...

I suspect another prob... a short ? may be the new bat was bigger and very flat... more pics pls more info.

oursoul wrote:Hi

Hope someone can help with this - i've managed to fry a resistor in a battery charger for an 18v strimmer battery (by putting the wrong battery in it, oops). I've tried using various resistor calculators to find out what i need to replace it, as i know next to nothing about electronics so want to get a few matching results to be sure it's the correct one, but some of them simply won't let me put the colours in, like such a combination is impossible!

The colours are Black, Grey, Grey, Gold (as far as i can tell - it's a bit burnt!) and it's quite big - i ordered what i thought was the correct one from RS components but it was much smaller and probably not right.

Here's a picture if that helps:



Anyone have any idea what I should be looking for? Any help would be much appreciated cheers

is it bigger resistor or u take close camera shot !! ??

Hi, I dont know what size the resistor is but...
I assume there is a bit which plugs into the mains and two wires which connect to the batt, we need to see the circuit inbetween to work out what it does, all we can see is a circuit board with some bits on it, we cannot see how they connect together (other side of board) or to the batt or mains, I asume there are more bits.
Photos of other side of the board and any other wires or circuits between the batt and the mains pls.

I run 18V drills, saws etc on two 22Ah 12V batts connected in a 24V configuration, no black smoke yet and they very well.

Tar&stuff.