Posted: 5/23/2009 3:34:40 PM EDT
|
I have one of those rechargeable 12v spotlights that you can buy at the local auto parts stores, and it recently quit working. This is one of the models with a dimmer switch on top, and can be charged on 120v or 12v. Of course, being a man, I took it apart to see if I could fix it it. The small circuit board, which was attached to the dimmer switch and ran a small push button battery tester on the rear in the light, somehow cracked (which was causing the problem). Now, what I have done is completely bypass the circuit board (removing it all together), and have hard wired the light to the battery and put it back together. It works now as it should, albeit with no dimmer switch and no battery tester (which had various levels of lights to indicate relative charge of the battery) . Here's my question. Does the circuit board also serve any function with the actual charging of the battery? Specifically, does it function to "stop" the charging cycle once the battery has reached full capacity? The reason I ask, I can still plug the charger into the light and it seems to charge the battery. My main concern is not overcharging the battery, either at home or in the truck. I know both the home charger and car charger are putting out 12+v to the light, but what will stop the charging cycle now?
|
|
The plug that goes into the wall will have your rectifier circuitry(changes the 110AC @ 60htz into the 12VDC) in a black box. The battery should not be affected buy the lack of the CCA(circuit board). I cannot say for sure because that board appears to have a 555 timer chip on it. I could not tell you what it does without seeing a schematic. I'd say you are fine but watch it carefully. Upon further review of the board.... The circuitry at the bottom right(from your pic) Is a protective network for the flat pack chip 555 timer. It probably controls the voltage to the LEDs at the top of the board. What did those lights indicate? Complete charge or mode of operation?
ETA- OP amp. Got it. It does control the voltage to the leds. If you can see the solder runs in the board you should be able to jumper them out by soldering some 18gauge wire across the break. Thats what I would do. |
|
I would put money on the wall charger being a simple trickle charger, and the battery cells being dirt cheap nicads. That circuit board is probably just for the LED battery status & dimmer potentiometer.
You can usually trickle charge simple cells like SLA & NiCad for long periods without danger, but it's not the best thing to do if you care about the life of the battery. FWIW, consumer electronics at this price point aren't very state of the art. I wouldn't be surprised if that LED/dimmer board has been used in a hundred different products. The circuit probably came right out of a data sheet. |