DIY a Trickle Charger

**kinyo** · February 3rd, 2004 09:21 PM

The diode is 1N5402, a 3A/200V diode. Its reverse breakdown voltage is therefore 200V. Admittedly, the ratings of this diode is overrated for the application. I decided to use it for its more rigid terminal as compared to a 1A diode, a similar reason for the resistor which is overrated at 5W.

Except for the physical durability issue, the more popular 1N4001 1A/50V diode would work just the same and so would a tiny 1/4W resistor without them getting damaged due to self-heating.

**ebbfolls** · February 4th, 2004 02:51 PM

Is there any chance the car's standby current could exceed 500 ma, thereby approaching the transformer's current sustaining capacity? What would happen if say somebody tripped the alarm, activating the lights and the horn?

**kinyo** · February 4th, 2004 08:51 PM

500mA is too much of a standby current. I doubt if any stock car (with alarm) would exceed this value. My car's standby current is less than 100 mA.

When the alarm is tripped, the battery will supply most of the current required by the loads (horn, lights). The adapter is not likely to exceed its 500mA capacity in this condition.

But if somehow the battery is loaded continuously (light was left on, persistent alarm), then this will eventually discharge the battery and the adapter will eventually experience an overload as the battery's voltage drop further. I guess this is another reason for a fuse.

**333tinggay** · August 9th, 2012 10:22 PM

I truly appreciate your post of DIY trickle charger. Here's some questions. Can I use an AC Power Adapter rated at 1000 MA * 12 VDC? How do I tell which wire of the AC Adapter is positive and which one is negative? One black wire has a white stripe on it, while the other one is solid black. Thank