A recent thread on 12V test lights reminded me of this load tester I put together. It’s inspired by the Lisle 28800 that applies an 800mA load and displays volts.
For this one, I used one of the many “waterproof battery meters” found on Ebay and a starter relay from a 1980’s Dodge I once owned. The relay coil draws about 500mA. It doesn’t have a momentary switch to apply the load like the Lisle but for many situations loaded vs unloaded will either be very close to 12V (circuit okay) or a significant drop due to a bad connection or broken wire.
I did this mainly with my friends in mind- guys with just basic troubleshooting experience. These are guys that are handy with a test light but not a lot of experience with a DMM. They can use this in place of a test light and observe voltage in the process.
As a bonus, if it gets damaged or left on the side of the road, I’m only out $18…..$8 voltmeter plus $10 meter leads.
For this one, I used one of the many “waterproof battery meters” found on Ebay and a starter relay from a 1980’s Dodge I once owned. The relay coil draws about 500mA. It doesn’t have a momentary switch to apply the load like the Lisle but for many situations loaded vs unloaded will either be very close to 12V (circuit okay) or a significant drop due to a bad connection or broken wire.
I did this mainly with my friends in mind- guys with just basic troubleshooting experience. These are guys that are handy with a test light but not a lot of experience with a DMM. They can use this in place of a test light and observe voltage in the process.
As a bonus, if it gets damaged or left on the side of the road, I’m only out $18…..$8 voltmeter plus $10 meter leads.