Hello Friend. They brought me to fix a 12v battery charger. The first thing I did is to test the voltage I delivered and it turns out that it only gives 7v. Disarm it and it has two negative diodes (I upload photos) in parallel. From these diodes comes the positive that goes to the battery and the negative comes directly from the transformer. Measuring with the multimeter in the scale and voltage of alternating current I have 15v before the diodes, that is to say that that is what the traffic delivers. I measure in direct current after the diodes and it gives me 7v .. To the diodes the probe with the multimeter and apparently they are fine, in one direction they lead (giving me a resistance of between 500 and 600 ohms) and in the other direction they do not lead. I don't know if the tests I did are right or this type of diodes are tested differently. I hope you can help me. Thank you

Hi. The measurements are correct since you are measuring half wave. regards

Two negative diodes only? Well to charge a 12 volt battery you need another positive plate with two diodes, unless the transformer was 220 volts and is connected to 110 volts ...