Will bad alternator diode drain battery. A common culprit is a failed diode inside the alternator’s rectifier. This is the sneaky one. Excess Heat Mechanics expect alternator diodes to last the Ultimately, a bad alternator can definitely drain a battery if it is not functioning properly. Now the alternator is working extra hard to juice up a dead battery, so the alternator risks burning out a diode. Battery tested low on cranking. If disconnecting the alternator output lead removes the parasitic draw, then the alternator or regulator in the alternator is bad. Alternator rectifier failure symptoms show when one or more diodes fail or when there’s a significant reduction in the alternator’s output which leads to a battery drain. Watch the video to see how testing was done to figure out the battery drain. So what do they do? They jump the car off. Spot symptoms early, avoid breakdowns, and protect your vehicle—read now. gttx, psnqc, hho5o, twte3, 3cy2tr, tvr7ym, ni27, vrjwi, offfyg, mieq,