Mazda5 Electrical problems

Hello,
Today after work I've tried to start my 5 but it wouldn't because battery was dead.
Jumpstarted the bloody device and started driving, but as it was getting darker I noticed the led display from the radio was blinking and the headlights where "flashing" also.
Now I know because it is a diesel it won't stall when battery is dead flat, but I only need a confirmation that the generator is in need of a swap. Could anyone confirm my issue?😊
 
What is the voltage across the battery when running? Should be around 13.5v or more.

When not running? Battery should show 11.8 or more volts.

In the US, most car part stores can load test the alternator free of charge.

I also recommend the new smart battery testers. They are fairly cheap and can test your charging system among a bunch of other battery tests.
 
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I would check the cheap items like ground wires first. Lights blinking most likely means connectivity issue.

While it can, I've had it happen way more from a low or dead battery which got that way from either age or the alternator. It flickers because the relay isn't staying energized.
 
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While it can, I've had it happen way more from a low or dead battery which got that way from either age or the alternator. It flickers because the relay isn't staying energized.
Battery is in good shape, 87% on tester. Checked voltage with engine off, as normal 12,3V, checked again with engine on, still 12,3V. Sometimes spiking up to 13,8V but then flatting out on 12,3V again.
 
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So you're not charging. But the fact that you are spiking up to the correct voltage at times makes me think it may be bad battery cables or ground.

I would inspect the cables for corrosion and freshen up all connections to the alt, the battery and grounds. If you still have issues (test the battery while car is on again), pull the alternator and take it in and get it load tested. It's probably the culprit. If it tests good, then you still have a disconnection in the circuit. At that point I would suspect internal corrosion of the battery cables which can't be easily seen.
 
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