24v battery applied to 12v system

[D60]

A friend accidentally tried to charge a 24V boat battery from his '15 Tundra in Mexico.

His truck was running at the time (so I'm concerned about alternator).

He said immediately after his truck started on its own, so it seemed all was OK. Now, three days later his (isolated from camper batt) is at 11V and vehicle won't start.

I'm guessing he may have toasted his alt or damaged the 12V battery.

What would be most common concerns?

 

[D60]

Also, for those who speak Toyota, are there main (like 100A) fuses or fusible links? @The Critic

But would higher VOLTAGE trip such a protection? Aren't these AMPERAGE based?

 

[andyd]

," are there main (like 100A) fuses or fusible links?"
Pasted
Got me this , https://www.toyotanation.com/thread...al-issues-after-a-short.477025/#post-14432439

 

[eljefino]

Highly suspect the main fuse is blown. Check for +12V at the main stud on the back of the alt with the engine off.

 

[meep]

His alternator would not have been overwhelmed, it would simply have been commanded to output no power.

His 12V battery would have absorbed all of the power. If the 24V source was weak, the 12V battery may have kept it down enough to not destroy vehicle components. Over 17 volts and I’d expect things to start to pop - lightbulbs, electronics.

The 12V battery may have been damaged, and hopefully thats it. You should troubleshoot this from the ground up pretending you don’t know the cause. Test the battery, test the charging system.