Aux (passenger side) battery boil-over!

[BruteForce]

I've been out turkey hunting these past few days. Each morning, I'd find my truck dead and no power. The only way to get it started has been to jump both batteries.



Got home today, pulled both batts. The AUX (passenger side) was venting/boiling over and swollen. After removing that battery, I found a cable (+ side) that said "fusible link" on it and it connected to what the service manuals calls "the generator". The end of the cable where it connects to the "generator" is totally melted up.



Bought two new batts and with just the drivers side batt installed, was able to start up the truck and get it back into my garage (many CEL's came on due to voltage issues).



So, would just replacing the cable resolve or is it possible the "generator" is pushing too much juice?

 

[cerberusiam]

It is not an auxillary battery, both batteries are primay. The ECU reads driver side battery temp to control charging. The batteries charge thru the passenger side battery. If the driver side battery goes bad or the cross over cable goes bad or the battery temp sensor goes bad or just dirty connections on the batteries, it will over charge and kill the passenger side battery.

The fusible link off the passenger side battery is usally the grid heater power supply. If the relay hangs or the grid heater goes bad it will draw the battery down and cause it to charge. Usually blows the link though and thta will stop the draw. The alternatro output lne mau have a link in it also and if that is melted it is likely due to overcharging you were seeing that boiled the battery. The alternator only charges what the ECU tells it, usually it is a connection problem that is causing the ECU to think the batteries need charged.

Look the cables over real well and there is any indication of issues replace them, or, replce the ends with solder types. The cross over is almost easier just to replace because it can corrode under the covering and totally mess up the charging system.

 

[BruteForce]

So, would it be safe to drive the truck to the dealer with just the drivers side battery connected? Since my truck still has 100% warranty coverage for another 30k miles, I figure it would be best for Dodge to determine the root cause, rather than me piling more cash into it (2x batts cost me $300). .

I know that with no AUX/Passenger battery connected, it will throw a few codes, especially the "generator voltage sense high code. . "

 

[cerberusiam]

As long as it will run that far probably fine. Any damage should be under warranty. Not sure you gonna get batteries covered but you never know.

 

[BruteForce]

So, I just reconnected the AUX/Passenger battery -- with and without the alternator hot lead. With the hot lead connected, truck starts fine, no codes. In-dash volt meter is showing about 14 volts. I took the alternator hot lead off and checked voltages at the lead and the ground terminal on the battery: voltages were jumping from 18v - 11v. Possible bad alternator?