Why would my passenger side battery have exploded on the way home today? Check gauges light came on and then the voltage meter slowly dropped to 8V and held steady the rest of the way home. I had just bought 2 new Diehard Platinums from Sears on Friday but didn't get around to putting them in. I decided it was time to replace them because I was getting some weird blinking and clicking of the dash warning lights immediately after starting for a second and I did see the voltage drop one other time recently. Is it because of the battery or would it have been caused by another component of the truck that I should be worried about the new battery going if I install it?

 

I may have this wrong but you can also search here for better answers but the computer only reads voltage from the driver side battery so if it is low it sends the signal to increase voltage output from the alternator and this will cause the passenger (good) battery to over charge.

 

While its uncommon batteries can explode. Had a fellow co worker in a little Honda car start it up to leave and heard a bang......opened the hood and the batt had grenaded..........


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Check the positive cross-over cable from passenger side battery to drivers side battery. If they have issues they will cause an over charging of the passenger battery boiling it over or blowing it up. Take a peak. You may have just had a bad battery.

 

Had my pass side battery swelled up and started leaking last year. Made a bad odor inside cab or I wouldn't have known. Just replaced it but prob should do drivers side too.

 

I'm no expert by any means but most times if a battery explodes it's because it's low on acid. Once low (below the plates inside the case) it can cause an arc between the plates.......air space, acid fumes, arc.......BOOM BOOM. I could be wrong but it's a very plausable.

 

I didn't see anything that stuck out other than a little corrosion on drivers side battery. I brushed and coated all connections when installing the new batteries. I'm thinking it was just the result of bad battery since they were both still factory. It sure did make a mess but the hood liner and aftermarket rubber I take boot caught the main spray keeping it off alot of other stuff. Still a royal pain to clean up!

 

Check your crossover cable and be sure to clean all of the ground connections. You will likely find the problem to be between the two batteries. You may think that the cable is clean because you wire brushed the corrosion from the cable ends;however, the corrosion tends to creep into the stranded wire under the rubber cable sheathing right behind the cable end. This is what you must look for or it could happen again.

Even a dead drivers battery alone, will cause the same symptom and will compromise the passenger battery very quickly due to overcharging. It is a best practice to replace batteries in pairs.

 

I'll jump on the crossover cable bandwagon here.
I had the same problem and couldn't figure out why. I had a voltage tester on the truck once when it amped up voltage and I got almost 27 volts at the drivers side battery! Made everything go weird.
Turns out my crossover cable has corroded through on the passengers side, so the truck only saw 1 good battery, tried to raise voltage to charge the second.
When I looked the cable was on national back order but that was a few years ago.

 

Wouldn't I see a voltage increase on the dash gauge if it is putting out more than a hair over 14 (normal reading)? Or is it another dummy gauge that I need to consider picking up an aftermarket to add to my growing cluster?

 

I thought so too, but when mine was doing that, I could hear the air dog SCREAMING! Apparently it's just another dummy gauge. Maybe better then the oil pressure gauge, but it still lied straight to my face

 

To add to your "growing cluster" comment, I've always wanted to pull the guys apart on these and build in a REAL oil pressure and battery gauge that's built in.
Sun pro or someone should look into a factory looking, matched, replacement cluster with actuall sending units vs computer drivin needles.

 

THIS! Your battery was low on acid. The exposed top of the plates arced across and ignited the fumes.

Also our trucks do not read nor see a passenger and driver side battery independently. They are linked in parallel. They do not charge independently, they don't work independently, they are linked together for longer reserve and sustained cranking amp ability. The reason you see increased voltage is due to resistance in the so-called crossover wire when there is corrosion present.

If you ever suspect one bad battery, you can disconnect the bad one and run on one. Been there and done that. Also never never never disconnect both batteries with the truck running. Like an old school trick to check the alternator. You will kill the $2000 ecm. Been there and done that accidentally.

You will find out quick if you missed washing any acid off anything. If you haven't already I would ditch the hood liner since it will act like a sponge.

 

I would say that my crossover is fine then as I have not seen an increase in voltage and visual inspection did not reveal anything out of the norm.

I already ditched the hood liner and battery blanket that were soaked in acid. All of my body paint still appears to be good so I would say that wont be an issue. I did end up with some discolord plastic and rubber peices but overall for what happened I think the damage could have been much worse.

The new batteries have been in for a day and are acting normal.

I am still kicking myself in the rear for not putting the batteries in the day I got them. I would not have had to go thru all of this.

 

Boiling the passenger battery by overcharging is not uncommon in the 3rd Gen Cummins.
It's always the passenger side battery that boils over.

As was mentioned, the ECM is controlling the output voltage of the truck's alternator.
The ECM is monitoring the driver side battery voltage, however the alternator is connected to the passenger side battery.

If there is a voltage discrepency between the 2 batteries, ie. bad connections on the cross-over cable, the driver side battery voltage will be low,
so the ECM will crank up the charging voltage, overcharging the passenger side battery.
The in-dash voltmeter reading is from the ECM which means it is only monitoring the driver side battery.


Bottom line, keep all the battery connections perfectly clean at all times.