Hi All,

Well, after a few weeks, I decided to crank the old lady up. Turned the key, all looked normal. Tried to crank and a huge explosion and slightly oily water dripping out from the bottom of the battery tray onto the garage floor. Great. I took the battery out and huge crack on its side. It was a 2018 battery, so 3-4 years old. Car always on trickle charger.

So, obviously, I am going to get a new battery. Q: Is there anything I should check? Is this just a result of Arizona heat, rarely used but always fully charged battery getting a large crank load or is there something else I should check, just to be safe, before cranking with a new battery?

Thanks

 

I've heard of this before. A close friend of mine with an Alfa Spider religiously uses a battery tenders on his boutique parts store battery (Interstate). One day last summer, he put the key in, turned it and BOOM! 5k in damage to the arear of trunk that held the battery.

Personally I never leave batteries on charge becasue of this. I fully disconnect them when they need to sit. If there is some resistance in the battery tender's connection terminal or quick connect the tender will not get a good reading and will boil the battery even though it already fully charged. That's my theory.

 

Interesting! I spoke with the PO and he told me he has had this happen to him before in the same car. This was also an Interstate battery (from COSTCO). Luckily, no damage at all. The 928 battery is well insulated, which would also make it quite hard to cut off for firefighters. Disconnecting a 928 battery is not that easy, unless if you install a quick disconnect in the trunk.

 

Overcharging a wet cell battery can produce hydrogen and oxygen through electrolysis - if the resultant mix is in the explosive range not too difficult to visualise what might happen if there is a spark.

You said you leave it on a trickle charge- maybe that was doing a bit more than "trickle"? Was it a sealed battery or one with a vent and caps you can add acid through?

 

Could well be. The trickle charger also doesn't seem to be connected directly to the battery. Haven't checked, but I guess it goes to the jumper post as it is in the front.

 

Is the trickle charger that you are using the exact same one that the previous owner was using on this car when this happened to him? If so start there. Apparently there are different types of trickle chargers with only specific ones designed to be used for long durations; you will need to research. It seems that this happens often, but not often enough to be considered common. But your car has been struck by lightning twice now so there is obviously an issue, hopefully just the charger type.

To easily disconnect the battery just unlatch the distal end of the ground strap, easily accessible.

 

You also might want to see if the venting of the battery was obstructed or intact. As FredR mentioned the fumes likely created the explosive mixture.

 

Well, I've already got a new battery, put it in, and the car starts, so at least no harm (especially not $5k) done. Therefore I can't check the vent plug, but I doubt it was severely clogged. My best guess is that the trickle charger, since it is not connected straight to the battery, it is overcharging slightly. :-( Yes, I am using the exact same charger as the PO; he gave it to me with the car. It is a CENTECH float charger. Like this one:


I assume overcharging will also result in the excess production of hydrogen.

 

I'd suspect the battery charger is either defective or not smart enough to stop charging when the battery is fully charged - you do not want to charge all the time - that just creates off gassing of hydrogen and may heat the battery up (especially in a hot climate) and can damage and warp the electrolytic plates.

If there was an explosion - I'd suspect the battery was not vented properly (or at all - most aren't) and there would need to be a spark so I'd also suspect the battery connections were not tight enough.

But it could also be (to me more likely) that the battery case crackled due to heat or plate damage - which would not technically be an explosion (just a bursting event). If there had actually been an explosion - I would expect damage to the car - broken battery box lid latch and spare tire cover damage at least and some level of interior acid spray damage.

Get a new charger (I'd just throw it away) and put in place vent tubes from the battery to outside the battery box.

Alan

 

Thanks Alan,

There certainly was a loud boom when I started cranking the car; I would call it an explosion for sure. Luckily, likely, not powerful enough to do damage. There was smoke and battery acid leak right after. I do remember very high battery readings previously when I started the car (18 and higher) on the dash, but just assumed that the gauge was wrong in the cluster. Now, with the new, it read between 12 and 13 when running. So, I guess it is ok and it overcharged. The connections seemed to be on tight when I removed the old one, but that does not mean you cannot have a spark.

Certainly yes on the vent tubes and a new charger! And wiring that does not go from the front connected to the jumper post. I am quite certain at this point that that resulted in underestimating the charge level of the battery, due to excess resistance.

 

Check the voltage when the car is running - its possible to have an alternator issue that would also overcharge the battery - but what you describe sounds like the battery was defective and not acing like suitable load ballast for the alternator - that will cause the voltage regulation to be poor all on its own (a damaged battery could short out internally dur to high voltage). I still think the charger is the most likely root cause suspect here for long term battery damage, especially given the history.

Alan

 

Again, thanks for the input. I'll get a new tenderer and route its wires through the drain holes in the battery pan. That will be a direct connection. At this point, I still think that the extended connection is the culprit.

 

No - the extended connections will NOT be the reason - I'd throw the charger away. This could have been much much worse.

Alan

 

Alright, new charger it is. Good to know about the extended connections. It is convenient. Yes, I have worries. An enclosed battery case is not too smart.

 

Hey, I see you are a local AZ member! Fantastic. I now know 3 928 owners in AZ on here (including myself).