Is my dual battery setup killing my batteries??

[SupraBoarder]

Last season, I replaced both my optima yellow tops under warranty because they were occasionally getting warm when charging and emitting a very strong sulfur smell. After rewiring my entire stereo setup, replacing the batteries, brand new wires, new fuses & distribution panels, and even adding automatic chargers, I thought I had the problem licked... But alas, one of the batteries is heating up and emitting the sulfur smell again.

I have the following:

2001 Supra Launch DD
Upgraded HO 100 amp alternator
One US Acoustics 4085 (4x85w RMS) amp for interior speakers
Two Infinity Kappa Four (4x125w RMS) amps for tower speakers and two 12" subs
Two Optima Yellow Tops
Perko 4-position switch
One ProSport 12amp (dual bank) battery maintainer
All wiring is 1/0ga

After upgrading the system and installing the new batteries, I first noticed the heat/smell when I took it off the ProSport charger. Only one battery was warm.

I didn't think much of it, so we fired the boat up and ran it all day. When I reached into the battery compartment towards the end of the day, I noticed the smell was pretty bad and the battery was very hot.

In order to isolate the problem, I switched the batteries and plugged them into the charger and monitored the voltage with a multimeter. Never got above 14v, yet still produced the sulfur smell. I disconnected that battery, turned on the boat, and read about 14v coming from the alternator, as well. No sulfur smell on the other battery and it was cool as could be. Turned up the stereo and ran the boat at fast idle, and still got the normal 13.8-14.4.

Could it really be possible that I just happened to get three consecutive bad optimas? The store won't warranty the bad battery because we have already "used" our warranty. I wrote optima and they agree the system seems to be setup just fine, but they also find it odd that I've blown through that many batteries. They also made it known that it's up to the store to handle the warranty.

Is there something I'm missing??

[CornRickey]

I would check out your altenator voltage regulator. I wonder if you could have cooked the battery previously with the alternator and continues cooking it with the charger. I know with lead/acid batteries when you have a bad cell the rest of the cells will get cooked because the system is seeing a low voltage from the bad cell and continue over charging the good cells.

[SupraBoarder]

I'll be heading up this weekend to test the charging system, but it's odd that only one battery seems to be having the issue even when we completely switch them out. Any other ideas?