Overheating battery

Last time i bough batteries from Volvo it was 1 year warranty. Same as you have batteries fail right after warranty expired.
I have good experience with AGM Duracell batteries from Sam's club. They are more expensive but still good after 2.5 years.

 

Whenever the vehicles I drove had that smell it was always the alternator over charged the batteries . did the smell show up before new alternator??. Most were charging wide open.

 

Is there a way to test this yourself? My battery voltage gauge consistently read 13.5-14 volts. Should be good yeah?

 

I run Interstates. The warranty is 3 years, but they are pro rated so by the time I need new ones there is only about $40 left on each battery. As said by others, watch for over charging. This will cause the gas and smells and the batteries can swell up like a balloon and burst. Also, anything over 15 volts can start torching the ECM and various modules. It's really bad to run with overcharging. On many of the Leece-Neville alternators the regulator is really easy to replace. It's just 4 little screws and unhook the two wires then that's it. You don't have to pull the alternator or the belt or anything.

 

Maximum alternator voltage setting is measured with a volt meter on the alternator large + and - terminals. The regulator for Delco 20 through 36SI alternators is # 351262. They come set at 14.1 volts. I expect all other brand heavy truck alternators to be similar. If one is putting out around 15 volts or more constantly it will boil the guts out of the batteries.
Interstate Commercial battery is 18 month 100% replacement.