teotwaki
Senior Member
I had to go look up what was different about the "SA" model and it has to do with the "smart" alternators in newer vehicles.
Smart alternators are essentially those that have their output voltage controlled externally via the Engine Control Unit (ECU) rather than by an internal voltage regulator as found on traditional alternators.
When an alternator is running and producing a charging voltage the electromagnetic field generated inside it produces a mechanical load on the engine via the alternator drive belt. This load increases as the output voltage rises, meaning that the engine has to work harder to turn the alternator which consumes more fuel in the process. Traditional alternators maintain their voltage between 13.8-14.4V depending on the state of charge of the battery and various other factors. This means that there is always a significant load on the engine from the alternator which requires fuel to be consumed.
As smart alternators are ECU-controlled it enables manufacturers to vary the voltage output more than can be achieved with an internal regulator. This provides the opportunity to bring the voltage below 13.8V during periods when no further charging is required (e.g. when the battery is nearly full) meaning that engine loads are reduced, fuel consumption is reduced and emissions are lowered, all helping manufacturers to comply with industry environmental regulations.
For an "overlander" it would be cool to have at least a nominal capacity solar panel on the vehicle that was always plugged into the 250SA if the vehicle had a smart alternator.
For my 5th gen battery choices I have to say I've grown tired of the shortcomings of the expensive high end Odyssey and Optima brands. After 2009 (IIRC) Optima went to production in Mexico and quality sucked. There is some guy called Optima Jim who has the main purpose of trying to counter that bad news wherever it is posted on the forums. I personally have gone through a lot of Optima AGMs under the hood of my 4th Gen and that was one reason I chose the CTEK. Regardless of what voltage the alternator happens to be supplying the CTEK's DC-DC converter will output the right voltage to fully maintain the second battery. It is also great that it has the solar charger built in. Just watch out that you never ever exceed the CTEK voltage input limits. A normal car alternator is just not built to provide the charging profile those two brands need as the alternator is designed to charge a normal lead acid starter battery.
It just so happens that I have a pre-Mexico pair of Optima Blue tops that are still doing very well and I have a Sears Diehard Platinum (Odyssey PC-1500) that also looks to be doing well.
The PC-1500 type battery really likes a voltage that is higher than what a standard battery needs so I have had to pull it out every so often, discharge it to 10-ish volts and then hit it with a high current charge to recondition it
Initially I will give one of those a trial but my opinion is that money wise buying a CostCo marine battery and replacing it every one to two years could be cheaper.
