This seems like a pricey "option" for $210.

Anybody have any additional context on why one might want to shell out the extra cash for it? Is more amp-hours would be the only thing it can offer?

From the build & price site:

"Medium Duty Battery is optional on Super Duty XL, XLT, LARIAT, and King Ranch® and Platinum F-250 and F-350 models.

Requires 6.2L Gas engine."

 

In the order guide, in parenthesis it says "dual 78AH" so I think this option is for dual batteries with the 6.2. I think the 6.7 gets the dual batteries standard.

 

Yes, it the option to have factory installed dual batteries.

There are situations we encounter fairly often where the truck is stationary, I'm working out of it and my work trailer, and the current draw on the truck would exceed its ability to keep one battery charging. I think $210 is a good deal. Even for an Rv, having two batts is nice.

 

That should totally get spelled out on the build & price site.

A second battery is totally different (and worth $210), as opposed to replacing the primary battery with another battery with a higher amp-hour rating.

 

I know it's an old thread, just wanted to add a pic for future searchers.
6.2L with dual battery or as Ford calls it Medium Duty Battery

 

Thanks!! I was planning to get this option but had not seen one.

As I figured, with 2 batteries I don't see any space for an air compressor under the hood (where I currently have it on my F-150). I'll have to go on the frame rail, in the bed. We'll see. I'll have to check where some of the air bag guys are mounting them.

 

Yep, pretty tight in there. If ordered without the 2nd battery you get a different coolant reservoir that takes up the space of the 2nd battery so it's kind of a dead end any way you look at it.
Reports of ample space up under the bed as you suggested and some have used the spare tire carrier as a mounting location.

 

I got the second battery along with the extra extra heavy duty alternator for an additional $85. It seemed to me that it is a lot of extra capability for just under $300. Especially towing an RV.
YMMV, Paul

 

Some points to consider regrading the dual battery and HD alternator options:

1. I suspect the operational intent of the dual battery option for trucks fitted with the 6.2 V8 is to provide a solution to the “double whammy” condition encountered in very cold ambient temperatures. Specifically, available battery cranking amps drop along with temperature, but the current required to start a cold engine increases. For an example of how temperature affects cranking amps, check the difference in any auto battery's CC vs CCA specs (cranking amps at 32F vs cold cranking amps at 0F).
2. I don't believe the dual battery option is of any benefit to RV applications. For one thing, automotive starting batteries (aka SLI) are designed to deliver high current for short periods of time. This design strategy makes them unsuitable for deep-cycle applications such as RV's and golf carts. Secondly, the truck's trailer battery charging circuit via the 7-pin connector is disconnected when the truck's ignition is off. This is done purposely to protect the starting battery(ies) from excessive discharge abuse, which would reduce battery performance and shorten operational life.
3. For RV- and other external load applications, the “Extra Extra HD” 240 A alternator is a cost effective- and probably wise option for the 6.2 V8. Depending on other vehicle loads, temperature, and RV battery voltage, it will help deliver full charging current (fuse-limited to 30A) to the RV batteries, and it will provide power to external loads connected directly to the truck battery while minimizing the battery's load.

HTH,
Jim / crewzer

 

Good points SD. I did get the extra extra hd alternator option on mine as well. Just in case.

 

Same here. I ordered the XXHD alternator to complement the camper package suspension option, but because we live in a "moderate" temperature range in western NC, I skipped the dual-battery option.

An alternative to the dual-battery option for operation in very cold climates is the engine block heater, which is standard in many northern states and Canada.

As a side note, the optional generator in our '86 Suburban's heavy-duty trailering package was rated at 66 A.

Regards,
Jim / crewzer

 

I wonder how much the larger alternator will effect MPG

 

Thanks for posting this picture. Very informative.

 

I too would have ordered the 2nd battery if it had been labeled as such. I wonder if the wiring is that much different to retrofit it now.

 

The alternator load on the engine (and impact on fuel economy) will be greatly dependent on the electrical load.

HTH,
Jim / crewzer