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2014 Ford Fusion Hybrid - Why not a backup battery?

Why can’t auto manufacturers connect one of those small backup batteries that is kept permanently charged and will allow you to jumpstart your vehicle in the evident the battery is drained by simply pressing a button inside your vehicle.

Because most people don’t routinely drain their batteries dead. One battery is plenty.


It’s an interesting idea, but I’m pretty sure the manufacturers feel that the expense and added complexity of this system isn’t justified by the number of times it’s needed. In the past, I would have also listed the extra weight and volume, but the new lithium batteries are surprisingly light and small.

I’d actually rather see a standard plug-in connector added for safer jump-starting, especially given the number of times we’ve read here about people somehow managing to reverse the cables and cause electrical damage.

One word - Weight.


One word - COST. Would you be willing to pay an extra $200-250 for a back up battery? It’s not just the cost of the battery but the cost of the labor, wiring and switches, plus a redesign to incorporate it.

Unnecessary weight and cost. These days spare tires are no longer included for alot of new cars because the weight savings eeks out a extra 0.1 MPG, which is significant in the way that CAFE works. The manufacturers don’t want to add another 10 pounds of weight if they don’t have to.

Plus a lot of cars now limit the discharge of a battery when sitting just so it never goes completely bust. No extra money or weight, the computer just does it.


Some vehicles actually do this. It’s often found in motor homes, but back when I was a TV guy, our live trucks also had a button that would connect the “house” (back of truck) battery to the “car” battery for an instant jump start.

Came in handy because the onboard generator only charged the house battery, but if you left doors open (which you always did in summer because the roof air almost universally sucked and you had to sit in there writing and editing sometimes for hours) the multiple dome lights could drain the front battery to the point where the thing wouldn’t start. Especially since TV stations are notorious cheapskates, and would only replace that front battery if they absolutely had to. This usually meant “so far gone that even a boost from the house battery won’t start it.”

Maybe you just have to buy the police package. You’ll get all that along with white doors.

Some years back, I seem to remember a replacement battery that had a knob on the top. If the battery couldn’t turn the engine over, the driver turned the knob and some internal battery was connected through the battery that would crank the engine.
Does anyone else remember this battery?

So it wasn’t just my imagination, I remember those, just not when or where.

Yes, I think they were sold under the Champion brand. Never looked at the specifications, but I bet the CCA and AmpHours were reduced on the primary battery.