Spare battery inside main battery

[Big_Ed]

I remember back in the late 80's - early 90's there was a car battery that had a built in spare battery. Just in case you left your lights on or something, and came out the next morning to a dead battery, you just popped your hood and flipped a switch on top of the battery that activated a smaller spare battery inside the main one so you could start right up without having to get a jumpstart.

First off, who made this battery, and what was it called?
Second, why did they stop making this battery? It seems like it was a great idea?

 

[crinkles]

i'd bet some folks would just flick the switch then drive tillt he internal one died again and then they'd be back at square 1

 

[Kruse]

Without Googling it, wasn't this a Champion labeled battery?
They stopped making it because it didn't perform like it was advertised.

 

[Shannow]

I had one back in the day.

It was red and blue, looking like it was made of vertical plates of plastic, with a section of battery (less than 10% of the plan area) looking segregated like it was the spare.

My first maintenance free sealed for life battery...life was pathetic.

Crinkles is spot on about early 20s and battery management.

 

[The_Jeff]

I remember it as a die hard. Agree on the logic faults, how would you keep it charged if you didn't flip the switch once in a while (or if it had some fancy internal circuitry)?

 

[Shannow]

Mechanic I worked with at the time reckoned that there was a diode to keep the spare constantly charged.

Could have been part of it's issue, in that a dioded battery parallel to the main couldn't really stay charged.

 

[Chris Meutsch]

Yep, it was indeed a Die Hard. I remember those commercials.

 

[The_Jeff]

Wouldn't a diode cut 1/2 a volt from the charge? Yuck.

 

[willix]

P/U trucks commonly have a dual battery option. It would seem to me to enable a single battery with a dual/circuit capacity it would be actually 2 smaller batteries co-mingled together in the same space as the original one & the end result would be a weak primary battery and a weak back up for it. Both having shortened service life.

 

[moklock]

IIRC, the battery in question was not truly a 'dual' battery, it was a regular battery with an integrated rundown protection device. There was also a version that included a keyfob activated 'security system' that cut battery power while activated.

They were both expensive and did not last like a regular battery at all IIRC.

 

[severach]

Good idea or not car companies made the computer shut off the dome light when it was left on. That was the complete solution costing almost nothing that eliminated the need for the battery buddy or spare batteries.