I am a master auto technician, and I am seeking the opinion/advice ofother master technicians who work in the field.We've all come to know (and love, in my opinion) battery jump-boxes inthe last 10 years or so. The days of jumper-cables are pretty muchover.What would it take to make a jump-box part of an automobile?Let me explain... a jump box can easily be connected to a battery, andeven left there if desired. A basic parallel circuit. It would thentake a charge from the alternator right along with the regular carbattery. Trouble is, if something were left on such as an interiorlight, the jump-box would be drained right along with the car'sbattery. Not the result I am looking for.What device might be created that would allow a jump-box to be wiredinto a vehicle were it would be charged during vehicle operation, butnot drained when the vehicle was turned off?Example: vehicle drives from point A to point B. The battery and thejump-box are charged along the way. Owner shuts the car off butaccidentally leaves the dome-light on, thus killing the battery.How might it be possible for the jump-box to receive the alternator'scharge but not be drained by the forgotten dome-light?Some sort of magnetic switch (a solenoid, perhaps) comes to my mind,but how that configuration might be alludes me.It has occured to me that constant charging of a battery (jump-box)might not be a good thing, but I have also observed that a vehicle cancharge a battery for dozens of hours without said battery exploding. Ihave also seen jump-boxes be left on a plug-in charger for weeks (evena month) with no apparent negative effect.The final product I seek: An jump-box stored in perhaps the trunk orelsewhere that is kept charged by the alternator during vehicleoperation, but would not be drained if a device were accidentally lefton after the engine was shut off. Should the vehicle have a deadbattery, just take that jump-box out of the trunk and get going.Is it possible? It must be. It has to just be a...

I believe that you can buy a box that will cut off your battery before it drains, thus leaving enough juice for one attempt at starting before it goes dead flat. I think you pop the hood and press a button to reset it before starting or something like that.The other option would be an extra full sized battery with one of those electronic isolators like RV's use, with a switch to cut over the auxiliary battery when the primary goes dead. Space and weight are the downsides of that setup.nate

How to make a mobile jump-box?

Aug 14, 2007 22 Replies

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Comboverfish 18 years ago

Didn't the first wave of these have the Champion brand name? I haven't seen them in years either.

Really small jump boxes are becoming popular now. I bought one back when they were a bit newer and no reviews existed for such a product. Luckily it has been absolutely great. I see no reason to carry around the larger portable type units (almost the size of a car battery), let alone a roll around monstrosity, when these mini jump units work so well. I wouldn't bring it to start a diesel though...

Toyota MDT in MO

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Ad absurdum per aspera 18 years ago

I haven't taken one apart, but wouldn't be surprised to discover a row of lithium-ion laptop-computer batteries or at least the cells used therein. A lot of those batteries happen to have output of 14-ish V, and the economies of scale must be sizable.

--Joe

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Comboverfish 18 years ago

I'll be taking mine apart when it fails -- hopefully not for 10 years though.

Toyota MDT in MO

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