charging one battery from another (using a charge controller, natch)

I'm thinking about the simple scheme of charging a portable device's rechargeable internal battery from an external battery (which should have a little higher voltage, obviously). The portable device should have an internal charge controller to protect its battery and manage the charging.

Find a suitable battery or stack of cells, and plug it in. Simple.

Using AA cells in an product like Belkin's iPod charger is an example.

I'm looking for specific instances of products, or of people doing this themselves and making the suggestion to others. One caveat, these instances have to be during the 1990s or before. Sorry! :-) That rules out Belkin and their AA-cell holder, since Apple introduced the iPod in 2002 and they brought out their product sometime later.

Thanks, Win.

I believe those miniature R/C racing cars used this approach. You know, those 1 inch long cars? I know R/C electric helicopters use this approach as well. I suspect it started some time in the 90s.

snipped-for-privacy@yahoo.com a écrit :

Electric RC racing cars do this all the time from car batteries. Remember this from when I was a teen (end of 70s).

Here are two leads--both unsure--for you:

It could use either wall-power or d.c. in, and held 4xAA cells, IIRC. It could charge those 4xAAs from external a.c. or d.c. power, and could supply an external device with a switchable/selectable voltage from, as I understood it, any of the three power sources (i.e., DC-DC, AC-DC, or battery-to-DC). Its literature suggested it as useful to recharge other portable, d.c.-input devices.

I picked it up and put it down a few times, considered, then ultimately left it. Since this was at least 4-5 years ago, and on close-out, it might have been introduced within your timeframe. Maybe they have a manual in their archives?

Best, James Arthur

Hahaha!

Nice. Did it have some type of current-limiting resistor or some other way to control the charging from the external power source?

Ah, but did the miniature RC cars contain a built-in current-limiting resistor or some other way to control the charging from the external battery?

Prior art search for a patent tussle?

I remember a guy in Germany who had this setup around 1987/88: Mobile phone in his car. Back then mobile phones were "mobile" but not really portable unless you were a weight lifter. So, since he had to inspect construction on high rises he had another phone in his car. That one was a wireless phone just like most of us have at home. Only talks to its base. This base in turn was linked to his mobile phone in the car.

The handset came with a cradle that had a 12V cigarette lighter plug and it was definitely some NiCd current limit scheme. Else the handset would have exploded I guess. The cradle was meant to be bolted to the dash and the phone clicked into it so it wouldn't fly about after hitting a pothole. Supposedly you could leave it on the charger indefinitely. Of course this guy didn't since he wanted his car to start after a few days of parking. Also, he was a smoker and needed that cigarette lighter once in a while ;-)

I just don't remember who made this stuff. He had it installed at some pro-shop and it was a major European mobile phone brand.

Another idea: I have also seen radios in charger cradles which were mounted on fire trucks. Probably 24V and IIRC the brand was Hagenuk (Europe). Early 80's.

ZipZaps, they're called. Fun while they last (about 3 days).

Cheers,

Phil Hobbs

Mine appears to:

Cheers! Rich

Yes. We had a Motorola 4800x in about '86. Battery powered luggable phone but with a 12V cigar lighter adapter for car charging. Vague memories of the battery pack being NiCad.

Switchers all around, AFAICT. It was light, and compact--not noticably larger than typical 4xAA chargers.

Once upon a time Radio Shack had an FTP site with downloadable service manuals--with parts lists and schematics--for all their stuff. Very nice. That site would be an easy place to search for info., if it still existed. I don't know if it does. You could also order from any store for just a few dollars, and they'd mail it to your home. Here, though, you'd first have to know what manual to order!

Best regards, James Arthur

That looks like control circuitry in the external battery-charging station, right? I'm looking for control circuitry in the device being charged.

Ah, I might've misinterpreted your question. Yes, clearly the Radio Shack device had a controller to manage charging of its own, local rechargeable cells (that is, 4xAA cells installed by the user for charging).

The device could also use the 4xAA user-installed cells-- rechargeable or not--as a power source, and produce selectable voltages to drive external devices. I assume this output was a voltage-source, albeit likely current-limited for safety-- and that any external device would be responsible for managing its own re- charging.

Hope that clarifies it.

James

Do you know if the charging-control circuitry was in the lighter adapter or in the phone itself?

These days in a way it's in both, thatis the car adapter regulates the voltage down to about 6 volts and the phone controls charging to its battery from the 6-volt power from the adapter. A Belkin adapter I looked at current limits at 125mA, but others go all the way to 600mA, etc., providing high currents like the phone's regular ac-line charger / power adapter.

There definitely were simpler devices with the limiting circuitry in the device itself. I had one as a kid, a rechargeable flashlight. It could be plugged into the cigarette lighter of a car which has no limit other than its fuse. This was at least 30 years ago which unfortunately also means that I don't have it anymore. But of course I opened it back then. There was one resistor and a tiny bridge rectifier which explained why the packing slip said it could also be used on cars with plus on the chassis (they existed back then). Also, both 6V and 12V was allowed. Very handy around the campground.

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If anywhere then in the 'phone The plug looked a standard black plastic, plug-in adapter on a curly lead. S'pose there could have been a resistor in there but with the shoebox size of those batteries, it would seem illogical and unsafe without assistance from some kind of external heatsink. Pity, nearly bought a 4800x off Ebay the other month, could have confirmed the charging and whether Nicad or not.

Hey, Win! Remember: cross-post, don't multiple-post!

My Braun 5414 shaver runs from both 115vac and 12vdc using the same cord. The battery will charge on either voltage. Battery is NiCd AA "non-replaceable" (which I've replaced once already).

It's pushing it (my memory) but it's about 10 years old, give or take a few.

Yep, got one of those as well. But it doesn't work as well as the old non-rechargeables :-(