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Old Aug 27, 2003, 9:06 AM   #11
NHL
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Just an observation here...

This is the same effect noticed by the Rayovac's 1hr charger owners. Unlike the Powerex wall adapter (500mA), the Rayovac charger power supply is rated for 12V @ 1.5A, same as the car adapter fuse (but it has no cover) :lol: :lol: :lol:
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Old Aug 27, 2003, 3:20 PM   #12
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Quote:
Originally Posted by jawz
Gee, when I got my C204F kit about 2 years ago, it came with a car (cigarette lighter) adaptor which included a built-in 1.5A in line fuse. The fuse is housed in the little center conductor plunger thingy. My unit has a knurled ring which secures the spring loaded plunger and the fuse in the plastic lighter plug/ cable assembly.

That being said, I only used the car adapter hook-up once just to see if it worked... it did. I didn't notice that the batteries were any warmer than when charged from house power.
Interesting, I didn't see the little hidden glass fuse in the power cord, but its there. It the 1.5amp 250volt max fuse just like yours jawz

So if its only allowing 1.5amps in which is the same that the @home ac/dc adapter offers then why is it still getting so much warmer compared to the @home ac/dc adapter? :? I think its time to break out the multimeter and see what sorts of voltages are coming out of my lighter socket in the car now that we have eliminated excess current (amps) as the possible issue as to why it got so smoking hot after less than a hour of being plugged in.

voxmagna I am willing to bet your right and the built in converter for the charger that drops the input voltage from 12volts DC to the 2.4volts DC actually used to charge the batteries doesn't work to well when the input voltage is higher than 12volts DC. Since the wall socket adapter already does the conversion from 120volts AC to 12volts DC the charger doesn't have to deal with the extra voltage that will potentially be present from a lighter socket in a car which can be 12-16volts.

Hmmmmmm. To use the charger in my car I may have to look for or build what will basially be a line conditioner/voltage regulator for the car socket adapter to deal with the extra voltage to drop it down to a constant 12volts since it doesn't look like the charger can deal with it well, if this turns out to be the issue. Experimentation time!
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Old Aug 27, 2003, 7:09 PM   #13
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I think there are plenty of small switchmode dc units around that people use to connect games boxes/dvd's to their car. Sort of thing Tandy might sell. Perhaps a little experiment is needed to see if you can actually reduce the input voltage to the charger to 9-12 volts. If it's using a series regulator, the closer you can get the input volts to it's regulated output (+1.5volt) the less it will dissipate. If It's charging batts in pairs, I'd have thought it wouldn't need more than about 9 volts. I suppose there's a slim possibility it's circuit is unstable and it's self oscillating (any car radio interference?).

If the charger power unit gets hot when batts are on trickle charge (small load) there's a clue that they are using a series regulator. That's not the sort of design I've seen, which is based on switching (very efficient) regulators. VOX
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Old Aug 30, 2003, 5:55 AM   #14
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A most interesting discussion of tkmckay's warning about the C204F charger. I have one. It seems to be a quality unit, with good comments on this forum, and on Steve's reviews.

It appears several replies have made assumptions that the charging current depends on the 500ma current limiting of the of the AC plug pack, or the rating of the car plug fuse.

It is very unlikely that Maha would rely on that in designing the C204F. If you refer to the Maha specifications, it states:

Rapid charge current 500ma
Trickle charge current 24ma
Discharge rate 240ma
Car vechicle voltage between 9v & 15v

It is more likely that the necessary regulators are incorporated within the unit, to provide the required current regulation.

But, as to tkmckay's experience with the charger in the car. We can not say it was due to overvoltage. The engine was not running, and so the battery would be sitting at about 12volts.

However possibly the charger lid was closed, ventilation may be obstructed, & the car interior was hot. But one would not expect it to be as hot as he described. Possibly his particular unit is faulty.

One reply confirmed no problems using the charger in the car.
If any other members can offer their experience in using this charger in the car, it could be helpful for us & tkmckay to know if it it is a general or isolated problem.
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Old Aug 30, 2003, 6:06 AM   #15
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Quote:
It appears several replies have made assumptions that the charging current depends on the 500ma current limiting of the of the AC plug pack, or the rating of the car plug fuse.
The point doesn't seem to get through that a car battery is a power station and it doesn't matter whether you connect a sophistocated electronic regulator to it or not, even the cable from the plug can be a health hazard/fire risk if it shorts and is not protected.

I would't want to think about even a metre of pvc covered wire vaporising as I was driving along! Protection starts at the centre pin of the car plug. VOX
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Old Aug 30, 2003, 7:07 AM   #16
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Thankyou Vox for your reply. Your opinion is valued. Your point got through alright, but it is beside the point. We have already established that the C204F charger has a 1.5amp fuse at the centre pin of the car plug.

You are quite correct in that a car battery like a 'power station' can provide a massive current. And of course fuses are necessary to prevent the cable hazzards you describe.

On this thread, tkmckay, has described that his C204F charger became overheated when powered in the car.

And so for the purposes of checking the correct operation of the C204F charger in a car, would you not agree that it does matter if the unit has an electronic regulator for proper charging current.

Any comments from C204F users with in car operation experience are welcome.
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Old Aug 30, 2003, 9:40 AM   #17
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... Can someone explain how one can charge a 1800mAh (or a 2200mAh for that matter) rated battery (or batteries) with 500mA in 60 minutes?

Isn't it true also with most microprocessor chargers that the charging is done with pulses (with higher energy) rather than a constant current? Or that one can't measure with a multimeter (that will average out the current) but a more sophisticated scope...

May be we should open it and see what makes it ticks! :lol: :lol: :lol:
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