Unsmoothed car battery charger - is it crap?

My car battery is oversized for the car. The battery is a bit old but usually works fine. The battery is flat (I left the lights
on).
My fancy new modern charger senses a poor battery and only puts in very little charge.
I used to use a really old charger to charge this battery successfully. I opened up the old charger and saw it was only a transformer and a big rectifier. That's it. No soothing.
Is this ok for a car battery or is it way too crude?
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Eddie coughed up some electrons that declared:

Well, it always has been OK - never seen a car charger that was anything but a transformer and some rectifiers - but then I haven't actually bought a new one for 20 years!
The only concern is for the electronics in the car, but generally the battery itself will do the smoothing, which only leaves over-voltage to be a problem, so don't over charge the battery, which would be bad for the battery anyway.
If you're paranoid you could disconnect the +ve and charge the battery in isolation.
Cheers
Tim
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Check the electrolyte level in your battery.Filtered DC causes polarization of the battery.
Bob
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An unpolarised battery isn't much use.
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On 7 Jun 2009 20:50, wrote:

It's a sealed battery. Are they better or worse than electrolyte batteries when the charge drops to very low?
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Gel electrolyte batteries use gel electrolyte,
There are wet batteries marketed as sealed. These typically have no user accessable ports to access the electrolyte, but will still leak if inverted etc..
"zero-maintenance" car batteries often have the electolyte ports under the label.

yeah they have a catylist that oxidises most of the free hydrogen back to water. as long as you don't overheat them they can tolerate some overcharging.
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iN uk.d-i-y,alt.engineering.electrical,sci.electronics.design,uk.rec.cars.maintenance, On Thu, 25 Jun 2009 21:55:18 -0700 (PDT), Too_Many_Tools

What do you mean? African or European battery charger?

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Africa? Careful - South of the Equator the polarity reverses.
--
Roger Hunt

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Roger Hunt wrote:

>uk.d-i-y,alt.engineering.electrical,sci.electronics.design,uk.rec.cars.maintenan
Then its a good thing that the troll is bipolar.
--
You can't have a sense of humor, if you have no sense!

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how do you deal with mains fluctuations?
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Jasen Betts wrote:

How do you do it with any battery charger? Hint: You don't. It would require the AC line to be well out of tolerance, either high or low before the charging current would change more than a few percent. That is what a transformer does. I used a 24 volt 15 amp transformer after the variac. That reduces the change in line voltage by a factor of 5 to 1. The variac raises it to around 7 to one at the five amp charge rate I use most of the time, so the line voltage would have to go up to 128.4 for a 1% rise in the transformer's secondary voltage. The change in charging current is quite small.
If the battery is quite low, or dying I have a garage type charger that will start most car engines, even with no battery in the vehicle. It has no adjustments, other than a mechanical timer to set the charge time.
--
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Too_Many_Tools wrote:

Yawn
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I believe it was the bulb rectifier chargers that had a bad-news side effect.
They were half-wave, directly coupled to the line. If a shop had a large one, & not much other loads; the pole pig transformer core would start to saturate with DC.
And when it did... it would fail rather spectacularly.... as in KaBoom...
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