unusual way to charge a car battery

[Oznog]

When a light bulb fails it does not always go to an open circuit right away. Every now and then when a light fails at home, I notice quite a flash followed by the opening of the circuit breaker. I have to presume that a significant amount of current was flowing, if only for a moment.

I remember 2 or 3 light bulbs that ran for an extended period- hours maybe- at a much greater intensity and almost a "silvery" light. Kind of pretty.

IIRC at least one was due to knocking over a desk lamp while it was working. I am certain the filament, which is sort of a spring, stretched out and then formed a tangle when it sprung back, leaving some of the filament shorted out of the current path.

 

[ZIGGY_DAN]

Ziggy, you are confusing yourself.
The DC value of 1.414 x RMS is only applicable when there is a filter capacitor after the rectifier. Without the the filter cap the average (?) DC voltage will still be 230volts.

JimB

sorry about that, i naturally assumed there would be a filter capacitor, otherwise there could be large voltage spikes and a lot of noise and ripple, the large spikes perhaps allowing a VERY large current to flow, possibly damaging the bulb or battery.

 

[Thunderchild]

dearest brian this is a spare battery you have a fixation with cars sure there is not one running around without a battery ?

as stated the 330 volts is if a capaciter is used and no i was quite plain in explaining the circuit seems the simpler a thing is the more chaos is cause over it then we wounder how come it is even being patented. my current bvroken charger has not got a capcitor in it it is basically what I described with the adition of the transformer and using an amp meter as a resistance insted of the light bulb

 

[Hero999]

sorry about that, i naturally assumed there would be a filter capacitor, otherwise there could be large voltage spikes and a lot of noise and ripple, the large spikes perhaps allowing a VERY large current to flow, possibly damaging the bulb or battery.

Why would they damage the bulb when it's rated to 230V?

Why would they damage the battery since the bulb behaves like a resistor and limits the current?

 

[ZIGGY_DAN]

because you will get voltage spikes larger than 230V that may damage the bulb, you could damage the battery by overcharging, i think it would be easy to overcharge a car battery when using little more than regulated mains, as mentioned earlier the bulbs 'cold' resistance is but 1/10 of its 'hot' resistance, this large current at 240V could probably easily damage the 12V car battery

 

[Death By Bass]

a globe to limit the current to charge a battery... hmm...

me thinks you'd have to get the wattage right, or you'd kill the battery.

 

[ZIGGY_DAN]

why don't you just get transformer, bridge rectifier and a large capacitor and be done with it, it's much safer, although you do lose energy in the transformer, does it really matter.

 

[Hero999]

You need to think about things more.

because you will get voltage spikes larger than 230V that may damage the bulb,

It's a bulb designed for use at 230V AC, (peek voltage of about 330V), now why would these spikes damage the bulb when it's suitably rated?

you could damage the battery by overcharging,

Quite possibly but the bulb will limit the current to <400mA which is a safe trickle charging current.

i think it would be easy to overcharge a car battery when using little more than regulated mains, as mentioned earlier the bulbs 'cold' resistance is but 1/10 of its 'hot' resistance, this large current at 240V could probably easily damage the 12V car battery

What happens when you sart your car?
The starter motot uses 100A and the inital surge when the motor is first tunr on is probably much higher, so how could it be harmed by a 4A pulse lasting for mo more than a few miliseconds?

 

[ZIGGY_DAN]

Yeah it is drawing 100A when starting but there are no car battery chargers on the market that supply 100A, and besides you are applying a potential much greater than that of the battery.

the bulb is rated for 230VAC RMS, and is unlikely to recieve harmful voltage spikes up to 330VAC but when rectified sustainable voltage spikes of 330VDC are possible.

 

[Hero999]

Yeah it is drawing 100A when starting but there are no car battery chargers on the market that supply 100A, and besides you are applying a potential much greater than that of the battery.

It makes no difference to the battery whether the 100A pulse is leaving or entering it.

330VAC but when rectified sustainable voltage spikes of 330VDC are possible.

Look at the scematic, are there any capacitors to store the charge?

No, the battery is connected though it doesn't act as a capacitor, it doesn't charge in the same manner, it gets to 14V or so then stops.

Is the battery connected to the output of the rectifier?

No, it's connected in series, in fact the bulb will last longer since the battery and rectifier drop the voltage so it's being powered off 216V instead of 230V so it'll actually last longer.

 

[ZIGGY_DAN]

Look at the scematic,

schematic?, did i miss something here(evidentaly) where is the schematic??

i didn't realise there was a schematic, probably where my misconception was derived from, didn't notice a schematic.

 

[Death By Bass]

schematic?, did i miss something here(evidentaly) where is the schematic??

i didn't realise there was a schematic, probably where my misconception was derived from, didn't notice a schematic.

I saw none either... lol

but as far as I can tell, we're talking about using a light globe, as a current limiting resistor, to charge a battery...

and I have no idea why you'd want to anyway!!! it would be EXTREMELY inefficient, using like 40watts for example, to charge a battery at 14volts/ 500mA... 7 watts?!?!?!

 

[ZIGGY_DAN]

and I have no idea why you'd want to anyway!!! it would be EXTREMELY inefficient, using like 40watts for example, to charge a battery at 14volts/ 500mA... 7 watts?!?!?!

i agree, just use a transformer and rectifier, or build a SMPS(switch mode power supply) or use an ATX power supply from a computer.

 

[AllVol]

Did you read the original post, or merely jump to the tail wagging?

 

[ZIGGY_DAN]

i read the original post, and didn't see any schematic and still don't??

 

[Death By Bass]

i read the original post, and didn't see any schematic and still don't??

X2 read every post.

see no schematic...

 

[ZIGGY_DAN]

if somebody can see the schematic i can't could they point out it's location??

is it a link or attatchment??

i have re-read everything??

 

[AllVol]

I wasn't referring to the schematic, just your general response. Of course, Ziggy, there are better ways to do it. Thunderchild just came up with another way and reported it. That's all.

Regards, and good morning to all.

AllVol

 

[Hero999]

schematic?, did i miss something here(evidentaly) where is the schematic??

i didn't realise there was a schematic, probably where my misconception was derived from, didn't notice a schematic.

Can't you picture it?

There isn't a schematic but it's so simple it doesn't need one, the description shloud be good enough. Alright for nubesake I'll draw one so everyone's clear on what he means.

Look, notice how the bulb is in series with the bridge so it limits the current and the voltage across it is lower than 230V.

However, I do agree this isn't a good way of doing this, it dangerious and wasteful, you're better of using a transformer, rectifier and LM317 constant current source.

 

[ZIGGY_DAN]

i didn't need a schematic, but someone did mention of one, i could quite easily picture that, but as has been mentioned several times before, including a transformer would be much safer and easier.