Forums

Will a dimmer switch work instead of an incandescent light bulb in a simple battery charger?

Started by Unknown July 4, 2013
The other day, I came upon this: http://www.alpharubicon.com/elect/3dollarb=
attggn.htm

It's plans for a very simple battery charger that uses a light bulb and dio=
de in series to make a constant current battery charger. Benefits include p=
ulse charging for desulfation and the fact that it can charge batteries of =
any voltage.

Well, with incandescent light bulbs getting scarce and me having many diffe=
rent size batteries needing different size currents, I'm wondering if a dim=
mer switch would work instead? If so, what kind? If not, can you tell me wh=
y? I'm just getting into this stuff (despite being a computer science major=
 and having taken electronics courses) and want to learn all I can.
On Wed, 03 Jul 2013 21:27:53 -0700, kanon11 wrote:

> The other day, I came upon this: > http://www.alpharubicon.com/elect/3dollarbattggn.htm
Good gawd. It may not raise the average intelligence of the human race by killing the one who builds it, but it may well take out his kids.
> It's plans for a very simple battery charger that uses a light bulb and > diode in series to make a constant current battery charger. Benefits > include pulse charging for desulfation and the fact that it can charge > batteries of any voltage.
Drawbacks include -- oh, where to start?
> Well, with incandescent light bulbs getting scarce and me having many > different size batteries needing different size currents, I'm wondering > if a dimmer switch would work instead? If so, what kind? If not, can you > tell me why? I'm just getting into this stuff (despite being a computer > science major and having taken electronics courses) and want to learn > all I can.
How about a wall-wart and a resistor? Or maybe even just the right wall- wart. Go shopping at rummage sales and garage sales -- if you hit one that's selling wall warts they'll be cheap. Or go check your local Goodwill store. The incandescent light bulb acts as a resistor -- a 100W bulb is going to limit the current to somewhere between 1/2 and 1A (I'm not sure how much, because the average voltage on the bulb will be less than 60V, and the bulb resistance will drop with temperature). A dimmer won't do that; you'd always have either way too much current or none. Note that lead-acid batteries don't put up well with being charged to a too-high voltage. Read this: http://batteryuniversity.com/learn/article/ charging_the_lead_acid_battery. There's not much "simple" that you can do to prevent it -- you pretty much need a specialized charging circuit. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
On 7/3/2013 9:27 PM, kanon11@gmail.com wrote:
> The other day, I came upon this: http://www.alpharubicon.com/elect/3dollarbattggn.htm > > It's plans for a very simple battery charger that uses a light bulb and diode in series to make a constant current battery charger. Benefits include pulse charging for desulfation and the fact that it can charge batteries of any voltage. > > Well, with incandescent light bulbs getting scarce and me having many different size batteries needing different size currents, I'm wondering if a dimmer switch would work instead? If so, what kind? If not, can you tell me why? I'm just getting into this stuff (despite being a computer science major and having taken electronics courses) and want to learn all I can.
Incandescent light bulbs make wonderful current limiters for charging batteries as long as you watch the voltage and don't overcharge. But you'll forget and you WILL overcharge. But use a transformer to keep from electrocuting yourself. I won't argue the merits of pulse charging, but most any battery charger will do the same thing that this one does. And that same goodwill store will sell you an actual battery charger for about the same price. Or you can go to harbor freight when they have the light duty one on sale for $5 less the 20% off coupon.
On 04/07/2013 05:51, Tim Wescott wrote:
> On Wed, 03 Jul 2013 21:27:53 -0700, kanon11 wrote: > >> The other day, I came upon this: >> http://www.alpharubicon.com/elect/3dollarbattggn.htm > > Good gawd. It may not raise the average intelligence of the human race > by killing the one who builds it, but it may well take out his kids.
Anyone daft enough to build it is surely heading for a Darwin award. I this doesn't kill them then something else will.
>> It's plans for a very simple battery charger that uses a light bulb and >> diode in series to make a constant current battery charger. Benefits >> include pulse charging for desulfation and the fact that it can charge >> batteries of any voltage. > > Drawbacks include -- oh, where to start?
Death of the user or his kids seems to be the most likely side effect. (either way it qualifies for a Darwin Award) eg http://www.darwinawards.com/darwin/darwin2010-03.html -- Regards, Martin Brown
On Thursday, July 4, 2013 12:27:53 AM UTC-4, kan...@gmail.com wrote:
> The other day, I came upon this: http://www.alpharubicon.com/elect/3dolla=
rbattggn.htm
>=20 >=20 >=20 > It's plans for a very simple battery charger that uses a light bulb and d=
iode in series to make a constant current battery charger. Benefits include= pulse charging for desulfation and the fact that it can charge batteries o= f any voltage.
>=20 >=20 >=20 > Well, with incandescent light bulbs getting scarce and me having many dif=
ferent size batteries needing different size currents, I'm wondering if a d= immer switch would work instead? If so, what kind? If not, can you tell me = why? I'm just getting into this stuff (despite being a computer science maj= or and having taken electronics courses) and want to learn all I can. A dimmer alone will not work well, but a dimmer in series with a power resi= stor will work well. The circuit in the link should be plugged into a GFCI = for safety. It's main weakness is the charging current is too small, at lea= st for utility grade lead acid batteries. That crummy 0.3A will take foreve= r to charge a car or tractor or tool battery
On Thursday, July 4, 2013 12:27:53 AM UTC-4, kan...@gmail.com wrote:
> The other day, I came upon this: http://www.alpharubicon.com/elect/3dolla=
rbattggn.htm
>=20
>=20 > Well, with incandescent light bulbs getting scarce and me having many dif=
ferent size batteries needing different size currents, I'm wondering if a d= immer switch would work instead? If so, what kind? If not, can you tell me = why? I'm just getting into this stuff (despite being a computer science maj= or and having taken electronics courses) and want to learn all I can. A cheap 1200W electric heater with overheat protection and thermostat wired= short: http://www.ebay.com/itm/Holmes-Adjustable-Electric-Fan-Heater-Warmer-Manual= -Controls-1200W-White-NEW-/150993887107?pt=3DLH_DefaultDomain_0&hash=3Ditem= 2327efdf83 A cheap 1200W dimmer: http://www.ebay.com/itm/1-pc-Lighting-Control-Dimmer-AC100-120V-50-60Hz-120= 0W-/130289651050?hash=3Ditem1e55de4d6a A cheap ammeter: http://www.ebay.com/itm/1-X-Analog-Panel-AMP-Meter-AC-DC30A-Ammeter-Panel-N= eednt-Shunt-/140937035637?pt=3DLH_DefaultDomain_0&hash=3Ditem20d0807f75 A high power, but cheap, diode bridge rectifier: http://www.ebay.com/itm/1000V-50A-GBPC5010-Diode-Bridge-Rectifier-AC-to-DC-= Gift-/330949821814?pt=3DLH_DefaultDomain_0&hash=3Ditem4d0e258576 A little know-how, and you'll have yourself a REAL battery charger.=20
Well, true, 110 volt ac current is more dangerous than a wall wart's output=
, but a circuit like this can't be THAT dangerous, can it? More so than an =
old incandescent lamp? I know people who lost their houses in fires caused =
by old wiring, but a little circuit like this properly insulated, monitored=
, and kept away from flammable objects and enclosed spaces... is it really =
that much of a problem? Of course, one should always be careful around ac c=
urrent, but are there any other flaws in this circuit design? Tim mentioned=
 charging at too high a voltage, but the article says the battery will draw=
 just what it needs. Is that not true? Also, I've read that charging at a s=
lightly higher voltage and a very low current for a long time is a good way=
 to desulfate a battery. As for leaving it on too long like Mike mentioned,=
 I could just attach a timer. (I do know that there's a second phase to cha=
rging lead acid batteries, the constant voltage phase with auto-shutoff whe=
n current falls to a certain level. For this, I'll use a readymade store-bo=
ught charger.)

See, the thing is, I don't like the cheap battery chargers I can buy, and t=
he expensive good ones are out of my price range. I have a 6v/12v Schumache=
r right now, and it will only do 2, 4, or 6 amps. This whole thing started =
because I wanted something that would charge at whatever amps I want. If I =
could vary the voltage too, that'd be ideal. I like the pulse idea, though =
some say that's not what actually desulfates batteries. My Schumacher goes =
into 2 amp trickle charge mode after shutting off. I'm trying to squeeze so=
me life out of old lead acid batteries, so I want to overcharge but on a lo=
wer amperage to reduce sulfation. All I need is a little electricity at nig=
ht, and an old car battery that came with my trailer was working fine. (Yes=
, the previous owner replaced the deep cycle with a car battery. I deal wit=
h what I have.) I just want to desulfate it to get more useful power out of=
 it and extend its life.

Finally, Fred says a dimmer switch will work, but Tim says it will always g=
ive too much current or none. Is it that the heater combined with the dimme=
r will make it work?

Thanks.
On Wed, 03 Jul 2013 23:46:41 -0700, mike <ham789@netzero.net> wrote:

>On 7/3/2013 9:27 PM, kanon11@gmail.com wrote: >> The other day, I came upon this: http://www.alpharubicon.com/elect/3dollarbattggn.htm >> >> It's plans for a very simple battery charger that uses a light bulb and diode in series to make a constant current battery charger. Benefits include pulse charging for desulfation and the fact that it can charge batteries of any voltage. >> >> Well, with incandescent light bulbs getting scarce and me having many different size batteries needing different size currents, I'm wondering if a dimmer switch would work instead? If so, what kind? If not, can you tell me why? I'm just getting into this stuff (despite being a computer science major and having taken electronics courses) and want to learn all I can. > >Incandescent light bulbs make wonderful current limiters for charging >batteries >as long as you watch the voltage and don't overcharge. >But you'll forget and you WILL overcharge. >But use a transformer to keep from electrocuting yourself. > >I won't argue the merits of pulse charging, but most any battery >charger will do the same thing that this one does. > >And that same goodwill store will sell you an actual battery charger for >about the same price. > >Or you can go to harbor freight when they have the light duty one on sale >for $5 less the 20% off coupon.
The cheap electronic chargers (switching regulators) usually won't charge a totally dead battery. You need an old-fashioned transformer-rectifier charger, or a bench supply, or some kluge, to get them going.
One more question, since people like the wall wart idea better: I've charge=
d with them before too, but my question is, what does the current do? Say I=
 have a 14 volt wall wart with a current rating of 500 mA. If I try to char=
ge a car battery with this, will it pull too many amps and overheat? Is a w=
all wart a way to do constant voltage charging? Is there a way to limit the=
 current?

Thanks. I'm just trying to learn by doing. It's been awhile since my electr=
onics course in college, and they didn't teach this kind of practical stuff=
 anyway.
On 7/4/2013 3:30 PM, kanon11@gmail.com wrote:
> One more question, since people like the wall wart idea better: I've charged with them before too, but my question is, what does the current do? Say I have a 14 volt wall wart with a current rating of 500 mA. If I try to charge a car battery with this, will it pull too many amps and overheat? Is a wall wart a way to do constant voltage charging? Is there a way to limit the current? > > Thanks. I'm just trying to learn by doing. It's been awhile since my electronics course in college, and they didn't teach this kind of practical stuff anyway.
There are as many different types of wall warts as there are wall warts. Just use a 19ish volt laptop power supply and a 12V car tail/stop light. That will give you four possible currents. And the series mode will let you start with a dead/dead/dead battery and not blow up the light.