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Phil Allison
Guest
Sun Feb 07, 2010 6:20 am
"Banshee"
Quote:
The article goes back to the seventies BTW
** The issue date is November 2004.
There were no power MOSFETS in the '70s.
Quote:
and was extensivly discussed and the circuit was considered pretty much
useless.
** Yep.
Most battery charger / rejuvenator projects are useless scams.
..... Phil
Ban
Guest
Sun Feb 07, 2010 7:04 am
"Phil Allison" <phil_a_at_tpg.com.au> schrieb im Newsbeitrag
news:7t70t6F1kmU1_at_mid.individual.net...
Quote:
"Banshee"
The article goes back to the seventies BTW
** The issue date is November 2004.
It was then done with some power Darlington AFAIR, and that's where that
zener came from.
BTW IR launched its first power Mosfet in '79
Quote:
There were no power MOSFETS in the '70s.
and was extensivly discussed and the circuit was considered pretty much
useless.
** Yep.
Most battery charger / rejuvenator projects are useless scams.
.... Phil
ciao Ban
Yvan
Guest
Sun Feb 07, 2010 7:59 am
Nedavno Jamie napisa:
Quote:
If D2 is the diode you are referring too, it's not a zener..
it's fast recovery diode of 6 amps.
I am going by the image of the GIF you posted earlier as you stated
it was the connected to the FET.
You are looking at the wrong link. Look at my first post, and there is a
link to PDF file, and there in the parts list:
D5 = fast zener diode, e.g., BZT03 24V, 27V or 33V)
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Yvan
Guest
Sun Feb 07, 2010 8:32 am
Nedavno Ban napisa:
Quote:
I can not find this diode where I am, so can you suggest a
substitute? I guess I can not just put regular 27V zener diode here?
Yes put a 3-5W 27V zener.
Local parts store only has ZY 27 (27V 1,3W), and ZX 27V (27V 10W) which
is to expensive to buy for making something that may not work, just as
a pastime.
Quote:
If diodes use the zener effect, they are always very fast, because no
charge needs to be removed. This is valid for z-diodes above 8V
rating. The circuit discharges the battery, in one year with more than
30Ah, together with the self discharge rate there will be 0 capacity
left after a year for a normal 45Ah, this is certainly not a good idea
and won't prolong battery life at all.
I wouldn't let it connected for a year. Perhaps a month or two, and then
recharge it. I used to do that, but as soon as the battery is out of
the car, unused, it dies quickly. I tried to connect my charger to a
timer that switched it on for a 20 min three times a week.
Unfortunately timer died while I was away for a three weeks, car
battery got charged all that time, and it died.
Quote:
Better to get a trickle charger
and keep the battery fully charged during the storage time.
What sort of voltage / current do I need? Do you have any links to a
good proven trickle charger design?
I've found different ones from small ones (like the ones for mobile
phone), to 1A. But isn't 1A (when battery is fully charged) cause
electrolyte to boil?
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Ban
Guest
Sun Feb 07, 2010 9:10 am
"Yvan" <killefitz_at_invalid.invalid> schrieb im Newsbeitrag
news:hkloda$n61$1_at_news.eternal-september.org...
Quote:
Nedavno Jamie napisa:
If D2 is the diode you are referring too, it's not a zener..
it's fast recovery diode of 6 amps.
I am going by the image of the GIF you posted earlier as you stated
it was the connected to the FET.
You are looking at the wrong link. Look at my first post, and there is a
link to PDF file, and there in the parts list:
D5 = fast zener diode, e.g., BZT03 24V, 27V or 33V)
I also think this circuit can be dangerous. If there goes something wrong
and that FET keeps conducting...
ciao Ban
Ban
Guest
Sun Feb 07, 2010 9:26 am
"Yvan" <killefitz_at_invalid.invalid> schrieb im Newsbeitrag
news:hklqa4$hhp$1_at_news.eternal-september.org...
Quote:
Nedavno Ban napisa:
I can not find this diode where I am, so can you suggest a
substitute? I guess I can not just put regular 27V zener diode here?
Yes put a 3-5W 27V zener.
Local parts store only has ZY 27 (27V 1,3W), and ZX 27V (27V 10W) which
is to expensive to buy for making something that may not work, just as
a pastime.
If diodes use the zener effect, they are always very fast, because no
charge needs to be removed. This is valid for z-diodes above 8V
rating. The circuit discharges the battery, in one year with more than
30Ah, together with the self discharge rate there will be 0 capacity
left after a year for a normal 45Ah, this is certainly not a good idea
and won't prolong battery life at all.
I wouldn't let it connected for a year. Perhaps a month or two, and then
recharge it. I used to do that, but as soon as the battery is out of
the car, unused, it dies quickly. I tried to connect my charger to a
timer that switched it on for a 20 min three times a week.
Unfortunately timer died while I was away for a three weeks, car
battery got charged all that time, and it died.
Better to get a trickle charger
and keep the battery fully charged during the storage time.
What sort of voltage / current do I need? Do you have any links to a
good proven trickle charger design?
I've found different ones from small ones (like the ones for mobile
phone), to 1A. But isn't 1A (when battery is fully charged) cause
electrolyte to boil?
The batteries have a self discharge rate which is dependent on temperature,
age and condition. If we assume 10%/month we have to replace 4.5Ah which
means a continuous trickle charge of only 6.5mA. You can use any small
supply with higher voltage and calculate the resistor value
(Vout-13.8V)/10mA if you have 15V then use a 120 ohms 1/4W resistor. This
won't hurt the battery.
Yvan
Guest
Sun Feb 07, 2010 1:08 pm
Nedavno Ban napisa:
Quote:
The batteries have a self discharge rate which is dependent on
temperature, age and condition. If we assume 10%/month we have to
replace 4.5Ah which means a continuous trickle charge of only 6.5mA.
You can use any small supply with higher voltage and calculate the
resistor value (Vout-13.8V)/10mA if you have 15V then use a 120 ohms
1/4W resistor. This won't hurt the battery.
But how does that work? Surely it is not the same if I connect charger
capable of delivering 10A, and the one capable of delivering only 10mA
with the same voltage.
What determines the current flow, 10mA or 10A or whatever?
And what happenes if, for some reason, battery discharges faster than
the charger can charge? Current flow rises, and charger dies?
When I connest my charger to partially discharged battery it starts
charging at ~5A, and gradually drops down.
I also decided to try this:
http://www.mikroe.com/sr/magazine/p2broj/slike/2b71.gif
It should start charging below 12.5V, and stop at 13.8V (adjustable).
What do you think? Good alternative to trickle charger?
--
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/ / \/ /\ \ ** Registered Linux user #291606 **
/__/\____/--\__\ **
http://counter.li.org/ **
Robert Baer
Guest
Sun Feb 07, 2010 1:57 pm
John Larkin wrote:
Quote:
discharge) and it is wise to do that in such a manner to have a net (or
long term average) charge rate at least equal to the trickle charge rate.
One needs to force the current without regard to voltage across the
battery.
One time i took a motorcycle battery that was made for the Army in
1945 that was made dry-charged and zero electrolyte; the idea was that
addition of electrolyte would give one a fully usable battery.
Well, by the time i bought it (surplus) it was in the 1980s and the
battery would not pass more than a milliamp at 6V (its rating); it was
"hopelessly" sulphated.
I used a 120v/120V isolation transformer, a series current limiting
resistor, and a reverse polarity protection diode across the battery and
let it run a week; reduced the transformer drive to half and ran another
week, etc until i was using a mere 12VAC for a 50mA peak current.
Then i could use a standard charger, and cycled it twice to get
almost full rating.
Lead sulphate is a good insulator, and you need to RIP it apart, but
keep the current down to create small lead particles for "re-plating"
and thus be able to be a regular part of the charging/discharging chemistry.
Robert Baer
Guest
Sun Feb 07, 2010 1:59 pm
Yvan wrote:
Quote:
Nedavno John Larkin napisa:
How will you know if they work or not?
The pulsed desulphator sounds bogus to me.
I have two old, unused car bateries. I'll connect desulphator to it, and
wait for a month to see if it works.
You will wind up with fully discharged batteries ASS-u-ME-ing they
had any charge in the first place.
You might be able to get them to charge slightly better afterwards
than before treatment.
Bill Sloman
Guest
Sun Feb 07, 2010 3:48 pm
On Feb 6, 10:58 pm, Yvan <killef...@invalid.invalid> wrote:
Quote:
I decided to built this:
http://notes.ump.edu.my/fkee/e-Magazine/Elektor%202004/Articles/E/e04...
It keeps the battery a little bit active, preventing sulphation by
loading the battery with a hefty current (40 A) for a short interval
(50 μs) approximately every two minutes.
But they used a fast zener diode (BZT03 27V) across the FET for
protection, as rather large voltage spikes can occur when the FET
switches off.
I can not find this diode where I am, so can you suggest a substitute? I
guess I can not just put regular 27V zener diode here?
The BZT03 is a big junction in a small package - it can dissipate 10W
continuously, or 600W for a 0.1msec.
http://www.vishay.com/docs/85599/85599.pdf
I don't recall that it was ever advertised as particularly fast,
though Vishay now claims that it can turn on quickly, which may be
true, once the first charge-carriers have appeared in the junction.
"Zener" diodes with breakdown voltages above about 8V are in fact
avalanche diodes, and the avalanche starts with a single charge-
carrier pair, which may come from thermal noise or radioactive decay.
--
Bill Sloman, Nijmegen
Yvan
Guest
Sun Feb 07, 2010 4:02 pm
Nedavno Robert Baer napisa:
Quote:
I have two old, unused car bateries. I'll connect desulphator to it,
and wait for a month to see if it works.
You will wind up with fully discharged batteries ASS-u-ME-ing they
had any charge in the first place.
You might be able to get them to charge slightly better afterwards
than before treatment.
I will monitor the process, and charge the battery when needed, or
connect a trickle charger (when I find / make one). Perhaps it will not
work, bat as the batteries are written off it can only get better.
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John Larkin
Guest
Sun Feb 07, 2010 6:24 pm
On Sun, 07 Feb 2010 16:02:27 +0100, Yvan <killefitz_at_invalid.invalid>
wrote:
Quote:
Nedavno Robert Baer napisa:
I have two old, unused car bateries. I'll connect desulphator to it,
and wait for a month to see if it works.
You will wind up with fully discharged batteries ASS-u-ME-ing they
had any charge in the first place.
You might be able to get them to charge slightly better afterwards
than before treatment.
I will monitor the process, and charge the battery when needed, or
connect a trickle charger (when I find / make one). Perhaps it will not
work, bat as the batteries are written off it can only get better.
The way to keep batteries from sulphating is to discharge and recharge
them occasionally. So a single resistor will work as well as this
circuit.
John
legg
Guest
Mon Feb 08, 2010 4:20 am
On Sat, 06 Feb 2010 14:06:09 -0800, John Larkin
<jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
Quote:
On Sat, 06 Feb 2010 22:58:00 +0100, Yvan <killefitz_at_invalid.invalid
wrote:
I decided to built this:
http://notes.ump.edu.my/fkee/e-Magazine/Elektor%202004/Articles/E/e04b020.pdf
It keeps the battery a little bit active, preventing sulphation by
loading the battery with a hefty current (40 A) for a short interval
(50 ?s) approximately every two minutes.
But they used a fast zener diode (BZT03 27V) across the FET for
protection, as rather large voltage spikes can occur when the FET
switches off.
I can not find this diode where I am, so can you suggest a substitute? I
guess I can not just put regular 27V zener diode here?
A zener is pretty much a zener. I've never heard of a FAST zener. Use
any similarly-rated (voltage, power) zener.
I wonder if the circuit actually works, chemistry-wise.
John
A 2K2 gate resistor pretty much prevents fast enough switching to
cause spikes. The fet swots it out, zener or no.
RL
Yvan
Guest
Mon Feb 08, 2010 3:50 pm
Nedavno legg napisa:
Quote:
A 2K2 gate resistor pretty much prevents fast enough switching to
cause spikes. The fet swots it out, zener or no.
Yes, but from the PDF file in my first post:
"Despite the relatively slow switching, rather large voltage spikes can
occur when the FET switches off. It is thus essential to connect a fast
Zener diode (D5) across the FET for protection."
--
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/__/ / \ ** Registrovani korisnik Linuksa #291606 **
/ / \/ /\ \ ** Registered Linux user #291606 **
/__/\____/--\__\ **
http://counter.li.org/ **
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