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Yvan
Guest
Sat Feb 06, 2010 11:58 pm
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 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?
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John Larkin
Guest
Sun Feb 07, 2010 12:06 am
On Sat, 06 Feb 2010 22:58:00 +0100, Yvan <killefitz_at_invalid.invalid>
wrote:
Quote:
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
Yvan
Guest
Sun Feb 07, 2010 12:35 am
Nedavno John Larkin napisa:
Quote:
A zener is pretty much a zener. I've never heard of a FAST zener. Use
any similarly-rated (voltage, power) zener.
Other opinions?
Quote:
I wonder if the circuit actually works, chemistry-wise.
I do not know, but I decided to try. I will also make this:
http://home.comcast.net/~ddenhardt201263/desulfator/n_channel_schem.gif
More info here:
http://home.comcast.net/~ddenhardt201263/desulfator/lowpower.htm
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Yvan
Guest
Sun Feb 07, 2010 12:39 am
Nedavno Jamie napisa:
Quote:
Mouser has them. Most like you can get them in Axle leads, these are
smt.
I am in Serbia. I'd be paying more for taxes for the part than for the
new car battery :-(
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John Larkin
Guest
Sun Feb 07, 2010 12:43 am
On Sat, 06 Feb 2010 23:35:58 +0100, Yvan <killefitz_at_invalid.invalid>
wrote:
Quote:
How will you know if they work or not?
The pulsed desulphator sounds bogus to me.
John
Fred Bartoli
Guest
Sun Feb 07, 2010 12:48 am
Yvan a écrit :
Quote:
Nedavno John Larkin napisa:
A zener is pretty much a zener. I've never heard of a FAST zener. Use
any similarly-rated (voltage, power) zener.
Other opinions?
Like John said you, just go for a similar power zener and you'll be OK.
Also, as you app seems to be single pulse, and have a very low duty
ratio, you can slow down the FET turn off quite a bit without any pb.
You could probably reduce the over voltage to the point of not needing
any clamp at all.
Quote:
I wonder if the circuit actually works, chemistry-wise.
Ditto
--
Thanks,
Fred.
Jamie
Guest
Sun Feb 07, 2010 12:48 am
Yvan wrote:
Quote:
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 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?
look for TVS diodes as your replacement.. They can handle some junk.
Look at that one. the 12V version is most likely what you want.
it has a clamp of 22 amps at 27V and only a 5ma of leakage at around
14v or so.
http://www.nxp.com/documents/data_sheet/PESD5V0S1UA_PESD12VS1UA.pdf
Mouser has them. Most like you can get them in Axle leads, these are
smt.
Yvan
Guest
Sun Feb 07, 2010 12:50 am
Nedavno John Larkin napisa:
Quote:
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.
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Yvan
Guest
Sun Feb 07, 2010 12:52 am
Nedavno Jamie napisa:
Quote:
Well, I don't know who you have there for parts supplier..
Farnell maybe?, Newark? etc...
Digikey? etc.
None of these. We have few parts supplier, I'll check if they have TVS
diodes, thanks.
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Jamie
Guest
Sun Feb 07, 2010 1:02 am
Yvan wrote:
Quote:
Nedavno Jamie napisa:
Mouser has them. Most like you can get them in Axle leads, these are
smt.
I am in Serbia. I'd be paying more for taxes for the part than for the
new car battery :-(
Well, I don't know who you have there for parts supplier..
Farnell maybe?, Newark? etc...
Digikey? etc.
Just look for TVS diodes.
Martin Riddle
Guest
Sun Feb 07, 2010 1:20 am
"Yvan" <killefitz_at_invalid.invalid> wrote in message
news:hkkrnj$hlo$2_at_news.eternal-september.org...
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.
They actually do work, but may take more than a month and the battery
will have reduced capacity.
Discharging and charging during desulfation seems to help the sulfur to
get reabsorbed back into the electrolyte.
Cheers
langwadt@fonz.dk
Guest
Sun Feb 07, 2010 1:52 am
On 6 Feb., 23:06, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
Quote:
On Sat, 06 Feb 2010 22:58:00 +0100, Yvan <killef...@invalid.invalid
wrote:
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 ?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
is the zener really needed?, if that little zener can handle the
spikes, surely a big avalance rated fet can too
-Lasse
Jamie
Guest
Sun Feb 07, 2010 1:57 am
John Larkin wrote:
Quote:
its just a Fast recovery diode of 6 amps with a Vr(rms) of 70v,
Tr(recovery time) of 150nS with 100pf
This is nothing special..
Jamie
Guest
Sun Feb 07, 2010 2:09 am
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.
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.
Ban
Guest
Sun Feb 07, 2010 7:15 am
"Yvan" <killefitz_at_invalid.invalid> schrieb im Newsbeitrag
news:hkkol8$fo4$2_at_news.eternal-september.org...
Quote:
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?
Yes put a 3-5W 27V zener.
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. Better to get a trickle charger and keep the battery
fully charged during the storage time.
The article goes back to the seventies BTW and was extensivly discussed and
the circuit was considered pretty much useless.
ciao Ban
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