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From: Yvan on 6 Feb 2010 16:58
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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From: John Larkin on 6 Feb 2010 17:06
On Sat, 06 Feb 2010 22:58:00 +0100, Yvan <killefitz(a)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

From: Jamie on 6 Feb 2010 17:48
Yvan 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 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.

From: Yvan on 6 Feb 2010 17:35
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?

> 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


--
___ ____
/__/ / \ ** Registrovani korisnik Linuksa #291606 **
/ / \/ /\ \ ** Registered Linux user #291606 **
/__/\____/--\__\ ** http://counter.li.org/ **
From: Yvan on 6 Feb 2010 17:39
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 :-(


--
___ ____
/__/ / \ ** Registrovani korisnik Linuksa #291606 **
/ / \/ /\ \ ** Registered Linux user #291606 **
/__/\____/--\__\ ** http://counter.li.org/ **
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