# [EVDL] Zener regs: Report after using for 2 years



## EVDL List (Jul 27, 2007)

Hi Chris and all,


>
> On the positive side, it points to the fact that the resistors seem to
> work as an effective backup. On the negative side it points out the bulb
> as a weak point.
>
>
> So is there anything that can be used instead of a bulb? They're bulky
> anyway, how good is the regulation with just a resistor? Has anyone else
> had any reports on how well the regs work?


I noticed when I was playing around with the Zener regs that the PR2 bulbs
only have a published life rating of 15 hours. The type 43 bulb, Mouser
number 606-CM43, with very similar specs to the PR2, boasts a life of 3000
hours! Price is within 30 cents of the PR2. I've not been able to verify
that life claim in the bumpy auto environment, but it might be worth a try
for those building the Zener regs.

-Ryan
-- 
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## EVDL List (Jul 27, 2007)

> Ryan Bohm wrote:
> >> On the positive side, it points to the fact that the resistors seem to
> >> work as an effective backup. On the negative side it points out the bulb
> >> as a weak point.
> ...


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## EVDL List (Jul 27, 2007)

> Chris Zach wrote:
> > Ok, this is a basic summary of my experience with the Lee Hart Zener
> > regs on my battery pack... Charging is either by using the internal
> > Dolphin (2.5a up to about 350 volts, then tapering down to 1a at 367
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > The light bulb acts as a simple current limiter. From 0.25v to 2.5v the
> > current goes from 0.25a to 0.5a. In the zener-lamp regulators, this
> > means it draws essentially zero current below the zener voltage, and
> ...


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## EVDL List (Jul 27, 2007)

Is there an "official" site with the part numbers for the regulators?
I've tried searching the archives, but with little success. I'd like
to build some regulators for 6V batteries. The zeners are available in
6.2V and 6.8V. I've come across a few websites suggesting how to make
them and some say use the 6.2, others the 6.8. My guess is to use the
6.8V. The typical circuit for the 6V is basically 2 regulators per
battery. I wonder if there is another light bulb that can take 1A
instead of having 2 of the PR2 bulbs (still using 2 zeners), just to
simplify. Also how dependent is this on heat sinking through the
battery terminal? What if I had the regulators remotely located
instead of on top of each battery?

I also find it interesting that in a related thread the use of 12V
batteries is discouraged, but the regulators were originally designed
for 12V not 6V batteries.

-- 
-Jon Glauser
http://jonglauser.blogspot.com
http://www.evalbum.com/555

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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > My guess is that you aren't limiting the current when the zener-reg
> > lamps light. The zener-reg can only bypass 0.5 amps max. If you're
> > charging at (say) 1 amp, even with the zener-reg bypassing 0.5 amps the
> ...


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## EVDL List (Jul 27, 2007)

> Jon Glauser wrote:
> 
> > I also find it interesting that in a related thread the use of 12V
> > batteries is discouraged,
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> >> I would look for some means to reduce charging current to 0.5a or less
> >> when the lamps light.
> >
> ...


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## EVDL List (Jul 27, 2007)

>> The size is needed to dissipate heat. If you substitute a resistor, it 
>> needs to be about 2 watts to handle the dissipation.



> Christopher Zach wrote:
> > Interesting. I am using half watt carbon resistors as the backups, and
> > none of them seem to have fried. Isn't most of the heat dissipated in
> > the zener diodes?
> ...


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## EVDL List (Jul 27, 2007)

> Jon Glauser wrote:
> > Is there an "official" site with the part numbers for the regulators?
> 
> Not that I know of. It's a public design, and people are free to use it
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart <[email protected]> wrote:
> 
> >Jon Glauser wrote:
> >> Is there an "official" site with the part numbers for the regulators?
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > No; you have a sigle light sensor in the batery box. If *any* lamp
> > lights, it detects the light and insures that the charging current is
> > low enough not to over-voltage any regulators/batteries.
> ...


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## EVDL List (Jul 27, 2007)

> Neon John wrote:
> > Do you know where there might be a schematic available?
> 
> View with a fixed-width font, like Courier:
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >> You want a single light sensor in the battery box. If *any* lamp
> >> lights, it detects the light and insures that the charging current is
> >> low enough not to over-voltage any regulators/batteries.
> ...


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## EVDL List (Jul 27, 2007)

> Neon John wrote:
> > Do you know where there might be a schematic available? I've always been a
> > flooded guy so I haven't paid much attention. The last week a set of 12 brand
> > new 100 amp-hour traction batteries came into my possession gratis. Free is a
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > Can you put a piece of fiber optic on each bulb, and collect all the
> > other ends at a central light sensor?
> 
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > What value of resistance? I used 10 ohms as my backup resistor. Assuming
> > two 6.8v zeners and a battery at 15 volts, there is 15-6.8-6.8 = 1.4
> > volts across it, so power P = (1.4v)^2 / 10 ohms = 0.196 watts. I used a
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> 
> > Lee Hart wrote:
> >> No; you have a sigle light sensor in the batery box. If *any* lamp
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >> Can you put a piece of fiber optic on each bulb, and collect all the
> >> other ends at a central light sensor?
> 
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> > Re-cranking the numbers for a 6.2/6.8 volt zener pair and a term voltage
> > of 15 would give me.
> >
> ...


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## EVDL List (Jul 27, 2007)

Perhaps using a PTC instead of the light bulb will make it less prone
to burning out or dying from vibration. You loose the visual indicator
though.




> Lee Hart <[email protected]> wrote:
> > Christopher Zach wrote:
> >> Re-cranking the numbers for a 6.2/6.8 volt zener pair and a term voltage
> >> of 15 would give me.
> ...


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## EVDL List (Jul 27, 2007)

> Peter Gabrielsson wrote:
> > Perhaps using a PTC instead of the light bulb will make it less prone
> > to burning out or dying from vibration. You loose the visual indicator
> > though.
> ...


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## EVDL List (Jul 27, 2007)

I kind of presumed a light bulb is also a thermal device?




> Lee Hart <[email protected]> wrote:
> > Peter Gabrielsson wrote:
> >> Perhaps using a PTC instead of the light bulb will make it less prone
> >> to burning out or dying from vibration. You loose the visual indicator
> ...


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## EVDL List (Jul 27, 2007)

> Peter Gabrielsson wrote:
> > I kind of presumed a light bulb is also a thermal device?
> 
> Certainly; the resistance change is caused by the temperature of the
> ...


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## EVDL List (Jul 27, 2007)

Visual indication is simple: place a LED and small series resistor
across the power resistor that is limiting the current and is
used instead of the lamp, because the experience of fellow EV'ers
show that indeed the lamps burn out frequently, so their only
rescue was that they already placed 10 Ohms resistors across
the lamp, now these resistors are the only thing keeping the 
pack healthy, because otherwise it would have died from his
IMbalancers.


Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Lee Hart
Sent: Saturday, June 14, 2008 4:34 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Zener regs: Report after using for 2 years



> Peter Gabrielsson wrote:
> > Perhaps using a PTC instead of the light bulb will make it less prone
> > to burning out or dying from vibration. You loose the visual indicator
> > though.
> ...


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