Re: negative contactor heating up and BMS analogue control

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Re: negative contactor heating up and BMS analogue control

Mike Malmberg
Date: Tue, 25 Jun 2013 22:13:00 -0500
From: Lee Hart <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Subject: Re: [EVDL] EV Digest, Vol 8, Issue 39
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Mike Malmberg wrote:  my responses below and thank you so much
> coil has 14 volts

The Tyco LEV200 data sheet says it has a 12vdc coil, and is rated for
9.6v minimum, 13.2v maximum. 14v is more than its rated voltage, so it
would get hot.

My suggestion would be to add a series resistor, with a capacitor in
parallel (called a "slugger" circuit). Choose the resistor to drop the
steady-state voltage a few volts. Oddly, the data sheet doesn't give the
coil resistance, so you'll have to measure it or experiment to find the
right resistor value.

--So a series resistor on positve or negative side of coil.   coil
resistance measured with an ohm meter across the coil while the coil
is off or energized?
Is there some math I need to do to calculate the resistor value that I need?

Then, the capacitor in parallel initially applies the full voltage, to
make the contactor pull in quickly. Something like a 10,000uF
electrolytic capacitor rated at 6vdc or more will do it.

--And this capacitor goes across the coil of the contactor, yes?

> I realize that the BMS should have control over that contactor, and so my
> charger negative should go on the other side of the contactor (controller
> side rather than battery side). Will that affect the contactor heating?

No. You aren't running enough current for its contact to produce any
significant amount of heat.

> Also, nobody responded on the bms control question,  I flipped the diode
> the other way around and I  have no throttle at all.

I can't help you there. Sounds like you had the diode the right way to
begin with. Was it in fact limiting the throttle when the BMS sensed a
low cell voltage?

--no that was why I started asking questions, it had no effect on the
current output at all.  when checking it the original way I had it
hooked up,
 I believe I had 5 volts on bms side of the diode and 1.2 volts after
the diode.  Does that sound right?
I have gone through the check that Orion recommended which was to pull
the current sensor to see if the BMS responded and it did drop to zero
volts.  so full pack 5 volts and no pack 0 volts (.03v )


--
For every complex problem, there is a solution that is simple, obvious,
and wrong. -- H.L. Mencken
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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Re: negative contactor heating up and BMS analogue control

Cor van de Water
The resistor and capacitor are in parallel, then those two are connected
to the contactor coil. There is no difference if they are connected at
the positive or negative side of the contactor coil. The only thing to
check is that the capacitor is oriented the right way, its positive side
to the positive supply that supplies the coil. Just put it in series
with the coil and measure the voltage drop, then verify that the
capacitor + is higher than its negative side.

Do not put a capacitor across the coil, that will only reduce the speed
of the contactor and cause severe arcing.

You can measure the contactor coil resistance when it is not active - if
it has a connector then you can pull the connector off and then measure
the coil itself.

I expect that as soon as the coil resistance is known, Lee or someone
else can make this circuit for you (power resistor + large capacitor)
and send it to you for a small fee.

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email] Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Mike Malmberg
Sent: Wednesday, June 26, 2013 11:27 PM
To: evdl
Subject: Re: [EVDL] negative contactor heating up and BMS analogue
control

Date: Tue, 25 Jun 2013 22:13:00 -0500
From: Lee Hart <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Subject: Re: [EVDL] EV Digest, Vol 8, Issue 39
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Mike Malmberg wrote:  my responses below and thank you so much
> coil has 14 volts

The Tyco LEV200 data sheet says it has a 12vdc coil, and is rated for
9.6v minimum, 13.2v maximum. 14v is more than its rated voltage, so it
would get hot.

My suggestion would be to add a series resistor, with a capacitor in
parallel (called a "slugger" circuit). Choose the resistor to drop the
steady-state voltage a few volts. Oddly, the data sheet doesn't give the
coil resistance, so you'll have to measure it or experiment to find the
right resistor value.

--So a series resistor on positve or negative side of coil.   coil
resistance measured with an ohm meter across the coil while the coil
is off or energized?
Is there some math I need to do to calculate the resistor value that I
need?

Then, the capacitor in parallel initially applies the full voltage, to
make the contactor pull in quickly. Something like a 10,000uF
electrolytic capacitor rated at 6vdc or more will do it.

--And this capacitor goes across the coil of the contactor, yes?

> I realize that the BMS should have control over that contactor, and so
my
> charger negative should go on the other side of the contactor
(controller
> side rather than battery side). Will that affect the contactor
heating?

No. You aren't running enough current for its contact to produce any
significant amount of heat.

> Also, nobody responded on the bms control question,  I flipped the
diode
> the other way around and I  have no throttle at all.

I can't help you there. Sounds like you had the diode the right way to
begin with. Was it in fact limiting the throttle when the BMS sensed a
low cell voltage?

--no that was why I started asking questions, it had no effect on the
current output at all.  when checking it the original way I had it
hooked up,
 I believe I had 5 volts on bms side of the diode and 1.2 volts after
the diode.  Does that sound right?
I have gone through the check that Orion recommended which was to pull
the current sensor to see if the BMS responded and it did drop to zero
volts.  so full pack 5 volts and no pack 0 volts (.03v )


--
For every complex problem, there is a solution that is simple, obvious,
and wrong. -- H.L. Mencken
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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(http://groups.yahoo.com/group/NEDRA)

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Re: negative contactor heating up and BMS analogue control

Lee Hart
In reply to this post by Mike Malmberg
Lee Hart wrote:
> My suggestion would be to add a series resistor, with a capacitor in
> parallel (called a "slugger" circuit)...

Mike Malmberg wrote:
> --So a series resistor on positive or negative side of coil?

It doesn't matter. The resistor goes in series with either coil wire.

Without the resistor, you see 14v across the coil with it on. Choose the
resistance value so you get about 10v across the coil, and 4v across the
resistor.

Then, wire the capacitor across the resistor (not the coil). The
capacitor has a polarity; connect it so your meter shows a positive
voltage across it (with your meter red + lead on the capacitor +, and
the meter black - lead on the capacitor -).

The capacitor should be rated at about 10,000uF (the value is not
critical -- 2:1 either side of this is fine). It should be rated for
16vdc or more.

The Tyco data sheet doesn't tell me the coil resistance; you'll have to
measure it with your meter. Then the resistor value is about 4/14th of
the coil resistance. For example, if your coil measures 10 ohms, then
the resistor is 10ohms x 4 / 14 = 2.85 ohms. Again, it's not critical;
anything from 2 to 3.5 ohms will work. Since the coil draws about an
amp, the resistor needs to dissipate power; about (4v)^2 / R. If your
resistor is 4 ohms, that's 4^2 / 4 = 16 / 4 = 4 watts; so use a 10 watt
resistor.

If you can tell me the coil resistance, I can send you the parts. The
postage costs more than the parts do!

--
For every complex problem, there is a solution that is simple, obvious,
and wrong. -- H.L. Mencken
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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dealer network and selling EV's

rodhower
There are several states trying to prevent Tesla from selling online without a dealer network.
Here's a petition to allow Tesla to enter those markets
https://petitions.whitehouse.gov/petition/allow-tesla-motors-sell-directly-consumers-all-50-states/bFN7NHQR
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Re: negative contactor heating up and BMS analogue control

Mike Scott-13
In reply to this post by Lee Hart
I just happened to receive an LEV200 in the mail today, coil measures 10.7
ohms according to my Fluke*. So the ideal resistor value bumps up to 3.05
ohms for this one. (Dang all I have in 3 ohm are expensive "non-inductive"
resistors I was saving for a speaker crossover, have to hit the junk shop
next week.)

* (Fluke also says that the battery that was in it was down to 5 volts! It
was still working as a beeper, but the ohms setting produced negative 5
ohms when the leads were shorted, so the coil reading is with a fresh
battery!)


On Thu, Jun 27, 2013 at 6:03 AM, Lee Hart <[hidden email]> wrote:

> Lee Hart wrote:
>
>> My suggestion would be to add a series resistor, with a capacitor in
>> parallel (called a "slugger" circuit)...
>>
>
> Mike Malmberg wrote:
>
>> --So a series resistor on positive or negative side of coil?
>>
>
> It doesn't matter. The resistor goes in series with either coil wire.
>
> Without the resistor, you see 14v across the coil with it on. Choose the
> resistance value so you get about 10v across the coil, and 4v across the
> resistor.
>
> Then, wire the capacitor across the resistor (not the coil). The capacitor
> has a polarity; connect it so your meter shows a positive voltage across it
> (with your meter red + lead on the capacitor +, and the meter black - lead
> on the capacitor -).
>
> The capacitor should be rated at about 10,000uF (the value is not critical
> -- 2:1 either side of this is fine). It should be rated for 16vdc or more.
>
> The Tyco data sheet doesn't tell me the coil resistance; you'll have to
> measure it with your meter. Then the resistor value is about 4/14th of the
> coil resistance. For example, if your coil measures 10 ohms, then the
> resistor is 10ohms x 4 / 14 = 2.85 ohms. Again, it's not critical; anything
> from 2 to 3.5 ohms will work. Since the coil draws about an amp, the
> resistor needs to dissipate power; about (4v)^2 / R. If your resistor is 4
> ohms, that's 4^2 / 4 = 16 / 4 = 4 watts; so use a 10 watt resistor.
>
> If you can tell me the coil resistance, I can send you the parts. The
> postage costs more than the parts do!
>
>
> --
> For every complex problem, there is a solution that is simple, obvious,
> and wrong. -- H.L. Mencken
> --
> Lee A. Hart, http://www.sunrise-ev.com/**LeesEVs.htm<http://www.sunrise-ev.com/LeesEVs.htm>
> ______________________________**_________________
> UNSUBSCRIBE: http://www.evdl.org/help/**index.html#usub<http://www.evdl.org/help/index.html#usub>
> http://lists.evdl.org/**listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org>
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> *group/NEDRA <http://groups.yahoo.com/group/NEDRA>)
>
>
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Re: negative contactor heating up and BMS analogue control

Lee Hart
Mike Scott wrote:
> I just happened to receive an LEV200 in the mail today, coil measures 10.7
> ohms according to my Fluke*. So the ideal resistor value bumps up to 3.05
> ohms for this one. (Dang all I have in 3 ohm are expensive "non-inductive"
> resistors I was saving for a speaker crossover, have to hit the junk shop
> next week.)

The closest I have in my junk box is 3.5 ohms. Things like 1, 2, and 5
ohms are more common.

In a pinch, you can also use a car tail light. Try one or both filaments
of an #1157 tail light in parallel as your resistor. Aim for about 11v
on the contactor with 14v power (i.e. the other 3v is across the light).

--
The storage battery is one of those peculiar things which appeals to
the imagination, and no more perfect thing could be desired by stock
swindlers than that very selfsame thing. Just as soon as a man gets
working on the secondary battery it brings out his latent capacity for
lying. -- Thomas A. Edison
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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