[EVDL List]

Greetings,
We are currently running a 144V pack with a Curtis 1231C-86xx (96-144V spec)
and ADC Motor and "all systems are go". We would like to increase our range
by adding 2 more Optima D31's in series, thereby increasing the nominal pack
voltage to 168V. Is anyone out there running the same controller beyond the
specified input voltage? Will it handle the increased potential? Any
insight is greatly appreciated.

Martin Emde
Seabury Hall
www.seaburyhall.org/engineering
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On 10 Oct 2007 at 14:26, martin emde wrote:

> We are currently running a 144V pack with a Curtis 1231C-86xx (96-144V spec)
> and ADC Motor and "all systems are go". We would like to increase our range
> by adding 2 more Optima D31's in series, thereby increasing the nominal pack
> voltage to 168V. Is anyone out there running the same controller beyond the
> specified input voltage? Will it handle the increased potential?

Uh ... you said it yourself : "(96-144V spec)."

You are dealing with a cheap controller here. It's not some conservatively
rated, cast-iron industrial piece of equipment. The specs mean exactly what
they say : don't use this controller above 144v.

IIRC, Curtis uses input capacitors with barely high enough working voltage
to handle the rated input. There are probably other components that will be
stressed by excessive voltage.

In fact, Curtis controllers are already more reliable when operated below
their maximum specified voltage. Exceeding it is likely to mean a short and
zappy life.

You'll definitely need to buy a controller capable of handling the
additional voltage. If you get one now, you can still recoup part of its
purchase cost by selling the old one to someone else. Try running the old
one hot, and it's likely to become worthless.

David Roden - Akron, Ohio, USA
EVDL Administrator

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martin emde wrote:
> Greetings, We are currently running a 144V pack with a Curtis
> 1231C-86xx (96-144V spec) and ADC Motor and "all systems are go". We
> would like to increase our range by adding 2 more Optima D31's in
> series, thereby increasing the nominal pack voltage to 168V. Is
> anyone out there running the same controller beyond the specified
> input voltage? Will it handle the increased potential? Any insight
> is greatly appreciated.

In keeping with the Halloween spirit: A deep voice out of the darkness
says, "I wouldn't do that if I were you..."

The Curtis controllers have a barely adequate safety margin as it is.
Going past rated voltage is asking for trouble. So, you should look for
a way to increase your range without going over the controller's rated
voltage.

If you have 12 D31's now and want to go to 14, you could rewire them as
two parallel groups of 7 in series; but that would be an 84v system
which is a bit low for the Curtis 1231C-86xx (96-144vdc). But it could
work if you can add four more D31's. Acceleration would be slower, though.

You could add a second "buddy string" of some smaller batteries whose
voltage totalled 144v but whose weight matched the two D31's (or
whatever extra weight you think you can manage).

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Martin and All,
I had written the response below earlier today, but decided to wait for others to
chime in. Unlike Lee's Halloween voice, I'll be that other dark voice that says, "it is OK", but:

I'm thinking that this should not be a problem, IF you have a contactor on both sides of the battery pack to remove the controller while charging, which you should have anyway. A charger for a 144V pack could peek at 194V (2.7 VPC), so they use 200V components in the controller, and label it as 144V maximum pack voltage. A charger for a 168V pack could peak at 227V, which could injure the controller! Also, just after charging, you must make sure that the pack voltage has dropped below 200 volts before precharging the controller!
Hope this helps...
Suck Amps,
BB

>Date: Wed, 10 Oct 2007 14:26:24 -1000
>From: "martin emde" <[email protected]>
>Subject: [EVDL] Curtis 1231C-86xx @ 168V
>To: [email protected]
>Message-ID:
> <[email protected]>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Greetings,
>We are currently running a 144V pack with a Curtis 1231C-86xx (96-144V spec)
>and ADC Motor and "all systems are go". We would like to increase our range
>by adding 2 more Optima D31's in series, thereby increasing the nominal pack
>voltage to 168V. Is anyone out there running the same controller beyond the
>specified input voltage? Will it handle the increased potential? Any
>insight is greatly appreciated.
>
>Martin Emde
>Seabury Hall
>www.seaburyhall.org/engineering
>
>

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Let me try to explain why 144V pack is really the absolute max
you want to run this controller at, in case someone may be
tempted to try adding one more battery to get to 156V:

After charging a 144V pack, even after waiting several hours,
the batteries can still be at 13.25V each, total 186V for the
pack.
The internal component for the Curtis are very likely the
standard 200V type, which would leave 14V of headroom or
so it seems - enough to add another battery?
I recommend you find a high-speed memory oscilloscope and
hook it up to the motor output, preferably hooking it up
right at the pins coming out of the FETs, then try a tiny
bit of trottle and see what the voltage does.
The theory says that you should see a square wave output to
the motor, switching from pack voltage to ground many times
per second. But that is theory.
What you see in practice, is that the voltage across the FET
rises not to pack voltage but many volts higher (overshoot),
then quickly comes back and levels out at pack voltage.
The reason it does that is because the supply and the load
have inductance, causing the current to flow a little longer
after the voltage has disappeared.
Dependent on how short or how long the wires between the FET
and the nearest capacitor is, dependent on how good this
capacitor is, dependent on how fast the current switches and
dependent on how large the current is - that overshoot can be
easily be up to 10% of the switching voltage.
Now add that to the pack voltage of a freshly charged pack:
186 + 19 = 205V.
Do you see that the Curtis is already in the danger done from
breaking down its FETs in a large ball of smoke, simply from
the overshoot spikes every time the FETs turn off (many
thousand times per second) on a 144V pack, so they do not
need you to push them over the edge by adding another battery
and peaking them to 220V on a 200V part...

Hope this clarifies,

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
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Dave (Battery Boy) Hawkins
Sent: Thursday, October 11, 2007 4:02 PM
To: [email protected]
Subject: Re: [EVDL] Curtis 1231C-86xx @ 168V

Martin and All,
I had written the response below earlier today, but decided to wait for others to chime in. Unlike Lee's Halloween voice, I'll be that other dark voice that says, "it is OK", but:

I'm thinking that this should not be a problem, IF you have a contactor on both sides of the battery pack to remove the controller while charging, which you should have anyway. A charger for a 144V pack could peek at 194V (2.7 VPC), so they use 200V components in the controller, and label it as 144V maximum pack voltage. A charger for a 168V pack could peak at 227V, which could injure the controller! Also, just after charging, you must make sure that the pack voltage has dropped below 200 volts before precharging the controller!
Hope this helps...
Suck Amps,
BB

>Date: Wed, 10 Oct 2007 14:26:24 -1000
>From: "martin emde" <[email protected]>
>Subject: [EVDL] Curtis 1231C-86xx @ 168V
>To: [email protected]
>Message-ID:
> <[email protected]>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Greetings,
>We are currently running a 144V pack with a Curtis 1231C-86xx (96-144V
>spec) and ADC Motor and "all systems are go". We would like to
>increase our range by adding 2 more Optima D31's in series, thereby
>increasing the nominal pack voltage to 168V. Is anyone out there
>running the same controller beyond the specified input voltage? Will
>it handle the increased potential? Any insight is greatly appreciated.
>
>Martin Emde
>Seabury Hall
>www.seaburyhall.org/engineering
>
>

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Cor, could you re-look at your math here? 13.25 * 12 = 159V for a 144V
pack. 186V is 13.25 for a 168V (14-battery) pack.

Bill Dennis

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From: Bill Dennis
> Cor, could you re-look at your math here? 13.25 * 12 = 159V for a
> 144V pack. 186V is 13.25 for a 168V (14-battery) pack.

A better way to look at it is that your charger will take each 12v battery up to about 15v at the end of a charge cycle. 12 x 15v = 180v. If you leave your controller connected while charging, it is exposed to this full voltage. Even if your controller is disconnected while charging, when you stop charging and start to drive, the battery voltage won't have had time to fall much, so the controller still gets hit with most of this.

--
"Excellence does not require perfection." -- Henry James
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

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