RE: [force_ev] Re: Force still dead
When you pull the big plug, measure the pack voltage at that point. I
wonder if there is enough power getting to the DC to DC, have you measured
the voltage at that point. Since it comes on but then goes away. I wonder
if there is a loose connection on the input of the DC to DC that is not
allowing enough current flow to the DC to DC.
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From: Earl Killian [mailto:force_ev@...]
Sent: Wednesday, January 15, 2003 9:17 AM
Subject: [force_ev] Re: Force still dead
David Roden (Akron OH USA) writes:
> Date: Tue, 14 Jan 2003 02:52:45 -0500Yes. The AH meter does eventually come back to normal, though
> From: "David Roden (Akron OH USA)" <roden@...>
> By "LCD display" do you mean the amp-hour counter?
sometimes it takes hours.
> Does the charger act normally?Hard to say. Plugging it does something, but I'm not sure how much.
The green light on the dash starts flashing, for example, but it
doesn't eventually go solid after a while to indicate a full charge.
The yellow light in the trunk comes on and the green one flashes.
> What happens if you turn on the ^headlights^ with the ignition ^off^?The same thing: the electrical system goes dead and then AH display
> With the ignition on, can you get any heat from the heater (I'mNo, everything is dead when I turn on the ignition.
> assuming you have the standard electric heater)?
> What happens if you pull the big plug between the controller andI'll have to wait for it to come back to life after the headlight test
> the battery pack, then try to turn on the ignition?
before I can answer that.
I was once able to drive it for a minute after I unplugged and
replugged some cables, however the problem started again the next time
I tried to drive it. I.e. it is slightly intermittent.
When this first happened, I measured the voltage at the orange plug
around 180V. Kevin thought this was high, but not unreasonable. Now
I measure it as 34V. That does not sound good! I guess the batteries
have been discharging.
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- If you measured 180 volts across the pack at some point, I hope it was right
after charging. It wouldn't make sense otherwise. (Orange plug? My car
hasn't any orange plug. Is that the one that goes to the DC:DC converter, or
the one that goes to the controller? Or something else?)
I'm assuming this is pack voltage on that orange plug. If that be true, and if
you are now measuring 34 volts across a 144 or 156 volt pack, there's a
^major^ problem. Either the pack is severely over-discharged (and probably
damaged as a result), or you have a loose connection OR at least one junk
battery in the pack.
The amp-hour counter will keep working down to around 10 volts or so, and it
uses only a tiny amount of current. This means that if you have a very high
resistance connection (or battery) in the pack, it'll still deliver enough current
and voltage to operate the amp-hour counter ^until^ you put another load on
the pack. That could indeed be the load presented by the DC:DC converter
when you try to use anything in the 12v system. When you do that, the
resistance causes the pack voltage to go to nearly zero, and the amp-hour
counter quits entirely.
Have you checked all the interconnects between the batteries? One or more
might be loose or damaged. Battery terminals can loosen over time because
of lead creep. Be sure to also check the cables going from front to rear
battery boxes. Also check the connections to the shunt and main fuse (look
inside the front battery box). It might even be a burned or melted post on one
of the batteries; this happens sometimes when a terminal loosens.
As mentioned above, it could be one or more really bad cells or batteries.
Connect a voltmeter's negative probe to the most negative terminal of the
battery pack. (You'll need to add an insulated extension so you can move
the meter to reach the other end of the pack.) Turn something on to apply a
load, and touch the positive probe to the positive terminal of that battery. It
should read around 12.8 - 13.2 volts. Move on to the positive terminal of the
next battery, and see if the voltage increases about 13 volts. Then go on to
the next positive terminal and see if you get about 13 volts more. Keep going
and testing at each point for that ~13 volt increase.
Be careful! Wear rubber gloves, protective clothing, and safety goggles. As
you proceed the voltage gets higher and higher, up to 144 or 156 volts. This
can give you a very unpleasant and dangerous jolt.
If the problem is in the pack, you should eventually find the point where the
voltage you measure drops drastically instead of increasing. By visual
inspection and probing around the battery terminals with your meter, you
should be able to determine where the problem is.
If the batteries and interconnects all check out, keep following the wiring and
testing at every terminal until you locate the problem. I would suspect that
you'll spot it pretty easily as it's apt to have evidence of considerable heating.
Of course I could be way off on this; long distance diagnosis is always a
challenge. But it does sound like you have a main battery pack problem.
Akron OH USA
- I spent half of yesterday working on the my Force with Kevin Doherty
of Solectria (who had been up in Napa working on a Solectria bus).
We eventually found that one of the pack fuses (the front one
unfortunately) was bad. It wasn't completely open, it had a
resistance of 2K ohms or so, so that I would read 170V at the power
connector going to the motor controller one time, and 34V another,
depending on the current.
We unfortunately got distracted by the fact that the DC to DC
converter was crackling, and went so far as to open it up, and tried
all sorts of tests (this despite the fact that it had been tested on
the bench at Solectria and returned as ok). Apparently a low voltage
to the converter will cause crackling.
So there are two things to watch out for in future.
Now I have to wait for Solectria to send me a new pack fuse and DC to
DC converter (or to reseal/retest the one we opened) before I will
know if it is really fixed.
> We eventually found that one of the pack fuses (the front oneWhoa. Hopefully this will get you going again. Good thing to file away for
> unfortunately) was bad. It wasn't completely open, it had a
> resistance of 2K ohms or so, so that I would read 170V at the power
> connector going to the motor controller one time, and 34V another,
> depending on the current.
future reference! Thanks for the report, Earl.
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