[BC] Light and Motion Li Ion ARC lamp info
martygoodman
Back in 2002 and 2003, I was involved with analyzing and making the required
minor modifications (determining
polarity and changing connectors on) a NiMH battery-powered Light and Motion
ARC lamps, so that they could use
disposeable, light weight LiSO2 SAFT battery packs on PBP and BMB events.
I posted at the time what I'd learned, along with information Willie Hunt
kindly provided from his analysis of
that lamp system.
I recently got invovled in modifying a more recent Light and Motion ARC
lamp. This one was fundamentally very
similar to the old one, but with slightly different settings for its battery
cut off voltage and warning,
consistent with use of their LiIon battery pack. It also had a slightly
different proprietary connector: Light
and Motion changed from a connector with only two pins, to one with three
pins, on the lamp.
I will here report what I found, for those interested:
Color Code for Polarity:
(1) Light and Motion's new (as of a year ago or so) LiIon-powered lamp (says
"LiIon" on the lamp head) still has
only TWO wires inside its cable. One red, one black. And the red wire
still is the positive wire, the black the
negative wire. There is no data or heat sensing or other line communicating
to the battery pack. The battery
condition indicator appears to work based on the measured battery voltage
(tho it may also involve integration of
voltage change with time... I did not carefully test for this).
Polarity and Pin Assignment for Lamp Connector:
(2) The OLD Light and Motion NiMH-powered ARC lamps had TWO pins on their
proprietary connector. Newer NiMH and LiIon
models have THREE pins. The middle pin is NOT USED, as far as I can tell.
Note that this pin was the NEGATIVE
battery line in the older style lamps. If you hold the lamp's connector so
that its pins are pointing AWAY FROM
YOU, and so that you are looking directly down on it with the ARROW on it on
top (you are looking directly down at
the arrow, which is now pointing away from you, as are the pins), then the
pin on the RIGHT is the POSITIVE pin,
and the pin to the LEFT is the negative pin. Again, the middle pin is NOT
used. This differs from the older
lamps, which had two pins. They were missing that left (negative) pin, and
instead used what on the newer lamps
would be the CENTER pin as the negative battery connection. The positive
battery pin of these older lamps is the
SAME as that used in the newer model lamps.
I note in passing that L&M uses VERY high quality wire in its cable: It
appears to be 18 gauge, and consists of
VERY fine strands... much finer than used in ordinary lamp cord... resulting
in excellent ruggedness and
flexibility. THey also wisely do NOT mess with "curley cord", but instead
understand that the right way to go is
high quality, highly flexible, STRAIGHT cord, that can, if need be, be
wrapped around bicycle frame tubes, or
folded back and forth and neatly tied up with a wire tie or twisty tie, to
be adjusted to the right length.
Test of the Lamp:
(please display the following tables using a NON PROPORTIONAL FONT, such as
Courier!)
The lamp, I am told, goes into low power mode when the voltage gets low.
Also, it was Willie Hunt who analyzed the electronics inside the L&M lamp (I
never was able to open one up) and
assured me... and I've tested this and it clearly in practice seems to be
correct... that although the batteries
used with this lamp are nominally rated at 10.8 (NiMH) and 11.4 (LiIon)
volts, the lamps regulation circuitry can
handle applied voltages up thru 15.0 volts.
These tests done using a bench power supply hooked to the lamp:
Light and Motion LiIon version of their ARC lamp
(bought in 2005 or 2006)
High Power Lamp test:
Volts Amps Watts comments
----- ---- ----- --------------------------------
15.0 0.90 13.5
14.5 0.94 13.6
14.0 0.98 13.7
13.5 1.01 13.6
13.0 1.05 13.7
12.5 1.07 13.4
12.0 1.12 13.4
11.5 1.16 13.3
11.0 1.18 13.0
10.5 1.15 12.0
10.0 1.11 11.1 lamp appears to be switching to low power
9.5 0.69 6.5 green LED flashes very quickly
9.0 0.71 6.4
8.7 ---- --- lamp goes out
NOTE that I did not see the lamp go into its SLOW flashing of the green LED,
which is supposed to be the first
stage of warning of low battery. Perhaps, in high power mode, the voltage
has to be decresaing more slowly for
this mode to work.
Low Power Lamp test:
Volts Amps Watts comments
----- ---- ----- --------------------------------
15.0 0.66 9.9
14.5 0.68 9.9
14.0 0.71 9.9
13.5 0.73 9.9
13.0 0.75 9.75
12.5 0.79 9.9
12.0 0.83 10.0
11.5 0.87 10.0
11.0 0.89 9.8
10.5 0.93 9.8 green LED flashes slowly
10.0 0.97 9.7
9.5 0.66 6.3 green LED flashes QUICKLY
9.0 0.70 6.3
8.5 ---- --- lamp goes out
Compare this to comoparable tables for their old NiMH lamp of a number of
years back:
(note that when testing THAT lamp I didn't yet know it was safe to feed it
15 volts, so the highest voltage tested
will be somewhat lower in these tables that follow)
High Power Mode Test:
Volts Amps Watts comment
----- ---- ----- -------
10.8 1.22 13.2
10.5 1.20 12.6
10.3 1.18 12.2
10.0 1.15 11.5 green low battery warning starts flashing
9.8 1.13 11.0
9.6 1.11 10.6
9.4 1.09 10.2
9.2 1.07 9.8
9.0 .80 7.2 lamp dims, and begins to flicker
8.6 .86 7.4 lamp continues to flicker
8.4 lamp flickers then goes off
Low (REGULATED) Mode Test:
In this mode we tried starting at a somewhat higher voltage than 10.8 volts.
Someone at L&M told Zach that the
lamp should not have more than 10.8 volts applied to it. This is obvious
bullshit. Because their NiMH battery
will invariably apply more than 10.8 volts to the lamp when it is fully
charged and first connected to the lamp.
So just WHAT the highest voltage on can safely apply to the lamp is in some
question.
Volts Amps Watts comment
----- ---- ----- -------
11.5 .93 10.7
11.4 .94 10.7
11.3 .94 10.6
11.2 .96 10.8
11.0 .97 10.7
10.8 1.00 10.8
10.5 1.03 10.8
10.3 1.04 10.7
10.0 1.06 10.6 green led flashes quickly / low bat warning
9.8 1.08 10.6
9.6 1.11 10.7
9.4 1.09 10.2
9.2 1.07 9.8
9.0 .78 7.0 lamp dims and flickers noticeably
8.8 .79 7.0
8.6 .80 6.9
8.4 lamp goes off
I hope folks find this information to be of interest, and use.
REMEMBER, tho, when hacking and tinkering on your own L&M lamp system, BE
SURE to check the information I've
provided! There is nothing preventing L&M from switching to red is negative
/ black is positive polarity (a la
Nighsun's old cables!) at any time!
happy tinkering!
---marty
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