Question about B&M LUMOTEC IQ Cyo T Premium senso plus + battery

Ciclista

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Aug 15, 2016
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Hi, I post here because I've been told that there are some very knowledgeable people around here. My question is: have any of you had real life experience powering a LUMOTEC IQ Cyo T Premium senso plus with batteries? I ask this because I'm going to do an all-night bicycle ride and would really like to use this light, but for various reasons can't use my dynohub wheel.
B&M instructions for Cyo T say:

"The headlamp is intended for powering with dynamos (AC voltage) only.
If you require a special E-bike version of the headlight for DC voltages from 6 to 42 V, please contact your specialized dealer.
When powered by DC voltage, the polarity of the connection has to be reversed: mass connected to +, current connected to -."

For Cyo (non T):

"Connection to rechargeable battery
If you connect the headlamp to a rechargeable battery (entirely at your own risk) make sure to observe correct polarity, i.e. "plus" to the earth inlet and "minus" to the current inlet. Maximum brightness is attained at a voltage range between 7.2 and 7.5 V (7.5 V must not be exceeded)."

To me this isn't clear at all. Would some B&M expert advise me? Thanks.


 

znomit

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It's not clear from that if the T model will blow up or not when connected to DC. Please let us know. :popcorn:


This is what I found with my old Cyo (not T, and not premium)
You wire up the tail light connectors to the battery. Its brighter if the white striped wire goes to +, but it works if you reverse the wiring too, just dimmer and about 1/3 the current draw.
:thinking:
The Voltage vs Current data from my Cyo:

V mA
8.0 170 (don't try this at home)
7.5 140
7.0 120
6.5 100
6.0 80
5.5 66
5.0 52

The brightness seemed to follow the current. I thought the Cyo ran the LED at 700mA which would mean its only drawing about half the current needed off the battery. The LED cooling plate never got hot so I'm going to speculate that B&M say 7.5V max because at that voltage the light will not overheat with no cooling airflow.

If you're using a common double 18650 pack then the nominal freshly charged voltage is 8.4 so you'll need to burn off about a volt at 140mA to feed the light 7.5V. Use a 7Ω resistor for this.
 

Ciclista

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Thanks znomit! I appreciate your data but I'm interested in this particular Cyo T Premium type.

It's not clear from that if the T model will blow up or not when connected to DC. Please let us know. :popcorn:

That won't happen... I'll connect it only if reasonably sure it won't blow up. :D
This light is hard to get where I live, and I don't want to put it at risk.
 

Ciclista

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Finally decided to go the safe way - disassembled my 700 dynohub wheel and built the hub with a 26" rim. Only cost were spokes, since I had the rim already.
 
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