I have a Lupine Wima front light with a Lupine 6.8Amp-Hr battery. I'd like to get a Dinotte 400R tail light and power it from the Lupine battery (using one battery to power two lights)--the Lupine charging system is excellent has enough capacity to power two lights. The 400R is normally powered by a lithium battery and has a voltage cut off of 6v.

Do you see any problems with proceeding with this kind of setup?

I don't really have any idea.

I can tell you that if you had a 400L front light and a 400R tail light, and a 4 cell Dinotte battery, they will even sell you a splitter that would let you power both off the same battery.

Personally, I actually found it easier to just use 2 batteries than the mess around with running a cord to the back of the bike though.

Off hand, any two lights that are drawing from a single power source will draw different current.

It is likely that the tail light would draw more current. If you need to run the lights for a short period it's probably no big deal. But as the battery drains, the head light will dim first unless for some reason the Dinottee regulating circuit produces more resistance than the Lupine head lamp. (unlikely)

Supposing both lamps have dual value regulating circuits you could have unexpected results. By the way, my old Dinottee lights do more than a simple "cut off" at 6V. The actually maintain a near constant wattage across a range of values.

At the point where the Lupine would dim, wouldn't the voltage of the battery be sufficiently low to set off the Lupine's various low battery warning lights? Specifically: First Warning at 7.2V, Second at 6.5, the Reserve at 6.0 and off at 5.4?

Secondly, what are the consequences of two lights drawing different currents? Doesn't this happen when two different models from the same brand are powered from a single battery?

Thank you for the information.

The reason the lights draw differing current is because electricity is like water with respect to "resistance."

In theory, even two identical lights may draw differing currents simply because of imperfections, or the mounting and temp of the light emitter or the length of the cord they attached by.

I don't know how these led light regulators work, but the "voltage cut off" levels are functions or "results" of two other variables - current and resistance. And in the case of Dinotte, there "current cut offs" as well voltage controls. (short circuit protection?)

What I can safely say is - powering two lights will affect each light's regulation circuit. Whether or not you notice it when reading voltage only. (this part is not BS) And then of course there may be an on-battery protection circuit that will not be affected.

The unexpected results part - which is BS - means that one light or the other may go into power saving mode prematurely, and battery run time may seem unpredictable.