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Discussion Starter · #1 ·
Got my 7 UP finished. Its great and bright (pictures later) And I need to feed this hungry thing, but I only have a 6x18650 battery pack from my dual MCE light.
Is it safe to run both lights at the same time from the same battery? Isn't it going to suck to much power on maximum? I don't want my batteries to explode... :skep:

cheers
 

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Your cells are probobly good for 2C call it 4A so you are theoreticaly OK but you want get much runtime and the you will get a lot of voltage sag as well. I would not realy recomend it.

You realy need to say what you driver setup is with a 6 cell in series it is not at all obvious what you have to driver those two lights.
 

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Sergio, is the six cell wired 11.1v or 24v?
Either way it's too high or too low as you want 14.8v for the seven up, having just said that I'm using a 5 cell 18.5v for my seven up.... but then I'm a bit naughty like that

I finished mine a week ago, look forward to the pics, hope you got a better beam than I did as I think I got a crap optic.
 

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Discussion Starter · #4 · (Edited)
Hi yeti

I have the batteries wired, 3S2P 11.1Volt and 4800mAh. Why do I want 14.8V for the 7UP? Maxflex is boosting from 11.1 to the needed LED voltage, well It works good at 11.1V so far.

Guess it's theoretically safe to run both lights, as ifor said, but I think I need a second battery pack to achieve the same runtime. So the recommendation is 14.8V and 8x18650 4S4P?

Here is my 7UP in assembly:
The minidriver to stat led was removed because maxflex already regulates this current and I didn't know.


The 'ON' legend is upside-down, because I couldn't make the button fit in any other way. I will be removing the 'ON' legend anyway.
It was a PITA to work in a small space, and make all electronics and wires fit inside, but it the end it was fun! :D


I am very satisfied about how it looks! I will try to polish the entire body to make it shiny like in the back plate and looking even nicer! :) I also have to make the mounting, maybe tomorrow.


Beam shots tommorow.

The light beam inside the house looks good and well centred AFAICT. Sorry about your optic, maybe you could try to get a replacement from the seller.
 

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Hey Sergio, I do like that switch, I may have to try one next time.

Did the optics fit OK?

14.8v will be less work for the maxflex so it should run a little cooler than with 11.1v.
Looking forward to those beam shots.
 

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Discussion Starter · #6 ·
yetibetty said:
Hey Sergio, I do like that switch, I may have to try one next time.

Did the optics fit OK?

14.8v will be less work for the maxflex so it should run a little cooler than with 11.1v.
Looking forward to those beam shots.
Yes, optics and PCB fit very well. :thumbsup:

That makes sense about the batteries, I'll get a new pack later.

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6 x 18650's should be good for 1.8Ah's each so 6 * 1.8 * 3.7 = call it 40watts, your 7XPG ran at full whack should draw 21watts, 2 x MCE requires @20watts on full power so your just outside you'll get away with the batterys won't draw more than that so they won't pop you'll just lose a small fraction of output.
 

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Discussion Starter · #11 ·
Didn't find time for beamshots yet, and its just raining know...:(
I have tested both lights on full power and its a lot of light! :thumbsup:
But it should last only one hour on full.

I'm thinking about making a new independent battery pack with 8x18650 for the 7UP, it should give about 3hr on full :D
What is the best option, advantages and disadvantages:
-build a new pack buying 8x18650 cells and placing them in a 8xholder, charging them individually when needed on a dual charger, or;
-buying a pre-made battery pack with installed Protection Circuit Module, and charging with a smart charger?
 

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sergio_pt said:
Hi yeti

I have the batteries wired, 3S2P 11.1Volt and 4800mAh. Why do I want 14.8V for the 7UP? Maxflex is boosting from 11.1 to the needed LED voltage, well It works good at 11.1V so far.

Guess it's theoretically safe to run both lights, as ifor said, but I think I need a second battery pack to achieve the same runtime. So the recommendation is 14.8V and 8x18650 4S4P?
Your setup will work with an 11.1 V battery pack... but you'll be stressing the Maxflex to the limits if you run the battery toward the tail end of its capacity.

Yes, the Maxflex will boost from 11.1 V to 23.1 V nominal for the 7-up configuration (based on est. foward voltage of 3.3 v per XPG)... so the issue isn't voltage.

However, there could be a problem with current (amps), especially as the battery gets consumed.

Per George at Taskled:

Step 1: Determine output power

Power_output = Number_of_LEDS * Vf * Output_current

Step 2: Determine input power

Power_input = Power_output/efficiency

For calculation purposes we can assume efficiency will be around 88%

Step 3: Determine input current

Input_current = Power_input / Battery_voltage

Do this calculation for the lowest Battery_voltage you plan to run

Note, Input_current should be around 3A or less for optimal performance of MaxFlex5.

Based on the math - you're over the max recommended 3 A limit for the Maxflex from the start... and you'll easily get into the 4 A range as the battery volts drop. :nono:
 

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sergio_pt said:
Didn't find time for beamshots yet, and its just raining know...:(
I have tested both lights on full power and its a lot of light! :thumbsup:
But it should last only one hour on full.

I'm thinking about making a new independent battery pack with 8x18650 for the 7UP, it should give about 3hr on full :D
What is the best option, advantages and disadvantages:
-build a new pack buying 8x18650 cells and placing them in a 8xholder, charging them individually when needed on a dual charger, or;
-buying a pre-made battery pack with installed Protection Circuit Module, and charging with a smart charger?
Sergio, Charging 8 cells in pairs at a time will drive you crazy each time you want to go for a ride, also the unloading/loading of the battery holder is a pain with 8 cells ( I know as I did it for a while ). There will also be a lot of resitance at each of the 16 unsolderd terminals.

Battery holders a great but I feel are better suited to small packs.

Shame that the ready made packs are so expensive:mad:
 

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Discussion Starter · #15 ·
OK some fast beamshots

Everything off


2 MCE minimum


2 MCE maximum


7XPG minimum


7XPG maximum


2MCE maximum + 7 XPG maximum, sorry this one didn't come out right.


Its awesome to ride both light on high :D :thumbsup:
The 7UP really gets hot fast, maybe it needs a better casing.

I did exposure time of 3 seconds or else you would only see white.
 

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Discussion Starter · #16 ·
Who wants to buy my 7UP light? Now the light is silver shiny polished, everything is waterproof, trailtech connectors are also waterproof, so you are even safe to go deep sea for fishing with it. :D
 

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Discussion Starter · #20 ·
Whitedog1 said:
hey sergio_pt what's the reserve in the auction?
Just want to know if it is worth for me to bid....
That's secret, place a bid you might get lucky or I might give you a second offer.

MtbMacgyver said:
Have you been able to resolve the problem with the driver overheating in this light that you posted over in this thread?

http://forums.mtbr.com/showpost.php?p=6523949&postcount=83
Probably wrong battery configuration.
 
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