External battery solution for MTE P7 flashlight- Mtbr.com
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  1. #1
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    External battery solution for MTE P7 flashlight

    I wanted to be able to connect an external battery pack to my MTE flashlight for longer runtimes & a lighter package on my helmet. I didn't like the idea of making irreversible changes like drilling a hole into the body.

    This is my solution. Its not quite a finished work yet, but it is useable for now.
    I'll let the pictures tell the story.

    The light with the tailcap stripped
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/ocH_DGMiY_344NHoSygaHA?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh3.ggpht.com/_F6ejuoULyLI/SoU7aDCZgCI/AAAAAAAAOSQ/Pz6dpuskB0M/s400/DSC06983.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    The donor cable from an old... actually I don't know where it came from, but I found it in a box "junk" in my garage.
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/VL4Ay3YXrd5ncW5tGZmuWQ?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh5.ggpht.com/_F6ejuoULyLI/SoU7b6Is1YI/AAAAAAAAOSU/8blbCFOfmhA/s400/DSC06985.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    Some pieces of irrigation pipe which are the same diameter as an 18650 cell.
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/zM2uFN_WWdraV3x0uXZv1w?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh5.ggpht.com/_F6ejuoULyLI/SoU7cqUFnyI/AAAAAAAAOSY/SPDSPHFxP9s/s400/DSC06986.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    I used a a Crayola marker as the "dummy cell" with a screw on the end for the + terminal
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/ggmem-K1kFxWaeGJwa0TYg?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh6.ggpht.com/_F6ejuoULyLI/SoU7dkuKA2I/AAAAAAAAOSc/C_m7l9Mnz9g/s400/DSC06989.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    The cable with the + lead fed through the dummy cell
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/yZmZvD82APgilYe8EjB8JA?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh4.ggpht.com/_F6ejuoULyLI/SoU7euBw1NI/AAAAAAAAOSg/V8o-qFctCDc/s400/DSC06990.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    I sawed a groove into the screw to make a slot to attach the + cable. I crimped the cable in place with a large pair of pliers.
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/1GHvxSwEBnMUfvLFtvVpTw?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh3.ggpht.com/_F6ejuoULyLI/SoU7fdLsdqI/AAAAAAAAOSk/bQEUop7gtsE/s400/DSC06995.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    Then soldered it for good contact
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/jDhZ0wrIvfdEfceRu0M8vw?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh6.ggpht.com/_F6ejuoULyLI/SoU7gJgs27I/AAAAAAAAOSo/5aWpZgOjxJw/s400/DSC06999.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>
    The + terminal on my dummy cell
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/95f5dUSAZlo1STgNFE2MqQ?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh3.ggpht.com/_F6ejuoULyLI/SoU7g8CqXKI/AAAAAAAAOSs/ROg4147JsGM/s400/DSC06992.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>
    The negative lead coming out the back of the dummy cell
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/yxk2ZVtEf9VEHolMC1OBXA?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh3.ggpht.com/_F6ejuoULyLI/SoU7hiXrplI/AAAAAAAAOSw/V3K4eHlQq0s/s400/DSC06994.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>
    I made a hole in the body of the pen just big enough to feed the negative lead through from the inside. Then I soldered it to a piece of battery terminal connector which was left over from one of my salvaged laptop batteries. I heated up the plate just enough to start melting the plastic, and then let it cool. There are jagged edges on the plate which allowed the plastic to ooze through and once set, it created a nice firm seating.
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/mM2DCWNHwh69Sq9eI9vbuQ?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh4.ggpht.com/_F6ejuoULyLI/SoU7icmRIdI/AAAAAAAAOS0/K6rZm9Jc1Ew/s400/DSC06996.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    The threaded ring from inside the tailcap gets slid on from the front end and the tailcap screws onto the back creating a snug fit.
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/MWtvPQe8AQSBrdBmgBoh6w?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh5.ggpht.com/_F6ejuoULyLI/SoU7odFK2gI/AAAAAAAAOTI/qOEz2tgW3hM/s400/DSC07008.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/ojlUD1RDCauksN9PYg4PNQ?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh4.ggpht.com/_F6ejuoULyLI/SoU7ja81ubI/AAAAAAAAOS4/EvQ8e97q8ew/s400/DSC07001.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>
    My battery pack, made up of 4 x 18650 in parallel. They are enclosed in 2 soda bottle preforms which are cable tied together. Then a female DC socket is soldered to the terminals
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/5ZoPYnkydenTgBNQicqtmw?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh5.ggpht.com/_F6ejuoULyLI/SoU7ksaF75I/AAAAAAAAOS8/ApiKwOfkESQ/s400/DSC07003.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>
    The whole lot connected up together
    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/NUiv-WKa3iIrEpEWQwt5Dw?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite"><img src="https://lh3.ggpht.com/_F6ejuoULyLI/SoU7lxdeY_I/AAAAAAAAOTA/t8TlEKxRk8s/s800/DSC07005.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/bradjackson78/MTEExternalBatteryMod?authkey=Gv1sRgCKTV8Nby8a-RNw&feat=embedwebsite">MTE External battery mod</a></td></tr></table>

    I haven't added a switch yet, that will come later. For now, you turn it on by screwing it together or plugging it in.

    Its possible to return the flashlight to its original configuration just be re-assembling the tailcap.

    I would like to find something to replace the tailcap altogether, that way I dont need to disassemble it to use my external battery.
    Does anyone know of something which has the same thread and can be screwed on in place of the tailcap?

  2. #2
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    Great way of rigging up an external battery pack!
    I want to do something similar.

    Is there some way of knowing if a flashlight can handle the current of a 4x external battery pack? The light I just got is a MTE SF-15 P7 flashlight.

  3. #3
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    The current will be the same, the light will only draw what it needs. However your runtime will double.

  4. #4
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    your runtime will double.
    nah, it will be even better than that ... 4 x runtime!!
    BTW piesoup, your username constantly gives me the munchies !
    ...Scun.thorpe, UK

  5. #5
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    Theres another new thread over here http://forums.mtbr.com/showthread.php?t=546215 discussing the current draw while running a P7 direct drive on a battery pack.

    I did a very rough runtime test last night.
    Starting with a not-quite-fully-charged battery pack (forgot to measure it before I started), I ran it for about 3 hours on full. The battery measured 3.83v in the end before I turned it off.
    The temperature of the light body was no different to running a single cell, and I would say the brightness stayed the same throughout the test.

    I will try do a more scientific runtime test then post my results.

  6. #6
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    Quote Originally Posted by HEY HEY ITS HENDO
    nah, it will be even better than that ... 4 x runtime!!
    BTW piesoup, your username constantly gives me the munchies !
    Ahhh, I thought it was 2S2P! 4 x, thats mega!
    Yeah, i choose piesoup as an email address when I get fed up of hotmail saying that everything else I wanted was taken already! I stick with it as I can type it without looking at the key board! Now I am gettting the munchies!

  7. #7
    aka RossC
    Reputation: ocean breathes salty's Avatar
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    Quote Originally Posted by piesoup
    Ahhh, I thought it was 2S2P! 4 x, thats mega!
    Yeah, i choose piesoup as an email address when I get fed up of hotmail saying that everything else I wanted was taken already! I stick with it as I can type it without looking at the key board! Now I am gettting the munchies!
    A friend of mine was doing his internship at a hospital. He was interviewing a 12 year old morbidly obese child who was type 2 diabetic and around 100kg.

    As part of the interview, he had asked "what is your favourite food"

    The kid replied "pie sandwiches"

    We all thought this was hillarious, then one day we tried one..... the little boombalada was right! They are awesome

    Anyway, enough pie annecdotes. Back to the main show.

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