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  1. #1
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    Overvolting by a lot. Will it last?

    I've got a guy here where I work wanting me to torture test some batteries. He told me that they were 14.4 volt LiOn but seem to put out about 15.5v even under load. I'm thinking that I'll give them a try with an old 12v MR11 Halogen system that I have and see how they work overvolting. It is a dual bulb bar mount, I'll run one bulb and have another as a spare. Any idea how long the bulbs will last? Will I make it out of the parking lot? It looks like probably around 10% of normal life according to a couple of places I've looked. Is anyone overvolting 12V bulbs by this much?
    What do I want to be when I grow up.....Dead!

  2. #2
    Spanish biker
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    Uffffffffffff, 15 volts to a bulb of 12v I think that if you apply this 15 volts to the lamp this blow...

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    msxtr
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  3. #3
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    There was a post somewhere of a guy running his 12v lights with an 18v battery pack. Might have been in the pond scum thread.

    BM
    "I've come to believe that common sense is not that common" - Matt Timmerman

  4. #4
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    Quote Originally Posted by bmadau
    There was a post somewhere of a guy running his 12v lights with an 18v battery pack. Might have been in the pond scum thread.

    BM
    I don't think I posted my experience but I had done that when I was first putting together my pond scum light. My AA rechargables weren't quite ready, so I used some AA Alkalines (not realizing the 1.5v and 1.2v difference ) I ran the light for about 30 minutes....it got HOT and the batteries were quite toasty as well. The bulb still works, but I wouldn't suggest doing it on a regular basis.

  5. #5
    I like Monkeys
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    According to the guy supplying the batteries they will probably drop to around 14.4v pretty quickly. I'm going to give it a shot anyway. I don't use the lights anymore since they use a SLA battery that's toast. If they last 50-100 hours or so which is 5-10% of normal life or so that would get me through the season. Cheaper and brighter than new batteries, it looks like he may give me the battery permanently, if that is the case I'll probably use it for an achesalot LED build.
    What do I want to be when I grow up.....Dead!

  6. #6
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    Hi, heres an article about overvolting.
    http://www.myra-simon.com/bike/lights.html#overvolting
    I think your light will last a few hundred hours, go for it

  7. #7
    Its got what plants crave
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    I run a 14.8v lithium ion battery on a bulb designed for 12 volts. I have several rides on it with no problems, it's bright and the battery lasts forever.

  8. #8
    I like Monkeys
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    Quote Originally Posted by Jim311
    I run a 14.8v lithium ion battery on a bulb designed for 12 volts. I have several rides on it with no problems, it's bright and the battery lasts forever.
    The coworker showed me the site where he bought the batteries for testing. It was all-batteries.com and on the page for the 14.8v battery that I have it indicated the battery was for bike lights, both halogen and HID. So I'm good to go. Even at 10% of normal life I should get 1-200 hours out of the bulb. Thats a couple of years of weekly night rides in the winter. No worries.
    What do I want to be when I grow up.....Dead!

  9. #9
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    Li-ions would be 14.8v (peak voltage will be 16v+). That is what I use now on all of my 12v halogen lights. I haven't had a bulb burn out yet, and one bulb is about 5 years old. Before the 14.8v li-ion, I was using 14.4v nimh.

  10. #10
    I like Monkeys
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    Thanks, that makes me wonder why everything isn't overvolted. 100 Hours with a bulb I can get for less than 5 bucks online is a steal.
    What do I want to be when I grow up.....Dead!

  11. #11
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    I have been running a 20 watt 12V halogen at 14.4 V for a long time now and I haven’t had any problems at all.
    Bulbs are dirt cheep too...
    Last edited by Snowdawg; 12-20-2007 at 01:58 PM.

  12. #12
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    The life expectancy is = (battery voltage / bulb voltage) ^ -12

    For a 15.5 v ---> (15.5/12) ^ -12 = 0.046 or 4.6% of bulb life


    so, if the bulb is rated for 2000 hours you should get around 92 hours



    (i'm not an expert.... just a intraweb formula I found)

  13. #13
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    Worked like a charm so far. A lot more light than 12 volts and no problems. I think that will be the permanent setup for me.
    What do I want to be when I grow up.....Dead!

  14. #14
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    I'm overvolting an old Niterider w/ a 6v 20w bulb. My battery is a monster. 9.6v D cells. I'm sure it won't last long but it cranks out the lumens!! It's a 12 degree spot. It lights up a good 50 feet down the trail and very bright too. Lots of spill as well.

    Anybody know the approx. lumens it's putting out.

    MB

  15. #15
    Doesntplaywellwithmorons!
    Reputation: DeeEight's Avatar
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    Actually a fair number of brands do overvolt (vistalight did it for example), but usually its only by 10-20%. But that's not exactly a lot. Try 100% over like I do on one of my lamps.. now that's a LOT.
    I don't post to generate business for myself or make like I'm better than sliced bread

  16. #16
    Singletrack Daydreamer
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    When I first started playing with overvolted 20w MR11s I was using a 14.8v 4.0ah battery (16.8v fully charged) and it kept tripping the amperage limit control in the battery every time I hooked it up. I finally used two 1 ohm 10w resistors run parallel and it was adequate to control the warm up (which draws more juice than simply running). After it was warmed up, it ran the light just fine... well fine for something that was brighter than the sun. Just about that time I started playing with LEDs and lost interest as the LEDs were vastly more efficient. But still, dollar for dollar, overvolted halogens are the way to go if you don't need super long burn times.
    Train 'til you puke. Cheat to win. Party like a rockstar. We miss you, Jan!

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