# Serfas TSL-750 problems



## afrizzledfry (Feb 26, 2012)

Yesterday (9/14/13) I bought this light, charged it fully, and then mounted it to my cyclocross bike (fully rigid) for a 74 mile gravel grinder starting at 6pm (first one. Had a freakin' blast, but that's another thread). 

Unfortunately, the light turned off on its own about a dozen times. At one point I was going downhill on a gravel road 20+ mph. Not ideal. Thankfully I had a backup light and was not alone. It did not appear to be a battery issue, as I was able to get it back on. I plan to contact both my LBS and the manufacturer about this to see if they've dealt with it before, but thought I'd post here as well to see if anyone else has had this problem? I'm wondering if mounting it on a rigid bike was the problem. Maybe I should use the helmet mount? It seemed like big hits/vibrations are what caused it to turn off, but know knows.

Otherwise, it is a great light. I'm hoping I can get this figured out- I want to do as many of these gravel grinders as I can.

Thanks,
Thomas


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## Vancbiker (May 25, 2005)

Impacts cause the battery to "bounce" inside the light and lose connection for a split second. Though not on a Serfas, I had similar problems with my first light using replaceable batteries.


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## afrizzledfry (Feb 26, 2012)

A new development...I took the light out this AM and looked at it. In order the remove the battery, the back part of the light (cylindrical shape) rotates clockwise/counter and then disengages. The back had moved slightly, and was halfway between open and locked. I'm wondering if this could have caused the issue. I locked it and then gently hit it against my hand. Was unable to get it to switch off after doing this. Hopefully I've found the cause! Time will tell.


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## cue003 (May 6, 2011)

I am thinking about picking this light up. It is a toss up between the TSL-750 and the Light and Motion Urban 700. Glad you may have figured out your problem. Will the light simply take replaceable "protected" 18650 batteries or are they something else all together battery wise that will only come from Serfas?

Did you cross shop the tsl-750 with any other light before making your decision? How is the beam and what have you seen for real type of runtime?

Thanks.


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## androgen (Apr 28, 2005)

afrizzledfry said:


> the light turned off on its own about a dozen times.


return it for refund ...

i have lights installed on my wheels that run on replaceable AA batteries ( Monkeylectric ) and they don't turn themselves off from vibration. if momentarily losing power from vibration is likely then a proper design will have memory and resume the previous mode of operation after briefly losing power.

bottom line if you're not satisfied you demand your money back.

i don't understand some people who get a defective product then start repairing it etc lol what's wrong with them ? it doesn't work ? GET YOUR MONEY BACK. then buy something else. it's not rocket science. well, for some people apparently it is.

if i were you i would get a NiteRider PRO ...


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## varider (Nov 29, 2012)

cue003 said:


> Will the light simply take replaceable "protected" 18650 batteries or are they something else all together battery wise that will only come from Serfas?


Their old lights use a 18650 that is encased in a special plastic housing. It includes the part that screws into the light and metal contacts. I don't think it will work with just a regular 18650. They aren't cheap either. It's a major minus point on these lights.

The Lezyne lights use regular 18650's.


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## StumpyElite2010 (Feb 3, 2011)

I had similar issue last night with my Serfas TSL 500, but it was my error.
I didn't close the battery cover tight enough.
Once installing the battery, or after opening the cover,make sure to close it a tight as possible
(using a quarter or other medium size coin.)

Over all I have 4 of those lights and used them for many miles - never failed.


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## Cat-man-do (May 16, 2004)

afrizzledfry said:


> A new development...I took the light out this AM and looked at it. In order the remove the battery, the back part of the light (cylindrical shape) rotates clockwise/counter and then disengages. The back had moved slightly, and was halfway between open and locked. I'm wondering if this could have caused the issue. I locked it and then gently hit it against my hand. Was unable to get it to switch off after doing this. Hopefully I've found the cause! Time will tell.


Sounds like you found the problem. If the issue resurfaces ( and you can't figure out whats' wrong ) you might consider returning before the warranty runs out. Just make sure you have a back up when you go out again. At least until you know you have everything under control.


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## androgen (Apr 28, 2005)

Cat-man-do said:


> Sounds like you found the problem. If the issue resurfaces ( and you can't figure out whats' wrong ) you might consider returning before the warranty runs out. Just make sure you have a back up when you go out again. At least until you know you have everything under control.


when i just got into lights i was looking for something that has replaceable cells like a tactical flashlight - i didn't like the idea of shelling out $200 to get an extra proprietary battery and / or charger, and i thought being able to use my NiteCore charger ( that i already have ) and a few $10 cells made a lot more sense.

i thought it is stupid to buy a system where replacement parts cost so much when you can just buy a system that uses generic cells.

i was wrong.

what i didn't realize is that by offering replacement parts at such ridiculous costs as Light & Motion does they are able to offer the light itself at a lower cost. because they don't care if they make the money on the light, or on spare batteries. that's why the Seca Race costs $320 while the enduro costs $500 because they know when you buy the race you will eventually have to buy an extra battery anyway. so the actual cost of the system is $500 and when you buy the Race model you simply make a down payment on the mortgage.

so you're not actually outsmarting anybody by buying a system where you don't need to spend $200 on replacement battery. you're simply paying full system price upfront while with something like Seca Race you're mortgaging the price.

so there is no benefit to having replaceable cells. unless it's a tactical light - because Tactical lights are often used with nonrechargeable cells. when i bought my first tactical light it included something like a pack of 20 nonrechargeable lithium cells with it. i never got to use up even half of them - they died of old age.

but a biker will never use use nonrechargeable cells for a light because we need consistent training. a tactical light maybe might never be used until world war 3 starts at which point you might have boxes on top of boxes of nonrechargeable cells ready to go. but a bike light has a different use pattern so we use rechargeable.

and as long as we never use nonrechargeable cells we simply don't need lights where the cells can be replaced. pointless. all it does is cause problems like this with bad contact, or in case of for example Hokey Spokes lights they have a problem with loud rattling of the cells ( they are wheel mounted spoke lights ).

the standard model used by all reputable makers where you have a light head and a proprietary armored battery pack and a proprietary charger is the right way to do it. all this replaceable cell stuff is nonsense, except in a tactical light that is designed for emergency use.

SureFire actually now makes some flashlights with nonreplaceable batteries - but they are designed specifically for law enforcement, not for any kind of zombie apocalypse. The zombie apocalypse lights still need to be able to take regular 123 lithium cells - all other lights should use custom batteries.


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