I’ve just got my first ever 501b last week (an XML t6) with 1.4amp driver and OP reflector.
Have modded the torch with Alu foil to help the heat and so far so good.
I’ve been doing a discharge test using a known good Samsung 2800mah 18650 this afternoon (yes, bored and it’s raining buckets!).
I’ve noticed the following and wondered if its normal behaviour of the battery is actually weak?
When fully charged, battery is 4.2v and torch runs at 1.4amps on full, and does look very bright. Measured at the tail cap using my multimeter on amps setting.
After 15 mins on full, torch got hot to touch (expected, have done the foil thing) and battery is at 3.9v, giving 1.1amps on full.
After 60 mins on full, battery is at 3.5v and giving 0.8amps on full
After 1hr 15 mins on full, battery is at 3.25v, 0.35amps (torch a lot cooler, as expected!)
Obviously the light output is going down all the time as the amps drop.
So, I thought the 18650 batteries were supposed to be fairly static in terms of output during their discharge?
Just wondering if this is the same as everyone else (ie torch gets gradually dimmer over the discharge in line with amps output) or if my battery is just a bit knackered!
I just thought that the driver in the torch would have been running at 1.4amp regardless of the voltage?
i have noticed that my blaze and 502b does the same thing, fully charged, the blaze does the rated 2.1 amps, but after the battery drains, for example 3.8v, the output will drop to like 1.65a or so. same goes for the 502b. fully charged batt i have gotten 2.8a, but after some discharging it drops to 2.2a.
also 1.4a is very under driven, i was surprised that mine is driven fairly high when most are usually driven low
So, no doubt it will take 15-30 days to turn up, but maybe it will help resolve the issue. It’s going to put some strain on the battery though for sure!
Edit - have also just ordered from DX one of the 105c drivers, rated at 2800ma which gets good reviews on here, so will also give that a go.
Let me be one of the first to say it's probably your battery ..Do you have another battery ? I've never heard of an xml drop in that pulls only 1.7 on high
Yes, I have a collection of batteries - 3 Samsung 18650 2800s and a load of reclaimed Sanyo ‘reds’ from a dell pack.
I’ve never measured it drawing more than 1.4amps with any of the batteries I have, it’s more the fact that the amp draw rate seems to be dropping in line with the voltage of the battery.
I’d say that your lowering current with voltage is a result of a poorly regulated buck driver. I’ve run across several different drivers with a similar problem.
The linear drivers don’t tend to have as much a problem with current regulation but have the disadvantage of not being able to use multiple cells.
Ok - sounds like I need to take a look at the existing driver to get to the bottom of this. Is there a simple wiki or photos anywhere that shows how to dissassemble a P60 drop in? Clearly I can take the drop in out of the 501b, unscrewing the reflector and outer earth spring, but what next?!
I’m a newbie as well and I’ll be getting my 2 501bs soon. I’m on my phone at the moment so posting links is kind of messed up.
Anyway after google searching “how to upgrade 501b xml” there are a couple neat videos and a picture link that shows proper soldering etc. (Might be from this forum acctually).
Also if you look up “p60 driver upgrades” on this site there are a number of helpful people who offer which driver to use etc.
Hope that helps you and whenever I can get on the laptop (hopefully tonight) I’ll try to get some links for you.
There’s a video of a guy who takes out driver and shows how to connect new one and some various tech specs that I’m not yet familiar with.
I was too with one humdrum, ordinary P60 I got for a friend earlier this year. In a box of 8 of them (most of them underdriven profoundly), one was as bright - if not brighter - than my U2 from Intloutdoors driven at 3.3 amps. He is one happy dude with that thingy! I have no idea how some old T6 does that. Gotta love Chinese quality control variances.
But if the amps are dropping with the voltage, isn’t that a sign of poor (or no) regulation??
