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A question for the diy light experts. I have a diy made light that uses a maxFlex and single MCE. I'm using it on my commuter with the batteries from my hope vision (7.4V), however I'm find that it cuts out very much quicker than I'd expect (Between 5 and 20 minute runtime). After cut out the light will not restart until the battery is disconnected. If left for a while (10 mins ride time) the light will power back up and run for another 5-10 minutes on full before cutting out again.
My initial theory was that I hadn't charged the batteries properly and they had run out, however I used one of the batteries for a further hour on max with my other light. I'm now thinking that perhaps the driver is getting too hot and is kicking into thermal management mode. However I'd expect that this would reduce light output not flake out completely. Could anyone confirm how a maxFlex behaves when it thermal limits? Or any other suggestions of what to check.
How have you set up the driver, are you sure it's not low voltage cutoff?
I didn't make the light so not sure on that front, will need to check.
It does sound rather like a voltage cut off though.
I've played quite a lot with the bflex driver, which I believe has the same firmware.
The thermal cut-out, if enabled, will reduce brightness, not turn it off completely.
The low voltage protection will turn off the light, but, depending on how it's configured it can either flash the main light to warn you, or flash the status LED (if there is one). Of course, if it's set to do the latter, and there isn't a status LED, you won't get a warning.
A final possibility is that as the battery voltage drops, the current increases and you're tripping the over-current protection in the battery. This is less likely, but possible if the battery current limit is borderline for your light.
I'd grab a copy of the maxflex manual, and have a fiddle with the programming to set the voltage and thermal cut-out modes:
[url] http://www.taskled.com/techmaxflex.shtml [/url]
Thanks, have got the manual printed now so going to play. I want to fit a new lead and connector so going to have a play with the back off and probably add a status led (got some laying around so silly not too). Since the default appears to be alter via status LED I think this could well be happening.
I think I know the answer already however in case I have missed anything is there a way to get the driver to report its current settings?
If it was your final suggestion is the only solution here to generate less load? I.e. turn down the max level at which the led is driven so it won't try and draw to much current.