Do Dimmable Bulbs Last Longer? - Page 1
Forum section: electronics / general

author: Mattyuk
author_rank: Newbie
timestamp: November 23, 2023, 05:02:22 pm
content: Hi AllI can't seem to find this discussed anywhere online - I was wondering if anyone had a view?Question - all other things being equal, is a dimmable led 230v bulb likely to be more robust ie. last longer or be better protected against voltage spikes etc. than an equivalent NON-dimmable bulb used in the same lighting circuit? Please assume the lighting circuit is a standard UK domestic circuit and does NOT have any dimmer switches on it.eg.https://www.screwfix.com/p/lap-0324784031-gu10-led-light-bulb-345lm-3-6w-10-pack/463ppvs.https://www.screwfix.com/p/lap-0318784030-gu10-led-light-bulb-345lm-3-6w-10-pack/186ppOr conversely does the extra electronics in the dimmable bulb to make the bulb dimmable make it MORE susceptible to failure ie. last less time?All views welcome. Experience or theory.

author: Zero999
author_rank: Super Contributor
timestamp: November 23, 2023, 06:35:27 pm
content: If the lamp is dimmed, then it should last longer, otherwise I wouldn't expect there to be a significant difference. It will be the same as anything else. A crap lamp, with overpowered LEDs and inadequate cooling won't last as long, as one with under-driven LEDs and excellent cooling.I would thought going for as higher lumens per watt as possible, would result in longer life, because less heat will be produced and the LEDs are more likely to be under-drive, as efficiency is higher, at lower current densities. The lamps discussed in the original post have a similar lumens per watt, which isn't great by today's standards. I would recommend looking for something more efficient.

author: tooki
author_rank: Super Contributor
timestamp: November 23, 2023, 09:17:05 pm
content: Given the OP’s specification that the question is whether a dimmable bulb will last longeron a circuit without a dimmer, I would hazard a guess that it statistically might fail a bit more, since it requires a much more complex circuit to detect the duty cycle and adjust the power to the LEDs. With that said, I would also be very surprised if the failure rate were meaningfully higher, given that other factors (like how hot the bulb is designed to run, how much ventilation is available, etc) surely have a far larger impact.

author: Whales
author_rank: Super Contributor
timestamp: November 23, 2023, 09:52:42 pm
content: It depends on the exact failure mode of standard (non-dimmable) bulbs and exactly what has changed in the dimmable units.Is it because of electrolytics drying out in a high-heat environment? I've seen vented electrolytics in some failed CFLs. I've not had any compact (bayonet/edison) LED bulbs fail yet to have a look at them.The dimmable unitsmightneed a better switchmode PSU in them to withstand the wider variety of duty cycles. Perhaps they have better or bigger caps as a result? Or a higher operating frequency and/or efficiency? In that case they _might_ last longer.Regardless: I'm lead to believe the best choices you can make to increase bulb life are:(1) Run them very well ventilated, ie not inside a glass/plastic enclosures (like a lightshade)(2) Run multiple, smaller wattage bulbs in a multi-way adaptor. I run 2x adaptors in edison screw sockets.As a vague approximation: the Arrhennius equation says that for every 10degC you reduce of operating temp the life is increased by 2x.

author: Mattyuk
author_rank: Newbie
timestamp: November 23, 2023, 11:57:12 pm
content: Thanks all. It sounds like, unless there is a fairly standardised method that manufacturers would use to make their bulbs dimmable, this might be too hard a question to answer as there may be too many variables to know for sure. But thanks for the input regardless!

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 24, 2023, 12:13:38 am
content: Exactly.

author: wraper
author_rank: Unknown
timestamp: November 24, 2023, 12:38:01 am
content: For the price premium of dimmable bulb you can buy a better quality non-dimmable bulb. A good quality indication is lm/w figure (brightness in lm divided by power consumption in W). High power consumption with subpar brightness means that LEDs are driven hard. It's better to buy bulbs with lowest power rating for particular brightness. I personally would avoid any bulbs with less than 130lm/w. EDIT: although in GU10 form factor it's not that easy to find high efficiency bulbs.

author: amyk
author_rank: Super Contributor
timestamp: November 24, 2023, 03:05:48 am
content: Being dimmable rules out a capacitive dropper supply, which in my experience has been the most reliable type (although the linear regulator ones are close if not run at their limits), so I'd say a dimmable one is more likely to fail due to the increased complexity alone.

author: Zero999
author_rank: Super Contributor
timestamp: November 24, 2023, 08:42:04 am
content: if you can sacrifice some brightness, then buy a much brighter bulb than you need and hack the power supply to reduce the current. It's as easy as changing a resistor, if it's a linear or switched mode, or a capacitor, if it's a capacitive dropper.

author: tom66
author_rank: Super Contributor
timestamp: November 24, 2023, 10:18:58 am
content: Quote from: tooki on November 23, 2023, 09:17:05 pmMost dimmable bulbs use a very trivial circuit. Essentially they omit the large input capacitor that smooths the mains voltage and the buck converter/linear regulator is set up to regulate the current in proportion to the mains voltage.These controller chips are not complicated at all and will likely outlast the LEDs.

author: tom66
author_rank: Super Contributor
timestamp: November 24, 2023, 10:23:46 am
content: On LED lighting in general - I've been using LED lights for over a decade now and have had two fail in my lifetime that I purchased.One was a cheap RGB Wi-Fi smart bulb. The bulb still lit up but it would not 'connect' to anything. It however has become annoying as once it is de-paired you can make it flash for 5 minutes if you cycle the mains a bit too often (putting it into pairing mode). Whomever thought that flashing on and off at 1Hz to indicate "pairing" for 5 minutes was a good idea needs to have their head examined. (I have since removed all Wi-Fi smart bulbs from our home network, we are Zigbee only.)The other one was a bathroom light replacement, a capsule bulb. I bought a cheap one and it died a year later.Every other bulb is going strong.Buy cheap, buy twice. Buy quality bulbs from manufacturers who have a reputation to keep and they'll last a very long time indeed.

author: tooki
author_rank: Super Contributor
timestamp: November 24, 2023, 12:15:32 pm
content: Quote from: tom66 on November 24, 2023, 10:18:58 amAs I said: the added complexity is likely to be overshadowed by other factors. Nonetheless, it does add another, albeit small, theoretical point of failure.