Date: Mon, 19 Jun 2017 23:39:55 +0000
Reply-To: Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Subject: Re: Don't yell at me but I tried led H4
In-Reply-To: <78DF87E9-F9A1-4ED0-94C4-5D0DC4C9F8F4@shaw.ca>
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Hi Alistair,
Thanks for your very detailed study of the LED beam pattern and actual power consumption on your blog. I take it that you did not notice any dimming of the LED headlights over the past six months?
A comment on the specs you reported in the blog (copied below): The 4000lumen rating seems optimistic. Most LED's produce 70-100lumens/watt, so with 16.5W in, there would be about 1500 lumens from each headlight.
A regular H4 light (55/60W) puts out 1000-1500lumens. Since you found that (except for the light color) the LED had similar brightness to the previous H4 bulbs, they likely have similar lumen outputs.
Thanks again,Martin (82 and 85 Westies)
On Saturday, June 10, 2017 9:32 AM, Alistair Bell <albell@SHAW.CA> wrote:
Hi,
Yes I'm still running those bulbs. Just as an aside, my full write ups on my blog (https://shufti.blog/ and use the search box on the right with search terms h4 led) goes into detail why I chose those particular units.
One thing I haven’t mentioned before is my puzzlement with what the data sheet says. It states, and it does not specify if this is for the pair or a single, “input power L/25W H/25W”.
Ok then, let’s see if we can make any sense of that. On low beam only the cup shrouded led elements are powered up. That’s half of the available elements on the bulb. And on high beam all the led elements are powered. So how come the wattage figures remain the same?I hooked a bulb up to a power source and ammeter. The current draw varied with input voltage. At 14V the current measured 1.20A. At 10V the current measured 1.10A. But curiously, at 11.5V the current measured 1.47A. My power source only goes up to 15.5V, at that setting the current was 1.10A.That was for high beam, low beam values very similar.So a couple of things strike me. One is that the current draw had a peak at 11.5V and dropped of on either side of that voltage. Must be something to do with the power regulating circuits in the bulb, I bet it’s obvious to those with a bit of electronic knowledge. The second things is that the current draw was pretty well the same for both high beam and low beam. So that goes a little way in explaining how the spec sheet claims 25w for both high and low beam.
But do my measured values even come close to the spec sheet values? Let’s take the 14V reading, 1.20A. (1.20A)(14.0V)= 16.8WThat’s a fair bit from 25 isn’t it? Again it’s not clear if the spec sheet is for one bulb or two. If it’s for two then doubling measured value for one bulb would give 33.6W. Closer to 25W but come on…
> On Jun 6, 2017, at 1:31 PM, Poppie Jagersand <poppie.jagersand@yahoo.ca> wrote:
>
> I'm planning to try LED headlights. I already have the 7" Hella H4 buckets, so just need bulbs.
>
> Alistair, I was curious how your H4 LED bulbs have held up over the past months? Is the light output the same? Some years ago I bought LED tail light bulbs for the Westy. They were bright initially, but dimmed within a year. Have had same problems with some other LED bulbs.
>
> What are others long-term experiences with LED headlights? I calculated that over 100,000km switching to LED would save about $200 in gas (assuming 70% efficient alternator and specific fuel consumption of the engine at 300g/kWh). So converting my Westy and the wifes Toyota Matrix would potentially save $400 - price of bulbs.
>
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