Revo Full Power Speed

[sean_iow]

At what speed does the Exposure Revo reach full power with all 4 LED's lit up? I've never been as impressed with mine as I thought I would be reading the reviews before I bought it. I used it briefly at the beginning of the year but for various reasons that bike didn't get used all year. It's now back up and running so I commuted to work on it this morning. At 12mph two of the LEDs are at full power but the second pair are only dimly lit and not really adding much. You can see this by holding your hand in front of the light or by tilting the light up and having a look. When I used it earlier in the year it only seemed as bright as my Lezyne Macro Drive I use on my helmet and that's only rated at 400 lumens. It might be that the Revo has a wider spread so the output is better but as the light is broader it appears less bright if that makes sense?

The bike has 650B wheels and 2.35 tires and I've got a Exposure branded SP PD8X hub. I should also point out that it's single speed which limits the top speed on the flat depending upon the gear ratio I run. I realise that you don't get something for nothing and the dynamo can only supply so much power but Exposure lumens are usually twice as bright as other brands so I had high hopes for it. Am I being unreasonable in my expectations or could there be an issue with my light or the hub? I don't know anyone else local with one to compare it to.

Sean

[atk]

About 20km/h? I'm almost certain I'd get 4 LEDs at that speed, even with the RedEye plugged in. Will try and check tomorrow evening.

[GregMay]

20kph all 4 should be on - or at least mine are. Even with a Redeye.

Edit: Mk1 Revo with SP hub.

[sean_iow]

Thanks for the replies, I must be just on the cusp of getting full power at the speed I was going. I'll pedal faster on the way home.

I also have a RedEye and I'm very impressed with how bright that is and how little power it seems to require. When I put the bike in the shed last night I'd ridden it around for a couple of minutes to test it and the stand-light was on. I took the Revo off the bike and left it in my kitchen, the two LEDs were still on dimly an hour later, this was about 22:00 last night, and may have still been on for longer than this. When I got the bike out of the shed this morning at 07:30 the LED's on the Revo were no longer on but as soon as I plugged the RedEye in there was enough power still in the capcitor to light it up so the rear light was on as soon as I started riding

[sean_iow]

I peddled faster on the way home and I get all 4 LEDs properly on at about 15 mph (24 kmh) minimum and maybe a touch more Obviously wheel size makes a difference as it's the speed the hub is rotating at which matters but my 650B with 2.35 tyre is probably a tiny bit smaller than a 29er so should be the same speed or slightly slower than those.

On the way to work yesterday (when it was light) I could check the light output by putting my hand just in front of the lens and seeing the dots from the individual LEDs on my glove. On the way home (in the dark) this technique worked less well as I found out on the first try as it plunges you into darkness, hadn't thought of that before I tried it

It was very foggy on the hills on my journey home and I could see just the 2 beams from the LEDs most of the time even at 13 to 14 mph. Could there be an issue with the output of my hub? It's and exposure/SP QR15 one so reading the reports of other users it's only a matter of time before it will fail anyway

When it was on full power it was more than bright enough and even at half power output I managed to work out where I was going but if it reached full power at say 12 mph that would be better as that's about my cruising speed on the flat off road. Does anyone know that determines the change over? I think I read somewhere that the dynamo is a fixed output with regards to current and the voltage increases with speed? And that the output is a/c?

[Bearbonesnorm]

And that the output is a/c?

Yup, it's actually an alternator rather than a dynamo.

Are the contacts nice and clean? Mine seemingly used to reduce output if they were dirty.

[sean_iow]

Good suggestion, I'll give them a clean up and see if it helps.

[Trail-rat]

Might be a figment of my imagination but mine seems to get bright quicker if it's not plugged into red eye.

[GregMay]

Might be a figment of my imagination but mine seems to get bright quicker if it's not plugged into red eye.

Well it would do...less draw to an external source so there is more going to the capacitor and LEDs.

[Mariner]

Yup, it's actually an alternator rather than a dynamo.

Are you sure its not a magneto?

[Bearbonesnorm]

Are you sure its not a magneto?

I'm absolutely certain.

[Trail-rat]

That's kinda what I was getting at Greg.

It's designed as an off road light . If you need full power off road at low speed -unplug the red eye.it wasn't really designed for road use given its lack of side visibility or beam shaping. Which is a shame - I'd have had them on both my bikes if they sorted that one but they didn't even respond to my email asking if a mk2 was in the pipeline and offering suggestions on how the mk1 could be improved - so I fitted a Busch Muller iqx to my commuter and frankly for road use it pisses all over the revo. In terms of beam shape and usable power , low speed power and the ability to run a toplight senseo out back for idiots on cycle path who can't tell when your slowing down and ram the back of your bike

The only reason I still have the revo is that once the red eyes unplugged it performs better when hikey bike as the standlight is better. - the b+m drops down to 2 be seen LEDs rather than seeing light that the revo manages.

[sean_iow]

I've checked and cleaned the connection at the hub and that hasn't helped. On my ride in to work this morning the 'glove in front of the lens' showed two bright spots and two much dimmer showing at 15 mph (without the red eye plugged in) so I think there is an issue with either the hub or the light - probably the hub.

I bought it for off road use and also wanted a hub to be able to charge things during the day, I'm only on the road for the testing as it's easier to control. Even on the road it's quite hard to spin my 34/20 gearing at 15 mph + (new lower ratio for hills over the winter) whilst riding with one hand just in front of the light and in traffic on an A road

I've managed to track down a friend of a friend who's just got a new road bike equipped with dynamo hub and light. I'll get in contact with him and bicycle my light up to his bike to see when it reaches full power. I'd like to know my hub is producing the correct power as this will make a difference to charge times when used in the day connected a battery bank.

Thanks for all the help, without the BB community I'd still be in the dark about the correct performance from the light and would just think that's what it's like.

Sean

[whitestone]

Get yourself a multi-meter and measure the voltage and ampage that the hub is outputting. According to the SP spec sheet it should be 6 volts and 0.5A but it doesn't say at what speed that the unit will output that. Stick the bike in a stand and spin the wheel as fast as you can

If the hub is working OK then it's going to be the Revo.

[Trail-rat]

[sean_iow]

I've found this on the SP website

[/URL]

Looks like I should get 6v at 15 km/hr. I'll wire in my multi-meter to the power lead to the light over the weekend and head out on some more test rides. I might bicycle up my go-pro to record the meter and garmin at the same time to allow post ride analysis and it will be safer than trying to ride the bike and look at two screens at once.

Edit: beaten to it by Trail-rat.

[sean_iow]

So I set up the bike in test mode, that's the Revo pointing backwards with tape over the front so the LEDs can be seen when on but don't dazzle me (they are on as I rode it round the yard to check it all worked and the stand-light is on), the Garmin is to record the speed (in MPH) and a multimeter set on AC Volts to record the output of the hub. The meter is measuring the voltage across the input wires from the hub to the light. On the left is the go-pro which records both screens and the light so I can see what happens afterwards and concentrate on riding.



Obviously it would be raining by the time I got all this lot on the bars and wired in, so I headed up the road on a test ride. The pic below is after riding a half mile up the road. I was riding at about 10 to 12 mph. I have stopped in a lay-by to turn around for the return journey and the stand-light can be seen through the tape.



The next pic is heading back down the road, the meter shows 15.4V and the Garmin shows 15.4 mph. The second pair of LEDs are on but not very brightly.



This next pic is further down the road, I've been riding for nearly half a mile down hill. We're now at 19.5 mph but the voltage is only 12.1V, the second set of LED's are brighter but not as bright as the other pair.



Watching the video the voltage seems to rise as I accelerate and then it gradually drops off even if I maintain the same speed. I'm not sure I've learnt much, apart from I can't get the second set of LEDs to full power so I think there must be a fault somewhere? Next step will be to contact Exposure and see what they say.

[rufus748]

I was never that impressed with my Revo. I ran it on 29+ though and I assumed that was part of the problem at slower speeds.
I felt like I had to be verging on motorway speeds to get all four to light up, in tests it showed it was about 24mph.
I eventually bit the bullet and bought a K-Lite, pricey but very impressed with it.
With the exception of long slow up hills when I supplement it with my Joystick. I was most impressed on the BB200. When at a reasonable speed I was unable to see the light from the joystick (800lumens) as it was washed out by the K-Lite.

[Chew]

Nothing constructive to say, but impressed by the geekery

[sean_iow]

Thought I'd post an update. I sent the Revo to Exposure who put it on their test jig and there was no apparent fault, it reached full power after a short while at 15mph. From this I assume the jig as actually a wheel with dynamo hub with the wheel powered somehow to get it up to speed.

The light was returned and I used it on an overnight trip. I thought it was brighter than before I sent it off but as Exposure had only run it up to test I couldn't see why it would be.

I set up the camera again an did another test on the commute to work. After less than 2 minutes and only half of that at between 13mph and 15 mph all four LEDs were at full power. I've been comutting on the bike since last week and the light is definitely brighter and powers up quicker. The image below was less than 2 minutes into the journey and the light had not been used for 14 hours so had no residual charge.



Compared to the previous photo after 4 mins at 13mph to 15mph it's clearly brighter. Even at 19mph I didn't get all the LEDs to full power on the previous test. I had to re-wire the hub connector when I removed the multimeter so maybe that could of been it but the previous connection all looked ok so maybe just coincidence. The difference from before I sent it off is enough that I even checked the serial number to make sure I had the same light back. No explanation but I'm not complaining

[whitestone]

Maybe they took it apart to do a quick visual inspection and something got knocked or moved somehow?

[benp1]

That sir, is the law of the sod. Go to the effort of trying to sort it and it sorts itself!

Cracking geekery

[Scud]

Love the "Mythbusters" level of experimentation and geekery.

So would you recommend the K-Lite over the Revo?

I've just had my old Fargo powdercoated and in process of being re-built, always just used a Maxx-D but no have a dynamo wheel built up, and was waiting a while to see if the much rumoured Revo Mk2 would rear it's head but it doesn't seem so, then found the K-Lite at Travers bikes.

[sean_iow]

I've only used the Revo and so I cant compare it to the kLite. I'm sure someone here will have used/seen both in action.

I'm very happy with the Revo. It has a 'floody' beam pattern so it illuminates a good size area of the ground. I've mounted mine on an accessory mount

http://www.wiggle.co.uk/tate-labs-the-b ... sal-mount/

This lifts it above the level of my front harness but also allows me to change the angle on the fly. The Exposure mount has a soft sleeve inside of it to stop it rotating on the bars so it's not possible to move it without loosening the bolt. The above mount being plastic can be done up tight enough so it doesn't move on it's own but can still be moved on the bars by hand to angle the light further up when off road and then move it back down for road sections so as not to dazzle oncoming traffic.