Anyone noticed if Smart rear lights drain their batteries?

davmaggs

I run two rear Smart lights (both bought at different times), but one of them seems to drain its batteries within days so it runs dimly whilst the other one carries on nice and bright.

I thought at first that I might have a duff rechargeable battery (newish Eneloops) in there and so I swapped them out, but I don't think it made any difference. Then I thought that it was because one is the 1/2 watt version (this stays bright), and the other is the 1 watt type (this goes dull). However the specs say that they should both last 100 hours.

I'm now wondering if the 1 watt light is draining power when it is off, some kind of short circuit.

Anyone got any ideas?

spen666

I have that issue as well

cyclingprop

Doesn't sound very clever.

IGMC.

davmaggs

spen666 wrote:

I have that issue as well

Is that the 1/2 watt or the 1 watt version that kills your batteries?

I'm reluctant to start pulling the batteries out every night as I don't think that the casing would wear well with daily opening.

andyrr

Maybe got water in and there is a short ?
Some of the Smarts do seem to be prone to water ingress - I've now taken to smearing the sealing edges with Vaseline plus have wrapped some clingfilm around the light as extra insurance, so far so good. I have found that some lights, and not just Smarts, short-out when they've got soaked and then the light won't switch off at all and I had to take the battery out to dry out the light.

fossyant

They won't last 100 hours. I've never known any rear light do that.

Charge your batteries once a week in a smart charger. The 1 watt will eat more juice than the half watt.

rolf_f

fossyant wrote:

Charge your batteries once a week in a smart charger. The 1 watt will eat more juice than the half watt.

I think those of us who have noticed this appreciate that - obviously, for the same rated batteries, a 1 watt will consume more power than the half watt. The point is (and I get this too with my 1 watts) that whereas a half watt will easily last say 10 hours (which covers me for a weeks commuting and it seems reasonably painless to recharge once a week rather than taking a chance on leaving them on for two or three weeks) a one watt will have lost brightness after about an hour and a half. If a 1 Watt would last a week, I'd be delighted. The half watts are far more useful and adequately bright tbh.

The question is, how powerful are the batteries people are using - mine are 1000 mah Duracels which I don't think are really very good quality.

jimmypippa

My smart 1/2 watt has not had that problem. It is about 4-years old and the switch is getting a bit iffy. However everything else (including waterproofness) is still pretty good.

rolf_f

jimmypippa wrote:

My smart 1/2 watt has not had that problem. It is about 4-years old and the switch is getting a bit iffy. However everything else (including waterproofness) is still pretty good.

It's not a half watt problem (as far as anyone has suggested so far) so you wouldn't have had that problem!

Headhuunter

You sure it's not switching itself on when the bike is parked out of sight? I often find that if my Smart lights get wet I need to remove the batts otherwise they switch themselves on when the bike is in the shed and when I get back to it, the batts are very low or completely dead...

davmaggs

I don't keep the lights in the shed as cold temperatures kill battery power. They sit near the front door, and so I'd notice if they came on.

My plan is to put the Eneloop batteries to one side and fit a new batch this Friday evening to both lights, that are charged to the same value. Then on Sunday evening I will see if there's been any drain.

I also plan to run the lights on fully recharged Eneloops permanently to see how long they last some other weekend. That'll give me a maximum life in hours, which I can translate into numbers of commutes. It may also disprove my gut feel that somehow the batteries are draining power when off.

mudcow007

my smart lights (R1 & R2) eat batteries

i have to change batteries every 2 weeks i reckon

my commutes arnt that long either

meanredspider

Applying very simple power equation and numbers

W = I x V

W = 1W
V = 1.25V
therefore I = 1/1.25 = 0.8A

Say you had 2x 2000mAH batteries

4/0.8 = 5 hours run time

That's probably the best you can hope for. 0.5W ought to be approaching twice as long.

Headhuunter

mudcow007 wrote:

my smart lights (R1 & R2) eat batteries

i have to change batteries every 2 weeks i reckon

my commutes arnt that long either

That's nothing, I literally have to change the batts in my Fenix torch front light every day... They're rechargeable and probably a bit past their best though...

rolf_f

meanredspider wrote:

Applying very simple power equation and numbers

W = I x V

W = 1W
V = 1.25V
therefore I = 1/1.25 = 0.8A

Say you had 2x 2000mAH batteries

4/0.8 = 5 hours run time

That's probably the best you can hope for. 0.5W ought to be approaching twice as long.

That probably makes sense - I'm only using 1000maH batteries on the half watts but they last a good 10 hours - but that is on flash mode. On your calc, 2000maH x 2 on a half watt should run for 10 hours so 1000maH x2 on a half watt on flash mode should also run for 10 hours.

In theory the 1 watt should then last 5 hours but the flash sequence on that is different with the lower two leds on permanently.

Of course, the worst thing about the 1 watt is not so much the battery life itself but that it seems to drop power quite quickly too. The obvious solution for me is to get some much better batteries.

meanredspider

Typically full flash mode uses a lot less power - typically 4-6x less.

My calcs use the "quoted" power (1W and 0.5W) - I have no idea if these numbers are accurate for overall power consumption but are likely to be "best case" for full power mode

rolf_f

Which then goes back to the original point - that the 1W seems to eat power up disproportionately quickly compared to the half watt.

The leds that are on permanently are much smaller and less bright than the main one so presumably they ought not to account for the difference alone. But that is the only obvious explanation.