battery

[sweet spot]

Oct. 29, 2009: New battery installed.

Reading: 304 ( )

Oct. 31: Same battery.

Reading: 261 ( )

Temps: 50s and 60s (Winston-Salem, N.C.)
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Folks,

I have been a fan of my (wired) Gen III iPro. In fact, I'm pretty certain that two of my friends (40+ racers) will be treating themselves this Christmas to some ibike power meters, possibly in part because of my positive reviews. I have no ax to grind, but I have to say that I am starting to get more than frustrated with the iPro because of the speed with which the battery dies in cooler weather. Although my iPro gave consistent power readings during the summer, it has been terribly inconsistent this fall.

Inconsistency breeds a lack of confidence (in the data).

I have had several questionable readings lately. I have been tolerating it, mostly because I have been doing a lot of easy rides with long hours. But yesterday's numbers were especially frustrating. I went out for my monthly 20-minute FTP test (no fun). Before the ride, I put my iPro outside for a while, before I turned it on, so that it could adapt to the climate. The day before the test, I had even put in a new battery because the old one, which was only a few days old, was down to 274. I then pedaled out to my test road. Before the test, I did another wind cal, in a spot with no wind, and got set to go. Five minutes into the test, while pushing 29 mph on a level road and into a slight but noticeable headwind, I generated for more than two minutes only 178 watts. 178 watts? I'm just a cat 3, but that's not much. It's definitely not what propels a 150-lb rider (174 total weight) at 29 mph on a level road. Bottom line: After a week of tapering, I had to stop the test. Frustrating.

iBike needs to fix this battery problem.

If there is a fix, please let me know. I hope that replacing the battery isn't the only remedy. I have done that --- three times, lately. Within days, it faded below 275. And it faded in weather that isn't even that cold (50s and 60s). I have seen a post in which a rider with mad electronics skills rigged an external battery. Really? Is that the remedy? I simply don't know how to do that, and I wouldn't want to teach myself while tinkering with a $400 product. Shouldn't iBike sell something like an external battery? Or offer some other solution?

When I bought the iPro this summer, I was very happy with it. I gloated about how my power meter cost and weighed much, much less than Brand X while also producing much, much more data during the ride. And I was aware that cooler weather affected the battery. However, I didn't know the weather would affect it this much. Velocomp should post a clear warning that its power meters won't work -- reliably, all the time -- from October to April, or the time of year when a rider really needs a power meter for training.

[rruff]

At those temperatures my wired unit lasted at least 20 hrs. I suspect your batteries might not be so good... maybe. I got an external battery mount anyway, and it seems to last a very long time. Yes it takes a little work to set up, but it is worth it for cold riding. While you are at it you can splice in a wire to read speed from the rear wheel, too.

[sweet spot]

Thank you. You may be right that the batteries might not be so good. I hope so.

Is there a particular brand of battery that you like to use?

About splicing and setting up an external battery: I'd pay someone to do it, but I'm not sure who (bike shop? electrician?) would do the best job.

[rruff]

It's really a DIY thing, but I'd vote for an electrician over a bike shop. VC sells a "kit" that is an open mount that allows you to solder extra wires in. You'll also need an external battery (mine is a 123a) and holder, and wires. I filed a small slot at the front of my stem, and the battery is wrapped in closed cell foam and sits inside there.

I bought a pack of Energizer 2032 batteries off ebay a long time ago... don't remember who the seller was.

[Russ]

Sweet Spot,

Yes the external battery is a DIY thing but, to clarify there are two levels of that on this board.

One is the very low cost method of adding strips of thin copper of brass craft or machine shim stock on top of the mount contacts, pictures have been posted on this board.

Second, Velocomp sells, by special request, an external battery mount kit. I found out by asking that you can get John to supply which ever mount type you want as a kit (I suppose as long as he has parts stock as opposed to completed units). These do require assembly but you can do anything, wiring harness wise, you like with it.

A local electronics repair shop could build it for you (soldering and all) and a bike shop could then install it, though I imagine you would do the installation, since you probably did your current one.

You could also ask and John might possibly build it for a fee, even with rear sensor also for a bit extra.

I got my battery from Battery's Plus and had them spot weld leads on to a CR123 which is I installed early in the spring, still running well down to a 49F ride the other day. I have replaced the battery in the unit once since then, just because it did slowly go down, mostly for off mount usage.

Oh, I had to discuss the packaging with Batteries Plus, they by habit wanted to put head shring sleeving on it in a way that would not allow it to be inserted into my bar end. So I had them remove the first heat shrink and install a piece such that the battery was slid up into the heat shrink in line with the axis of the heat shrink instead of cross ways.

Russ

[rruff]

I bought a holder for the 123 battery... that way it is easier to replace... and wrapped it up in electrical tape.

One very odd thing that happened is that the wind scaling jumped from 1.2 to 3.1 when I did this. On the TT bike (which doesn't use an external battery) the wind scaling didn't change, and the old Gen2 unit reads about the same as always (1.3 scaling) on the mount with the external battery. So the Gen3 is greatly effected by the external battery, and the Gen2 isn't.

Did you notice any change, Russ?

[Russ]

rruf,

I have not noticed a change in wind scaling with my battery but then too, at the time I changed to the external battery, I had not gotten it dialed very well.

It seemed my wind scaling changed after the iBikes one really heavy rain exposure, even after it was dry (it took several days).

I have made some observations about stability of wind offset and that seems to not be affected by voltage. For example, usually I can check the voltage on the mount after a ride and check the wind offset, then remove the iBike and the voltage, esp after a cold ride, drops but the wind offset stays put. I haven't seen it below about 2.68 or so after a cold ride after the removal.

Oh yea, I usually forget about checking the iBike (off mount) voltage pre ride anymore. When I saw the low voltage mentioned above, I observed it warm and still used the same internal battery for awhile.

Russ

[rruff]

I did a test with the old mount and didn't notice a significant effect of voltage on wind scaling... I switched back and forth between a new battery and an old one. Voltage does seem to effect the offset though.

I've also done some experiments to see if temperature has a consistent effect on the offset, and on the Gen3 it doesn't seem to. VC says they attempted to calibrate this out of the Gen3s. The offset does vary randomly though... it isn't unusual for it to change +-3 or so during a ride even when there is no temperature change.

[Russ]

Well, the main source of wind offset change for me is temperature. That said, some explanation.

I have two iBike gen 3's - one pro and one aero. This all goes back to when I had to send my first gen1 back to Velocomp, I bought a second one for backup.

Both of my gen3's were bad about wind offset vs temperature change at first. The firmware update improved both. The aero is probably totally up to what John described in that it should be completely stable from 70F up. My aero is nearly that. My pro seems to be nearly flat or stable from somewhere above 80F and up.

So late day temperature drop rides (my usual) with the pro in the 60's would result in maybe a 2.x to 3.x change in wind offset. The aero in the 60's maybe less than 1 nearing 70 and above to maybe approaching 2.0 nearer to 60. These are not well profiled as I usually correct the offset several times during a ride. But frequently the temperature drops rapidly near the end and I see the larger offsets start to show up.

I'd like to see a feature that tracks the corrections vs temp and builds an internal correction table from real on the road corrections, if that be possible. Thus converging on perfection, or however good it can get, over time!

Russ

[rruff]

My offset varies typically 2-4 during a ride and it is *not* temperature consistent... ie it may go up when temperature goes up, or it may go down. You can do an experiment easily enough by setting your unit under a lamp to warm it to 100F or so, and putting it in the frig to cool it, then bring it back to room temp (repeat).

I'm going start another thread for this, since it's way off topic for this one.

Here: http://www.ibikeforum.com/viewtopic.php?f=6&t=1332