Replacing an SRM battery... at home :o)

Discuss light weight issues concerning road bikes & parts.
joeturner
Posts: 3
Joined: Fri Dec 23, 2011 10:43 pm

by joeturner

I just replaced both batteries in my sram s975 SRM, and everything seemed to go smoothly. The zero offset was right around where it had been before the thing ran low on battery, so it seemed alright. I took it out today, and 95% of the time, everything matched the numbers I was getting with my other SRM. But every once-in-a-while, the power numbers would about double for a bit (5-6 seconds), and then go below what I knew I was doing, and finally settle back around where I expected it. When this happened, I would go re-zero it, and the ZO was almost exactly what it had been before. Normally, I would blame this on the garmin trying to auto-zero it when it shouldn't, but that never happened nearly this often. On longer stretches of around constant power, this happened a lot less often, it seemed more frequent with stop-and-go.
I'm wondering if anyone's seen something like this after replacing batteries?

EDIT: Here's a screencap of what happens. The cadence data is fine, but the power spikes up for around 2 seconds, and then down to 0 for one, and then back to normal.
Image

by Weenie


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micky
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Joined: Thu Sep 21, 2006 8:57 pm
Location: Vicenza
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by micky

Hey guys,
I've got a friend who needs to replace the battery on his PCV (see picture attached) and I told him he can use a normal battery but he's worried cause there's 3 wires; anyone can help?
Thanks in advance!

Image

Squint
Posts: 240
Joined: Mon Oct 10, 2005 9:23 pm

by Squint

It looks like they added a diode. I wonder if they also severed a trace on the PCB.

I've always just used a cylindrical CR2-sized lithium ion battery with a round PCM at its base. It fits a lot better and gives you a lot more battery life. I only connected two wires, the red and black.

I guess if it was me I would desolder the diode and try with just the black and red wires. If it doesn't charge then put the diode back.

WeightySteve
Posts: 293
Joined: Wed Jun 09, 2010 10:44 am

by WeightySteve

I had 2 PCV's. One had the Diode, one didn't, so don't suppose its too important.

My guess is it's probably there to stop the battery discharging back into the charger or wiring harness in the event of a short circuit.

Do what Squint says, its what I did.

alvagro
Posts: 1
Joined: Sat Aug 22, 2015 12:52 pm

by alvagro

Hello to all,
are an athlete handbike Italian, I would like to replace the battery on my SRM handbike but can not open it, there are no cracks of any kind. can anyone help me?

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ms6073
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Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Not sure exactly when SRM changed the design or if this applies to the Dura Ace or Campagnolo SRMs, but when I changed the battery on my early 2013 Hollowgram SRM last month, I noticed two changes from the earlier models. First, the removable cover that protects the PCB had been moved to the outboard face of the spider, not the inboard/torque ringside. Second, although I already had the old style Keeper LTC-7PN-S4 batteries on had, the ones that I found installed were from a different manufacturer - Harris AN/PRC-152 HUB Battery lithium LTC-7PN-S4 w/ leads & plug) - and would not have required soldering.

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Michael - The Anaerobic Threshold is neither...

rma
Posts: 165
Joined: Mon Apr 21, 2014 9:17 pm
Location: Belo Horizonte, Brazil

by rma

Maybe a little overtopic but my ROTOR 3D+ SRM (still with plenty battery life) has a fractured locking. Zero offset is normal and the readings are stable. I get a click from this part whenever I stand up on the pedals. I have spare lockrings, Loctite, lockring tool, vise, torquimeter and so on. I'm afraid to loose the factory calibration (don't have the tools to perform calibration here). Should I exchange the lockring myself? If so, what's the recommended torque? Thanks

el condor
Posts: 524
Joined: Sun Jan 16, 2005 1:52 pm
Location: Switzerland

by el condor

Does anyone know which battery being used in the spider of a dura ace 9000 srm? I get low readings in the rain/after the rain, cadence reading is ok, or could be the zero offset that much off?

clm2206
Posts: 206
Joined: Wed Oct 24, 2007 6:56 pm

by clm2206

rma wrote:Maybe a little overtopic but my ROTOR 3D+ SRM (still with plenty battery life) has a fractured locking. Zero offset is normal and the readings are stable. I get a click from this part whenever I stand up on the pedals. I have spare lockrings, Loctite, lockring tool, vise, torquimeter and so on. I'm afraid to loose the factory calibration (don't have the tools to perform calibration here). Should I exchange the lockring myself? If so, what's the recommended torque? Thanks


I have a 2012 Campy SRM, and reed switches are sticked with mounting tape to the mainboard. If they get loose, they can click every time the magnet pass close to the switch.

el condor
Posts: 524
Joined: Sun Jan 16, 2005 1:52 pm
Location: Switzerland

by el condor

Since I got some problems with my SRM Dura Ace 9000 I opened it up to have a closer look. It's running with different cells than the srm's I had or know,even though the cells item number is on the rear side and since the battery is sort of glued in I'm still reluctant to take it out to see the model of the cell and it's capacity.
Opposed to most SRM Cranks the DA9000 version has the lid on the outside, in order to access the electronics, the crank arm will have to be taken off and there's a small groove to place a screw driver to pop the cover out.
My problem is-while riding in the rain, after some time the power reads zero, only if I push hard I get some numbers (approx. a fifth of the what it should read), had this now for the second time-but always when riding in the rain, I noticed that the zero-offset is "zero" when checking while riding-(coasting), and if in "manual" mode it can't be set as it remains zero
When dry it works perfectly again. I noticed that this SRM crank has a small hole in the front just under the crank arm close to the center, can only be seen when the crank arm is off, and on the inside (other side of the hole)-there's a sort of membrane (White circle on the picure of about 10mm's). Guess this is to regulate humidity like the holes in bike frames. Now I'm wondering whether this causes to enter humidity while riding in the rain.
I will try to do some rain sessions with the hole taped off and see what happens.
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ms6073
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Location: Houston, Texas

by ms6073

el condor wrote:It's running with different cells than the srm's I had or know

Those are Eve ER14250 1/2AA 3.6v 1200mah batteries with tabs welded on each terminal that have damn small 32awg wires soldered to the tabs on the battery and a JST SH 2-pin nano connector that plugs into matching plugs on the PCB. Two guesses why/how I know that? :oops:

el condor wrote:I noticed that this SRM crank has a small hole in the front just under the crank arm close to the center

It sounds to me like the inner or outer o-rings which seal the cover from the elements are worn and need to be replaced, but my SRM is presently on the workbench with the cover off, but I did not notice a hole like that in the outer cover so I will have to re-check.
Michael - The Anaerobic Threshold is neither...

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pritchet74
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Joined: Tue May 30, 2006 10:38 pm
Location: NorCal

by pritchet74

Does anyone have pics of a D/A 7950 SRM with the cap off? I can't sort out how to get mine off.
Have you ever wondered if there was more to life, other than being really, really, ridiculously good looking?

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ms6073
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Location: Houston, Texas

by ms6073

I would think it would require removing the chainrings then un-screwing the 5 flat head screws which should allow you to lever a sharp edged instrument into the split in the torque ring to remove the cover:

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Michael - The Anaerobic Threshold is neither...

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pritchet74
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Location: NorCal

by pritchet74

This is mine. No screws and no spot to easily put the screwdriver in there. Any ideas?

Image

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Have you ever wondered if there was more to life, other than being really, really, ridiculously good looking?

wetpaint
Posts: 82
Joined: Sat Feb 06, 2010 2:55 am
Location: USA

by wetpaint

Some were glued together, my 1x SRM on fat bike doesn't have screws and is glued on per SRM

by Weenie


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