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

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Slack
Posts: 206
Joined: Fri Dec 27, 2013 11:37 pm

by Slack

ms6073 wrote:
Sat Feb 27, 2021 1:11 am
While I no longer own an SRM, when we had DA 9000 models - both of which were purchased new from an SRM distributor - we got nearly 2.5 years out of them before sending them to SRM US for battery replacement and firmware udpates and even then that was really out habit more than due to any issues. Given that the seller sounds less than reputable, it is possible there is an issue with a PCB that is causing the battery to drain in which case, you would need to contact SRM. My guess though is that the seller misrepresented the conditionof the SRM nor had it actually been proferssionally serviced. A quick way to check would be to pair it with a Garmin or similar head unit and check the About screen which would show the firmware that is installed and compare that with what SRM says is the latest.
Where do you find what is the current version for the PM? There doesn't seem to be a logical path or place to find it on SRM's website.

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PinaRene
Posts: 856
Joined: Mon Feb 12, 2007 12:08 pm

by PinaRene

I replaced mine last year March, and it still works fine.

I soldered the 2 new battery's and it workes fine ! It is quite easy , just mounting back the backplate is the hardest part because of the 2 rubber seals. The read out without torque wass constanly ( 505 Hz ) just a bit lower than last year ( 508-518 Hz ), so I was going to calibrate the thing, incl. adapting the slope if needed. I did made a Excel file with all needed variables that can be filled in. After that it will calculate the new slope.

If the difference is smaller than 2,5 % - fill in the the new meassurement. If it is bigger than 2,5% but smaller than 5% - do the meassurement again to see if things are correctly, and if the meassurement is constantly bigger than 5% ship the SRM to the factory for a complete check. If someone needs the Excel file I can sent it to you, here is a screenshot. As you can see it will do an average of 2 ( Zero torque ) and 3 ( Load torque ) meassurements and it will calculate new slope - difference between new and old ( raw value and in % )

Now one year later PC8 tells me battery is still new - it works perfectly - and there are no drop-outs.

To fill in :

* Used weight to check 10 or 20 Kg or ( needs to be calibrated - I used 10 Kg )
* Crank lenght
* Zero toque read out left and right
* Measured toque under load left and right
* Old slope reading from last calculation or factory setting ( In my case 21.7 )

* Sorry it is in Dutch, but can be changed.

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Slack
Posts: 206
Joined: Fri Dec 27, 2013 11:37 pm

by Slack

So after fitting the new batteries yesterday and having a battery report of good on the head unit I thought I was in the clear. Unfortunatley this morning I got 2 low battery warnings, once when I turned the head unit on and one on my ride, so I thought there is probably a battery drain issue. I've just finished riding and the battery is back reporting as good so I think I'm just going to have to wait it out until they're dead and see how long they've lasted.

Coolcat
Posts: 70
Joined: Tue Apr 06, 2021 7:21 pm

by Coolcat

Any advice on getting the lid off SRM DA 9000? I have taken the PM7 off the crank arm and taken off the small torx screws for the lid.

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ms6073
Posts: 4289
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Been a couple years, but you remove the front cover which is press-fit in place of an SRM DA 9000. If you use a magnifying Iglass or the camera on your phone on 2-3 x zoom you will see very small indentations which can be used to lever a small flat blade screwn driver under the cover to remove it.
- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"

markc
Posts: 194
Joined: Thu May 17, 2007 2:23 am

by markc

Gang... been doing DIY battery changes for many years. On the newer SRM PM's the battery is soldered to pigtails with a small white two-pin connector which presses into a small socket on the PC board. Have been browsing electronics parts catalogs to try and identify a part number for the connector and pigtails -- anyone with better electronics skills able to help with a part ID for the connector?

Thanks,

Mark

MichaelK
Posts: 452
Joined: Wed Jul 04, 2018 4:50 pm
Location: London, UK

by MichaelK

Mark, measure the distance between the two contacts on the connector. I haven't seen it myself, but Im guessing it'll be something like a JST SH or XH connector.

Coolcat
Posts: 70
Joined: Tue Apr 06, 2021 7:21 pm

by Coolcat

ms6073 wrote:
Wed Nov 04, 2015 6:58 pm
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.

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ms6073
Posts: 4289
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Thanks @Coolcat. Forgot I had posted that after messing up that very connector.
- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"

markc
Posts: 194
Joined: Thu May 17, 2007 2:23 am

by markc

Thanks guys! I thought it might be a JST but wasn't certain.

I've used the larger JST male and female pairs in the past for custom shimano Di2 harnesses and battery packs.

Cheers!

markc
Posts: 194
Joined: Thu May 17, 2007 2:23 am

by markc

Thanks guys! I thought it might be a JST but wasn't certain.

I've used the larger JST male and female pairs in the past for custom shimano Di2 harnesses and battery packs.

Cheers!

sqber
Posts: 42
Joined: Sun Dec 21, 2008 12:51 am
Location: Tallinn
Contact:

by sqber

After watching and reading about replacing SRM batteries, I found this battery in AliExpress.

The instructions I have seen all show how you must use soldering iron to first remove the wire from the old battery, cut the terminals of new battery and then solder the wires to the new battery. The battery I found today, already has a wire attached, but my question is - is the plug attached to this battery compatible with the female part on SRM power meter? If so, it is purely the matter of swapping, no soldering or cutting anything. Seems sweet.
Thanks!!

Bfriesen
Posts: 46
Joined: Wed Feb 26, 2020 5:20 pm

by Bfriesen

sqber wrote:
Fri Apr 01, 2022 11:19 am
After watching and reading about replacing SRM batteries, I found this battery in AliExpress.

The instructions I have seen all show how you must use soldering iron to first remove the wire from the old battery, cut the terminals of new battery and then solder the wires to the new battery. The battery I found today, already has a wire attached, but my question is - is the plug attached to this battery compatible with the female part on SRM power meter? If so, it is purely the matter of swapping, no soldering or cutting anything. Seems sweet.
Thanks!!
I ordered the same battery when I replaced mine. I can't say for certain for all SRM units, but for my SRM Dura-Ace FC-7800 I had to cut the leads off the battery and solder directly to the PCB in the unit. As far as I'm aware, they're all directly soldered, no connector.
2020 Cannondale Supersix
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uraz
Posts: 116
Joined: Thu Dec 12, 2013 9:48 pm

by uraz

Compact Cannondale Hollowgram SRM PM7. Even it's 110 BCD it has 2 batteries inside.

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Last edited by uraz on Mon Apr 18, 2022 10:24 pm, edited 1 time in total.

by Weenie


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RyanH
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Location: Los Angeles, CA
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by RyanH

It depends. Left is a Cdale 130bcd pm7, right is a compact pm6.

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