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

Discuss light weight issues concerning road bikes & parts.
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JimboP
Posts: 14
Joined: Wed Mar 17, 2010 3:52 pm

by JimboP

@kimaswan: did you find the problem?

I replaced the battery as described above in my crank and it worked fine for a couple of months.
then suddenly at the end of the ride it went dead.
No power, no zero offset, no cadence.

I thought it might be wiring unit, so I got a new one. Still didn't work.
The PCV was due a new battery and I didn't fancy fiddling with that one so got it done by the SRM agent. Still didn't work.

I carefully took the white cover off to check the battery contact wires hadn't come lose.. Looked fine.

So, I guess I'm looking at sendin it back to SRM which could be costly. It's an old second hand unit so not sure if it's worth the money it'll cost to get it fixed. :?

by Weenie


mcknightp
Posts: 13
Joined: Thu Jun 18, 2009 7:00 am
Location: Mosman, NSW. Australia

by mcknightp

JimboP, suggest while you have the PM off the bike, take a spare wiring harness if you have one, plug it into your PCV, press the mode button to wake up the PCV, then run a wheel magnet or similar over the speed reed switch & see if it registers speed. If OK, then rub the same magnet backwards & forwards over the white cover of the PM where you can see the internal reed switch, this should trigger the reed switch & give you a cadence number on the PCV if the PM & cable are ok. Ideally you should use a cable you know is GOOD. If you do get a cadence reading doing this then it's just a simple sensor positioning issue. If OK, then repeat the rubbing while the PCV is in the Zero Offset mode & check the ZO. You can use this to determine the "range" of where the sensor will & will not pick up a frequency. If this doesn't work then & the new PM battery only went a few months, you probably have a bigger problem in the PM that is draining the battery prematurely.

Phil

JimboP
Posts: 14
Joined: Wed Mar 17, 2010 3:52 pm

by JimboP

Phil, you are a star!

Looks like the old harness is indeed faulty. I'll need to raise the cadence/power sensor on the new one as it won't register anything when it's flush to the bottom of the bb. The sensor is quite a bit smaller than the old one which could explain it.

Many thanks! :beerchug:

mcknightp
Posts: 13
Joined: Thu Jun 18, 2009 7:00 am
Location: Mosman, NSW. Australia

by mcknightp

Hi JimboP

If you are using the "new" under BB style sensor it is only suitable for the newer 10sp SRMs & not the older 9sp ones. The reason is that the older units have the sending coil wound around the very outside of the white disk & the newer ones have it wound around closer to the centre of the white disk. Here's a pic that may help you with an idea of how to mount the sensor if this is your prob. Let me know how you get on.

Cheers, Phil
Sensor Mounting Pos NEW.jpg

JimboP
Posts: 14
Joined: Wed Mar 17, 2010 3:52 pm

by JimboP

Sounds precisely what the source of the problem is.
Old unit, new wire harness.

And thanks for the piccie. I'll get it back on the bike at the weekend.

Scarpa
Posts: 72
Joined: Wed Sep 13, 2006 3:43 pm

by Scarpa

So does anybody have the Batterie name of the PC5
and where i can find it! Really hard to find

mcknightp
Posts: 13
Joined: Thu Jun 18, 2009 7:00 am
Location: Mosman, NSW. Australia

by mcknightp

I have some of these. Exact same specs as the original SRM batteries. You can buy them from me. US$10/battery +$10 postage for any qty 1-10pcs. Let me know & I can send you a Paypal request.

Cheers, Phil

snorre
Posts: 68
Joined: Sun Oct 30, 2005 2:41 pm

by snorre

Hi! I'm thinking of changing the battery in my Dura-Ace SRM at home, since the whole process of sending the crank all the way from Norway to Germany is expensive and VERY time-consuming (2 months last time, and a lot of phones and mails to both SRM and the custom-authorities...)

I contacted a domestic batterystore about the battery, but they didn't have the exact model in store... They came up with this: http://www.altitec.no/index.php?main_pa ... s_id=13383

Do you think this will work with my crank?

Thanks.

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

by Squint

As long as it's close to 3.6V and physically fits in the available space, it should work. I've used batteries very different than the originals in the past.

2 wheels
Posts: 4907
Joined: Tue Mar 21, 2006 12:56 am

by 2 wheels

snorre wrote:I contacted a domestic batterystore about the battery, but they didn't have the exact model in store... They came up with this: http://www.altitec.no/index.php?main_pa ... s_id=13383

Do you think this will work with my crank?

It has the same voltage (3.6 V) and use the same LiSOCl2 (Lithium Thionyl Chloride) battery chemistry, so it should work. It's just a question if it will fit or not.
Have you checked if your SRM use the rectangle or round battery?
Altitec list all the dimensions of the Sonnenschein Lithium - SL340/P at their website, so we can compare them to the dimensions of the original Eltrochem 3B880 battery, which can be found here: http://store.batteryspecialists.com/3b880.html

At the pictures belo, the dimension's for the Eltrochem 3B880 on the left are in inches and the dimensions for the Sonnenschein Lithium - SL340/P on the right are in mm, so the numbers have to be converted.
The original battery has a height of 0.297'' (7.54 mm); the other one is about the same height (7 mm).
The original battery has a diameter of 1.001'' (25.4 mm); the other one is a bit smaller (22.8 mm).
So the Sonnenschein SL340/P should fit in the hole, but since it's a bit smaller than the original you will probably have to glue it so it won't rattle. Try with a bit of hot melt glue or silicone. Don't use epoxy, then you will probably not be able to remove it again.

Image Image
Last edited by 2 wheels on Tue Jun 15, 2010 7:51 pm, edited 2 times in total.

snorre
Posts: 68
Joined: Sun Oct 30, 2005 2:41 pm

by snorre

Thaks a lot! :D
Then I think I'll give it a go with the battery they had in store.

2 wheels
Posts: 4907
Joined: Tue Mar 21, 2006 12:56 am

by 2 wheels

Please not that the original Eltrochem 3B880 battery has a capacity of 1000 mAh, and the Sonnenschein SL340/P only has a capacity of 400 mAh. So the Sonnenschein will only last approx 40% of the time the original Eltrochem 3B880 will last.

Have you checked that your SRM use the round battery and not the rectangular?
The rectangular LTC-7PN-S4 battery is only 0.65'' (16.5 mm) wide, so the round battery won't fit in the rectangular hole.

Image

Image

mcknightp
Posts: 13
Joined: Thu Jun 18, 2009 7:00 am
Location: Mosman, NSW. Australia

by mcknightp

Hi 2wheels

In that pic with the 2 rectangular batteries, are both those connected to the circuit board? What type of PM is it? Cannondale BB30? I've heard that the Wireless uses 2 of the rect batts in your pic, can you confirm?

Thanks, Phil

2 wheels
Posts: 4907
Joined: Tue Mar 21, 2006 12:56 am

by 2 wheels

The pictures above have already been posted by others earlier in this topic, I justreposted them to show the different batttery shapes.
Look here for the original pic with the rectangular battery, posted by coloclimber: viewtopic.php?p=591862#p591862

by Weenie


kimaswan
Posts: 102
Joined: Mon Feb 18, 2008 10:15 am
Location: France, Bordeaux

by kimaswan

Hi, does anyone know the name of the battery that is in the powercontrol PCV ???
Does anyone already tried to change it by themselves ????
It seems the battery is maintained with a kind of glue.

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