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

[jrennie]

Call SRM and check with them first. If they had a known batch of bad batteries they will replace it for free.

[mcknightp]

Here is a link to a replacement guide I have put together for SRM Powercontrol battery replacement. Pretty simple to do yourself. The poblem here is you cannot buy these custom battery packs from SRM or their agents any longer. I have had some manufactured.

http://www.swerve.net.au/Images/webguide/



Cheers, Phil

[Chirobike]

That's one of the best online DIY guides I've seen yet. Very, very good job. One like that for the spider battery replacement on a wireless SRM would be great.

[GonaSovereign]

Here is a link to a replacement guide I have put together.....

You, sir, are awesome. Thanks for doing this!

G

[slyboots]

Great job, Phil! Very helpful.

[2 wheels]

Very nice step-by-step guide.
I think you should add something about what replacment battery you have used and where it can be purchased.

I think you should also add a remark in your guide about being careful not to short-circuit the red and black wires while cutting and soldering. Especially with the new replacement battery.

5. Small Philips Head Screwdriver: to remove the front/rear cover screws

Not that it matters much for low tourque applications like here, but actually the pictured screws are not Phillips-head screws, but Pozidriv (PZ) screws. For low tourqe apllications like these, mixing PH and PZ screws and screwdrivers will still work ok, but for high tourque applications mixing PH and PZ won't work well.
http://en.wikipedia.org/wiki/Henry_F._Phillips
http://en.wikipedia.org/wiki/Pozidriv

Differences

Phillips drivers have an intentional angle on the flanks and rounded corners so they will cam out of the slot before a power tool will twist off the screw head. The Pozidriv screws and drivers have straight sided flanks.

The Pozidriv screwdriver and screws are also distinguished, visually, by the second set of cross-like features set 45 degrees from the cross. The manufacturing process for Pozidriv screwdrivers is slightly more complex. The Phillips driver has four simple slots cut out of it, whereas in the case of the Pozidriv, each slot is the result of two machining processes at right angles. The result of this is that the arms of the cross are parallel-sided in the case of Pozidriv, and tapered in the case of Phillips.

Phillips (PH)

Pozidriv (PZ)

[2 wheels]

The orignal 110mAh 3.6V Ni-Mh battery pack can be hard to find.
So you can use a slightly smaller 80mAh 3.6V Ni-Mh 'CMOS' battery pack instead. These are more common and can be found in some comupter stores etc.

jrennie recently made a guide on how to replace the original SRM battery with one of these 80mAh packs:
Subject: SRM PCV battery replacement

So my battery died in my PCV late friday and I didn't want to send it in to SRM for replacement. The cost and downtime is unacceptable so I took it apart and tried to match up the battery. I was able to locate an 80mAh replacement(original is 100) at batteries plus for $8 but it can be ordered on the internet for half that. The replacement takes about 10 seconds with a soldering iron. Simply snip off the old battery and re connect the red lead to the + and black to - the 80 is slightly smaller than the original so a wrap of electrical tape keeps it tight in the case. So far it works perfectly. I imagine the stand by time will be reduced by the slightly smaller battery but not by much.

1st picture is the original SRM battery. 3.6v 100mAh
2nd picture is the inside of the case where the battery goes
3rd picture is the battery cells taken out of the shrink wrap.
4th is the battery replacement found at batteries plus for $8(stock internet photo)

In the UK it's sold here for example: http://www.budgetbatteries.co.uk/20498/gp80bvhx3-ni-mh-pcb-mount-memory-batteries-3-6v-80mah
And in Canada: http://www.thebatterypoiint.com/products/GP80BVH3A3H_CMOS_Battery_Pack-497-12.html

[mcknightp]

"2 wheels" asked that I should advise where I got the replacements. I had them made to the original SRM spec.
The other batteries mentioned above as replacement are either Ni-Cd or smaller capacity Ni-MH that will require charging more often & will not last as long.

Cheers, Phil

[Cycloholic]

Very useful guide!!!!
/sticky

[Cycloholic]

Hey Mike i saw that you have broke two cranksets :O
Whats your max power output???

[ElDuderino]

So, after months of the SRM spider sitting on my shelf, I managed to get the battery changed. Nervously checked the sensor afterward for a cadence/power reading......and it worked! woooo for DIY.

Now, I'm having a bit of a tough time getting the plastic plate to clip back in. Any tips on getting this in without too much drama? Vise grips?

[mcknightp]

Do not use anything other than hand pressure to push the white disk back in place. It will tend to try and pop up, but this is normal. Just get it in position as best as possible & then replace the chain rings. The chain rings are actually what is used to hold the plastic disk in place & relies on them to keep the unit water tight.

Phil

[kimaswan]

Hi,
did you read cadence while the battery was down ?
Because my srm cannot read neither the cadence nor the power. I checked with another srm and :
- even with the wires + captor + PCV of the guy, I cannot read anything from my SRM crank.
Don't know if that's a pb with the battery because I think the cadence should work even if the crank battery is down (for the cadence, it is just a magnet I think).

[mcknightp]

No, that won't work, I just tried it on a good PM & a good cable & the magnet will not trigger a cadence reading. You can try replacing the PM battery, but it could be something else. I had an open circuit in the transmitting coil once that had to be re-wound by the local SRM agent here in Aus.

Phil

[kimaswan]

Ok, I also heard that it may be something else (broken capcitor) because I am pretty sure it cannot come from the battery.
I am gonna send it to SRM, and we'll see.