X35 DIY aliexpress solution to dead battery

stevebry

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Mar 11, 2025
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After killing X35 battery on lapierre esensium with a youtube inspired DIY battery extender I needed to consider options. Battery is £650 and must come from importer as it’s coded to frame, fitted is £950 ish with lots of labour and new cables etc (bike shop intimated others are scrapping such bikes). Out of warranty there must be many bikes in similar condition and I couldn’t find credible solutions online. Already having a 9AH cage battery and the knowledge n+1 = optimum bikes I challenged myself and aliexpress to fix esensium DIY and also convert a nice unused steelie, for LESS than a new X35 battery.
I don’t want thumb throttle, I want the closest experience to a road bike that I can as health has led me to ebikes. So ordered a tongsheng tsdz2b 250w for the steelie, and a sutto (bafang) 250w hub motor kit and 15.4 AH hailong type battery, total cost £550 delivered
Was quite a bit of trial and error and some swearing etc, key point is you cannot use Mahle hub (I stupidly/stubbornly wanted to as it had a strong DT Swiss rim build) it partially works then cuts out, presume signals between hub and controller are different (I guess this is why it’s a 9 pin connector there is info on speed, torque and obviously battery power being shared through controller).
PAS being the challenge of many road conversions, I tried hollowtech right side but esensium has a push fit oversize bottom bracket and although I got it partially working it was weak and unreliable. Then thinking PAS cannot be an overly complex electrical signal I reused chainstay integrated Mahle PAS, 3 very flimsy wires soldered and taped up (black/black, orange/white, red/brown) and it’s superb, as good as x35, more torque but otherwise identical riding. I couldn’t find any clear info on web so hopefully this could inspire other X35 fixes.
I’ve fed the cables through the downtube to hide the unused (brake lever sensors x 2 & throttle) connectors, so no external cables between front and back of bike preserves original slick look as best as possible, together with small controller box on down tube.
As to the steelie the tongsheng is outstanding, so easy to install, set-up. So much torque “turbo” mode is silly and is like a Deliveroo rider, other modes equate to X35. Key learning is tightening the bottom bracket nut with the shortish spanner provided, despite lock tight it came loose so used hammer (rag over paintwork) to get another half a turn and put marker paint over nut and bottom bracket so I can see any movement. Bike built 10 years ago, an ebay find of 1980s columbus tubing Dave Quinn, I think son of legend 70s framebuilder Harry Quinn, has modern ish forks allowing modern headset and stem.
Which is better? They’re subtly different, mid-drive steelie so smooth and with single chainring is a tourer with mudguards and big 15.4 AH battery, esensium with double chainset, disc brakes and lighter 9 AH battery is more of a racing type feel. Most importantly I can maintain them going forward and they both have longer range, being my original target to overcome the short X35 range. Thanks for reading. 6239862399
 

Peter.Bridge

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Apr 19, 2023
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Very interesting. My friend (who used to be a semi pro cyclist, now in his 60s) was looking at a Ribble Hybrid AL E (they are on offer at the minute) with the x35 motor for his wife so they could go for rides together (she prefers "flat" handlebars to drops)

He was talking to me and I found a women's Boardman Hub 8.6 (11kg) secondhand (in pristine condition for £200) I did consider a tsdz2, but she is very light and they don't want to go up any really steep hills so went for a hub motor. I've ordered a bare 280rpm akm100 cassette motor, and using Arrow Wheels to build the wheel with the same spec rim. We've actually gone for a 630Wh Panasonic celled downtube Hailong 1 battery (which is quite compact) with built in KT controller, which is maybe slightly over the top but is considerable cheaper than the x35 209Wh range extender by itself !

It will be 2kg heavier than the Ribble, but if you added the range extender there would be less than half a kg difference and a better range than the Ribble (630wh Vs 460Wh)

I think the same approach would work with a drop handlebar bike as long as it had a qr rear axle
 

Bikes4two

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Feb 21, 2020
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Hi @stevebry
Was quite a bit of trial and error and some swearing etc, key point is you cannot use Mahle hub (I stupidly/stubbornly wanted to as it had a strong DT Swiss rim build) it partially works then cuts out, presume signals between hub and controller are different (I guess this is why it’s a 9 pin connector there is info on speed, torque and obviously battery power being shared through controller).
I don't know if you've seen the YT vid by 'Ebike repairs' (link) in that after Mahle X35 problems he successfully re-used the rear hub motor (although some in the comments were unsuccessful) - without know the motor parameter like the number of magnets plus the type of PAS sensor being used, then there would be some trial and error in setting up the KT controller which may account for some people being unsuccessful?

And BTW, the X35 doesn't have torque sensing unlike the newer X20 and X30 which do.
 

stevebry

Just Joined
Mar 11, 2025
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Hi @stevebry


I don't know if you've seen the YT vid by 'Ebike repairs' (link) in that after Mahle X35 problems he successfully re-used the rear hub motor (although some in the comments were unsuccessful) - without know the motor parameter like the number of magnets plus the type of PAS sensor being used, then there would be some trial and error in setting up the KT controller which may account for some people being unsuccessful?

And BTW, the X35 doesn't have torque sensing unlike the newer X20 and X30 which do.
Interesting thanks for sharing, I had such a headache of believing Pas was my issue to finally getting the bafang working I was over the moon. X35 hub was a no go for my knowledge and exasperated patience. Reason I shared is I have no ebike knowledge hence buying x35 in the first place but I've learned and found a solution. Also after botched DIY extender I'm nervous of believing YouTubers who may have had many efforts and failures to come up with their wonderful so quick and easy solution!
 

Peter.Bridge

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Apr 19, 2023
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I don't know if you've seen the YT vid by 'Ebike repairs' (link) in that after Mahle X35 problems he successfully re-used the rear hub motor (although some in the comments were unsuccessful) -
OMG - that's impressive - although I think you could do a much simpler build by just ripping out all the internal Mahle stuff (battery and controller) and fit a downtube Hailong 36V battery with internal KT controller and connect that up to the X35 rear hub motor
 
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stevebry

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Mar 11, 2025
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OMG - that's impressive - although I think you could do a much simpler build by just ripping out all the internal Mahle stuff (battery and controller) and fit a downtube Hailong 36V battery with internal KT controller and connect that up to the X35 rear hub motor
This simplicity doesn't work, x35 motor doesn't talk to controller properly, not for a novice like me, it starts then cuts out
 

Peter.Bridge

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This simplicity doesn't work, x35 motor doesn't talk to controller properly, not for a novice like me, it starts then cuts out
was that with KT controller ? did you experiment with all the motor settings ? eg P1 , P2 number of pulses per revolution, number of magnets ?
 

stevebry

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Mar 11, 2025
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was that with KT controller ? did you experiment with all the motor settings ? eg P1 , P2 number of pulses per revolution, number of magnets ?
Not really it's above my pay grade tbh, fiddled a bit but then as I already had the new wheel it was a no brainer when I realised Pas wasn't the issue Mine is generic controller that came in sutto/bafang kit. Playing around was hampered by manuals for new colour display sw m58 on main websites are for a throttle, brake lever type set up, for a Pas only road set up it's a whole different manual and menu on the computer! Which is very hard to find online but it's out there. Bonkers but this added to headaches...
 
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Bikes4two

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Feb 21, 2020
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Not really it's above my pay grade tbh, ......
That's understandable but TBH in the absence of the necessary knowledge that is most likely why you were unable to get the X35 motor working rather than the motor won't work with a KT controller.

I had a not too dissimilar experience when I acquired a Swytch front hub motor from a dissatisfied owner: the KT settings 'published' in various posting didn't work for me and the 12 magnet PAS sensor was poo-pooed by some, but after wider reading on the function of the various KT controller settings, the Swytch motor runs sweet on what is now my favourite ride.

I'm wondering if like ex-Swytch users, could you sell the X35 wheel 'as is'?
 
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saneagle

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Yes, on the video, I think it mentioned it needed a separate speed sensor
The problem is when you have the wrong speed sensor setting in the controller for the actual speed sensor you have. The motor starts up, but the speed is calculated too high so the speed limit immediately cuts it. That happens when you have 6 magnets in the motor and you have the controller set to one, or you have the controller set to one or 6, but you have no functioning speed sensor. In that case the controller gets the speed signal from the hall sensors, which pulse at a higher frequency, so, again, the controller calculates the speed too high.