Legacy Cytronex NiMh 12 pin wiring. Info thread and a story


1 GW
Nov 27, 2010
49.17303, -2.05354 Jersey, Europe
Just had the misfortune to have to look at a Cytronex bike , a kit built on a nice little Cannondale

Motor labelled as 180W 36 volt front motor, geared
Three magnets on RSH of motor and sensor on the crank
Unknown controller looks 6 FET, stuck under th bottom bracket.
two nice little switches on the bars, one for power on off on the RHS and light switch on the left. Lights come built on to the system
Did not even look for crank or torque sensor..I doubt it.

Battery NiMh 30s1p 3.6 Ah 18660 sized cells.
max current drain probably 4-5 amps max.

Basic operation..hit the RH switch and red light comes on and power is applied when pedalling, no power level control..but at this low power level, not an issue.

My first into to this bike was when I saw it parked out side a local store..with no drip loop and motor axle fitted 'upside down' funnelling water to the motor.
I pencilled a not and stuck it to eh bike saying it was wrong and it would fill with water and scrap the motor.
No reply for the not.

T a year or so later..they come and see me ..motor making funny noise...

Well I rebuilt the motor, as best I could ..ratchet mech is small balls and ball point pen sized springs. Springs rusted away. Replaced them. and greased it up. still sound like a bag of nails in a coffee grinder..but it worked.

It came back to me last week.

Motor trash again..no surprise there, plus battery now dead

Looked at Battery, nickel straps on NiMh cells had popped off..water in battery. Replaced them recharged but one string of cells dead.

Ordered new motor from Cytronex UK. Eventually ...they would not supply me directly with out speaking to the customer first.
Basically they offer no or little support for their product. They did help, Sam replied to e-mails very quickly and was extremely pleasant, but without actually telling me anything ..as it is their policy not to support their older products. They would not give me any info like like LVC/HVC, what the PCB in the battery did etc etc...I think actually they have not idea themselves..

So ordered new cells. easier than building a Lithium pack and BMS worries, new charger etc...so ordered same physical size 4.5Ah Sanyo SDK NiMh cells from Strikalite in UK. Basically 18650 NiMh cells old were 3.6Ah, these 4.5 I think...pack is 30s1p. Jeremy and Roger who run the business..father and son I believe, are the most helpful people you coil imagine. I just bought cells form them to re pack a pair of old yamaha PAS bikes too. If you are in UK and need cells built up as a pre tabbed up pack they are the best!

Motor arrived...after a Special delivery Guaranteed Next Day delivery ..that took a week. UK post office opens the pack and decide that an e-biek motor breaches Dangerous Goods Regulations and has to be shipped sea freight, not air freight. ..Wrong! Gauss values no where near the figures quoted in DGR regs!
Any way it arrived..I laced it up, and re pack duh bottle battery with new cells.

All appeared OK...but bike would not run :shock: Spin the pedals ...motor no go...light on handle bar came on, headlights system worked..but no motor.???

So took the battery pack apart and started probing with the DMM.
PCB in the bottle pack had no power on any pin (Gnd Vin Vout)..most odd..this has to be the problem

Cytronex would not help or give any info at all..apart form offering a £38.50 diagnostic charge for 30 minutes of phone chat, but they did admit that even with that they'd not be able to help as they outsource all their repairs.

A post on ES Facebook and Pedelecs forum confirmed fact the board was a DC-DC convertor.
So WTF..why have your 5volt reg for the throttle etc outside the controller..msot odd..but they did say it was a custom controller.

Any way I went to bed, dreaming of wiring and the horrid 12 pin bottle connector that I could not get out the bottle to access properly. My thought was that maybe if the DC-DC convertor was dead, no 5 volt line to the speed sensor on the front wheel. I could check that..

By next morning I realised that the DC-DC convertor was probably not the 5volt line for the controller, but was probably the DC-DC to run the headlights. It also occurred to me I had not put the front brake cable back in the V-brakes..so it was probably a Brake Cut out switch that was the reason the bike did not run.

So I got up all keen the next morning...

So with the pack dismantled but plugged in to the bike I turned on the lights, they worked and DC-DC convertor had power. So I had discovered what the PCB did..but there was no brake cut out switch on the front brake so that still did not explain why the motor was not running.
The bike was in the lowest gear, so I wondered if there was torque sensing on the crank..so i shoved it in to biggest sprocket up from smallest at the back and with the bike still on the service stand, spun the pedals..The bike motor spun up too :D :D :D

Then I went back to easiest pedalling gear...and motor spun up too ? eh ? did not work before ...Then a light came on in my brain...no front brake switch..but is there a rear one...Yep..that was it all along...doh ! Muppet some little brake switch under the rear brake lever handle..Coudl be reed with I did not examine it ..but some times it needs a flick to release the Cut Out.

So by then I had already traced al the wires on the bottle battery 12 pin plug.

So attached is the pin out to this horrid little plug should any one else have the misfortune to need to work on one of these.

Three other items apart from the DC-DC lighting PCB within the battery pack:

Charging thermistor, think it was about 12k at ambient, connected between one of the central pins of the plug (Pin L) and battery ground
Main fuse, did not un shrink wrap it to see what it was..Cytronex sell them for £40..so maybe some fancy electronic reset device. It is in series within string of cells, stuck to the outside.

White 7 amp 250volt charging fuse/device, yellow wires, one connected to Batt Positive, the other to blue wire and Pin K

Here is a link to their Legacy part section

A few pics of it etc for reference



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