SwampRodent

Its kind of the same bike, its a bit like triggers broom every thing has been replaced even the frame when the original cracked. I'm on the 3rd battery, the 1st was a cheap ebay battery that eventually failed after about 5000 miles, the second I build my self which did about 20,000 and was still going strong but got pensioned off and fitted to my AWD snow bike, the current battery is another home made unit. Another reason for charging at work is that the evening charge is finished by bed time so no charging takes place when I'm asleep.

There is a lot of variables involved to muddy the waters, if I'm fighting a 30 - 40mph head wind on the way into work the battery will be way under 50%, also due to the nature of the terrain for the homebound journey the roads up in the hills often get closed due to landslides, snow, flooding etc so the 14 mile journey can easily become 30 mile so riding 30Kg of dead ebike 800 feet up a pitch dark alpine road kind of looses some of the magic. I definitely wouldn't leave a lithium battery on an unattended charge without a timer no no no.

That was my original plan to install a PV panel and a small wind turbine that would charge a big lead acid battery / inverter as I do at home, I was even going to pay for it out of my own pocket, the firm I work for is involved with green energy so it would be a great way of showing their green credentials to visiting customers and clients however they refused to even discus it, ( we had a contingent from NASA once and they were standing around my bike, man was that cool!!!). There are 6 car charging points in the car park that I could possibly find a way of using but I'm pretty sure the staff are not allowed to use them. There is about 8 e-bikes at work now so a communal charging system would be really good.

Ok its been a while so thought I would give you an update on this. To recap, I needed a way to charge my bike at work ready for the long uphill climb back home after my work moved to a new premises without any bike shed charging facilities. The 14 mile home journey consumes around 8-10Ah depending on wind direction up in the hills ( I ride through a wind farm ) and the depth of mud in the forest / swamp (more than once I have had constant wheel spin for over half a mile which is awesome fun!), the battery often gets hammered on the way into work as there is usually a brutal head wind blowing down from the Pennines. I chose to build a portable battery/smart charger unit that can be charged up in the work shop and carried out to the bike shed, then after about 3 hours its brought back in and recharged ready for the next day. It didn't cost a whole lot as I had 15Ah worth of LifePo4 cells from a previous project and several military spec DC/DC converters (don't ask). The unit will charge my battery at 42.0V / 2.0A and cut off when the battery is charged incase I get called away from work. The charger has now been in use daily for exactly a year, my bike has covered over 32,000 miles in 6 years but the most impressive thing is that the charger alone has now covered 62 miles in 12 months from being carried out to the bike shed and back!!

Hey all, I figured I would give an update on this to help anyone else with a similar issue. Basicaly new pads fitted in the rear callipers would fail after only a day or twos use leaving no useable braking efficiency, then the front brakes also started to repeatedly fail. After a continued dry spell, i.e. the bike was not still soaking wet from rain at weekend when I service it the cause became evident. It was kind of obvious really but as the hydraulic callipers are the thick end of £70 each I probably didn't want to admit it. It seems that the seals in the pistons had failed and were allowing brake fluid to creep onto the friction surfaces over night. The callipers always have a build up of black brake dust but when dry it could be seen that it had an oily texture that was not obvious when wet with rain. The brakes would even work reasonably well in the rain but fail in the dry, they would genuinely sound like a fully laden freight train coming to a halt! 2 New callipers later and everything is still tickety-boo a couple of weeks on. To change the Shimano Zee callipers is pretty easy, just make sure you have a bleeding kit and plenty of brake fluid. The rear calliper gave me a bit of grief as the banjo bolt rounded off where the allen key fits (they are super tight!), however a slot made with a hacksaw allowed me to use a regular screwdriver to remove the bolt.

OK, bit of an update. New 4 spline clutch fitted and new bearings, so about £75 spent but there is absolutely no play in the bearings now and the new clutch is working a treat. The bearings were a doddle to change. I put 20 mostly off road miles on the motor yesterday so looking good.

I have a set of front and rear indicatirs on my ride as I spend a lot of time in the centre of the road waiting to turn right especialy in the winter when its dark. They work an absolute treat. I also have brake lights as I have to ride in the traffic especially again when turning right. My rear lights are Ebay motor cycle lights which have built in indicators and brake lights so would be a no brainer not to use them. Front indicators are ebay motor cycle units, these are quite cleaver as they don't need a flasher unit, they can also be wired as white day run lights then turn orange when indicating. My biggest issue was finding a decent switch, I bought a proper ebay moped switch but this was rubbish as it was far too fiddly and not water proof so bought a big centre off toggle and this works like a charm, the only issue is that some times I forget to cancel them after I turn.

You were absolutely correct with the bearings mine are the same, unfortunately my clutch is the old 4 spline type so I've placed the order with e-bike solutions Germany, lets hope my faith in Google translate holds up or I might be in for a surprise in a few days time! I've taken my clutch apart, its impressively made, it looks like it should last a life time, I can't really see anything that would make it fail, I'll give it a good clean and see what happens. Interestingly now I'm using my retired old high speed CST I've realized that the low speed wind version is so much better for my application, its way better at climbing steep hills, better in a strong head wind and best off all uses a LOT less battery, the low speed wind uses about 7Ah for my 14 mile homeward commute and the high speed wind is currently still charging and has passed 11Ah!! Definitely an incentive to repair the motor.

I know what you mean, I often spend the entire weekend maintaing / repairing my ebike just so I can get to work on a Monday morning

Fab, thanks guys.

Electricaly the parallel strings are even, there are 5 cells in each parallel group but physicaly there are 10 cells in a couple of the cell holders. I only have voltage measurements from taking the battery off the charger, when I balance charge the cells I charge the pack to 42.0V, then wiat for the current to drop to about 1A, that way I don't have to spend to long charging individual cell groups as this can take up a whole weekend. The voltage of the 'good' cells would be 42.0V (42.2 ish if the BMS has tripped) and the 'not so good cells' 4.05 - 4.15V. When I balance charge them I try to get the charge current the same on all cells, the 'good' cells might be drawing a few mA, if I can get the other cells down to about 250mA the bms appears to be happy, by this time I've run out of weekend so can't get the charge current any lower which may be something else causing the issue.

"2. Are you giving the BMS chance to balance the cells for a few hours after the pack is fully charged? This needs to be done every so often, not necessarily on every charge." OK that kind of confirms my suspicion, I'm not leaving the charger connected long enough for the BMS to balance charge the cells, then once the cells are to far out of balance the BMS trips and no further charge can take place. My home charger terminates the charge at 200mA, this is obviously too early, and the work charger is on a timer which again turns of too early so I think this may well be the root of the problem, hopefully this might be what's happening with Mike who started this thread.

Fab thanks Nealh, they look similar to my bearings. The motor failed completely this moring on the way to work so now I've got nothing to loose so I can tear it apart and check the bearing numbers. I think there are some electrical gremlins as well, some times it feels like its running on 2 phases so between this the worn bearings and broken clutch I think this motor is whats known in the trade as a pup. Any idea if the CST clutch assembly is the same as the BPM (obviously taking into account the single or 4 slots)? I wonder how feasible it would be to lock the clutch so I could benefit from regen braking? I guess probably not wise on a rear wheel and the fact I can reach 40mph by freewheeling down some of the hills I don't think the motor would thank me, probably realisticly the increased load would limit the top speed to about 20mph, and the thought of riding a heavy dead ebike up a 700 foot climb into a head wind working against the motor doesn't bear thinking about

It sounds like you know your way around these motors, any idea who might sell a clutch / gear set assembly, I have drawn a blank with BMS battery and Greenbikekit only show an assebly for the smaller SWXK type motor. I didn't want to get to far into stripping it at the time as I need the bike to get me to work, I was just looking for telltale debris or broken gear teeth. At one point I thought the motor might be randomly spinning backwards then suddenly spinning forwards but I think it is more likely to be a clutch issue, when the motor is behaving it works flawlessly. Someone did a write up once on what bearings were required, they were all of the shelf bearings but when I took the motor apart they seemed a bit more obscure, one had quite a large inner diameter. If the bearings and clutch are readily available I will definitely look at a full rebuild. I have my original motor as a stand by however having grafted a new connector on to it I can no longer change the cassette which is quite worn.

Unfortunately I only had the option to solder, I built a couple of dual pulse spot welders but wasn't happy with the results and don't believe a cheap commercial welder would be any better, soldering I know is the hight of bad practice but I'm confident that my technique put minimal heat stress on the cells i.e big iron, flux, lead solder, heat for a fraction of a second and cool rapidly, probably less damage than a low quality spot welder punching a hole through the cap. The bus connections are tinned copper braid. This process does make the pack serviceable so I can easily swap out cells if need be. I do wonder if the 20 new cells I bought might have been seconds or there is an issue with my charging technique. Apologies if I have hijacked this thread.

Well there’s the thing, 30 out of 50 of the cells were about 2 years old but very lightly used, however by and large these are the cells that are behaving, the 20 newer ones are usually the problem. All cells are decent Panasonic NCR18650PF (I think 2700mAh). All cells in each parallel block of 5 are from the same ‘batch’. The BMS is a regular ebay job but these have worked fine before although this bike gets some serious off road commuting abuse (forrest tracks, fields, cobbled streets). Charging at work is by a regular 2A 42V Lion charger on a timer in case I get called of site. Home charge is an intelligent charger based around an Arduino microcontroller that charges at 2.0A until 42.0V and then when the current tapers to 200mA terminates the charge, this also gives me an Ah figure of what has been put into the battery and the time taken. If this is showing 42.0V and 0.0A I know that the battery BMS has tripped on over voltage, the last time it did this was at 97% charge which off the top of my head is around 220mA. My last battery built the same way and using the same charging regime is still running strong after 1600 charge cycles (20,000 miles), I don’t discharge more than 50% unless there is a detour or particularly savage head wind. I use built-in battery heaters if the temperature is below 0 degrees, I have a temperature read out fitted so I can keep an eye on the cells. The physical construction is by 3D printed cell holders inside a carbon composite battery box mounted under the downtube in a similar way to an oversize crud catcher.

I'm having similar issues with the latest pack that I've built, this is a 36V 5P10S. Originally I thought this was down to the cells being purchased from 2 different suppliers so having different states of charge, all cells were balanced charged to 42V and terminated at about 500mA. However twice now in 3 months (1500 miles) several of the 5 paralleled cells have gone out of balance and triggered the BMS to shut down on over Voltage. I do wonder if this might be due to the charger at work being on a timer and possibly turning off when still in the constant current phase of charging. I think the bypass resisters on my BMS are 68 Ohm so the packs of cells have to have very similar states of charge for the BMS to balance the cells successfully Checking the cell voltages hot off the charger after an aborted charge cycle gives 6 of the paralled cells a Voltage of 4.2V and 4 other around 4.05V, however not always the same ones.

Morning fellow pedelecers, My 500W CST has recently started to sound unhappy, occasionally when I open the throttle I hear the motor spinning but with no drive then get a sound like 2 or 3 spokes snapping then I get power and it might be perfectly OK for the next 50 miles. The first time this happened I had a squealing sound like a broken spring all the way into work (private roads of course). The motor is a bit of an unknown as it is second hand, it appears that the 500W 36V CST has been discontinued probably due to their habit of burning up plugs (I've got through 2 plugs on the last motor in 20,000 miles). I've had the motor apart and the planet gears look fine and there are no broken teeth floating about and surprisingly no water inside after riding through the recent floods up this way, there is however a lot of play in the bearings which makes me think there may be mega mileage on this motor, I can rock the wheel rim side to side by a good 6mm which doesn't exactly inspire confidence. I haven't yet dismantled the actual motor itself. I'm also not convinced its 500W as compared with the last motor it is so sloooow, it's either 350W or a very slow wind, it is however about 20% better on battery consumption although this might be due to the lower speed. The last motor would top out at about 22mph this one is about 19. So I guess I'm asking has anyone else had this happen, and if as I suspect the motor is on its way out I need to replace it with something else, I am kind of stuck with 36V and a 9 speed gear train. I also get many punctures so the wheel has to be easy to remove (especially in the dark and wet) and my commute is in a VERY hilly area with a 700ft climb on the way home often into a savage head wind. At the moment it looks like my only option is to buy the 350W version of this moter.

Those rotors aren't stupidly expensive, worth a try. Good looking bike btw, mine looks like Frankenstein's monster!

That's actually an interesting point, the last leg of my homeward commute is down a steep hill into the village, I have to turn right at the bottom of the hill so have to be doing traffic speed (30mph + ) to get over to the centre of the road then hammer the brakes at the bottom for a mini roundabout, I know when I get off the bike at home I felt the front rotor once and burnt my finger ( yeah OK I know....). The strange thing is that its generally always the rear pads that fail. Just to be clear, I don't have a 30mph e-bike I just live somewhere VERY hilly

OK, this is going from weird to bizarre! Yesterday my front brakes decided to leave the party,( I've kind of got used to getting only two or three days out of the rear pads). The night before the front brakes were perfect then yesterday morning they barely worked, we are talking 203mm discs, 4 pot callipers and sintered pads, at 20 mph if I grabbed the lever full on the bike would slow to a halt like a 1920's rod braked boneshaker but with the sound of a dozen people scratching their finger nails down a blackboard...erm...chalkboard at the point of the wheels coming to a halt. On one of the steep descents into work I braked as hard as I could from 25 - 30 mph down to standstill several times to get some heat into the discs to try and burn anything off, they improved somewhat but had a bit of a 'rubbery' feel to them. I noticed the day before that after the rears failed they would work in the rain so I let the discs cool for a few hundred yards then squirted some of my drinking water on them and try again...they were suddenly back to 100% and I locked up the front wheel!!!??? This morning it was raining so I had both front and rear brakes which is a bit of a novelty, tonight its supposed to be dry so I will see what happens. Its almost as if something does the opposite of bedding the pads in, what ever it is it usually happens at the weekend when the bike is not being used.

Yes its a pretty awesome comute, the alternative is sitting in a car for over an hour staring at someones brake lights...nah! I have a second bike that is built as a full on ice bike, studded tires, front motor, heated battery etc, last year the weather was a bit boring but the year before we had a good bit of snow with a bit of drifting out in the sticks (beast from the east) the whole commute was out of this world but the best bit must have been climbing up a steep hill in a little hamlet, the road was hard packed ice that had been polished by all the cars that tried to climb it and failed, the bike just sailed up it. I found with the studded tyres it was easier to ride on hard packed ice than though fresh snow as the front would slide about more in the snow especially with any sort of camber. The only real issue I had was that in really deep snow the derailleurs were dragging in it so I lost a lot of the gears as they were encased in a block of ice, oh and then a couple of days later the front forks snapped... that was exiting

Loving the idea but unfortunately I cant use any sort of lcd as the ride is so brutal I can neither take my eyes of the track or my hands off the handle bars, plus for 6 moths of the year I'm riding in 100% darkness unless the moon is out. My current setup has the thumb throttle on the left handle bar side so I can change gear at the same time as using the throttle, the gear lever from the left hand side has been relocated to the frame, kind of old school style. On the right side as well as the gear change I have a switch to disable the cruise control (or PAS if fitted) and the switch for high / low headlight beam, this way I can use everything purely by feel and in a fraction of a second. I understand what you are saying about limiting the power to the front wheel, when I first started this commute I was running a front motor so had to balance pedal power to front wheel power, even so there was little to no steering in deep mud, I just have to follow where ever the front wheel is heading, with rear wheel drive only its a lot easier excent I regularly ride for a good 1/4 mile sideways with constant whelspin, once the front wheel jammed solid with mud and was just acting like a ski! What I'm planning is controlling the rear wheel direct from the throttle but building in a traction control by comparing front and rear hall sensors then if the front is going faster than the rear to modulate the power.

OK thanks that's interesting, I think AWD would work better for me as it would move some of the weight from the rear wheel which currently gives a horrible ride over broken ground and it would help with a very long and very muddy uphill climb up the side of a slag heap where I have spun out and stalled more than once in the rain. It will also give me some redundancy in the event of one motor failing and locating 2 x 250W controllers will be so much easier than locating the 500W 'house brick' of a controller. It would be great to use a pedal sensor again, it's never worked properly with the 500W controller, I have to use a throttle and cruise control which has led to many an exiting moment when I've forgotten to switch it out!

Hey all, anyone know where I can buy a new Bafang CST 36V 500W rear motor from? I've been keeping an eye on Greenbike and BMS for months but they are constantly out of stock. My motor has now completed more than18,000 miles of hard commuting abuse (off road use only of course), so need to be getting a replacement ready, it was originally supplied damaged from China so after removing / refitting the wheel some 100 times for puncture's the wiring is in danger of failing (already changed the plug / socket after one of the pins burnt out), the motor spends a good amount of time at full current when ploughing through deep mud for extended periods as well as some savage hill climbing, I had to ...erm.... lets say sprinkle some water on the motor in the recent 35 degree temperature as it was red hot and I had used all my drinking water on it. As an alternative I might go AWD with a 250W mini hub front and rear, but the CST is such a great motor I would like the same again especially as the bike cruises nicely at 22 mph so I can complete my 14 mile homeward commute in 40 minutes.