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.