Pedunculate

I was looking at adding some wiring to one of my bikes, which is a commercial e-bike that uses 'Julet' waterproof connectors. It seems these aren't easily available, but there are 'Higo' connectors - but they're rather expensive. Other waterproof connectors from the likes of Farnell aren't cheap either. I did some digging around ebay, and I came up with an interesting alternative: LED strip connectors. If you search ebay for 'IP65 LED connector' it brings up a number of listings. The only downside is they come moulded on to a 20cm pigtail, so you need to make an additional join to your wires on from there (heatshrink?). I bought some of these (15mm, 5 way, 0.3mm version) which took about a week to arrive (in the UK). https://www.ebay.co.uk/itm/2-3-4-5Pin-Waterproof-IP67-IP68-LED-Strips-Connectors-Cable-for-3528-5050-5630-U/232894388715 At 8 pieces (4 male/4 female) for £9.59 that wouldn't get you one pair of Higo, and these look pretty nice, with no crimping or vibration-sensitive solder terminations. There's a metal locking ring - I wouldn't say for definite it's rust proof, but it might be anodised aluminium. They're labelled 'yczx' which it turns out means Shenzhen Yongchangzhixing Electronics Co., Ltd, and they can also be found on Aliexpress.

My Chinese controller (made by yiyun.cn) arrived courtesy of ebay. It turns out the battery and motor connectors are almost but not quite the same as the XPC26. After bodging them to connect, shorting the 'lock' pins, and applying a twist throttle to the 'derailleur' pins, it happily powered the XPC26 motor and wheel. Somewhat quieter than the original controller too. I then turned my attention to the torque sensor. It's screwed into the side of the gearbox. It has an arm that pokes into the gearbox and presumably rotates to measure torque. I think mine is flaky: it records 8Kohm to ground at maximum travel, about 2.5Kohm at almost minimum travel, but then open circuit when under no pressure. It doesn't feel loose, but I'd guess the potentiometer track is worn. It's labelled only 17Y0 or 17YO which wasn't the most helpful thing to google for, but then I came upon this thread on pedelecforum.de That has some pictures of the inside, and indeed the track on that one is damaged. The page of the service manual shown there also confirms that flash-flash-pause means a problem with the pedal sensor (according to my German friend). Also, they confirmed my suspicion that it's a motorcycle part of some sort. It seems to be a throttle position sensor (TPS) used on Yamaha motorbikes and other small engines (boats, snowmobiles). Googling around, it seems that unreliable TPSes are a known problem on Yamaha motorbikes. However they're frighteningly expensive (EUR200), for something that's just a potentiometer in a plastic case with a return spring. Part number is 5AT-85887-10: http://images.cmsnl.com/img/products/5at8588710-sensor-angle_medium5AT8588701-01_bace.jpg I did some poking around generic car TPSes (Chinese probably) which start at about £5, but I didn't manage to find anything that looks the right dimensions. One problem is that many have a connector moulded in the body, while the XPC has a part of the gearbox housing where that connector would go. Also it's unclear if the spring tension is carefully calibrated. Otherwise it might require cracking open and trying to clean the potentiometer tracks. That could be the simplest option.

Interesting. I have ordered a cheap eBay controller (seems like all the fancy ones are brushless, so cheap it is) and will have a go. How many flashes do you get on the LEDs when it dies? I get a repeating sequence flash/flash/pause when I turn it on with the torque sensor disconnected. I don't remember how many it flashed when it was dying after about 8 miles.

I've been playing with my olde Yamaha XPC26 (24v NiMH battery, bottom bracket DC brushed motor, torque sensor). It has a fault where it'll run fine but if you stop pedalling for a few seconds it indicates a problem, giving two flashes on the LEDs. That's when it's freshly charged and the multimeter shows it has about 26.4v. Turning the PAS off and on again makes it work again. When I scope it the battery voltage is rock steady under load. The controller is pretty simple, having inputs: 24V battery +/- 1K battery thermistor in series with thermal fuse (no markings on the fuse or that thermistor, but the charger side has a 103AT - appears to be 10K, beta=3435) Motor +/- Torque sensor: +5V/GND/torque, with idle at 0.8V, under torque gives up to about 1.5 V (I'm a little suspicious that the pedalling fault is related to this sensor) Handlebar unit (7 pins) - my guess is that's power switch (3 positions, 3 wires) and 3 LEDs (4 wires). It's possible the unit is cleverer than that, but I doubt it. Unfortunately it's potted in silicone so it's not easy to see what's inside. Under power (giving a steady voltage into the torque input rather than pedalling) it gives 24v PWM to the motor, with some filtering (ie cut the torque and it gradually ramps the power down over a few seconds) I am pondering whether it's feasible to replace the controller with something more modern. What I'd like is a controller that can cope with the torque sensor and the DC motor. Since throttles also have a 0-5V output, I wonder if it's possible to use the torque sensor instead of/in addition to a throttle input. What would be very nice is if it had a sensible gas gauge - for example, put a coulomb counter in the battery like a laptop, so it knows how much went in (via the external charger) and how much came out. I'm pretty sure the existing gauge is just looking at voltage. I'm happy to replace the handlebar controller with something more useful. Will the common e-bike controllers handle this kind of thing? I see a lot of three-phase and 'torque simulation' controllers, but not sure if the brushed controllers will handle a real torque sensor.

If anyone is interested I have four of these battery packs for sale... bought them for an e-bike conversion project that never happened. I'd just like to recoup my investment so £34 a piece? Collect from Cambridge or I can try and find a courier to ship them at cost (suggestions welcome)

An update... I soldered up a new battery pack, after having a practice on some cheap Poundland zinc-carbons. It needs a really hot iron - I had a 450degC bit for my Weller TCP temp-controlled iron, and use lots of flux. I tinned up a baked bean tin by covering it all over with solder (plumbers' leaded solder is cheaper and thicker than the electrical stuff), chopped it up into strips and soldered them between the cells. The trick is to put flux on the cell, cover the end of the strip with a blob of solder, let it cool, then push the strip onto the cell using the iron... done in less than a second. The replacement cells just about fit in the battery case, but I had to omit the shrinkwrap due to the raised bumps on the positive ends of the ends which take up a bit of extra height. I charged the battery on the standard charger by watching the power on a mains wattmeter and it was roughly right (~5 hours at 70W = 350Wh). The battery works just fine, and is able to power the bike... but I get about the same range as the old battery (about 5-10 miles) until it complains of low battery. At this point the terminal voltage is still 25V so I suspect the on-bike battery manager is getting confused. I'm not keen on pulling my bike to bits (the circuit is probably potted in epoxy), so I'm currently looking around for a spare bike battery circuit so I can pull it apart to see what might have gone wrong...

I suppose I could take tin cans and hammer them flat... time to get eating those beans! (I do enjoy wandering around supermarkets looking for items for the packaging not the contents... currently the cheapest glass bottle in Sainsbury's is 22p... anyone want a dozen litres of Economy Brown Sauce? Actually, I could probably use it as bathroom limescale remover...)

I looked into making a spot welder like this one... I have a 68000uF 35V capacitor so I might try it sometime, if I can work out a cheap way to make a 35V power supply (which would get me about 30% of the joules of the above design). I've also had a play with soldering up some dead alkalines to tin/brass-plated strips cut from the lid of a baked bean tin (no expense spared here!). I've got a good mechanical strength, to the extent that they took several blows with a hammer (denting the battery) before I got them off again. My technique is: Make sure your soldering iron is really hot. I'm not sure my gun is working 100% as it takes some time to come up to temperature (odd, when it has 150W to play with). I kept the trigger down for the whole of this procedure. Dip the end of the metal strip in flux (coat both sides) Put a blob of solder on the end of the gun (about 4-5mm in size) Bring it onto the metal strip, wait for the flux to boil away and a tinned surface to form Repeat to tin the other side of the strip Now dip the end of the battery in flux Put another blob of solder on the end of the gun Bring the gun down onto the end of the battery, wait for the flux to start to boil and the end of the battery to be tinned. Leave the solder blob there. About a second. A fresh blob of solder on the end of the gun (these blobs ensure good thermal contact, which is vital) Bring the soldering gun down on the top side of the metal strip, wait for the topside solder to melt (which indicates the bottomside is melting too), keep the gun there. Bring the gun and tinned strip down on top of the blob of solder on the end of the battery. Wait 1 second. Remove gun Hold steady and wait for it to cool (2-3 seconds) I have some cheap'n'nasty new zinc chloride Ds and 800mAh AA NiMHs to test later and check I'm not damaging anything. I also tried abusing alkaline batteries: I didn't get anywhere with overheating them, but after a fair bit of hammering I managed to piece one and at the same time short it, causing it to get warm and acid to leak. So I think it's hard to overcook alkalines. Now, another question: is there somewhere to get the metal strips to link cells? I asked at my local metal supply place and the best they could do is 0.6mm copper sheet, which is a bit thick. I see some Hong Kong suppliers have precut tabs on eBay, but they're either too short or too narrow for me. Is nickel the best metal for this? I don't really want to eat that many beans ;-)

Hmm, at 4x the price (£8.50 for 2 against £13.65+VAT=£16.38 for 1). And they don't give any technical data. Think I'll pass I'm also plotting... I'm wondering whether I can make a little board to fit inside the battery to do charge monitoring. This thread has some ideas. There's a small amount of space available (about half a D-cell's worth) - it'll be tight but the charge monitoring chips are small. Ideally I'd like a USB port on the battery so I can download the performance

This bike is unusual as the battery has separate charge and discharge connectors. The discharging connector is at the bottom of the battery and has (in order) thick red (+ve current), thick black (-ve current) and thin black (?). The charger connector is a different type at the handle end of the battery and has (in order) thinner red, thin 2-core fig8 black and thinner green (thinner=thinner than the discharge wires). Presumably the thermistor is on the 2-core fig 8, and the other two are 2A charging inputs (thinner red has the 2A spade fuse in series). I'm guessing that the single-core black on the discharge connector is a voltage sense line for the handlebar power meter, so it isn't confused by voltage drops in the current-carrying conductors. Though I'd have expected a 4-terminal measurement, not a 3-terminal one (after all, there will be just as much voltage drop in the ground wire as in the positive wire) I'll see if I can put some pictures up somewhere in case anyone else is interested (I didn't find much info about the XPC26 out there) On the subject of 'overbuying' cells, how many extra cells would you recommend buying? And how to work out which ones match? I'd need to overbuy anyway to perfect my soldering technique (unless someone can point me in the way of a supplier of tagged cells).

Thanks for the advice. I finally got around to cracking the lid on the battery (4 big self-tapping screws plus a single long plastic clip in the middle on each side of the battery: a few old credit cards got me in eventually). And the news is... it contains 20 NiMH D cells! Which is a right turnup for the books, since Yamaha only sold SLA and NiCd versions of this bike and this one was bought as new as SLA. I didn't think there were NiMH powered e-bikes available in 2000-2 when this was bought as new/old stock from a Yamaha dealer. The battery charger only says 'Yamaha battery charger' on the outside - makes no mention of chemistry, so I suppose it's a NiMH charger after all. The 9Ah NiMH D cells I was looking at were 'consumer' GP900DHCs from buyabattery.co.uk at £8.50 for 2 (datasheet). The bad news is that these are only rated for C/10 charging at 900mAh, and the max discharge current is 27A. The GP900DH (datasheet) which I confused them with has fast charge of up to 4.5A when using termination control (think there's a thermistor in the pack, though there's also a 2A car spade fuse on the charge connector) and discharge current rated up to 45A. The cells themselves in the pack are unmarked, so I have no idea what kind of rating they actually are. The charger is 24V 2A. Would I be hugely abusing the consumer cells by charging them at 2A (so 0.22C)? And then what kind of current drain does an e-bike take? Is 27A (so 650W peak, at cell voltage 1.2V, or 540W when flat at 1.0V) sufficient? I've also regeared the bike by putting a smaller chainwheel on the rear hub, which probably increases the load. I suppose I ought to buy one of the R/C battery charge monitor gadgets and put it in series to find out. Anyone suggest another source of NiMHs at sensible prices? ETA: I've just discovered that the connector between the battery and the bike comes apart, and contains two car-style spade connectors. One is a single pole with a thin black wire, not sure what it is (voltage sense perhaps?). The other is a dual-pole with thick black and red wires, with a spade fuse mounted in the middle of the connector. It's a 30A spade fuse. So that presumably answers my question about the max discharge current: I think 27A will be sufficient. ETA2: I've dug out the brochure, which says: Battery: Yamaha 24V/5Ah NiCad Battery charger: Automatic quick charge Battery charge time: 3.5h Motor: 235W Range: 25 miles Range in economy mode: 37 miles The brochure doesn't necessarily correspond to the bike as-bought, of course. But that suggests a charge rate (allowing 20% extra charge time due to inefficiency) of (5x1.2/3.5)=1.7A. So that would be 0.19C. While this is twice the specced charge current, is it likely to be a problem? I would feel not, but I'm not sure. And a 235W motor doesn't say what the peak current is - only 2x doesn't leave much of a margin. The fuse isn't going to notice the peak current, which could be higher than it is rated. I'm feeling like the 'consumer' batteries are worth a go. Anyone have any opinions?

I have a 2000-vintage Yamaha XPC26 that is probably up for a recell soon. It's been barely used, stored in the garage and until I got it probably done less than 50 miles from new. It's the lead acid version - the battery (24V, think it's 96Wh) is surprisingly good after all that time - I get about 10 miles out of it on a good day. However it's being a bit erratic, deciding to cut power after only a few miles (switching off and on again cures that), or claiming that I'm on low battery about a mile off a fresh charge. I've done 'refresh charge' a few times, but that seems to make it worse. The 10 mile range is a bit annoying as it sometimes isn't enough for a round trip. Anyway, I've been looking at recell options. I haven't actually got the case apart yet (hidden plastic clips) as I've been using it a lot, but I assume some appropriately-sized SLAs would be easy to obtain. So it looks like my options are a straight SLA swap, or change to NiMH. I can get 20x 9000mAh D-size NiMHs from a non-eBay retailer for £85, which would make a 216Wh battery (tagless, so I'll have to solder them into a pack). I presume I'll need a new charger (NiMH charging not being rocket science, this shouldn't be too expensive). I'll have to check the NiMHs are rated for high discharge current. One question: the bike has its onboard charge gauge. This is what's causing some problems with the power cutting out when the bike incorrectly thinks the battery is flat. If I recell with NiMH, will the change in battery discharge curves cause trouble with the charge metering? I imagine it's stored on the microcontroller somewhere, so not easy to change. The bike also comes in a NiCd version, so unless there's a handy SLA/NiCd jumper somewhere? Any other tips for doing a recell? I have a 150W soldering 'gun', so the plan is to make up packs by direct soldering to NiMH cells (soldering fast with lots of flux). Cheers!