Tuesday, 22 November 2016

6, 9 or 12 MOSFETs - Are more MOSFETs Better?

1 - Introduction


I am unsure what other applications MOSFETs could be used in other then EBike controllers, as that is as far as my limited knowledge of electronics extends, but I have pondered long and hard as to whether it is a worthwhile exercise upgrading my 6 MOSFET Controller, to a 9 MOSFET or 12 MOSFET controller.

Will there be any benefit?

2 - What is a MOSFET?


A MOSFET when used in an EBike controller works like a valve or gate that allows current to be drawn from the battery and used in the motor. The MOSFETs are there so as to switch off the current supplied from the battery when it reaches its minimum safe volatage.

The MOSFET is left "open" while the battery has charge left in it, but once a minimum voltage is reached the MOSFET is "closed" to prevent the battery becoming over discharged, which can damage the battery / cells.

3 - Are more MOSFETs Better?


A quick look for MOSFETs on google shopping will show you that they come in all sorts of sizes, in terms of their rated current. Some can handle 0.5A whilst others will handle 50A. So in order to say whether more MOSFETs are better, one would need to establish whether they were the same type of MOSFET, when comparing 2 controllers.


3 - 6, 9 or 12 MOSFETs


When looking at a controller from the same manufacturer say Crystalyte you can see that there controllers have more MOSFETs relative to the current they can handle. Their 15 Amp controller has 6 MOSFETs, whilsts their 25 Amp has 12 MOSFETs.

4 - Conclusions

If you are comparing EBike controllers from the same manufacturer then there is a chance that their 6 MOSFET controller will handle half the current of their 12 MOSFET controller. But this presumes the same MOSFETs are used in each.

So really the number of MOSFETs is not really important, concentrate instead on whether the controller receives good reviews, and pick the correct Amperage for you intended application.

For more advanced users some controllers can be programmed so say a 40A contoller with say 12 MOSFETs can be used to provide a maximum of 10A. This would possibly provide a benefit in terms reducing over heating, but using a high Amperage controller, when you do not need the amps, and have no means of controlling them may damage your motor.


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Custom Lithium Battery


Saturday, 5 November 2016

Choosing a EBike Headlight

Choosing a EBike Headlight


Choosing a EBike Headlight - Intro


EBike have variable voltages 12 volts, 36 volts, 48 volts . . . . .and more exotic. So you would think that finding a headlight would be tricky, but with some very simple wiring and a few bits from EBay there are tons of ways to get a great headlight on your EBike.

LEDs are the light of choice as the use the least energy.


Very Bright - Can be Dangerous Dazzling Other Road Users


Choosing a EBike Headlight - A "Universal" Light


If you have deep pockets Busch and Muller make a EBike Headlight that takes 24v - 50v it is that easy. Just connect it up and away you go. But these lights cost £50 / $80 upwards so pretty steep.

However if you look hard on ebay you can find a Chinese equivalent for £5 / $8. There is no set term for these lights but try "universal scooter head lamp" or "universal ebike headlight".

NOTE: One important difference between a high quality Busch and Muller lights and the cheapo chinese versions is that the Busch and Muller Ebike lights have an excellent beam pattern, that is to say 95% of the light goes on the road ahead, and not up in to the sky, or in to oncoming drivers eyes. An 80 Lux Busch and Muller light will draw 3W and yet provides so much light on the road it compares to a 15W light that splashes light all over the place.

Choosing a EBike Headlight - 12V Lights


By far the most popular volatge for lamps and headlights (of any type) is 12V, this is because cars and 4x4s etc. use a 12V system, so there are plenty to choose from trying searching for "12V LED work lamp" and you will see for off road use there are some amazingly bright lights that will run off 12V.

I would not recommend any thing more powerful than 3W for on road use, as you will dazzle oncoming drivers. Of course you could set up a big headlight for off road, and a smaller headlight for onroad use.

But the problem remains that you have a 24, 36 or 48 volt battery, and a 12 v headlight, so you need to provide a 12 volts supply. . .  .

Choosing a EBike Headlight - Supplying 12V 


These lights do not use a great deal of energy especially is you keep under 5W, they will run for 12 hours on a 12 ah battery.

Choice 1 - Separate Battery


Although this complicates charging it also means that you will not be taking power from your main battery. You could choose a 12V SLA battery and charge with a cheap charger, or there are lithium 12v offering that although expensive do not require constant charging as they do not self discharge.

The choices (2 and 3)  below without spending a lot of money are limited to about 1amp current, which means another advantage of a separate battery is that  you can run very powerful lights.

Choice 2 - Variable Voltage Regulator


This a great choice, you connect you main battery (24v, 36v , 48v) one side and adjust the voltage to required which could be 12v or 6v if you wanted to re-use some older dynamo lights. You can choose. Most of the cheaper regulators are limited to around 1amp current of a 10W (at 12V) LED headlight.

Choice 3 - Buck Converter


A buck converter will drop a set voltage say 36V to 12V so you can run your headlights, this is probably the easiest option. Make sure you choose the right volatge, most reasonably priced buck converter will kick out about 1 amp so you are limited to about a 10W headlight.

Illustrator Devon

Thursday, 3 November 2016

TerraCycle Chain Idler and Chain Tube Guide

TerraCycle Chain Idler and Chain Tube Guide - Intro


I think these chain idlers and chain tubes are mostly used on recumbent cycles, but there is also a benefit to using these on any bike where there is a long run of chain, such as long tail cargo bikes or longtail cargo ebikes.

In fact the latter of these two alternate options is where I am using the TerraCyle idlers and chain tube.
My Bike - Nicer Pictures to Follow

TerraCycle Chain Idler and Chain Tube Guide - Idlers Explained


Idlers are a sprocket which can run on bearing or bushing and provide a mid point upon which the chain may be guided. TerraCycle do two types of idler, one for loaded (power) chain i.e, going towards the pedals under tension, and one for unloaded (return) chain going away from pedals which is normally slack and floppy.

The loaded idlers are toothed, and come with alloy or titanium sprockets, and the unloaded variant come with no teeth.

The mounting brackets for these idlers typically incorporate some sort of lateral slider, so the the idler can move from side to side, but not up and down.

You can buy the idlers separately or buy a kit. The idler will run on a shaft and this shaft is clamped to the bicycle frame. There are a limited number of clamp sizes available. Below nice images courtesy of TerraCycle, terrible blurred scruffy images below courtesy of me.
Note Shaft for Lateral Movement

Loaded chain run over the top of idler. 

TerraCycle Chain Idler and Chain Tube Guide - Chain Tube Explained


The chain tube is used to stop the unloaded chain flopping about during its trip to the rear sprocket. I have often seen these on bike and thought how terrible they are, but in fact they work really well, even on loaded chain, provided the chain does not exit or enter at a steep angle.

Chain Tube
Some very long tails use very long lengths of chain tube. . .

Mega Chain Tube

TerraCycle Chain Idler and Chain Tube Guide - My Setup

So as mentioned I used these on a longtail ebike, I want to introduce a triple chainring up front but I had to divert the chain under the rear foot plates.


Chain Idler used to direct chain under foot plate. 
Through no fault of the idler kit the gearing did not work out, (running 5/6/7 speed chain on a single speed rear sprocket is not pretty or quiet), so I opted for a larger front chainring, optimised to match speed of front hub motor. It is a really good option, and I can use the idler to tension the chain if required.

As above but different angle.
The kit I purchased (for Xtracycle Freeradical) also included a chain tube, which I used to stop the chain slapping against the lower rear chain stay.

Chain Tube - Way better than it looks.
One of the most important things for me is that the idler and tube both run quietly, there is little in any rubbing noises, which I have experienced on say after market chain tensioners in the past.

Most of the attaching for the chain tube is down with zip ties, which means that clamp sizes (as is the case with idlers) do not have to be worried about.

TerraCycle Chain Idler and Chain Tube Guide - Conclusion

Chain tubes are a very easy way to introduce some form of chain management to your bicycle / tricycle / quadracycle, they can be attached with zip ties and simple brackets. 

Idlers are trickier to fit, but if you can buy a kit to fit you model of bike then it should be a doddle. 

They really do make for a quieter and more pleasant ride. 

Eclat Ridgestone Traction Tire Review

Eclat Ridgestone Traction Tire Review - Intro


This is a BMX tire, with trendy marketing etc. But will fit most wide etro 406 rims (i.e. 20"). I was looking for a 20" tire to use on a cargo bike, which has . . .


  • Semi -Slick Tread
  • High Pressure Rating
  • High Load Rating
  • Very Wide
. . .and this tire seemed to tick all of the boxes, I would have liked some schwalbe type puncture protection, but I put some slime in the tubes instead. Plus these were £10 each on ebay, so pretty cheap. They are available in three widths from 2.2 to 2.4 inches. 




Eclat Ridgestone Traction Tire Review - Description

The Eclat Ridgestone Traction tire is a slightly nobbly version of the Ridgestone Slick tire. Whilst the ridgestone slick has a smooth center tread, the ridgestone traction has slight steps on the center ridge, allowing for perhaps a little more traction. Although the difference would be slight.

Ridgestone Slick (Left) vs Ridgestone Traction (Right)


The side wall tread of traction is significantly more knobbly than the slick variant, with enlarged lugs, and more aggressive tread off centre of the central ridge. 

 

Eclat Ridgestone Traction Tire Review - Build

The tires are very sticky rubber, so will probably wear quickly if used for commuting, i.e. high milage use. These tires has a very high TPI at 120, a quality touring tire such as the big apple from schwalbe would use a 67 TPI carcass so why such a high TPI?

Sheldon Brown links a high TPI tire to a thin wall, but these are fairly heavy tires. but one would assume this is for greater flexibility and thus lower rolling resistance. 

These tires are rated for 100psi, I doubt I will ever run them at that pressure. But it gives an indication of their quality. I have carried close to 200kg (including bike) on these tires. 

Used for EBike on this Occasion

Eclat Ridgestone Traction Tire Review - In Use

If you are using these on a BMX then perhaps it is time for you to tune out. As I am using these on a longtail cargo ebike, which will never do a jump or a bunny hop in its life. 

There is tire hum on the tarmac when in use owing to the slight knobbles on the centre ridge. I swapped these after using Schwalbe Jumpin Jacks for a while, but they just munch the battery being so knobbly (this would translate to leg ache on a normal bike). The eclat ridgestone traction tire role very nicely on tarmac.



On rough stuff these are grippy as you would expect. In heavy clay they struggle of course, but the advantage is that the shallow tread clears easily once you get back up to speed. 

These tires are not very puncture proof, a set of Schwalbe Dirty Harrys would be a cheap alternative to these, with better puncture protection, but these would not role as well, nor are they as grippy. 

I have been riding these through the hedge trimming season, in the UK with roads littered with thorns, and have unsurprisingly suffered numerous punctures, I am running tire sealant (in tubes) and this has stopped the tires deflating on most occasions but there is white sealant visible in numerous places on the outside of the tire. I have puncture during the "thorn" season with other kevlar or better tires, so this is not really a sign of weakness. 

Eclat Ridgestone Traction Tire Review - Conclusion

A performance grade tire, that is well suited for use on heavy duty cargo bikes, although its lack of a puncture protection belt is a slight draw back this can be easily got around by using tire sealant