Hello from CEGB...

[CEGB]

Hello all, another newcomer to the Pedelec World, and keen to know and understand more.

As you may have guessed by my username, I have a greater than usual level of involvement in the world of electricity, being employed as an Electrical, Control & Instrumention Eng. for a power station for a number of years. That being said, I can't say I'd ever thought about applying the technology to my bicycle until I saw a Pedelec driver hammer past me up a long hill the other day. I didn't see the riders face, but I'm willing to bet it was wearing a very smug grin...

Anyway, my current project is to make a 15 mile each way commute as easy as possible for a reasonable cash outlay. I can do most things, basic machining, wiring, wheel building etc. for myself, but I was wondering if my current choice of bike (see below) is an ideal candidate for electrification. It's a very comfortable machine, it's unusual rear suspension in particular making it particularly pliant, a characteristic I'd quite like to keep.

I have a motor already that I bought on a whim. It may or may not be any good for the job, but this seems like the ideal place to find a loving home for it if it turns out to be unsuited to my needs. It's a brand new Bafung unit that is currently laced into a 700c rim. I'd lace it a 26" rim (something light from DT Swiss perhaps) for use on this bike, but I wondered if you guys had an opinion on what battery, controller, and voltage this 24v unit would be best suited to? Can these units be driven at 36 or even 48 volt?

The only other questions relate to some of the nomenclature used on the site, like the use of 's' when referring to batteries (12's, or 16's for instance?), is there a handy guide for this anywhere? Also, I note that the use of Hall sensor equipped motors seems to come with a potential reliability disadvantage, but what are the advantages to having them in place?

Many thanks in advance

CEGB

 

[flecc]

These motors can usually be run on 36 or even 48 volts safely, just using the appropriate controller. You will lose 7% of the design assist speed by going down to a 26" wheel, but increased voltage increases that pro-rata. Don't forget the legal position though, the 15 mph assist limit. If your 24 volt specified motor is intended to give 15 mph, a switch to 36 volts will increase that by 50% to over 22 mph, and increase to 48 volts will double the potential speed to 30 mph.

The S and P used with battery cells merely refers to series or parallel connections. For example, most lithium cells are 3.7 volts, so 10 cells in series, expressed as 10s will give 37 volts. To increase cell and thus battery capacity, the bank of 10s cells have to be paralleled by more banks. For example two banks to give the same voltage but twice the nominal cell capacity will be expressed as 10s 2p.

Hall sensor motors are brushless and have a better torque curve than brush motors, giving a wider useful power band. They are the norm now and generally very reliable and don't have to have routine replacement of worn brushes.

A few motors use sensorless controllers, reading the back emf at startup to decide what to do. That means they are momentarily lost which direction to start the motor so starting off can be a bit rougher in a few cases, especially with higher power motors.
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[Dubster]

Welcome aboard CEGB, you're around 22 years too late though I'm afraid

Both my father and I worked for the CEGB then PowerGen thereafter. It's been along time since I last set foot on a Power Station site though. I still have a strong interest in the industry and electricity/engineering in general.

 

[CEGB]

Thanks guys. Very helpful stuff. Looks like I'll be keeping the motor after all then, just a shame it's not disc capable, but I think I can live with that.

.The S and P used with battery cells merely refers to series or parallel connections. For example, most lithium cells are 3.7 volts, so 10 cells in series, expressed as 10s will give 37 volts. To increase cell and thus battery capacity, the bank of 10s cells have to be paralleled by more banks. For example two banks to give the same voltage but twice the nominal cell capacity will be expressed as 10s 2p.

Well when you put it like that it's obvious! Thanks though, it did have me puzzled for a moment. The hall effect thing is also rather obvious now you mention it!

@Dubster, Whilst Power Generation has been a lifelong love for me, it isn't the same business as it used to be. Its certainly not home grown anymore. British engineered plant powering the nation has given way to imported turbines from France, Switzerland and Germany. Parsons, Rolls-Royce, and Reyrolle have given way to Siemens, Alstom and ABB. Powergen is now German, Nuclear Electric is French, National Power is now German, and Scotish Power is, well, Scottish...

More stations are being closed than built, and the market for modern efficient gas powered generation is almost non existent. Just like in the days of the CEGB, coal is king...