Dummies Guide to eBikes ...

SpudULike

Just Joined
Apr 24, 2020
2
0
... is what I need.

Does anyone have recommendations for resources to get a sound understanding of an eBike?

I have a woeful lack of understanding to a lot of the subject matter discussed in these forums, and, while I'm sure you would answer individual questions, it would be no fun trying to drag me up to speed on my general understanding. I've found lots on the net, but it is all piecemeal, and sometimes leaves me more confused.

A couple of examples to highlight my gaps in knowledge:-

  • 36V vs 48V - Someone mentioned running a motor at 48V. I've got some idea of what this means, but huge gaps in understanding how to do it, when to do it, implications, legality, etc.
  • Connectors
  • Controllers vs displays - not sure if the controllers manage the state of the battery, or of the motor, or if the displays manage both, or neither. Just dunno!
Not looking for answers to these here, but offered as a small example of what is spoken about as basic knowledge, which I don't have.

I need the Sheldon Brown or Rob van der Plas of eBikes please.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,993
Basildon
There is no such thing as a dummies guide. they tried on the Endless-Sphere forum, where there is some good stuff, but most of it is not relevant and misinformation regarding what we do in the UK and Europe.

If you're interested and hang around here, you'll soon figure it all out. It's all very simple. It just seems complicated when you don't know about it.

To answer your questions:

The battery has a management system inside it, which cuts off when it's too low, and it keeps the cells in balance. It aalso works as a fuse to cut off when you try to draw too much current.

Motors are dumb. They're just coils and magnets, and most have three position sensors in them some have speed sensors too, all of which are connected to the controller, which is where the intelligence is. There is no such thing as a 36v motor. The 36v is only a reference point for its speed.

Motors are normally designated by voltage and power, but both are absolutely meaningless. What you need to know is the Kv, which is the rpm/volt. It tells you how fast the motor can spin to at any voltage. The motor's max speed increases in direct relation to voltage. Don't get motor speed mixed up with bike speed. The motor can never reach its max speed, except with the wheel in the air. If you have a 15 mph motor, all the current in the world won't make your bike go any faster. Likewise, if you run your small hub-motor at 100v to get it to spin to 50 mph, it won't get past walking speed before it burns out. Without a complicated explanation, motor need to run at least at50% of their max speed, which means that you should run a 15 mph one below 7.5 mph with full power because they don't run efficiently at low speed, and instead of making motive power, they make heat instead. That's why it's important to match your motor to your modal riding speed. In general, you choose a motor to have a top speed aproximately 30% above your modal riding speed.

Two main types of connectors. You get the waterproof sealed round moulded type and the block types. It's really difficult to test the sealed type, while as you can get meter probes up the back of the block types. The leads are always too long with the sealed ones, so it never comes out as neat as you hope.

Both controllers and displays have CPUs in them. The CPUs talk to each other via two comms wires. The LCD is your interface to the system, so through that, you tell it what to do, and it tells you how it's getting on. Voltage setting can be manual or automatic depending on which ones you have. Controllers will also cut-off the power when the battery is flat. It's normally set a bit higher than the battery's cut-off, so you have belt and braces to protect your battery.

Now you have no gaps in your knowledge. Good luck.
 
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Reactions: JPGiant
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Deleted member 16246

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I'd like to express appreciation to VFR400 for his detailed and very useful posts on this forum. Thanks for putting time and effort into clearing up so many issues the way you have been doing.
 

PC2017

Esteemed Pedelecer
Sep 19, 2017
1,319
334
Scunthorpe

It's from a dude who lives in the US and Tel Aviv I think. They also have a YT channel
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,993
Basildon

It's from a dude who lives in the US and Tel Aviv I think. They also have a YT channel
I just looked at that website and his channel. I don't want to seem unkind, but what I saw very poor. I wouldn't recommend anybody here waste there time with it.
 

Ocsid

Esteemed Pedelecer
Aug 2, 2017
449
269
81
Hampshire
If my experience is typical then as with most things technical a "Dummies" guide only goes so far in upping one's understanding, typically only being of relevance as a reference after you encounter an "issue".