Wireless battery charging for e-Bikes

[mike killay]

So what are you saying? To avoid exposure to a room charger that is transmitting some sort of radiation 24/7 i will need to wear mesh suit?

You are Cathy Newman and I claim my £5

 

[Gubbins]

wireless charging is not different compared to your current e-bike charger.
The basic design is the same, except for the transformer that separates the battery side from the mains.

Well Yeah it is! Its radiating the power needed through everything thats between it and the battery

 

[Gubbins]

I should ask my mum.. She was a clippy during the war so may be able t explain it better..

 

[Woosh]

Well Yeah it is! Its radiating the power needed through everything thats between it and the battery

you need to look into exactly the quantity of strayed radiation and its absorption.
Design of the antena reduces stray radiation and also, human bodies absorb extremely little of radiation under 300MHz. We are looking at 10kHz-100kHz range, not X-ray or cosmic rays.
Just look at the design of the NFC on your credit card. The idea is pretty similar.
The receiving coil will tell the transmitter what it receives, the transmitter lines itself to the correct position before sending a large amount of energy.

 

[anotherkiwi]

I'll have to look at how the docks in San Sebastian work next time I am there. I am guessing mechanical related to the locking mechanism.

 

[flecc]

The problem isn't safety, it's the wastage due to the inefficiency of induction charging. In a world where we will be increasingly relying on hard won renewable energy, often locally produced, every watt will be precious and efficiency will be paramount.

There's simply no need whatsoever for docking e-bikes to use wasteful induction when contact pads are already proven in that low current application. Some successful e-bikes have even used contact pads for the motor drive current, the popular Giant Lafree series for example with up to 15 amps current. Against that the 1 or 2 amps for charging is peanuts.
.

 

[Woosh]

The problem isn't safety, it's the wastage due to the inefficiency of induction charging. In a world where we will be increasingly relying on hard won renewable energy, often locally produced, every watt will be precious and efficiency will be paramount.

the current e-bike chargers waste about 10% of input energy, wireless chargers for that sort of power range are not less efficient. Some designs claim 93%-95% efficiency.
Note that chargers under 5W are lousy on efficiency. The higher the power range, the better the efficiency of wireless charging.

Recent improvements to this resonant system include using a movable transmission coil (i.e. mounted on an elevating platform or arm) and the use of other materials for the receiver coil made of silver plated copper or sometimes aluminium to minimize weight and decrease resistance due to the skin effect.

https://en.wikipedia.org/wiki/Inductive_charging

 

[flecc]

the current e-bike chargers waste about 10% of input energy, wireless chargers for that sort of power range are not less efficient. Some designs claim 93%-95% efficiency.

A direct contact charger will always be more efficient than an inductive one if both are designed to the highest standards for efficiency. That many of our present chargers are not efficient enough isn't a good basis for comparison, they can be improved.
.

 

[spanos]

I had a crack at this 4 years ago

Wireless charging (a proof of concept type thing )
https://r.tapatalk.com/shareLink?share_fid=19542&share_tid=17016&url=http://www.pedelecs.co.uk/forum/index.php?threads/Wireless-charging-(a-proof-of-concept-type-thing-).17016/&share_type=t

 

[Woosh]

A direct contact charger will always be more efficient than an inductive one

that is missing the point. A wireless charger does not use extra transformer - only one like a normal charger. When you look closely at the construction of the separation transformer, the primary winding is replaced by the antennae, the secondary winding is replaced by the receiving coil, the ferrite core is replaced by thin air. The magnetic flux is collimated before a large amount of energy is transferred.

 

[flecc]

that is missing the point. A wireless charger does not use extra transformer - only one like a normal charger. When you look closely at the construction of the separation transformer, the primary winding is replaced by the antennae, the secondary winding is replaced by the receiving coil, the ferrite core is replaced by thin air. The magnetic flux is collimated before a large amount of energy is transferred.

But why? This cannot be more efficient than direct contact transfer of energy so why complicate for the sake of it?
.

 

[Woosh]

But why? This cannot be more efficient than direct contact transfer of energy so why complicate for the sake of it?
.

but there is no direct transfer of energy in a conventional charger. You have to separate the mains from the battery for safety and in any case, the voltage translation uses a transformer.

 

[flecc]

but there is no direct transfer of energy in a conventional charger. You have to separate the mains from the battery for safety and in any case, the voltage translation uses a transformer.

Which I maintain is more efficient than air spaced transfer.

But apart from that, again, why complicate? We don't want any more weight or complexity on bikes, using two simple contact pads directly to the battery is all that's necessary for charge input.
.

 

[Woosh]

But apart from that, again, why complicate?

The first advantage is better reliability. There is no simple way to stop corrosion and water ingress around the sockets, there is no way you could build mechanical contacts and switches to last forever. The best for now is to replace them by FETs.
I guess the charging circuit will be built into the battery in the future. While the battery is being recharged, user data can be uploaded etc.

 

[Gubbins]

On a morre practical note.. My Scott/Bosch charger has a chunky connector that is easy to plug in to the bike and hard to get wrong.. My Giant/Yamaha on ther other hand has a plug that has several bendable pins and a not so obvious small locating lug that is hard to see in an unlit garage or shed andI am surprised we havnt heard of problems in tthis area. I must admit that since buying a phone that charges wirelessly I would be without one..

 

[flecc]

There is no simple way to stop corrosion and water ingress around the sockets,

Not sockets, pads, plated metal that doesn't corrode like those on the Lafree series I mentioned. Fixed on the bike, lightly sprung on the charge base to ensure firm contact when against each other. Been working on those bikes with up to 15 amps since 2001, so e-bike charge current no possible problem.

I'm just not a sucker for all the unnecessary complexity being designed in far too often now, I'm sure you know the US acronym, KISS.
.

 

[flecc]

My Giant/Yamaha on ther other hand has a plug that has several bendable pins and a not so obvious small locating lug that is hard to see in an unlit garage or shed

Just like the charge socket on the Lafree, that had exactly the same two problems, while it's drive power was supplied through two simple metal pads. The chumps could just have easily made the charge connection as reliable as the drive power one.
.

 

[Danidl]

that is missing the point. A wireless charger does not use extra transformer - only one like a normal charger. When you look closely at the construction of the separation transformer, the primary winding is replaced by the antennae, the secondary winding is replaced by the receiving coil, the ferrite core is replaced by thin air. The magnetic flux is collimated before a large amount of energy is transferred.

Sorry woosh, on matters technical you do tend to be on the ball, but in this case you have missed it. The electronics needed to power the induction coil system, whether resonant or otherwise will have an efficient of E, the resonant circuit an efficiency of T the power conditioning circuitry from mains to the transmit electronics P , the electronics to convert the recieved energy R and then the battery charging efficiency B
The total efficiency is the product of B*R*T*E*P with all less than unity.
If a direct electrical connection is made using contacts the efficiency is P*B. There are three less terms ...

 

[Danidl]

On a morre practical note.. My Scott/Bosch charger has a chunky connector that is easy to plug in to the bike and hard to get wrong.. My Giant/Yamaha on ther other hand has a plug that has several bendable pins and a not so obvious small locating lug that is hard to see in an unlit garage or shed andI am surprised we havnt heard of problems in tthis area. I must admit that since buying a phone that charges wirelessly I would be without one..

I picked up a wireless charger for my Samsung and it is very convenient., Particularly going to bed bleary eyed. But it does require either removing the phones cover or else being very careful about placement. The tolerance is tight. I am happy as it puts less wear on the tiny connections on a microusb socket and minimises the damage which would result if ihe connections were forced in reversed.
But the Bosch charger is huge in comparison, and has locating lugs which make it impossible to misconnect. Having said all that, I don't see why the charger is not built into the bike and a two way B connector at mains voltage be used. There are plenty of electrical items, amplifiers, computers etc which use it, and the power levels are comparable. A rubber cover makes it waterproof.

 

[Gubbins]

I picked up a wireless charger for my Samsung and it is very convenient., Particularly going to bed bleary eyed. But it does require either removing the phones cover or else being very careful about placement. The tolerance is tight. I am happy as it puts less wear on the tiny connections on a microusb socket and minimises the damage which would result if ihe connections were forced in reversed.
But the Bosch charger is huge in comparison, and has locating lugs which make it impossible to misconnect. Having said all that, I don't see why the charger is not built into the bike and a two way B connector at mains voltage be used. There are plenty of electrical items, amplifiers, computers etc which use it, and the power levels are comparable. A rubber cover makes it waterproof.

I have 2 samsung chargers, one is the round one that came with the phone and the other is a rectangular that I bought later. I have an armoured two piece cover on the phone and charges through this however it is placed on the round charger and also with a little care on the rectangular one but if I want a fast charge I plug it in ..
Is yours a samsung charger or a micky mouse one? I recently went to enquire about selling the phone and they will only buy it with a genuine samsung charger. My samsung watch has a magnetic wireless charger which is good because it always goes in the right spot.
I suppose a similar system on the bikes would be good, with the magnet holding it in place the gubbins could be built in anywhere at any angle..