induction charger

[Hobbins]

I am looking for a kit or plans to build an induction charger for my robot(www.evolution.com) it has to be 12v ant not too large or heavy, anyone know where to buy or how to build a 12v induction charger?<p>similar to electric razors,toothbrushes,etc.

[hlreed]

Obviously your robot needs electricity (if not spring power) which can be supplied by batteries or power supplies. I have no idea what an induction charger is. If it is a matter of nomenclature, please spell out what you are doing.
Anything else, I would be glad to help.

[Dimbulb]

An inductor such as an autotransformer produces AC current. It is located below a thin sheet of plastic. Another transformer is located on the bottom side of the Bot, when it recieves the AC current from its inductor then the current is rectified to DC and fed to the battery charging circuit. The efficiency is not high but the lil shaver charges all night.

[unknown_entity]

I have seen something similar on Tech TV. They used it to power PDA's and other handhelds. The charger looked like a mouse-pad but a few inches bigger.

[Dimbulb]

I am not familiar with that device.
It seems wasteful to use induction, I have heard there is a piezo-electric generator but don't understand the principal.

[natcsparky]

Having dealt with induction chargers on the electric vehicle side, I can tell you that you have been receiving good posts from most members. The induction charger is nothing short of a mechanically coupled transformer. The supply (primary) is plugged into the wall (i.e. 120, 240 VAC) and the secondary is coupled through air AND / OR some other mechanism (but almost always air). The problem (as stated in previous posts) is efficiency. A transformer is not the most efficient device to start with.. Add on the obvious mechanical issues with coupling AC fields and it becomes worse.. The best way to build a use a charger is to put a BEEFY electrical connector on the vehicle that hooks up to the charging device, but (if you really need non contact) you must start by applying some specifications to your requirement. A place to start is:
What is the Voltage / AMP Hour capacity of the battery pack?
What is the expected charge time (how fast do you want it)?
What State of Charge (SoC) is expected worst case for the batteries (i.e. deep cycle can go to smaller numbers than standard lead acid packs).
Which you using: lead acid, deep cycle, nickle cadmium, nickle metal hydride, lithium ion (I hope not) batteries?<p>Then you can play with winding your own coils (THIS IS NOT SOMETHING TO BE TOYED WITH, YOU DO IT WRONG OR DO SOMETHING DUMB YOU ARE DEAD). The coils used on some of the vehicles I have worked on are almost all flat wound around a plate of some sort to give the most surface area. Ratio and wire size will depend on what voltage you want out, current and what air gap (or how far away the coils will be from each other). <p>Anyway, this is a start (if you are bound and determined to build your own). I am not an expert at design, I've just fiddled around enough to understand a little about the technology. Sorry to pose more questions than I ask.

[natcsparky]

Having dealt with induction chargers on the electric vehicle side, I can tell you that you have been receiving good posts from most members. The induction charger is nothing short of a mechanically coupled transformer. The supply (primary) is plugged into the wall (i.e. 120, 240 VAC) and the secondary is coupled through air AND / OR some other mechanism (but almost always air). The problem (as stated in previous posts) is efficiency. A transformer is not the most efficient device to start with.. Add on the obvious mechanical issues with coupling AC fields and it becomes worse.. The best way to build a use a charger is to put a BEEFY electrical connector on the vehicle that hooks up to the charging device, but (if you really need non contact) you must start by applying some specifications to your requirement. A place to start is:
What is the Voltage / AMP Hour capacity of the battery pack?
What is the expected charge time (how fast do you want it)?
What State of Charge (SoC) is expected worst case for the batteries (i.e. deep cycle can go to smaller numbers than standard lead acid packs).
Which you using: lead acid, deep cycle, nickle cadmium, nickle metal hydride, lithium ion (I hope not) batteries?<p>Then you can play with winding your own coils (THIS IS NOT SOMETHING TO BE TOYED WITH, YOU DO IT WRONG OR DO SOMETHING DUMB YOU ARE DEAD). The coils used on some of the vehicles I have worked on are almost all flat wound around a plate of some sort to give the most surface area. Ratio and wire size will depend on what voltage you want out, current and what air gap (or how far away the coils will be from each other). <p>Anyway, this is a start (if you are bound and determined to build your own). I am not an expert at design, I've just fiddled around enough to understand a little about the technology. Sorry to pose more questions than I ask.