Cutting off and diverting power

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#1
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Hi all,

Is there any device I can use that can divert high power (32v 22ah, for reference) from one node to the other via a low power toggle switch? Is there a device I can use that can cut off said high power entirely through another low power toggle switch? Or, even better, is there something that can do both of those actions?

 

Thank you.

Last Edited: Wed. Jul 17, 2019 - 02:44 PM
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Just use High side switches, such as from ST semiconductor or Infineon

 

Note your use of amp-hours (22ah) means nothing here.  How many amps do you want to control

 

here is a random example

https://www.digikey.com/product-detail/en/stmicroelectronics/VN920SP-E/VN920SP-E-ND/1852758

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Wed. Jul 17, 2019 - 08:31 AM
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The device is called a relay methinks.

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Kartman wrote:
The device is called a relay methinks.
... with "change over" contacts but "break before make".

Ross McKenzie ValuSoft Melbourne Australia

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Do you know any sources for relays? All the relays I'm finding are either too low of a wattage or they convert DC to AC.

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Relays aren’t rated in terms of wattage nor do they convert ac to dc. You’ve not told us what the load is and how much current it draws.

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I stated 32v 22ah in the beginning. That is what I need to be able to shut on/off and change the flow of.

Last Edited: Wed. Jul 17, 2019 - 02:35 PM
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SwordMan526 wrote:
I stated 32v 22ah in the beginning.

 

To which:

avrcandies wrote:
Note your use of amp-hours (22ah) means nothing here.  How many amps do you want to control

 

Which is pointed:

Kartman wrote:
ou’ve not told us what the load is and how much current it draws.

 

32v/22ah is what a battery is rated.  What are teh load(s) you are trying to control power to, and can you make a simple schematic of what you are trying to do?

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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I stated 32v 22ah in the beginning. That is what I need to be able to shut on/off and change the flow of.  

Show us what you have so far for your system...is this part of a small circuit board?  If so, then a pair of high side drivers is likely.  If it is some "big box" then maybe a relay.  The high side drivers might be  better for you, since they are protected against shorts & overloads.   Why are you not saying how much current you want to switch (3amps, 300 amps)...that is a vital parameter!! 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Ahhh, I see. In that sense, could you please give me a definition of what the load of a device is?

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Load = what "uses" the electrical power.

 

Examples might include : an electric motor, a light bulb, a circuit board, and such.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Wed. Jul 17, 2019 - 02:59 PM
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Really sorry for all the confusion, the current I wanted to switch was 22 amps.

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SwordMan526 wrote:
Really sorry for all the confusion, the current I wanted to switch was 22 amps.

 

I am going to ask a very blunt question.....DO you have ANY idea what you are doing?  I am guessing that you do not since you don't know what a load is.  22amps is a LOT of current at any voltage and if not handled properly the resulting fire will cost dearly.

 

 

East Coast Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Gonna be real with you here, not too much when it comes to electrical. I'm not sure how to construct a basic diagram when load seemingly doesn't deal with voltage or amperage, I hope this one will help clear things up though.

But, I can tell you that the reason the amperage is so high is because the hubcap motor requires about 16 amps/hour. I have a DC-DC boost converter that can supply 20 amps and 60 volts. I think I might've exaggerated it a few amps over in my initial question, though...

Link to the boost converter:

https://express.google.com/u/0/product/12032105751391515065_0_6099994?utm_source=google_shopping&utm_medium=tu_cu&utm_content=eid-lsjeuxoeqt,eid-wuakzuqbuq&gtim=CLuLzPWx7vLFfxC-v-yL5O7AmlsYsIeHCSIDVVNEKOD7guoFMJqo9AI&utm_campaign=6099994&gclid=Cj0KCQjw3uboBRDCARIsAO2XcYAg6JrwEwIUbqAsAMJuhZcos0ZYjr3dfpp__rZTX5iLzpmxFZnZXDAaAk09EALw_wcB

Link to the hubcap motor:

https://www.aliexpress.com/item/32764032658.html?spm=a2g0o.detail.1000023.7.2cb722f7gYEzEx

Last Edited: Wed. Jul 17, 2019 - 03:59 PM
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The motor IS YOUR LOAD!  and its not 16amps/hour, its 16 amps continuous @60v full power. 

 

From your other posts this all seems to be one big project that is going to end up on one of those YouTube Epic fails videos.

 

Jim

 

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Yikes, came here to ask a question and to learn something, not to get insulted.

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SwordMan526 wrote:

Yikes, came here to ask a question and to learn something, not to get insulted.

 

Take it however you want.  You havent replied to your other threads that are answering some of the questions you are presenting here since June 29th.  So either the information given is beyond you and rather than stick with the thread to get it sorted you start another one hoping to get a different answer for essentially the same question.  Controlling large amounts of power. 

 

Also, put your location in your account information.  It's possible that there is a local freak in your area that may be willing to work with you hands on.

 

Cheers,

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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I'm pretty certain ramping up power is different than directing the flow of it. You really glossed over it instead of actually looking at it. Suppose I'll go elsewhere; you know it's a bad sign when, of all people, a mod shuts down on you.

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SwordMan526 wrote:
I'm pretty certain ramping up power is different than directing the flow of it

When was "ramping up" power mentioned?

 

Jim

 

Click Link: Get Free Stock: Retire early! PM for strategy

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SwordMan526 wrote:
it's a bad sign when, of all people, a mod shuts down on you.

I did not shut down on you.  I am telling you what everyone else has been trying to show you.  Theres more to this than simply switching off and on power. 

 

If you feel you need to go elsewhere that is your choice.  Our door is always open. But before you do I suggest you re-read your threads and look hard at what you are asking and the replies.  there is a wealth if information in the other two threads.

 

ki0bk wrote:

SwordMan526 wrote:

I'm pretty certain ramping up power is different than directing the flow of it

 

When was "ramping up" power mentioned?

 

Jim

I thought the same thing.

 

ECJ

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Mr swordman, I think we need to cover the basics of electrical safety. Since you're dealing with relatively low voltages, electrocution is not a major issue, however with the high currents you are using, fire is very likely. For safety, the wire you use is chosen based on the current you expect it to carry. When current flows in a wire, it heats up. You chose the size of the wire so it does not heat up appreciably. The wire has isulation that has a temperature rating - exceed this and a fire is likely. So you need to protect the wire to ensure if there is a fault, that the wire is protected and cannot get too hot. A fuse is normally used. With batteries, the short circuit current can be 100's if not 1000's of amps - this is why you need a fuse. I demonstrated this recently to a young engineer to show what happens to a piece of wire. There was much smoke and molten metal.

 

How to chose the size of wire? There are many 'ampacity' tables on the web. If your wire is rated for 20amps, then make sure you have a fuse that ensures this cannot be exceeded.

 

Next - you seem to be confused by Amps and Amps/hours. Amp/hours is a rating for a battery, not a motor. For a 12V 60A/h battery, this means you can draw 60A for one hour or 30 Amps for two hours etc from a fully charged battery. Rating a motor by A/h doesn't make sense. Motors are rated by Volts/Amps and power (in Watts). Watts is Volts multiplied by Amps. So for your 60V 1000W motor, the Amps are 1000/60 = 16.6A. The motor can draw more, but for a short time only. So, your value of 22A is not unreasonable.

 

With your DC/DC boost converter, you want it to convert 32V to 60V with an output of 16+ Amps. The problem with your choice of dc/dc converter is it is limited to only 20A input. To get 1000W output, you need at least 1000W input (and a little more due to loss - factor 10-15%). This means the input Amps is 1000/32 = 31.25A. You've exceeded the specification of your dc/dc converter by over 50%. Time for Plan B methinks.

 

 

As for 'ramping' the power - why do you want to do this? To control the motor speed you have motor drivers to do this. So why 'ramp'? To switch the high current on/off  you can get automotive isolator switches or contactors (these are normally used in electric fork lifts) which are relays. With a relay you have a small control current to switch a larger voltage/current.

 

 

All said, why did you come to AVRFreaks for your questions? There are a number of specialised forums for electric bikes that would better suit you.

You get terse responses here as your question is akin to asking on a gun forum - "I have a gun - which way do I point it"? Basically, you're playing with dangerous stuff - educate yourself before playing around with it.

 

You might ask yourself "How hard can it be?" - that when the problems start!