Upload Your Circuit Schematics & Requests Here...

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glenn0010
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Re: Upload Your Circuit Schematics & Requests Here...

Post by glenn0010 » Sep 28, 2016 7:42 am

fechter wrote: There are lots of ways to do it. If you're just building one, I would just lay copper wire on top of the high current traces and solder it down.
In factory made controllers, I've seen a variety of approaches. One is to make a copper bus bar with legs. Legs are located close to the FET connections so the PCB traces are short and can be bridged with solder. The bar goes on the top of the board. You could do this with heavy copper wire as well.
Another approach is a strip of copper sheet that is cut to the same shape as the board trace and laid down on top of it before soldering. Much like a wire, but nice and neat. These traces should be extra wide wherever possible, like 0.25".

You can get an idea from the picture below. I think they just piled up a bunch of solder, but some copper in there is much better. The actual connection to the FET leg is narrow but as short as possible.
The attachment Controller traces.jpg is no longer available
Thanks once again :)
Capture.PNG
Capture.PNG (44.62 KiB) Viewed 1686 times
This is what I've done. I have managed to place 3, 70 thou traces between the transistors. 2 bottom copper and 1 top copper. I think these should be sufficient for 20A however I will also add some copper wire.

What do you think?

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Tom L
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Re: Upload Your Circuit Schematics & Requests Here...

Post by Tom L » Feb 12, 2017 5:53 am

If you are using 2oz copper pcb you will need about 370thou of track on external layers to keep the temperature rise to 10 deg C for a 1cm length. Listen to fechter's advice and have a look at this calculator:

http://circuitcalculator.com/wordpress/ ... alculator/

Remove the top overlay of the components and solder mask on the track so you can augment its current carrying capacity with solder and copper wire/sheet.

Solder has about six times the resistance of copper, keep that in mind.

dbIsMe
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Wiring brake cutoff into throttle?

Post by dbIsMe » Mar 20, 2017 7:30 pm

*I have a controller that has only one input analog signal that is available with 3 wires, +5V,-ve, signal.
*My throttle has 3 wires (+5V, -ve, signal) that outputs up to ~3.5V
*I also have a reed switch brake sensor with 3 wires (+5V, -ve, signal) that reads 0v when the brake is off, and +ve voltage (~1V i think) when the brake is pulled

So, I need some way to wire this so that when the throttle is twisted it sends its voltage to the controller, but if the brake is pulled - even at the same time as the throttle - then 0V is sent to the controller. I'm not familiar enough to know if it can be wired directly or needs some sort of 'widget' in between.

Can anyone help with wiring/components that are required? I need pretty idiot proof instructions, like connect the +5V from the controller to the +5V from the brake...

Thanks in advance

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amberwolf
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Re: Upload Your Circuit Schematics & Requests Here...

Post by amberwolf » Mar 20, 2017 8:08 pm

If it's a reed switch, it doesn't need power. So use a multimeter on continuity check or ohms, and see which pin is common (probably the output), and which is shorted when "off" and which is shorted when "on".

Then connect teh common to the throttle's power input, and the "shorted when off" to the 5v line.

Then when you engage the brake, it will cut off the power to the throttle, so there will be no output to the controller.


If it's not a reed switch, and requires power, then if the output pin is 5v when "off", and 0v when "on", then connect the throttle's power input to the output of the switch, so it only gets power when the ebrake is off.

dbIsMe
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Re: Upload Your Circuit Schematics & Requests Here...

Post by dbIsMe » Mar 20, 2017 9:21 pm

Thanks for your post.

I'm just not familiar with the terminology, so I'm instantly struggling when you mentioned common and shorted etc.

Supplying no power, with the brake 'off' (magnet near switch) I get no ohm readings from any of the 3 wires. With the brake on (magnet away from switch) i get a reading only from the -ve and signal wires.

Are you saying to connect brake +5V to controller, the +5V and brake -ve to throttle +5V, and just leave the brake signal wire not connected/terminated?

I just can't quite wrap my head around it...

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fechter
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Re: Upload Your Circuit Schematics & Requests Here...

Post by fechter » Mar 20, 2017 9:34 pm

It's odd that the brake sensor has 3 wires. Most I've seen with 3 wires are hall switches. A reed switch should give you a zero ohm reading across the contacts when activated. If the switch is closed with the brakes off and opens when you pull the lever, then you place it in line with the 5V going to the throttle. If the switch closes when you pull the brake, then you wire it from ground to the throttle signal line, which will short it when the brake is pulled.

Some throttles don't like this and can fry if you pull the throttle while the brake is on. To prevent any issues, it's best to place a resistor (usually 1k works) in line with the throttle signal and tap in the brake switch downstream, on the controller side. The resistor prevents excess current in the throttle line.
"One test is worth a thousand opinions"

dbIsMe
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Re: Upload Your Circuit Schematics & Requests Here...

Post by dbIsMe » Mar 20, 2017 10:04 pm

OK, so you're saying to protect the throttle:

*+5v controller to +5v throttle
*-ve throttle to -ve controller
*signal throttle to 1k resistor, 1k resistor to +5V brake, -ve brake to signal controller, and leave brake signal unconnected

TIA

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Re: Upload Your Circuit Schematics & Requests Here...

Post by Dream_Crusher » Jun 20, 2017 5:33 pm

can you guys just verify my design for a pack-fed 12v side? I also plan on keeping the charger inboard to allow for onboard charging. The battery is a 72v 20ah pack with an embedded BMS, and the charger is the one that comes with the battery.
Image

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fechter
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Re: Upload Your Circuit Schematics & Requests Here...

Post by fechter » Jun 21, 2017 2:21 pm

Dream_Crusher wrote:can you guys just verify my design for a pack-fed 12v side? I also plan on keeping the charger inboard to allow for onboard charging. The battery is a 72v 20ah pack with an embedded BMS, and the charger is the one that comes with the battery.
Looks good to me.

The battery isolator switch will sort of take a beating when turning on as the capacitors in the controller charge. I've seen people use circuit breakers made for solar systems that seem to work well for this.
"One test is worth a thousand opinions"

voodoop
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Re: Upload Your Circuit Schematics & Requests Here...

Post by voodoop » Nov 06, 2017 4:23 pm

Can anyone provide a dual pulse timer schematics (for spot welder) ?
Thanks !

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