How to wire up the easiest way? (Alltrax, Agni and Battery)

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Apr 30, 2012
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Germany
Hello, I thought its better to ask you guys for advice before I blow anything up :)

I found this build and it looks like they're not using a contactor:

evkart_rt_rear.jpg


I want to do the same. Reason is keeping it as simple, lightweight, less complicated and less "space consuming" (I don't know the word in english, I'm sure you know what I mean) as possible.

Do I need a contactor? Or can I switch my drive on and off just by connecting/disconnecting the Anderson-plug between my battery pack and the Alltrax?

Are there any risks other than [strike]not beeing able to turn the power off with a killswitch from the handelbar?[/strike]
Like sparks when I connect or disconnect the Anderson, or something like that?

Thanks

Edit: :idea: I forgot that I will still be able to turn the power off with a switch on the handlebar by the Alltrax "Key on" port.

Please tell me if it is a bad idea to run without the contactor.
I'm a noob with that stuff, so any any advice, general or specific, is very welcome.
 
Yes, there will normally be a (sometimes large) spark when you connect the battery to the controller because of the capacitors in the controller. This can be eliminated using a "precharge resistor".

However, a contactor would be better. The nature of a brushed motor controller means that it is possible for the controller to fail fully-on (motor shorted to battery). A contactor would allow you to stop the motor if this emergency should happen. If not, I would at least have a quick-release battery terminal that you can easily reach from the driver's seat.

That Kart looks very powerful - be safe!
 
Thanks Punx0r,
Good explanation!
Now I think I will keep the contatactor in my bike.

My contactor is a Tyco LEV200A5NAF.
I'm confused by the sticker on it that say's 24Vdc.
My Bike (2012 Zero X) had a converter for all the 12V stuff (lights speedometer etc.). I took all this stuff off the bike to save weight.
Could it be that the contactor coil was operated with the 12V out the converter? I have no clue why the 24V is on the sticker?
Or does it mean anything above 24V is ok to operate the contactor? Battery Voltage is around 74V when fully charged.

Edit: corrected typo in the Tyco model number
 
DolphLundgren said:
T
My contactor is a Tyco LEV200A5NAF.
I'm confused by the sticker on it that say's 24Vdc.
<snip>
I have no clue why the 24V is on the sticker?
Or does it mean anything above 24V is ok to operate the contactor? Battery Voltage is around 74V when fully charged.

The contactor has a 24V coil. The contacts are rated to 900VDC so it can be used in circuits up to that voltage. But you need 24V for the coil to turn the contactor on & off.
 
Thanks for clearing that up major!

I guess I'll just buy a contactor with 72V coil.

I still wonder why the bike has a converter for the 12V stuff and another for the 24V contactor coil.
 
I'd nix the contactor idea and use a manual disconnect and precharge. New contactor will be $100+. If you don't need auxiliary system or remote actuation of disconnect, KISS and use manual stuff. Anderson connector in battery line with shorted loop pull works for disconnect. Use a separate resistor (or light bulb) to precharge when connecting the battery.
 
KISS = Keep It Simple Stupid :) I didn't know that term.

Can you recommend a bulb or resistor for the intended use as a precharge resistor? What specs? Maybe a 55W/ 12V bulb from a headlight? Or do I need something with a higher power rating?

Did you think of something like this as a loop pull?

19922184bo.jpg


*Edit: uploaded the image to on a different website (does it show now?)
 
Sorry, the picture isn't showing for me.

A 100 ohm 5W wire-wound resistor (the square ceramic ones) should work fine for precharge. You just need a little connector that connects the resistor, wait a second or two and then connect the main power connector.
 
Punx0r said:
Sorry, the picture isn't showing for me.

A 100 ohm 5W wire-wound resistor (the square ceramic ones) should work fine for precharge. You just need a little connector that connects the resistor, wait a second or two and then connect the main power connector.

I see the photo. Yep, something like that. 12V bulb might pop on 48V. 110V bulb would work. Need the incandescent type. It should glow at first and then go dark as the controller caps charge. Maybe a little 5 or 10W nite-lite. Or Punx0r's resistor sounds about right. Exact values aren't critical. Try what you have on hand. Just touch to contacts before plugging in and hold there for like 5 seconds. Then plug in right away. It will stay adequately charged for 10 to 20 seconds while you put down the resistor and push the shorting plug in. Resistor may just get a slight bit warm. Really no electric hazard at 48V. Might feel a tingle if wet.

https://www.flickr.com/photos/93396776@N06/15298568721/

Image from Terry's race cart which he posted over on the diyelectriccar forum. He's said he does not mind it being copied :wink:
 
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