High Amp Master Switch

General Discussion about electric vehicles.
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SarDoX   10 mW

10 mW
Posts: 33
Joined: Aug 22 2015 2:48pm

High Amp Master Switch

Post by SarDoX » Nov 20 2015 8:24pm

Hi everyone!
I have some stupid questions - what type of switch is it better to use for high Amps? 80-100a (3kV)
I have 2*4s lipos, 30v total
motor max current can be under 100a
I need to install switch to turn on/off the scooter.. otherwise I have to unscrew board every time to plug connectors manually
I checked radioshack they have only 125v10a that is not enough

1a. what switches do u use?
1b. can I use something like 30 Amp 110v Single-Pole Circuit Breaker from homedepot? it should handle ~106A at 31V. And price is jsut 4$
2. is it safe to store scooter in garage with all connected wires but turned off master switch?
3a. topic unrelated question - I have a lipo low battery beeper and voltmeter for 8s battery, it has 9 wires - 1 ground and 8 for lipo cells
2 my batteries has 5 wires ea - ground and 4 for cells
can I use this beeper to controll voltage of all 8cells by connecting 2 grounds (from each battery) together and then all cells wires one by one?
3b. Can I use an extra switch to disconnect ground from this beeper to turn it off when scooter is turned off with a master switch? I dont need beeper working when scooter if OFF. Are these 8 cells pins with disconneted groun pin can drain lipo to 0 somehow?
switch.jpg (11.45 KiB) Viewed 953 times

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Nobuo   10 kW

10 kW
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Joined: Nov 21 2014 3:38am
Location: Madrid

Re: High Amp Master Switch

Post by Nobuo » Feb 20 2016 12:11am

1a: the best one is to don't need to use one. For 100A the switch must be enormous and will wear fast (unless you mount any pre-charge resistor). Controller use to have a switch On / Off function, use it preferably, and disconnect the battery for storage.
Otherwise you can use on of those
http://www.aliexpress.com/store/product ... 11547.html

1b: it could work

2: Basically yes, the controller switched off is pretty safe and the current draw extremely low. For long periods better to disconnect the battery

3a: If both lipo packs are working paralleled you only need to connect all their balancing wires paralleled and only one of them to the voltage buzzer (4s). If both batteries are working in series, just connect the B- of the second battery together with B4+ of the first battery (the main positive connection) then connect the rest up to 8s (B8+)

3: In the moment you disconnect negative lead to the buzzer two things could happen depending on the model, the buzzer could start to buzz if it is powered by the rest of the series, or just shut-off as you expect. All the rest 7 series or 3 series, depeding if you connected one lipo or two, would electrically connected to the buzzer, so they could have a small drain
* Lithium + Air = Fire * <-----> ** Lithium + Chemical-Additives + Air = ZERO Fire **
<Battery and EV works>
<Battery building resources>
http://www.endless-sphere.com/forums/vi ... 14&t=68005

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dogman dan   100 GW

100 GW
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Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: High Amp Master Switch

Post by dogman dan » Feb 21 2016 6:25am

The way big EV's like car conversions do it is a solenoid activated contactor. Big, expensive, etc. You can just use a large plug like the higher amp Anderson power poles for your main connection/switch. But then use a controller with separate low amps on off circuit.

When you really need it all the way off, unplug. To park overnight, or during the day, use a cheap low amps key switch.

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Deafcat   100 W

100 W
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Joined: Aug 13 2015 1:25pm
Location: City of Bridges (in the Canada Rectangle)

Re: High Amp Master Switch

Post by Deafcat » Feb 22 2016 9:07am


it's even fused! :wink:

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tiny_n_terrible   100 W

100 W
Posts: 243
Joined: May 19 2013 7:39pm

Re: High Amp Master Switch

Post by tiny_n_terrible » Feb 22 2016 7:28pm

I use one of these.

http://www.ebay.com/itm/12V-300-Amp-Bat ... 1367844857

I aso use a pre-charge resistor with a smaller switch.

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